eldo_user

Eldo® User's Manual
Release 15.3
© 1988-2015 Mentor Graphics Corporation
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Table of Contents
Chapter 1
Introduction to Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Overview of Eldo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Getting Started With the Eldo Simulation Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Eldo Input and Output Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Eldo Documentation Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Command Line Help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Related Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Documentation Syntax Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Chapter 2
Running Eldo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Invoking Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Running Eldo in 32-bit and 64-bit Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Multi-Threading Eldo Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Fast Launch Script for Small Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Simulation Connection Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Eldo Initialization File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Location Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Location Map Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Performance Bottleneck Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Statistics File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Statistics File Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Running Eldo Interactive Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Additional Tools and Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Chapter 3
Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Overview of Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Enabling Eldo Premier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Automatic Activation of Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Using Eldo Classic DC Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Handling Matrix-Like Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Solver Generation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Eldo Premier Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Temporary Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Generic Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Forcing Elaboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Eldo Premier Selectable Accuracy Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Netlist Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Supported Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Supported Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Eldo® User's Manual, 15.3 3

Table of Contents
Supported Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Other Supported Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Miscellaneous Limitations of Devices and Features in Eldo Premier . . . . . . . . . . . . . . . . 93
Chapter 4
Eldo Netlist Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Netlist Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Circuit Title. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Model Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Subcircuit Definitions and Calls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Element and Source Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Simulator Commands and Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
End Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
General Aspects of the Language Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Continuation Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Comment Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Parameter Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Case-Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Numerical Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Environment Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Functions, Operators and Expressions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Arithmetic Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Operator Precedence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Arithmetic Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Boolean Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Bitwise Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Specifying the Simulation Time in Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Conditional Evaluation of Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Directives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
IF, ELSE, ELSEIF, ENDIF Conditional Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
String Operator on If Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Directives Interpreted by the Eldo Parser (Default) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Directives to Postpone Block of Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Directives Interpreted using the C Pre-Processor (-E/-EE Arguments) . . . . . . . . . . . . . . . 126
Working With Subcircuits and Device Libraries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Subcircuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Device Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Search Path Priorities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Library Variant Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Library Nesting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Deleting a Library. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Search Rules and Naming Conventions for Adding Libraries . . . . . . . . . . . . . . . . . . . . . 136
Using Libraries in Eldo Interactive Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Encrypting Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
encrypt_eldo Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Protection of Encrypted Libraries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
4 Eldo® User's Manual, 15.3

Table of Contents
Preparing and Installing a Protected Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Coding and Encrypting a Protected Library. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Semi-Transparent Encryption. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Description of the Loading and Control Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Creating the IP Access Library. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Installing a Protected Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
List of Encryption Errors and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Automatic Recognition of MOS Instantiations in TSMC Libraries . . . . . . . . . . . . . . . . . . . 156
Running Multiple Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Merging Instances in Parallel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Chapter 5
Simulator Compatibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
HSPICE Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Hybrid Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Compat Mode Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Devices in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Sources in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Commands in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Options in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Netlist in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Arithmetic Functions and Operators in Compat Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Output Format in Compat Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Spectre Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Spectre Compatibility Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Spectre Compatibility Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Working with Multiple Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Troubleshooting the Spectre to Eldo Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Spectre to Eldo Converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Installing a Patch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Supported Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Netlist Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
spect2el Command Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Chapter 6
Setting Up An Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
DC and Operating Point Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
DC Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Performing a DC Analysis During Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Operating Point Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
Differences Between DC and OP Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
DC Convergence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Improving DC Convergence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
DC Convergence Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Saving and Restarting DC Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Transient Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
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Saving and Restarting Transient Simulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
AC Related Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
AC Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Adaptive AC Analysis Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Performing an AC Analysis During Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Saving and Restarting AC Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Loop Stability Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Pole Zero Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Pole-Zero Analysis Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Running Pole-Zero Analysis in Batch Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Running Pole-Zero Analysis in Interactive Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
Pole-Zero Analysis Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
FNS Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Pole-Zero Numerical Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Noise Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Noise Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Transient Noise Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Transient Noise Analysis Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Specifying .NOISETRAN Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
Transient Noise Analysis Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Generation of Time Domain Noise Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Noise Sources Generated From Random Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
Noise Sources Generated From a Sum of Sinusoids . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
Speeding Up Transient Noise Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Transient Noise Analysis Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Example: Extraction of the Phase Noise Spectrum at the Output of a PLL Circuit. . . . . 260
Statistical and Sensitivity Related Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Worst Case Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
DC Mismatch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
DC Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Transient Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
AC Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Sensitivity Analysis of Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Design of Experiments Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
Other Miscellaneous Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
Aging and Reliability Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
Check Safe Operating Area Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
High Impedance Node Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Power Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Viewing Power Analysis Results Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Electrothermal Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
RF Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
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Chapter 7
Running Parametric Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
Temperature Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
Assigning Parameter Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
Sweeping Parameters Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
.STEP Sweeping Parameters Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Nested Sweeps Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
.DATA Parameter Sweeps Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
Altering Netlist Data For Simulation Reruns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
Removing .EXTRACT Statements from a Simulation Rerun . . . . . . . . . . . . . . . . . . . . . . 299
Controlling Alter Blocks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
.ALTER Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
Using Output Results From a Previous Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302
Chapter 8
Specifying Simulation Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Output Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
Output Commands Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
Plotting, Printing and Probing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
Files Created . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
Types of Waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Monitoring of Hierarchical Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Using Wildcards for Plotting and Probing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
Plotting, Printing and Probing States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
Plotting Internal Pin Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Complex Modifiers and Initial Formatting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Compound Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
Plotting an Analog Signal as a Digital Bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
X-Axis of Waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
Tabular Listing Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Plotting Transmission Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Dynamically Adding Voltage/Current Plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318
Output Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
Extracting Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
.EXTRACT Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
Plot and Print Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Extract Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Extract Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Extraction Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Extract Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Example Extracting OPMODE, POW, and POWER Values. . . . . . . . . . . . . . . . . . . . . . 329
Example Extracting Parameter Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Example Extracting Model Parameter Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Example Extracting Element Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Example Extracting Transient Analysis Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
Example of Condition Function Reusing Extraction Results. . . . . . . . . . . . . . . . . . . . . . 332
Example Combining Sweep Extract and .ALTER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
Extracting Compression Point Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
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Defining Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
Examples of Defining Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
Safe Operating Area (SOA) Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Plotting Safe Operating Area Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Safe Operating Area Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
High Impedance Node Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
How to Enable High Impedance Node Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
High Impedance Node Check Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Limiting Output Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
Limiting the Size of Transient Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
Incremental Saving of the JWDB Database. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
Chapter 9
Analyzing Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
Output Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
Output Files Generated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
Interpreting the Output Log (.chi) File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
Output Log (.chi) File Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
Simulation Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Locating Eldo Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368
Error and Warning Message Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369
EZwave Joint Waveform Database (JWDB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370
EZwave Graph Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
Displaying Eldo Simulation Data in EZwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
Run Eldo With EZwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
Complete Eldo Simulation and View Simulation Data Later. . . . . . . . . . . . . . . . . . . . . . . 373
EZwave Reload Option. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Manual Status Update. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Marching Update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
Diagnosing Convergence and Performance Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Non-Convergence Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Time Step Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
Performance Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
Using the Statistics File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385
Statistics File Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
Chapter 10
Post-Layout Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
Post-Layout Simulation Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
DSPF Backannotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392
DSPF File Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
Parasitic Network Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Eldo Post-Layout Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Eldo Post-Layout Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395
DSPF Backannotation Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396
SPEF Backannotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398
SPEF File Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
SPEF File Example for Corners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
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Eldo Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403
Basic Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403
Parameters Controlling the Reduction Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404
Reduction Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
Reduction Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
Reduction Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
Reduction Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
Chapter 11
Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409
Introduction to Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
Introduction to Uncertainty Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
The Monte Carlo Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Basic Statistical Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Monte Carlo Basic Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417
Monte Carlo as an Integration Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417
Monte Carlo Incremental Approach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
Monte Carlo Analysis With a Varying Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
Specifying a Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421
Statistical Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Specifying Statistical Variations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Specifying Statistical Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427
Sharing Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429
How to Specify a Distribution Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431
Uniform Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431
Gaussian or Normal Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433
User-defined Distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435
Other Common Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436
Correlation Between Gaussian Input Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437
Basic Concepts on Multivariate Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437
Specifying Linear Correlation with .CORREL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440
Local and Global Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
Specifying Statistical Variations for Individual Model Parameters . . . . . . . . . . . . . . . . . . 445
Statistical Variations on Binning Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446
Assigning Statistical Variations using the .MCMOD Command . . . . . . . . . . . . . . . . . . . . 446
Tolerance Setting Using DEV, DEVX or LOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447
Sampling Plan Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Standard Monte Carlo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Importance Sampling Monte Carlo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452
Quasi-Monte Carlo Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456
Latin Hypercube Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457
Model-Based Monte Carlo Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 459
Post-Analysis of Monte Carlo Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463
Output of Uncertainty Analysis (the .chi File) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465
Extract Functions Specific to Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465
Extracting the Index and Total Number of Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 468
Basic Statistics and Histograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469
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Bootstrap Estimates for Mean and Standard Deviation . . . . . . . . . . . . . . . . . . . . . . . . . . 470
Global Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
Summary of Extracted Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
Primary Statistics of Uncertainty Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
Control of the Monte Carlo Post-Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
General Information and Status of Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474
Model Adequacy Checking for Model-Based MC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476
Mean and Standard Deviation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478
Confidence Intervals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 479
Probability and Quantile Estimators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480
Approximations of the CDF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 485
Coverage Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 487
Approximation of the Density Function (Histogram File .mch) . . . . . . . . . . . . . . . . . . . 489
Additional Uncertainty Analyses (the .mcm File) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491
Basic Concepts on Quantitative Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491
Robust Measures of Location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 492
Alternative Measures of Dispersion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494
Min/Max Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495
Parametric Fit and Normality Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495
Capability Indices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499
Coorelation of Test Concordance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500
Monte Carlo Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501
Input/Output Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
File Organization (the .mci and .mco Files). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
Input Sample. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
Output Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
Graphical Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509
Histogram Annotations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510
Cumulative Distribution Function (CDF) Annotations . . . . . . . . . . . . . . . . . . . . . . . . . . 511
Run-Length Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514
CONFIDENCE Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514
SETTLING Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
MCCONV Extract Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518
Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
Global Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
Large Scale Variable Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
Monte Carlo Analysis Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526
A Simple Passive Low-Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526
Importance Sampling Monte Carlo Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528
SRAM Bit Cell Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528
VCO Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531
Model-Based Approximations Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532
Further Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534
Parameter Naming Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536
Problems in Statistical Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544
Obsolete Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548
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Chapter 12
Statistical Experimental Design and Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555
Introduction to Statistical Experimental Design and Analysis . . . . . . . . . . . . . . . . . . . . . . . 555
Factor Screening Experiments in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557
DEX Example Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558
Factorial Design Comparison with Worse Case Analysis . . . . . . . . . . . . . . . . . . . . . . . . . 559
Statistical Modeling for Discrete Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560
Designing a Screening Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562
Reference Factors for the DEX Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562
Defining the Levels of Factors for the DEX Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565
Defining Levels for Noise Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565
Defining Levels With Respect to the Nominal Value . . . . . . . . . . . . . . . . . . . . . . . . . . . 570
Determining the List of Noise Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570
Conducting a Screening Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573
Choosing the Type of Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573
Selecting the Number of Factors and the Design Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . 574
Viewing the Experiment Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 576
Examples of Factor Screening Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
Example of Experiment Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
Example of Conducting an Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579
Example of Analysis Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581
Ordered Data Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 582
DEX Mean Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583
Formal Test of Significance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 584
Multi-Responses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 585
Unordered Data Table (CSV Table). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586
Chapter 13
Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 587
Optimization in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589
Optimization Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589
Optimization Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 591
Eldo Optimization Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 592
Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
Discretized Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
Specifying Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596
Specifying Tracking with Design Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597
Scaling Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599
Design Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603
Specifying Design Objectives Using .EXTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
Scalar Design Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605
Vector Design Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 606
Specifying Design Objectives Using .OBJECTIVE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608
Types of Design Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610
Minimization and Maximization Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610
Goal Values Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 612
Range Constraints Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 614
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Objectives for Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616
Design Objectives for Multi-Point Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618
Implicit and Explicit Data Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618
Specifying Design Objectives with Explicit Data Points. . . . . . . . . . . . . . . . . . . . . . . . . 619
Scaling Design Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621
Optimization Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 622
Eldo Optimizer SQP Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 622
Eldo Optimizer/Search Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626
Conducting an Eldo Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Global and Local Optimization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Continuous and Discrete Optimization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630
Smooth and Non-Smooth Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631
Multiple-Run Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
Optimization of Sweep Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 633
Inner and Outer Sweep Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 634
Specifying Outer Design Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635
Hierarchy and Depth of Sweep Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637
Post-Analysis of Optimization Simulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
Output from the Optimization Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
Explicitly Declaring Results For Graphical Viewing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641
Viewing the ASCII Output File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 642
ASCII Optimization File Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643
Initialization of Problem Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643
Optimization Phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645
Optimization Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 647
Optimization Results with Respect to the Outer Loop. . . . . . . . . . . . . . . . . . . . . . . . . . . 651
Monitoring Design Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653
Monitoring Goal Value Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653
Monitoring Minimize and Maximize Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 654
Monitoring Bound Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655
Final Diagnostic Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 656
Normal and Elastic Modes of Termination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659
Constraint Violations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659
Slack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 661
Examples of Circuit Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664
Designing a Low Noise Amplifier (LNA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664
Fourband Filter Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 671
MOS Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 675
Robust Optimization Using Corners. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 677
Setup Time Computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 681
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 682
Chapter 14
Working with S, Y, Z Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 683
Simulation Setup for S, Y, Z Parameter Extraction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 684
S, Y, Z Parameter Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 685
Matrix (G, H, T, A) Parameter Extraction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 687
Output File Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 688
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Simulating a Block Defined by S Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 691
Transient Simulation of Circuits Characterized in the Frequency Domain . . . . . . . . . . . . 691
Technical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692
Implementation Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 695
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 696
Basic Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Detailed Functionality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Instantiating a Block Defined by S, Y, Z Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 699
Touchstone Data File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705
CITIfile Data File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708
Instantiating a Block Defined by X-Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 710
Chapter 15
Aging and Reliability Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713
Running Reliability Simulation in Eldo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713
Chapter 16
Electrothermal Simulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 715
Electrothermal Simulation Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 715
Specifying an Electrothermal Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 716
Verilog-A Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 720
Reporting and Sorting Thermal Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 723
Electrothermal Simulation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 724
Chapter 17
IBIS Models Support in Eldo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 727
Introduction to IBIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 728
IBIS Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 728
Using IBIS Models in Eldo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 728
IBIS Resources on the Web . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729
IBIS File Types and Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729
Checking IBIS Files with the Golden Parser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731
IBIS Device Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 732
Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 733
Single-Ended Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 735
Pseudo-Differential Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 739
True Differential Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 741
Series Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 742
Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 744
Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745
Pin Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745
Series Pin Mapping and Series Switch Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 746
Node Declarations and Circuit Call . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 747
Electrical Board Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 748
IBIS AMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 748
IBIS Support in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 749
Backward Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 749
Analysis Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 749
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Digital Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750
IBIS Model Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 751
IBIS Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 752
IBIS Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 765
IBIS Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773
IBIS Electrical Board Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777
Supported Keywords and Sub-Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 780
IBIS Algorithmic Model Interface (AMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 787
IBIS Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790
Example 1—Single-Ended Tx-Rx System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790
Example 2—Pseudo-Differential Tx-Rx System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 792
Example 3—Package Parasitics Cross Talk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 794
Example 4—Simultaneous Switching Output Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 796
Chapter 18
Eldo Control Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 801
Overview of the Eldo Control Language. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 802
Eldo Control Language Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 803
Eldo Control Language Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 806
Testbenches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 809
Testbench Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 809
Testbench Instantiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811
Rules for Testbench Location Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 813
Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814
Task Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814
Task Instantiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 817
Statement Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820
Comments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820
Line Breaks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820
Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 821
Flow Control Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 835
Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 839
Defining and Running Simulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 841
Result Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 843
Generated Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 844
Collecting Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 846
Vector Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 848
Library of Functions for Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 854
abs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 861
acos. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 862
acosh. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 863
acot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 864
acoth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 865
append. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 866
asin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 867
asinh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 868
atan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869
atan2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 870
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atanh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 871
atof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 872
atoi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 873
avg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 874
beginval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 876
bitof. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 877
cat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 878
ceil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 879
compoundcontent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 880
conj . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 884
cos. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 885
cosh. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 886
cot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 887
coth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888
db . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 889
derive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 891
drv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892
exp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 893
fclose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 895
fft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 896
fgetc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 899
fgets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900
floor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 902
fopen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 903
fprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 905
frexp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 907
fscan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908
hypot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 910
ifft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 911
imag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 913
imax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914
imin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915
int . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 916
integ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 917
integral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 918
intersect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 919
isarray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 921
iscompound. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 922
kurt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 923
ldexp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 924
limit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 925
log. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 926
log10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 928
magnitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 930
max . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 931
mcconv . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 933
mcnbench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 934
min . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 935
mod. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 937
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modf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 938
mptpcomplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 939
nextval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 940
ongrid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 942
phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 943
pow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 944
pow_10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 945
pwr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 946
real . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 947
relation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 948
ritocomplex. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 949
rms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 950
rms_ac. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 951
rms_noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 952
rms_tran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 953
round. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 954
sgn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 955
sign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 956
sin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 957
sinh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 958
size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 959
skew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 960
sprint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 961
sqr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 963
sqrt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 964
sscan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 965
std . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 967
strtok. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 968
sum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 969
system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 970
tan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 971
tanh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 972
trunc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 973
var. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 974
wadd_data_enum_value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 975
wadd_scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 978
wclose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 979
wcreate_data_type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 980
wcreate_scale_table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 986
wcreate_wave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 987
wget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 995
wftoascii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 996
wftodata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 997
wmkfolder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 998
wopen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 999
wsave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000
wset_values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1003
xdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1005
xmax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1006
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xmin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1007
xofmax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1008
xofmin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1009
xup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1010
xval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1011
xwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1012
yval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1013
Simulation Dynamic Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1014
Callback Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1014
Extended Simulation Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1024
Netlist Monitoring Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1025
Simulation Flow-Control Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1025
Netlist Modification Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1025
_simu_end. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1026
_simu_get . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1027
_simu_get_extract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1028
_simu_load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1029
_simu_reload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1030
_simu_run. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1031
_simu_set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1033
_simu_set_cond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1036
_simu_get_wave. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1038
Parallel Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1039
General Settings for Parallelism in ECL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1039
Parallel Construct . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1040
para . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1045
Parallel Loops. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1046
Extended Simulation Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1053
Launching ECL Simulations on Different Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1055
Statistical Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1058
_simu_erase_all_runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1063
_simu_erase_last_run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1064
_simu_get_mcsens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1065
_simu_get_nb_stat_params . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1076
_simu_get_random . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1077
_simu_get_raw_sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1078
_simu_get_sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1079
_simu_get_stat_param_dev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1080
_simu_get_stat_param_distrib . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1081
_simu_get_stat_param_name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1082
_simu_get_stat_param_nb_draw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1083
_simu_get_stat_param_netlist_dev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1084
_simu_get_stat_param_netlist_dev_param . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1085
_simu_get_stat_param_netlist_mod. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1086
_simu_get_stat_param_netlist_mod_param. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1087
_simu_get_stat_param_netlist_param . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1088
_simu_get_stat_param_nom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1089
_simu_get_stat_param_ref_param . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1090
_simu_get_stat_param_sampling_val . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1091
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_simu_is_stat_param_dev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1092
_simu_is_stat_param_devx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1093
_simu_is_stat_param_locked . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1094
_simu_is_stat_param_lot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1097
_simu_lock_stat_param . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1098
_simu_reset_random_generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1099
_simu_run. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1102
_simu_set_mc_flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1103
_simu_set_stat_param_sampling_val. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1104
_simu_unlock_stat_param . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105
Running Monte Carlo Runs in Parallel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105
Advanced Simulation Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1114
Simulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1114
Debug Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1117
ECL Grammar Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1118
Examples Using ECL as an Alternative to Standard Eldo Commands . . . . . . . . . . . . . . . . . 1123
.STEP Alternative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1123
.EXTRACT Alternative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1125
.PRINTFILE Alternative #1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1127
.PRINTFILE Alternative #2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1129
.OPTIMIZE Alternative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1131
.MPRUN with Monte Carlo Analysis Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1133
Chapter 19
Post-Processing Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1135
Post-Processing Library Example Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1137
General Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1139
Registering User Defined Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1139
Making Specific Calls to User Defined Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1139
Waveform Definition With User Defined Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1140
Macro-Like Usage of User Defined Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1141
Keyword Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1142
Working with Waveforms Inside User Defined Functions . . . . . . . . . . . . . . . . . . . . . . . . 1142
evalExpr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1144
defineVec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1146
EZwave Waveform Calculator Functions Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1149
Built-In Waveform Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1150
ABS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1151
ACOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1152
ACOSH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1153
ACOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1154
ACOTH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1155
ASIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1156
ASINH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1157
ATAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1158
ATANH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1159
AVG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1160
COMPRESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1161
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COS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1162
COSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1163
COT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1164
COTH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1165
DB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1166
DEG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1167
DELAY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1168
DERIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1169
DRV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1170
EXP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1171
FALLTIME. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1172
GMARGIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1173
HISTOGRAM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1174
IMAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1175
INTEG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1176
INTEGRAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1177
INTERSECT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1178
INVDB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1179
LOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1180
LOG10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1181
MAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1182
MAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1183
MIN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1184
PHASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1185
PHMARGIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1186
RAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1187
REAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1188
RELATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1189
RISETIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1190
RMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1191
SAMPLE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1192
SETTLINGTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1193
SIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1194
SINH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1195
SQR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1196
SQRT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1197
SUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1198
TAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1199
TANH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1200
TPD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201
TPDDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1202
TPDDU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203
TPDUD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204
TPDUU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1205
VMAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1206
VMIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207
WINDOW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1208
XCOMPRESS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1209
XVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1210
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XWAVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1211
YVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1212
IIPX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1213
OIPX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1214
Built-In DSP Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1215
AUTOCOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1216
CONV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1217
CORRELO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1218
CT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1220
FFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1222
HARMONICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1224
HDIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1225
IFFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1226
PERIODO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1227
PSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1229
SAMPLER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1230
SNR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1232
Accessing Waves Inside an External Database Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . 1233
LOAD_FILE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1234
DISP_FILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1235
UNLOAD_FILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1236
Additional PPL Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1237
DISPLAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1238
GETSIZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1239
GETPOINT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1240
SETPOINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1241
CREATEVECTOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1242
Chapter 20
Speed and Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1243
Introduction to Speed and Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1243
Speed and Accuracy in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1245
Integration Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1246
Time Step Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1248
Overview of Time Step Control Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1248
Control of the Local Truncation Error (LTE). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1250
More About Time Step Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1251
Usage of a Fixed Time Step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1252
Newton Iterations Accuracy Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1252
Global Tuning of the Accuracy—EPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1253
Global Tuning of the Accuracy—TUNING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1255
Simulation of Large Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1256
Tips for Improving Simulation Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1259
Integral Equation Method (IEM) Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1260
IEM Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1261
IEM—Supported Circuit Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1262
IEM Tolerance Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1263
Efficient Usage of IEM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1264
20 Eldo® User's Manual, 15.3

Table of Contents
One Step Relaxation (OSR) Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1265
Chapter 21
Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1269
Example 1—AC Analysis of a Parallel LCR Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1272
Example 2—Transient and AC Analysis of a 4th Order Butterworth Filter . . . . . . . . . . . . . 1274
Example 3—AC and Noise Analysis of a Band Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . 1277
Example 4—AC Analysis of a Low Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1280
Example 5—Transient Analysis of a Colpitts Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1283
Example 6—Transient Analysis of a High Voltage Cascade . . . . . . . . . . . . . . . . . . . . . . . . 1286
Example 7—Monte Carlo Analysis Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1290
Example 8—DC Sensitivity of a Bipolar Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1293
Example 9—Transient and AC Analysis of a Switched Capacitor Low Pass Filter . . . . . . . 1295
Example 10—Transient Analysis of a Switched Capacitor Schmitt Trigger . . . . . . . . . . . . 1298
Example 11—Loop Stability of an Opamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1299
Example 12—Overshoot Extraction of an Opamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1301
Example 13—Transient Analysis of a 5th Order Elliptic SC Low Pass Filter . . . . . . . . . . . 1303
Example 14—Charge Conservation in MOS Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304
Example 15—AC Analysis of an Active RC Band Pass Filter . . . . . . . . . . . . . . . . . . . . . . . 1306
Example 16—Transient Analysis of an Integrator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1307
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier . . . . . . . . . . 1309
Example 18—Numerical Integration: TRAP versus GEAR . . . . . . . . . . . . . . . . . . . . . . . . . 1314
Example 19—DC Mismatch Comparison with Monte Carlo Analysis. . . . . . . . . . . . . . . . . 1316
Example 20—DC Mismatch Comparison with Monte Carlo Analysis using ECL . . . . . . . 1322
Example 21—Post-Layout Simulation using DSPF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1324
Example 22—Extract Gain and Phase Margin of a 2-Stage Opamp. . . . . . . . . . . . . . . . . . . 1327
Example 23—Parametric Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1331
Example 24—Cell Characterization: Setup Time Extraction . . . . . . . . . . . . . . . . . . . . . . . . 1334
Example 25—Setting up and Handling Analog Busses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1337
Example 26—Spectre Compatibility Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1339
Example 27—Monte Carlo Analysis Autostop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1340
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit . . . . . . . . . 1343
Tutorial—High Impedance Fault Detection of a PLL Circuit. . . . . . . . . . . . . . . . . . . . . . . . 1358
Transient Noise Analysis Example 1—High-Rate Particle Detector . . . . . . . . . . . . . . . . . . 1368
Transient Noise Analysis Example 2—Switched Capacitor Filter . . . . . . . . . . . . . . . . . . . . 1373
Appendix A
Error and Warning Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1379
Eldo Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1379
Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1380
Global Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1380
Errors Related to Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1384
Errors Related to Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1385
Errors Related to Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1392
Errors Related to Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1399
Errors Related to Macromodels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1401
Errors Related to Subcircuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1402
Miscellaneous Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1403
Eldo® User's Manual, 15.3 21

Table of Contents
Errors Related to Eldo Premier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1408
Warning Messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1411
Global Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1411
Warnings Related to Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1415
Warnings Related to Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1417
Warnings Related to Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1421
Warnings Related to Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1428
Warnings Related to Subcircuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1431
Miscellaneous Warnings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1431
Warnings Related to Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1450
Appendix B
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1453
Common Netlist Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1453
Tips for Troubleshooting and/or Improving Convergence and Performance . . . . . . . . . . . . 1454
Tips for Troubleshooting Performance Bottlenecks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1454
Troubleshooting File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1455
Appendix C
Eldo Interactive Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1457
Invoking Eldo Interactive Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1457
Reading Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1459
Resetting Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1461
Change Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1463
Controlling Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1466
Appendix D
Eldo Conversion Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1469
Utility to Convert .chi to .cir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1470
Utility to Convert VCD to Test Vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1471
Utility to Convert a Waveform Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1473
Appendix E
STMicroelectronics Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1477
How to Invoke Eldo-ST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1477
What Does Eldo-ST Mode Change? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1478
Index
Third-Party Information
End-User License Agreement
22 Eldo® User's Manual, 15.3

List of Figures
Figure 1-1. Cascaded Inverter Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 1-2. Inverter Subcircuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 1-3. EZwave Output (.wdb) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 1-4. Eldo Simulation Flow Input and Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 4-1. Circuit File Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Figure 4-2. IP Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Figure 6-1. DC Device Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Figure 6-2. Transient Analysis Plot for a Butterworth Filter Circuit. . . . . . . . . . . . . . . . . . . 219
Figure 6-3. AC Analysis Plot for an LCR Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Figure 6-4. Circuit Components with their Added Noise Sources . . . . . . . . . . . . . . . . . . . . 242
Figure 6-5. White Noise Signal From Random Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Figure 6-6. Random Pulses (Zoom). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Figure 6-7. PSD of a White Noise Signal Generated with Random Pulses. . . . . . . . . . . . . . 250
Figure 6-8. Flicker Noise Signal From a Sum of Random Pulses. . . . . . . . . . . . . . . . . . . . . 251
Figure 6-9. Flicker Noise Signal From a Sum of Random Pulses (Zoom) . . . . . . . . . . . . . . 252
Figure 6-10. PSD of a Flicker Noise Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
Figure 6-11. White Noise Signal From a Sum of Sinusoids . . . . . . . . . . . . . . . . . . . . . . . . . 254
Figure 6-12. White Noise Signal From a Sum of Sinusoids (Zoom) . . . . . . . . . . . . . . . . . . 254
Figure 6-13. PSD of a White Noise Signal Generated From Sinusoids . . . . . . . . . . . . . . . . 255
Figure 6-14. Flicker Noise Signal From a Sum of Sinusoids . . . . . . . . . . . . . . . . . . . . . . . . 256
Figure 6-15. Flicker Noise Signal From a Sum of Sinusoids (Zoom). . . . . . . . . . . . . . . . . . 256
Figure 6-16. PSD of a Flicker Noise Signal Generated From Sinusoids. . . . . . . . . . . . . . . . 257
Figure 6-17. Transient Noise Analysis Plot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Figure 6-18. VCO Control Node - Steady State Reached . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
Figure 6-19. VCO Control Node - Restarted Transient Noise Analysis . . . . . . . . . . . . . . . . 262
Figure 6-20. EZwave Waveform Calculator - Phase Noise Computation. . . . . . . . . . . . . . . 263
Figure 6-21. Phase Noise Plots Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Figure 6-22. Power Analysis Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
Figure 8-1. Compound Waveform Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
Figure 8-2. Defining Waveforms: PWL, PWL_CTE and PWL_LIN Functions. . . . . . . . . . 339
Figure 8-3. EZwave Display of SOA Limits Assertion Bus . . . . . . . . . . . . . . . . . . . . . . . . . 343
Figure 9-1. EZwave Waveform Showing Nodes Impacting Time-Step . . . . . . . . . . . . . . . . 382
Figure 10-1. Post-Layout Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
Figure 11-1. Central Tendency and Dispersion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412
Figure 11-2. Tail Probabilities and Yield Computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414
Figure 11-3. Propagation of Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Figure 11-4. Common Statistics for UNIF Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432
Figure 11-5. Percentage of Cases in Eight Portions of the Gaussian Distribution . . . . . . . . 433
Figure 11-6. Plot of the Truncated Normal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434
Figure 11-7. Plot of the Triangular Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435
Eldo® User's Manual, 15.3 23

List of Figures
Figure 11-8. Scatter Plot of a Gaussian Sample and Contour Ellipses . . . . . . . . . . . . . . . . . 439
Figure 11-9. Scatter Plot and Marginal Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441
Figure 11-10. The ISMC Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453
Figure 11-11. Comparison Between Low Discrepancy and Pseudorandom Point Sets . . . . 456
Figure 11-12. Latin Hypercube Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 458
Figure 11-13. Output Files Organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464
Figure 11-14. Illustration of Kurtosis and Skewness with μ=0 and σ=1. . . . . . . . . . . . . . . . 496
Figure 11-15. Global/Local Hierarchy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506
Figure 11-16. Histogram Annotations 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511
Figure 11-17. CDF Plot (with Confidence Bounds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512
Figure 11-18. CDF Plot Right-Tail Part of the Empirical CDF. . . . . . . . . . . . . . . . . . . . . . . 513
Figure 11-19. Principle of the SETTLING Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
Figure 11-20. Scatter Plots of Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 522
Figure 11-21. Monte Carlo Analysis Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 527
Figure 11-22. LIMIT Distribution with L=-1 and U=+1. . . . . . . . . . . . . . . . . . . . . . . . . . . . 549
Figure 11-23. Four Random Samples from NOR/UNI Distributions . . . . . . . . . . . . . . . . . . 551
Figure 11-24. Four Random Samples when AUNIF(0,1,MULT) is Specified . . . . . . . . . . . 552
Figure 11-25. Four Random Samples when AGAUSS (0,1,1,MULT) is Specified . . . . . . . 553
Figure 12-1. Percentage of Cases in Eight Portions of the Gaussian Distribution . . . . . . . . 566
Figure 12-2. Common Statistics for UNIF(x,h). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567
Figure 12-3. Factor Levels for a Circuit Parameter x . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568
Figure 12-4. Cuboidal Representation of Two 3-factors Designs . . . . . . . . . . . . . . . . . . . . . 575
Figure 13-1. Simulator as a Black Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
Figure 13-2. Discretization of Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 595
Figure 13-3. Illustration of Optimality Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
Figure 13-4. Illustration of Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
Figure 13-5. Non-Valid and Valid Zeros. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627
Figure 13-6. Different Types of Minima . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Figure 13-7. Examples of Non-Smooth Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631
Figure 13-8. Discretization of Design Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 633
Figure 13-9. Inner and Outer Sweep Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635
Figure 13-10. Scaling Transformation For Design Objectives Output . . . . . . . . . . . . . . . . . 644
Figure 13-11. Scaling Transformation for Variables Output. . . . . . . . . . . . . . . . . . . . . . . . . 645
Figure 13-12. Optimization Phase Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 646
Figure 13-13. Statistics and Diagnostics Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 647
Figure 13-14. Status of Variables Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 648
Figure 13-15. Status of Objectives Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 649
Figure 13-16. Analysis Of Last Simulation Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650
Figure 13-17. Optimization Results with Respect to the Outer Loop Output . . . . . . . . . . . . 651
Figure 13-18. Illustration of Constraint Violations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 660
Figure 13-19. Illustration of Slack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 662
Figure 13-20. Plotted Values of the Merit Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 671
Figure 13-21. Filter Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 672
Figure 13-22. Optimized Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 674
Figure 13-23. Illustration of I-V characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 675
24 Eldo® User's Manual, 15.3

List of Figures
Figure 14-1. Mixed-Mode S Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 694
Figure 16-1. Electrothermal Simulation Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 716
Figure 17-1. Input Buffer Model Building Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 735
Figure 17-2. Terminator Buffer Model Building Blocks. . . . . . . . . . . . . . . . . . . . . . . . . . . . 736
Figure 17-3. Output Buffer Model Building Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 737
Figure 17-4. I/O Buffer Model Building Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 738
Figure 17-5. 3_state Buffer Model Building Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 739
Figure 17-6. Pseudo-Differential Input Buffer Consisting of Two Single-Ended Input Buffers
740
Figure 17-7. Pseudo-Differential Output Buffer Consisting of Two Single-Ended Output Buffers
741
Figure 17-8. Example Analog-Only Model init Using an I/O Buffer . . . . . . . . . . . . . . . . . . 742
Figure 17-9. Simple Passive Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 742
Figure 17-10. Series Current Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 743
Figure 17-11. Series MOSFET Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 743
Figure 17-12. Common Package Parasitics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 744
Figure 17-13. [Pin Mapping] Model Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 746
Figure 17-14. Series Pin Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 747
Figure 17-15. Test_component Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 772
Figure 17-16. Package Model Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 776
Figure 17-17. Electrical Board Description Example Connections. . . . . . . . . . . . . . . . . . . . 780
Figure 17-18. Single-Ended Tx-Rx System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790
Figure 17-19. Single-Ended Tx-Rx System Simulation Results . . . . . . . . . . . . . . . . . . . . . . 792
Figure 17-20. Pseudo-Differential Tx-Rx System Simulation Results . . . . . . . . . . . . . . . . . 794
Figure 17-21. Package Parasitics Cross Talk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 796
Figure 17-22. Component Internal Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 797
Figure 17-23. Simultaneous Switching Output Noise (SSON) Simulation Results . . . . . . . 798
Figure 21-1. Parallel LCR Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1272
Figure 21-2. Example 1—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1274
Figure 21-3. 4th Order Butterworth Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1274
Figure 21-4. Example 2—Simulation Results—AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1276
Figure 21-5. Example 2—Simulation Results—Transient . . . . . . . . . . . . . . . . . . . . . . . . . . 1277
Figure 21-6. Band Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1278
Figure 21-7. Example 3—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1280
Figure 21-8. Low Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1281
Figure 21-9. Example 4—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1283
Figure 21-10. Colpitts Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1284
Figure 21-11. Example 5—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1286
Figure 21-12. High Voltage Cascade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1287
Figure 21-13. Example 6—Simulation Results 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1289
Figure 21-14. Example 6—Simulation Results 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1290
Figure 21-15. Non-inverting Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1291
Figure 21-16. Example 7—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1293
Figure 21-17. Bipolar Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1294
Figure 21-18. Example 8—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1295
Eldo® User's Manual, 15.3 25

List of Figures
Figure 21-19. Example 9—Simulation Results—AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1297
Figure 21-20. Example 9—Simulation Results—Transient . . . . . . . . . . . . . . . . . . . . . . . . . 1298
Figure 21-21. Example 10—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1299
Figure 21-22. Example 11—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1301
Figure 21-23. Example 12—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1303
Figure 21-24. Example 13—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304
Figure 21-25. Example 14—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1306
Figure 21-26. Example 15—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1307
Figure 21-27. Example 16—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1309
Figure 21-28. Example 17—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1314
Figure 21-29. Example 18—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1315
Figure 21-30. Example 19—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1317
Figure 21-31. Example 21—Simulation Results 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1326
Figure 21-32. Example 21—Simulation Results Zoom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1327
Figure 21-33. Example 22—Simulation Results 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1329
Figure 21-34. Example 22—Simulation Results 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1330
Figure 21-35. Example 23—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1333
Figure 21-36. Example 24—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1336
Figure 21-37. Example 24—Simulation Results Zoom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1337
Figure 21-38. Example 25—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1339
Figure 21-39. Example 26—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1340
Figure 21-40. Example 27—Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1342
Figure 21-41. PLL Circuit for Power Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1343
Figure 21-42. PLL Circuit for HiZ Fault Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1359
Figure 21-43. High-Rate Particle Detector Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1369
Figure 21-44. Simulation Results—Input & Output Signals. . . . . . . . . . . . . . . . . . . . . . . . . 1370
Figure 21-45. Noise at Amplifier O/P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1371
Figure 21-46. Noise at Analog Memory O/P. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1372
Figure 21-47. Switched Capacitor Filter Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . 1373
Figure 21-48. Amplifier Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1374
Figure 21-49. AC & Noise Simulation Results of Amplifier . . . . . . . . . . . . . . . . . . . . . . . . 1375
Figure 21-50. AC & Noise Simulation of Amplifier Macromodel . . . . . . . . . . . . . . . . . . . . 1376
Figure 21-51. Simulation Results of the Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1377
Figure 21-52. Frequency Response of the Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1378
26 Eldo® User's Manual, 15.3

List of Tables
Table 1-1. Documentation Syntax Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Table 2-1. Simulation Connection Manager Arguments . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table 3-1. Option PREMIER_MODE Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Table 3-2. Eldo Analysis Command Support in Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . 74
Table 3-3. Eldo Premier—Supported Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Table 4-1. Scale Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Table 4-2. Arithmetic Functions and Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Table 4-3. Arithmetic Functions Used Only in .EXTRACT, .DEFWAVE, .SETSOA . . . . 112
Table 4-4. Operator Precedence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Table 4-5. Boolean Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Table 4-6. Bitwise Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Table 5-1. MOS Levels with -compat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Table 5-2. BJT Models with -compat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Table 5-3. Diode Models with -compat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Table 5-4. Resistor Level with -compat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Table 5-5. Spectre Constants and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Table 5-6. Spectre Conversion Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Table 8-1. Special Characters for Plotting and Probing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
Table 8-2. Transient Extraction Language Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Table 8-3. General Extraction Language Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Table 8-4. Graphic Elements for SOA Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342
Table 9-1. Eldo Standard Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
Table 9-2. Activating Performance Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384
Table 11-1. Speedup of ISMC Over Standard Monte Carlo . . . . . . . . . . . . . . . . . . . . . . . . . 530
Table 11-2. Comparison of Standard Monte Carlo and SSD Methods . . . . . . . . . . . . . . . . 533
Table 12-1. Example Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558
Table 13-1. Eldo Optimization Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 592
Table 13-2. Optimality Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624
Table 13-3. Optimization Result Status Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 656
Table 13-4. Basic Examples of Circuit Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664
Table 13-5. Results of Optimization for GOAL Objectives . . . . . . . . . . . . . . . . . . . . . . . . . 667
Table 13-6. Results of Optimization for MINIMIZE Objectives . . . . . . . . . . . . . . . . . . . . . 668
Table 13-7. Extracted Information from .otm File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 669
Table 13-8. Combinations of N1 and LS Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 669
Table 13-9. Results of Restricted Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 670
Table 13-10. Values Extracted from fourband.otm File . . . . . . . . . . . . . . . . . . . . . . . . . . . . 674
Table 13-11. Nmos Example Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 677
Table 14-1. Mixed-Mode S Parameter Extraction Default Rule . . . . . . . . . . . . . . . . . . . . . 686
Table 14-2. CITIfile Data Format Supported Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . 708
Table 15-1. Eldo Reliability Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713
Eldo® User's Manual, 15.3 27

List of Tables
Table 17-1. List of Predefined Port Names and their Descriptions . . . . . . . . . . . . . . . . . . . 733
Table 17-2. Buffer Types and Port Names Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 734
Table 17-3. Digital Port Logic Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750
Table 17-4. Analog Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750
Table 17-5. Exceptions to Fast=Max, Slow=Min Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . 756
Table 17-6. Supported Keywords and Sub-Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 781
Table 18-1. Eldo Control Language Example Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 803
Table 18-2. ECL Result Structure Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 843
Table 18-3. Library of Functions for Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 854
Table 18-4. Extended Simulation Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1024
Table 18-5. Statistical Processing Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1060
Table 19-1. PPL Example Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1137
Table 19-2. General Usage Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1139
Table 19-3. C and PPL Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1143
Table 19-4. Built-In Waveform Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1150
Table 19-5. Built-In DSP Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1215
Table 19-6. Functions to Access Waves Inside an External Database . . . . . . . . . . . . . . . . . 1233
Table 19-7. Additional PPL Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1237
Table 20-1. Global Tuning of Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1254
Table 21-1. Eldo Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1269
Table 21-2. Additional Eldo Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1272
Table A-1. Global Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1380
Table A-2. Errors Related to Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1384
Table A-3. Errors Related to Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1385
Table A-4. Errors Related to Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1392
Table A-5. Errors Related to Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1399
Table A-6. Errors Related to Macromodels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1402
Table A-7. Errors Related to Subcircuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1402
Table A-8. Miscellaneous Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1403
Table A-9. Errors Related to Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1409
Table A-10. Global Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1411
Table A-11. Warnings Related to Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1415
Table A-12. Warnings Related to Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1417
Table A-13. Warnings Related to Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1421
Table A-14. Warnings Related to Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1428
Table A-15. Warnings Related to Subcircuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1431
Table A-16. Miscellaneous Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1432
Table A-17. Warnings Related to Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1450
Table C-1. Netlist Element Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1460
Table D-1. ffcv Output Format Modifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1473
Table E-1. Operating Point—optyp values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1479
Table E-2. Operating Point—optyp values—Dynamic Part for Charge Control Model . . . 1480
28 Eldo® User's Manual, 15.3

Chapter 1
Introduction to Eldo
The Eldo analog simulator is the core component of a comprehensive suite of analog and
mixed-signal simulation tools.
Overview of Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Getting Started With the Eldo Simulation Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Eldo Input and Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Eldo Documentation Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Command Line Help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Related Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Documentation Syntax Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Overview of Eldo
The following is a list of the major product features of Eldo:
• Core technology for analog, RF (Eldo RF ), and mixed-signal (Questa ® ADMS ,
ADMS-ADiT ) simulation.
• Simulation of very large circuits in time and frequency domains.
• Eldo Premier option provides increased performance and capacity without sacrificing
accuracy compared to the default Eldo Classic.
• Provides a 3× to 10× gain in simulation speed over other commercial SPICE simulators,
while maintaining the same accuracy.
• Flexible user control of simulation accuracy.
• Transient noise algorithm for noise simulation during transient analysis.
• Advanced analysis options such as pole-zero, enhanced Monte Carlo, DC mismatch.
• Circuit optimization and statistical analysis (design of experiments).
• S and Z-domain generalized transfer functions.
• Reliability simulation with Eldo UDRM (User Defined Reliability Model).
• Flexible DSPF netlist support.
• Behavioral modeling with Verilog-A.
Eldo® User's Manual, 15.3 29

Introduction to Eldo
Overview of Eldo
• Extensive device model libraries including leading MOS, bipolar and MESFET
transistor models such as: BSIM3v3.x, BSIM 4, MM11, Mextram, HICUM, and PSP.
• TSMC Model Interface (TMI) support for TMI1 and TMI2.
• IBIS (I/O Buffer Information Specification) model support.
• Waveform analysis and post-processing of simulation results with the EZwave ®
graphical post-processor.
• Integration into Mentor Graphics Custom IC flow, consisting of Pyxis® Schematic for
schematic capture, Pyxis Layout for the layout side, and Calibre/Calibre xRC for DRC/
LVS and extraction. This flow provides a complete, front-to-back design and
verification environment for analog, mixed-signal and RF.
• Integration into Cadence’s Analog Design Environment with Artist Link ® .
Analog Simulation Capabilities
Eldo uses a unique partitioning scheme that enables the use of different algorithms on different
portions of a design. It provides a flexible control of simulation accuracy using a wide range of
device model libraries, and gives a high accuracy yield in combination with high speed and high
performance.
See “Getting Started With the Eldo Simulation Flow” on page 31.
RF Capabilities
Eldo RF extends the capabilities of the Eldo simulator with added extensions for RF simulation
to enable the fast large-signal Steady-State analysis (SST analysis) of high frequency electronic
circuits. A set of dedicated algorithms are provided to accurately and efficiently handle the
multi-GHz signals in modern wireless communication applications. Of importance to the RF
designer, you can extract large-signal S parameters, and W elements and multiple lossy
transmission lines are supported.
See the Eldo RF User’s Manual.
Mixed-Signal Simulation
Questa ADMS incorporates Eldo Classic and Eldo Premier to efficiently simulate mixed-signal
designs within a unified simulation environment. Questa ADMS extends the familiar Questa
verification platform with analog and mixed-signal standard languages. You can mix all
languages in a single hierarchy; and you can combine VHDL-AMS, Verilog-AMS, VHDL,
Verilog, SystemVerilog, SPICE and SystemC anywhere and at any level in the design. The
testbench may be SPICE, an analog or mixed-signal language, or a digital language.
In Questa ADMS, you can use digital units that have been previously compiled and simulated
by Questa without any modification. You can use SPICE subcircuits anywhere in the design
hierarchy for greater flexibility in modeling.
30
Eldo® User's Manual, 15.3

Introduction to Eldo
Getting Started With the Eldo Simulation Flow
During a mixed-signal, or pure analog, simulation, Questa ADMS uses Eldo to simulate the
following:
• A mixed-signal design that includes SPICE subcircuits as components.
• A SPICE netlist that includes VHDL-AMS and VHDL design entities or Verilog-AMS
and Verilog modules as components.
• A pure SPICE netlist.
See the Questa ADMS User’s Manual.
Verilog-A
Verilog-A is an analog subset of the Verilog-AMS language, for use to help design analog
systems with high-level behavioral descriptions, as well as structural descriptions of systems
and components. The default Verilog-A implementation in Eldo is the same as that used by
Verilog-AMS in Questa ADMS. Eldo and Questa ADMS can share the same compiled Verilog-
A modules.
See the Eldo Verilog-A User’s Manual.
Waveform Analysis
The EZwave graphical post-processor enables waveform analysis and post-processing of
simulation results. The native waveform format of EZwave, called “wdb,” is extremely efficient
for manipulating huge databases. EZwave can load gigabytes of data in seconds. EZwave can
also load most popular waveform formats, and operates on both analog and digital signals.
See the EZwave Users Manual.
Viewing ASCII Simulation Output Files
You can use the AMS Results Browser to view simulation results and associated files.
Depending on the file format, results may be sorted, filtered, grouped, searched, printed, copied,
and exported.
The AMS Results Browser is mainly intended to be used to view Eldo outputs, but you can also
use it to view SPICE input files and any text file.
See the AMS Results Browser.
Getting Started With the Eldo Simulation Flow
The basic Eldo simulation flow is to setup a .cir netlist file, run the Eldo simulation on the
netlist file, then analyze the generated results.
This example consists of a simple cascade of three inverters. Figure 1-1 and Figure 1-2 show
the circuit diagram for the cascade together with the inverter subcircuit. To create the Eldo
netlist, node names must be assigned to the circuit. The complete netlist is provided.
Eldo® User's Manual, 15.3 31

Introduction to Eldo
Getting Started With the Eldo Simulation Flow
Figure 1-1. Cascaded Inverter Circuit
Figure 1-2. Inverter Subcircuit
The associated netlist for the simple cascade of three inverters is listed below:
* Netlist for cascade of three inverters
* MOS model definitions
.model m1 nmos level=3 vto=1v uo=550 vmax=2.0e5
+ cgdo=0.4p cgbo=2.0e-10 cgso=4.0e-11 cjsw=10.e-9
+ mjsw=0.3 tox=1.0e-7 nsub=1.0e16 nfs=1.5e10
+ xj=0.5u ld=0.5u pb=0.75 delta=0.9 eta=0.95
+ kappa=0.45 gamma=0.37
.model p1 pmos level=3 vto=-1v uo=230 vmax=1.9e5
+ cgdo=0.4p cgbo=2.0e-10 cgso=4.0e-11 cjsw=10.e-9
+ mjsw=0.3 tox=1.0e-7 nsub=1.0e16 nfs=1.5e10
+ xj=0.5u ld=0.5u pb=0.75 delta=0.9 eta=0.95
+ kappa=0.45 gamma=0.37
* Subcircuit definition
.subckt inv 1 2 3
m2 2 1 0 0 m1 w=10u l=4u ad=100p pd=40u as=100p
m1 2 1 3 3 p1 w=15u l=4u ad=100p pd=40u as=100p
c1 2 0 0.5p
.ends inv
32
Eldo® User's Manual, 15.3

Introduction to Eldo
Getting Started With the Eldo Simulation Flow
* Subcircuit calls
x1 1 2 6 inv
x2 2 3 6 inv
x3 3 4 6 inv
cload 4 0 1p
* Electrical source definitions
vdd 6 0 5v
vin 1 0 pulse(0 5 10e-9 5e-9 5e-9 30e-9 50e-9)
* Simulation options & commands
.tran 0.5n 100n uic
.ic v(1)=0
.plot tran v(1) v(2) v(3) v(4)
.print tran v(1) v(2) v(3) v(4)
.option eps=0.5e-3 tnom=50 list node
.end
Prerequisites
• The netlist file must include the following:
o
o
o
o
Circuit connectivity, that is, a netlist.
Model parameter values defining the specific device models to be used.
Electrical stimuli (sources).
Simulation options and commands.
Input and output formats are compatible with Berkeley SPICE 2G6, however Eldo
provides additional features not implemented in SPICE. See “Eldo Netlist Setup” on
page 95.
Procedure
1. Setup a netlist with the circuit description and simulation options and commands. You
may generate the .cir control file for Eldo using a basic text editor, or alternatively a
schematic editor capable of generating SPICE-like format.
See “Eldo Netlist Setup” on page 95.
2. Run Eldo on the netlist to simulate your design. To run a simulation from the command
line use the command:
eldo cir_file_name.cir
For a full list of options see “Running Eldo” on page 41.
3. Analyze the results of your simulation during or after simulation.
After the simulation has complete, Eldo writes simulator information to the .chi file.
This file contains details of the simulation, including any warning or error messages
which may have been encountered during simulation. A binary .wdb file is also
Eldo® User's Manual, 15.3 33

Introduction to Eldo
Getting Started With the Eldo Simulation Flow
generated by default as a simulation output. You can view the results written to the .wdb
file with the EZwave viewer, by opening it with the command:
ezwave cir_file_name.wdb
Figure 1-3 shows an example binary output file (.wdb) viewed with EZwave.
Figure 1-3. EZwave Output (.wdb)
See “Analyzing Simulation Results” on page 357.
Related Topics
Eldo Input and Output Files
Specifying Simulation Output
Output Files Generated
34
Eldo® User's Manual, 15.3

Eldo Input and Output Files
Introduction to Eldo
Eldo Input and Output Files
Summary of the input files that must be provided for an Eldo simulation run and the main output
files that Eldo produces.
Figure 1-4 shows the main input an output files used in the Eldo simulation flow.
Figure 1-4. Eldo Simulation Flow Input and Output Files
A brief description of each file type is provided below:
Input File
.cir The main Eldo control file, containing circuit netlist, stimulus and simulation control
commands. This file is SPICE compatible, the Eldo control language being a superset of the
Berkeley SPICE syntax.
Eldo® User's Manual, 15.3 35

Introduction to Eldo
Eldo Input and Output Files
.lib Optional file containing model or subcircuit definitions from library files for
inclusion in the input circuit netlist.
Output Files
.chi SPICE compatible output log file containing ASCII data, including results and error
messages.
.wdb A binary output file for mixed-signal JWDB format files. This is always generated
by default, and is viewed with the EZwave waveform viewer. By default, the .EXTRACT and
.MEAS waveforms are also saved inside the EXT folder in the waveform database. Waveforms
defined by .DEFWAVE commands combined with .PLOT are saved inside the appropriate
analysis folder (for example TRAN) in the waveform database.
.swd A saved windows file used by the EZwave waveform viewer. This file contains
information on: waveforms associated with the graph window; window size, position, axis and
background settings; complex waveform transformation settings; and waveform display and
cursor settings.
Tip
See Eldo Command Reference for a complete reference of Eldo commands, options, and
netlist syntax.
Related Topics
Getting Started With the Eldo Simulation Flow
Eldo Netlist Setup
Specifying Simulation Output
Output Files Generated
36
Eldo® User's Manual, 15.3

Introduction to Eldo
Eldo Documentation Access
Eldo Documentation Access
The Mentor Graphics Documentation System included with your software consists of a search
and navigational interface called InfoHub , and documents in PDF and HTML format.
You access the InfoHub documentation system using any of the following methods:
• Enter mgcdocs in a Linux or Windows shell window.
• Choose Start > Mentor Graphics > AMS_ > documentation in Windows.
The PDF documentation is supplied with a PDF bookcase and Adobe PDF index. These are
convenient if you only want to view the documentation in PDF format.
• To view the AMS bookcase, open the following file in a PDF reader:
$MGC_AMS_HOME/docs/pdfdocs/_bk_ams.pdf
• The Adobe PDF index is supplied to enable fast searching of the AMS PDF
documentation. To search the AMS PDF index using Adobe Reader, load the index from
a command line as follows:
acroread $MGC_AMS_HOME/docs/pdfdocs/ams_doc_index.pdx
The preceding command line assumes acroread is in your $PATH. The Acrobat Reader
Search dialog box opens with the index loaded and you can initiate your searches from
there.
Eldo® User's Manual, 15.3 37

Introduction to Eldo
Command Line Help
Command Line Help
Eldo PDF documentation is available from the command line, accessed using the -help
command line argument.
Syntax
eldo -help [user|ref]
Parameters
• user
Opens the Eldo User’s Manual as a PDF file.
• ref
Opens the Eldo Reference Manual as a PDF file.
Entering eldo -help without any option displays the list of available topics. You can specify
this argument without the cir_filename which is usually mandatory.
Related Topics
Invoking Eldo
Related Documentation
Other documents and manuals that are referenced in this manual, and that you may need to
reference are:
• Eldo Command Reference for a complete reference of Eldo commands, options, and
netlist syntax.
• Eldo Monte Carlo Quick Start manual for an overview of Monte Carlo analysis in Eldo.
• Eldo Device Equations Manual for a complete set of Eldo model equations.
• Eldo RF User’s Manual describes the extensions for RF simulation.
• Eldo RF Tutorials for a number of practical RF circuit simulation examples and
tutorials.
• Eldo UDM/GUDM User’s Manual describes the User Defined Model (UDM) and
Generalized User Defined Model (GUDM) interface.
• Eldo UDRM User’s Manual describes aging and reliability simulation.
• Eldo Verilog-A User’s Manual describes simulating with Verilog-A.
• Eldo cou Library User’s Manual describes the functional description for COU format
reading and writing.
• EZwave User’s and Reference Manual describes the EZwave waveform viewer.
38
Eldo® User's Manual, 15.3

Introduction to Eldo
Documentation Syntax Conventions
• AMS Results Browser User’s Manual describes the ASCII output file viewer.
• Questa ADMS User’s Manual describes the mixed-signal simulation environment.
• Questa ADMS Command Reference describes the mixed-signal simulation commands.
• ADiT User’s Manual describes the Fast-SPICE simulator.
Related Topics
Documentation Syntax Conventions
Documentation Syntax Conventions
The conventions described are used in combination with each other to describe the way you
must specify the syntax.
Table 1-1 lists the documentation syntax conventions used throughout the Eldo User’s Manual
both in the syntax and in the syntax descriptions.
Table 1-1. Documentation Syntax Conventions
USER INPUT Eldo netlist content is shown in courier non-bold typeface. Eldo is case
insensitive by default.
KEYWORD
S
Eldo keywords are shown in courier bold typeface. Eldo is case insensitive
by default.
Example: NONOISE is an Eldo keyword.
[ ] Brackets (square) indicate that a parameter is optional. Optional parameter
declarations may also be nested.
Example: [[DC] DCVAL] shows that the value parameter DCVAL is optional
with the possibility of specifying another optional keyword parameter DC.
{ } Braces (curly brackets) indicate multiple occurrences of a parameter.
Example: NN {NN} shows that the parameter NN may be specified more than
once. The parameter NN could be a node name for example.
{ } Certain syntax, for example expressions, have to be enclosed in braces (curly
brackets). In these cases, the braces are shown in bold to distinguish them
from the braces used above to indicate multiple occurrences. They are part of
the syntax.
Example: VALUE={2U*V(3, 4)*I(V5)} shows that VALUE is calculated by
the expression in braces.
Eldo® User's Manual, 15.3 39

Introduction to Eldo
Documentation Syntax Conventions
( ) Certain syntax, for example pairs of values or functions, must be specified
inside parentheses, often with a comma to separate values from one another.
They are shown in BOLD to avoid confusion with other parentheses. They are
part of the syntax.
Example: PULSE (V0 V1 [TD [TR [TF [PW [PER]]]]]) shows the parameter
specifications for a pulse function with BOLD parentheses ( ) to indicate that
all the parameters must be enclosed in parentheses.
, A comma separates pairs of values. It is shown in bold to indicate that it is
actually part of the syntax which must be specified.
Example: I(Vxx[, Vyy]) shows the syntax for obtaining the current difference
between the voltage sources Vxx and Vyy within the .PRINT command.
. Indicates the start of an Eldo command. All Eldo commands must begin with
a dot since it is part of the command syntax. The dot is shown in bold as well
as the command because it is considered part of the command keyword.
Example: .MODEL MNAME TYPE [PAR=VAL] shows the syntax for a
model declaration.
. An unbold dot indicates nodes or subcircuits within other subcircuits.
Example: .plot v(x2.x1.1) shows the plotting of node 1 which is inside
subcircuit x1 which is inside subcircuit x2.
< > Angle brackets sometimes indicate items which are not part of the syntax, but
which are descriptions, and so on.
Example:
......The angle brackets prevent the name
CIRCUIT_COMPONENTS from being confused with the Eldo syntax.
here simply means that between the dots, ...,
may be a number of different circuit components.
| The logical OR symbol indicates that one of the parameters must be chosen.
Example: R|C|I|V shows that either R, C, I or V must be chosen.
Example
Shows the syntax for a subcircuit definition:
.SUBCKT NAME NN {NN} [(ANALOG)] [PARAM: PAR=VAL {PAR=VAL}]
...
...
.ENDS [NAME]
.SUBCKT LIB FNAME SNAME [LIBTYPE]
Related Topics
Introduction to Eldo
Eldo Command Reference
Table 1-1. Documentation Syntax Conventions (cont.)
40
Eldo® User's Manual, 15.3

Chapter 2
Running Eldo
This chapter describes how to invoke Eldo and run simulations.
Invoking Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Running Eldo in 32-bit and 64-bit Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Multi-Threading Eldo Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Fast Launch Script for Small Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Simulation Connection Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Eldo Initialization File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Location Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Location Map Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Performance Bottleneck Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Statistics File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Statistics File Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Running Eldo Interactive Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Additional Tools and Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Invoking Eldo
To invoke Eldo and run a simulation from the command line use the eldo command:
eldo cir_filename.cir [arguments]
Where cir_filename is the name of the netlist control file (.cir) to be simulated. cir_filename is
mandatory. All other command line arguments are optional.
All setups described in this chapter are optional. You are encouraged to run your initial Eldo
simulations using the default settings before applying alternatives.
Tip
For a full list of arguments see “Eldo Arguments” in the Eldo Reference Manual.
Eldo® User's Manual, 15.3 41

Running Eldo
Running Eldo in 32-bit and 64-bit Modes
Running Eldo in 32-bit and 64-bit Modes
Eldo is available as 32-bit and 64-bit versions for Linux platforms. The 64-bit version enables
simulation of circuits which would require more than 2GB of memory, and which would
therefore not work on 32-bit machines. 64-bit mode is the default.
32-bit and 64-bit AMS software installed
If you have both 32-bit and 64-bit AMS software installed, by default Eldo and Eldo RF are
launched in 32-bit mode on 32-bit platforms and 64-bit mode on 64-bit platforms.
There are two ways to run 32-bit mode on 64-bit platforms:
• Specify the -32b command line argument; this overrides the setting of environment
variable $AMS_VCO_MODE.
• Set the environment variable AMS_VCO_MODE to the value 32, for example:
setenv AMS_VCO_MODE 32
To return to 64-bit mode: unset AMS_VCO_MODE or set it to 64; or specify the -64b
command line argument; this overrides the setting of environment variable
$AMS_VCO_MODE.
64-bit AMS software only installed
If you only have 64-bit AMS software installed, by default Eldo and Eldo RF are launched in
64-bit mode on a 64-bit platform. If you attempt to switch to 32-bit mode, an error will be
generated.
32-bit AMS software only installed
If you only have 32-bit AMS software installed, you can only run in 32-bit mode. If you attempt
to switch to 64-bit mode, an error will be generated.
Tip
See the “-32b” and “-64b” command line arguments in the Eldo Reference Manual.
Related Topics
Invoking Eldo
Multi-Threading Eldo Simulations
Eldo Initialization File
Multi-Threading Eldo Simulations
If you are using a multi-processor machine, you can instruct the Eldo simulator to share
computer resources to speed up simulation. This is known as multi-threading, and can be
42
Eldo® User's Manual, 15.3

Running Eldo
Multi-Threading Eldo Simulations
activated for DC, transient, RF and AC simulations. Eldo makes use of all the possible CPUs on
the machine, sharing the work between the different CPUs to speed up simulation.
Multi-threading is activated with the Eldo command line argument:
eldo -use_proc n | HALF | MAX k | ALL | HYPER | LSF
You can specify the number of processors n, half the processors, a maximum of k processors, all
processors except Hyper-Threading, all processors including Hyper-Threading processors, or
align the number of processors with the resource provided by an LSF external dispatcher.
(Hyper-Threading is not recommended because in many cases it can slow down simulation, see
“Notes” on page 45.)
Tip
See the “-use_proc” command line argument in the Eldo Reference Manual.
The number of CPUs being used is displayed at the beginning of the simulation (TRAN) and is
recorded in the statistics, generated at the end of simulation.
You can specify the -cntthread argument to provide more details about the computer
architecture, for example:
• Bi-Xeon dual core with no Hyper-Threading
Number of physical processors : 2
+ Hyper-Threading Technology : disabled
+ Number of cpu cores : 4
+ Number of logical processors : 4
• Bi-Opteron
Number of physical processors : 2
+ Hyper-Threading Technology : N/A
+ Number of cpu cores : N/A
+ Number of logical processors : N/A
• Bi-Xeon (PIV) with Hyper-Threading
Number of physical processors : 2
+ Hyper-Threading Technology : enabled
+ Number of cpu cores : 0
+ Number of logical processors : 4
Tip
See the “-cntthread” command line argument in the Eldo Reference Manual.
Eldo will make use of the multi-thread capability of the machine it is running on only if all the
following conditions are met:
• The -use_proc argument has been set.
Eldo® User's Manual, 15.3 43

Running Eldo
Multi-Threading Eldo Simulations
• The machine is a multi-CPU machine.
• The circuit contains devices which are thread-safe.
Eldo automatically computes if launching multi-threading is advantageous regarding the overall
device evaluation time. If it takes more time to wake-up the threads than computing the device
evaluations in one thread, then only one thread will be used.
If the circuit does not contain any thread-safe devices, multi-threading is ignored. Eldo provides
a notification when it cannot apply thread optimization on models, handles them in a single
processor. Thread-safe and non-thread-safe models can be used in the same circuit. See “Notes”
on page 45 for further information on thread-safe devices.
Eldo automatically adjusts the number of threads, and so the number of CPUs used, to minimize
the computation time. Eldo detects when other processes compete for resources, and decreases
the number of CPUs used if it will reduce computation time. Eldo also attempts to detect when
busy resources become available in order to use them. Eldo will never try to use more resources
than what has been specified with the -use_proc argument.
Note
Because this algorithm is always active, Eldo might use less threads than specified even on
a computer with no other active processes. The main purpose of the algorithm is to select the
number of threads that leads to the best performance; sometimes fewer is better.
Example Transcripts
When multi-threading is activated, the CPU time reported by Eldo is the sum of the CPU time
of all threads. This time will be much higher than the global elapsed time reported by Eldo. The
below example is an extract of a transcript showing this:
# ----- Summary run statistics ----
# Global Threads cpu Time 72h 27mn 31s 620ms
# Global Elapsed Time 47h 36mn 21s
Eldo prints information about the machine used for simulation including: clock frequency, the
number of cores, the number of threads used, and so on. Example output:
***** SYSTEM INFORMATION ...
44
Eldo® User's Manual, 15.3

Running Eldo
Multi-Threading Eldo Simulations
*** User : guest@machine
*** OS : Red Hat Enterprise Linux Client release 5.5 [VCO = ixl]
*** CPU :
Intel(R) Xeon(R) CPU
5130 @ 2.00GHz
Number of physical processors : 2
Hyper-Threading Technology : disabled
Number of cpu cores : 4
Number of logical processors : 4
*** Freq : 1995.089 MHz
*** Cache : 4096 KB
*** MEM : 4148040 kB
*** Date : Wed Oct 6 18:31:56 2010
When multi-threading is activated, the average number of threads used for the overall
simulation is printed at the end of the run.
Notes
• Thread-safe devices can be categorized as follows:
o
o
o
o
o
All MOSFET models are thread-safe except HVMOS and Mextram.
Verilog-A models are thread-safe when using the default Verilog-A flow.
Resistors, capacitors, diodes, and BJT models are thread-safe.
Sources and bias dependent objects are thread-safe.
User-defined models (UDM) are not thread-safe. If the model card leads to the
creation of access resistors, and if option NONWRMOS is specified, then the model
is not considered thread-safe.
• Using multi-threading is non-deterministic. Rounding can quickly accumulate because
floating-point computations suffer from rounding effects, and circuit simulators have to
perform millions of operations. With current hardware there is no way to guarantee
100% identical results when the arithmetic sequence changes. Multi-threading is one
case where the sequence of operations is not the same, and can therefore potentially
produce different results due to rounding.
• Multi-threading and DC computation
DC computation can be very sensitive to numerical noise (because of the algorithm
used), and as multi-threading cannot preserve the order of operations, it is possible to
obtain different DC computation times and even different DC solutions found from one
run to another. This can occur if the circuit has multiple valid DC points, and is the same
whether using multi-threading or not.
• Multi-threading and AC analysis
The part of the AC analysis related to matrix solving will be performed using multithreading.
The number of threads used is based on the number of operations that the
matrix solving requires and is dynamically computed. The number of threads cannot be
Eldo® User's Manual, 15.3 45

Running Eldo
Fast Launch Script for Small Simulations
greater than the -use_proc specification. The number of threads is automatically
adjusted at runtime to obtain the best computation time.
• Linux
When an application is multi-threaded on Linux, the “top” or “ps” operating system
commands may return misleading information, depending on the version of the library
libpthread.so provided with the Linux kernel. Each thread may appear as a separate
process, each of them consuming the same memory resources. You should consider that
the application only uses the resources indicated for one “process.” Do not consider the
addition of all indicated processes, which in reality correspond to the threads.
• Hyper-Threading
Selecting Hyper-Threading is not recommended because in many cases it can slow
down simulation. Hyper-Threading enables two logical CPU cores to be created for each
physical CPU core. However, it does not duplicate the main execution resources.
Simulation is a double precision computation intensive job and as there is basically one
processing unit per CPU core, selecting Hyper-Threading and putting a compute thread
on these logical units will not speed up the simulation. Simulation makes considerable
usage of the cache as well as the memory bandwidth, which becomes more stressed
using threads with Hyper-Threading, but on the other hand due to no additional floating
point units there will be no significant increase of floating operations using these extra
threads.
Related Topics
Tip
See also “Eldo Arguments” in the Eldo Reference Manual.
Invoking Eldo
Eldo Initialization File
Running Multiple Runs
Fast Launch Script for Small Simulations
By default, when simulating very small designs, the time taken by the common AMS script to
check that the environment is compatible can be longer than the simulation itself. To reduce the
time taken to launch Eldo for small simulations, you can use a utility script to create a
replacement Eldo fast launch script, valid for the local machine.
To create a new local fast launch version of Eldo, enter the command:
ams_localize eldo
46
Eldo® User's Manual, 15.3

Running Eldo
Simulation Connection Manager
This command checks the environment is compatible with the AMS tools, and if successful,
creates a script named eldo.local. You can then run your simulations with eldo.local instead of
the usual eldo command, with all the regular command-line arguments supported:
eldo.local cir_filename.cir [arguments]
This generated eldo.local script contains the minimum set of environment variables necessary
to run Eldo and the call to the executable. The script is machine dependent, which means that if
you want to submit multiple jobs on a computer farm you will have to generate the localized
script on each node of the grid and save it locally on the node.
Tip
See also “Eldo Arguments” in the Eldo Reference Manual.
Related Topics
Invoking Eldo
Simulation Connection Manager
You can dynamically add .PLOT or .PROBE commands while a batch simulation is running.
This is useful if a simulation is running for days and you realize when analyzing the marching
waveforms that you need additional waveforms to be plotted. You can send these new .PLOT or
.PROBE commands to simulations running on remote machines or submitted via dispatchers.
Procedure
1. To begin an interactive exchange to dynamically add .PLOT or .PROBE commands
while an Eldo simulation is running, run the simulation connection manager by entering
eldo -connect on the local machine.
eldo -connect
Eldo will browse the directory $HOME/.eldo/ in search of running simulations. The
active simulations are listed with their command line, for example:
Eldo® User's Manual, 15.3 47

Running Eldo
Simulation Connection Manager
+-----------------------------------------------------------------------------------
-------
| Id | Connection | Host | Simulator | Registration date | Input arguments
+-----------------------------------------------------------------------------------
-------
| 1 | | shamba | eldo | 2011-03-09 17:17:35 | test -outpath work
| 2 | | shamba | eldo | 2011-03-09 17:17:37 | test
| 3 | | shamba | eldo | 2011-03-09 17:18:19 | test
| 4 | | shamba | eldo | 2011-03-09 17:24:06 | test -outpath work
| 5 | | shamba | eldo | 2011-03-09 17:27:05 | test -outpath work
| 6 | | shamba | eldo | 2011-03-09 17:42:30 | test -outpath work
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
+------------------------------------------------------------ Page 1/1 (Home/End to
scroll)
command>
+-----------------------------------------------------------------------------------
-------
> help
This software provides the list of simulations submitted by the current user.
It allows to remotely interact with them.
Commands supported by this program:
connect, disconnect, kill, quit, load, help, clear
Type "help " for a detailed description of a command.
Commands supported by remote simulators:
.plot, .probe
Please refer to the simulator reference manual to have a complete description of
these commands.
+- Copyright 2011 Mentor Graphics Corporation. All rights reserved.
Page 1/1 (PgUp/PgDown to scroll) --
2. A prompt is displayed enabling you to interact with the remote simulations with the
following commands:
Table 2-1. Simulation Connection Manager Arguments
Argument
Description
help
Display the help.
connect
Open a communication channel with remote
simulation . The simulation is suspended
until the disconnect command is used or the
simulation connection manager is closed.
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Running Eldo
Simulation Connection Manager
Table 2-1. Simulation Connection Manager Arguments (cont.)
Argument
Description
disconnect [ | all]
kill [ | all]
.plot / .probe
load
quit | exit
clear
3. You can select the remote simulation, connect to it and enter the required .PLOT or
.PROBE commands with the usual Eldo syntax, for example:
$ eldo -connect
$ command> connect
$ command> .plot tran V()
$ command> exit
Close the communication channel with remote
simulation and resume the simulation. This
command only applies to connections in active/
opened state.
If is not specified, the command is sent to
the active simulation.
If ALL is specified, the command is sent to all
remote simulations with an open or active
communication channel.
Terminate the remote simulation causing the
simulation to end prematurely. This command
only applies to connections in active/opened state.
If is not specified, the command is sent to
the active simulator.
If ALL is specified, the command is sent to all
remote simulations with an open or active
communication channel.
Add a .PLOT or .PROBE command to the active
simulation.
Load the content of the specified file and send
each command to the active simulation.
Commands are filtered to send only those
supported (.PLOT/.PROBE) by the simulator.
Exit the simulation connection manager.
Reset the output transcript.
4. To disable remote access to a simulation specify -noconnect.
Note
The interactive exchange is only for outputs, not for inputs. It is not possible to force
signals during simulation with -connect.
Eldo® User's Manual, 15.3 49

Running Eldo
Simulation Connection Manager
Related Topics
Tip
See also “Eldo Arguments” in the Eldo Reference Manual.
Dynamically Adding Voltage/Current Plots
Invoking Eldo
50
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Running Eldo
Eldo Initialization File
Eldo Initialization File
Input for: Eldo system initialization
The eldo.ini file is the default initialization file containing some configuration options always
used for simulation. You can create an Eldo system initialization file to specify library paths and
simulator settings for inclusion in the .cir netlist file.
This Eldo initialization file is interpreted and loaded at the beginning of each simulation.
“Loading eldo.ini” is displayed whenever a valid eldo.ini file is found.
The search order is:
• Path specified by the environment variable $ELDO_INI_FILE_PATH.
• Current directory.
• $HOME directory.
Specifying the command line argument -noinit disables the loading of the eldo.ini file.
Format
• The beginning of each parameter block section is defined between brackets [].
• There is no mandatory order of the parameter blocks.
Parameters
The eldo.ini initialization file is organized into the following blocks:
• [env]
Contains the definition of environment variables.
• [argu]
Contains command line arguments, interpreted before any Eldo command line arguments,
Eldo command line arguments have higher priority.
• [netlist]
Contains netlist commands, interpreted as if they had been included in the netlist with a
.INCLUDE command.
• [include]
Contains include files. Multiple configuration files listed in this section are included. Only
one file per line is allowed. These files must use standard eldo.ini syntax and can themselves
define other [include] sections. An error is displayed if a recursive inclusion is detected. At
runtime, for each type of section, Eldo loads the corresponding sections from the files listed
in the [include] block, and appends the content of the current section at the end.
Examples
A typical eldo.ini file may look like:
Eldo® User's Manual, 15.3 51

Running Eldo
Eldo Initialization File
# This line is a comment
[env]
# There must be no blanks between variable name, equal sign
# and variable valueOPTION_DIR=.
MODEL_DIR=../models
LIB_DIR=../libs
[argu]
-outpath $OPTION_DIR/results
-gwl jwdb
-compat
[netlist]
.option noascii notrc
.include $OPTION_DIR/options.inc
.option post probe
An example with two levels of inclusion:
• File name: $HOME/eldo.ini. File content:
[argu]
-use_proc all
[include]
$HOME/config/command.ini
[netlist]
.probe i
• File name: $HOME/config/command.ini. File content:
[netlist]
.probe v
[include]
$HOME/config/option.ini
• File name: $HOME/config/option.ini. File content:
[netlist]
.option tuning=vhigh
The complete [netlist] section elaborated by the simulator is built from eldo.ini which includes
command.ini which itself includes option.ini. As a consequence, the final SPICE section
contains the lines from option.ini first, then the section from command.ini, and lastly from
eldo.ini, as below:
.option tuning=vhigh
.probe v
.probe i
Tip
See also “Eldo Arguments” and the “.INCLUDE ” command in the Eldo Reference Manual.
Related Topics
Invoking Eldo
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Running Eldo
Location Maps
Location Maps
Location maps are used to replace prefixes of physical pathnames with environment variables
(soft pathnames). The location map defines a mapping between physical pathname prefixes and
environment variables. Pyxis users can benefit from this functionality to run Eldo directly on an
Pyxis generated netlist.
By default, Eldo searches for a location map file in the following locations, in order:
• The filename specified by option USE_LOCATION_MAP in the .cir file, if not found
Eldo displays a warning message.
• The path stored in the environment variable $MGC_LOCATION_MAP.
• The netlist directory (./mgc_location_map).
• Your home directory (~/mgc_location_map).
When option USE_LOCATION_MAP is specified, a warning message is displayed if Eldo
does not find a location map file. When option USE_LOCATION_MAP is not specified, no
warning message is displayed by Eldo.
You can disable the load of the location map file by specifying the -ignore_location_map
command line argument or specifying the option IGNORE_LOCATION_MAP in the netlist.
Eldo® User's Manual, 15.3 53

Running Eldo
Location Map Structure
Location Map Structure
Input for: Eldo location map settings
The purpose of the location map file, in the Eldo context, is to be able to map a soft path with a
hard path.
Tip
See also “Eldo Arguments” and the “.OPTION USE_LOCATION_MAP” and “.OPTION
IGNORE_LOCATION_MAP” in the Eldo Reference Manual.
Format
The location map file structure is as follow:
• The first line is a header. This header is not mandatory with Eldo, which always ignores
the first line, but is necessary if the location map file has to be used inside Pyxis. In such
a case, refer to the Pyxis Project Manager User’s Manual (available on SupportNet) to
use the correct header.
• The file is then composed of a set of soft and hard pathnames, comments, and
INCLUDE pathname statements.
Parameters
• pathname
A soft pathname always begins with a dollar sign ($).
A hard pathname always begins with a slash (/).
A comment always begins with a pound sign (#).
You can specify one, several, or no hard pathnames for a soft pathname.
When a soft pathname is defined multiple times in the location map file, only the first
definition is used, others are ignored.
For a given soft pathname, if Eldo is unable to access to the specified hard pathname, a
warning message is generated (warning 939).
If a given soft pathname already exists as an environment variable, Eldo always uses the
value of the environment variable.
When multiple hard pathnames are given for a soft pathname, only the first one is used by
Eldo. That pathname must be visible from all computers that are going to use that location
map file. Defining multiple hard pathnames for one soft pathname is only valid in the
context of Pyxis because Pyxis can attempt, given a path, to find the mapped soft pathname.
As mount points can be different, according to the computer used and the network structure,
it might be necessary to specify all mount points of a given folder. Eldo only attempts to
expand a soft pathname into a hard pathname to resolve a file name (in a .INCLUDE
statement for example). This is why the first path has to be visible whatever computer is
54
Eldo® User's Manual, 15.3

Running Eldo
Performance Bottleneck Diagnostics
used on the network. More details are available in the Pyxis Project Manager User’s
Manual.
• INCLUDE
The optional INCLUDE keyword enables the inclusion of the contents of another file by
reference. The included files must not contain a header.
Examples
Here is an example mgc_location_map file, showing a soft pathname with no hard pathname, a
soft pathname mapped with two hard pathnames, and an include line:
MGC_LOCATION_MAP_2
#Here is a soft pathname with no hard pathname.
$REF_DIR
#Here is another soft pathname mapped with two hard pathnames.
$SOURCE_PROJECT
/home/user/projxxx
/mnt/remote_device/home/user/projxxx
#Here is an include file.
INCLUDE /usr2/home/maps/locmap2
For the soft pathname, $REF_DIR, with no hard pathname, there must be an environment
variable named REF_DIR; Eldo imports the hard pathname contained in that variable and maps
REF_DIR with that imported hard pathname.
Related Topics
Invoking Eldo
Performance Bottleneck Diagnostics
A set of diagnostics are available to help you understand why a circuit does not behave as
expected, or takes more time than expected to simulate.
These diagnostics can be triggered with the -diagmode command line argument as follows:
• -diagmode perf
Enables a set of performance diagnostics (command line argument -devcpu and
command .format_step_limiters) to help you understand why a circuit does not behave
as expected, or takes more time than expected to simulate. Equivalent to -debug.
• -diagmode conv
Enables the analysis of non-convergence issues. When Eldo stops because of a nonconvergence
a file is generated named .noconv, used as an input for the
convergence analysis. Supported by Eldo Classic only.
• -diagmode tstep
Eldo® User's Manual, 15.3 55

Running Eldo
Performance Bottleneck Diagnostics
Enables the analysis of time step management. Use this if Eldo performs too many
average Newton iterations or if it rejects too many time steps: if the ratio of accepted
time steps compared to rejected time steps is lower than six then specify this argument to
try to understand what is limiting the simulator.
Related Topics
Tip
See also “Running Eldo” in the Eldo Reference Manual.
Diagnosing Convergence and Performance Issues
Statistics File
Running Eldo
56
Eldo® User's Manual, 15.3

Running Eldo
Statistics File
Statistics File
The statistics output file from Eldo can be useful to understand how a design behaves and to
monitor node/device activity. It can help to monitor the simulation performance, determine
circuit size impact on simulation, debug simulation slowdown, and determine which nodes and
blocks should be treated for minimizing rejections.
Statistics File Generation
The statistics file can be generated by launching Eldo with the -stat argument.
-stat [-statfile filename [-statfsize val]]
-statfile filename [-statfsize val]
By default, the output file is named:
__.stat
where cir_filename is the name of the .cir netlist file to be simulated. For example, if you
execute the following Eldo command on March 24 2011 at 9.23am, a statistics file named
extract_overshoot_opamp_20110324_092325.stat will be generated:
eldo extract_overshoot_opamp.cir -stat
To specify a different filename, use the -statfile argument, for example, the following will
generate a statistics file named extract_overshoot_opamp.stat:
eldo extract_overshoot_opamp.cir -stat -statfile
extract_overshoot_opamp.stat
When -statfile is specified, -stat is optional.
The output file is generated in the directory where Eldo was launched. Specify the -outpath
argument to generate the statistics file in a different location.
Note
If a .ALTER command is specified in the netlist and a statistics file is requested, a single
statistics file is created for all the alter runs.
Statistics File Maximum Size
By default, a single statistics file is set to a maximum size of 50 MB. You can specify a different
maximum value using the -statfsize command line argument. If the maximum size is reached, a
new statistics file is created and a message appears in the transcript. The names of these files are
of the format:
__.
Eldo® User's Manual, 15.3 57

Running Eldo
Running Eldo Interactive Mode
where = 1, 2, 3, and so on. When the -statfile argument is specified, the date and time are
not appended to the output filename.
Example with the extract_overshoot_opamp.cir netlist delivered in the examples tree:
eldo -stat -statfile extract_overshoot_opamp.stat -statfsize 1
extract_overshoot_opamp.cir
Seven files (extract_overshoot_opamp.stat and extract_overshoot_opamp.stat.) will be
generated, where n is 1 through 6, each with a maximum size of 1kB.
Statistics File Options
To change the number of items to be listed in each of the Simulation sections of the statistics file
use .OPTION SPNNB=val. The default is 10. For example, .OPTION SPNNB=12 means every
list under “Simulation: Rejection node list” is limited to the “top 12” items.
To control the percentage threshold of the contributions from subcircuit instances, use
.OPTION SPNRAT=val. The default is 0.7 (70%), and the range is between 0 and 1.
Tip
See also “Eldo Arguments” in the Eldo Reference Manual.
Related Topics
Using the Statistics File
Invoking Eldo
Running Eldo Interactive Mode
Eldo interactive mode is a way of invoking Eldo and executing commands interactively instead
of providing the commands in a netlist. Some other AMS tools, such as ICanalyst, transparently
make use of Eldo in interactive mode. Eldo interactive mode is not supported by Questa ADMS.
Procedure
1. To invoke Eldo interactive mode, type:
eldo cir_filename -inter
where cir_filename is the name of the .cir netlist file to be simulated. Default extension
is .cir.
When working in Eldo interactive mode, a prompt is displayed in your terminal
window:
eldo>
2. When working in Eldo interactive mode, type your command after the eldo> prompt.
For continuation lines, type the backslash character (\) at the end of a line.
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Running Eldo
Additional Tools and Utilities
3. To view help information, at the eldo> prompt type:
help
to see the list of available commands.
help
for more information about a particular command.
help all
to obtain the complete help listing.
Related Topics
Tip
See also “Eldo Arguments” in the Eldo Reference Manual.
Eldo Interactive Mode
Additional Tools and Utilities
Encryption tools and conversion utilities are available with Eldo.
• “Encrypting Libraries” on page 139
• “Eldo Conversion Utilities” on page 1469
Eldo® User's Manual, 15.3 59

Running Eldo
Additional Tools and Utilities
60
Eldo® User's Manual, 15.3

Chapter 3
Eldo Premier
This chapter details the high performance Eldo simulation kernel dedicated to transient
simulation: Eldo Premier.
Overview of Eldo Premier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Enabling Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Automatic Activation of Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Using Eldo Classic DC Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Handling Matrix-Like Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Solver Generation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Eldo Premier Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Temporary Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Generic Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Forcing Elaboration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Eldo Premier Selectable Accuracy Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Netlist Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Supported Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Supported Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Supported Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Other Supported Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Miscellaneous Limitations of Devices and Features in Eldo Premier . . . . . . . . . . . . . . . . 93
Overview of Eldo Premier
The Eldo Premier simulator provides an increase in performance and capacity without
sacrificing accuracy compared to Eldo Classic. It accelerates the simulation of large circuits in
either pre-layout or post-layout phases by using sophisticated resolution techniques which do
not sacrifice accuracy compared to the “golden SPICE” (Eldo Classic) results. Eldo Premier
supports much larger circuits, up to ten million devices, compared to Eldo Classic. The easy use
model of Eldo Classic is preserved.
The Eldo Premier simulator accelerates both single-thread simulations and multi-thread
simulation. The acceleration of single-thread simulation is provided by new algebraic
techniques for the resolution of the system of non-linear differential equations that analog
simulators must solve. The acceleration of multi-threaded simulations is a consequence of the
natively parallel code of the Eldo Premier simulation kernel and its dedicated data structures.
These two acceleration factors naturally combine to offer a very significant speedup over Eldo
Classic. The most significant speedups are observed for large circuits (typically at least 10,000
devices) that exhibit some degree of hierarchical regularity.
Eldo® User's Manual, 15.3 61

Eldo Premier
Overview of Eldo Premier
Boosting performance over standard analog simulation can help in two ways. Critically
important simulations that require extremely long simulations times, sometimes measured in
days or weeks, can be reduced very significantly.
Together with the performance improvements for verification tasks, the additional simulation
power can be used to run many more corners or operating conditions, and thus verify a design or
analog IP block much more thoroughly. For example, it may become practical to verify an
entire temperature range or power-supply range instead of just the nominal point of the
specifications. This can dramatically improve the confidence in the design or IP before tape-out,
with the goal of eliminating silicon re-spins, and improving the final manufacturing yield.
Some of the features and benefits of the Eldo Premier simulator include:
• Raw performance improvement over Eldo Classic, on both single-core and multi-core
machines.
• Same golden accuracy as Eldo Classic.
• Much higher capacity (factor of 10) than Eldo Classic.
• Much better scalability of the multi-thread performance.
• Same device models and libraries as Eldo Classic.
• Same use model as Eldo Classic.
• Supports .EXTRACT, .MEAS, .STEP, .ALTER, and .CHECKSOA commands of Eldo
Classic.
• Supports RCC parasitic network reduction.
• Integrated in Questa ADMS for mixed-signal verification including VHDL/Verilog and
VHDL-AMS/Verilog-AMS descriptions, see “vasim -premier” in the Questa ADMS
Reference Manual.
Note
Eldo Premier is only supported on Linux platforms. It is not supported on Windows
platforms.
Target Applications
The Eldo Premier simulator targets applications that require CPU-intensive DC and transient
simulations, such as PLLs and DLLs, frequency synthesizers, delta-sigma converters, ADC/
DAC audio and video converters, automotive circuits, DC-DC converters, regulators, power
management circuits, memory critical paths analysis, and TFT/OLED panels.
The scope of applicability is the same as Eldo Classic because the algorithms do not presuppose
any particular structure within the simulated circuit. The much higher capacity of Eldo
Premier opens new possibilities in the field of memory (SRAM/DRAM) and TFT/OLED panel
62
Eldo® User's Manual, 15.3

Eldo Premier
Overview of Eldo Premier
simulation—see “Handling Matrix-Like Circuits” on page 67—which often challenge the raw
capacity of traditional analog simulators.
Eldo Premier Example
An example netlist, named ram8k.cir, is provided in:
$MGC_AMS_HOME/examples/eldop/ram8k/
where $MGC_AMS_HOME is the directory where the AMS software resides.
Run the example with the command:
eldo ram8k.cir -premier
You should see a speed-up of approximately 3× compared with Eldo Classic (comment out the
line .OPTION PREMIER).
Related Topics
Eldo Premier Output
Netlist Support
Eldo® User's Manual, 15.3 63

Eldo Premier
Enabling Eldo Premier
Enabling Eldo Premier
To activate Eldo Premier, use either of the following methods:
• Specify .OPTION PREMIER inside the netlist.
• Use the -premier command line argument when invoking Eldo.
Eldo Premier supports most of the same SPICE netlists and commands as Eldo Classic. Eldo
Premier is available for DC and transient simulations. When activated, the entire circuit is
simulated by the Eldo Premier kernel; nothing is solved by the Eldo Classic or ADiT kernels.
Some simulations (AC and noise for example) cause Eldo Classic to be activated (see
“Supported Commands” on page 74).
The command line flag, -use_proc, activates multi-threaded simulation on multi-core machines.
You can request a specific number of cores, half of those available, or all of them. The number
of cores is limited to 16.
The Eldo Premier simulator runs DC and transient analysis, including the save and restart
capabilities (frequency based analyses perform well in Eldo Classic).
Automatic Activation of Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Using Eldo Classic DC Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Handling Matrix-Like Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Solver Generation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Automatic Activation of Eldo Premier
You can set Eldo (or Questa ADMS) to automatically choose the most appropriate and efficient
simulation kernel between Eldo Classic and Eldo Premier, based on the characteristics of the
netlist (number of nodes, number of devices, connectivity, commands).
To enable automatic Eldo Premier activation, use either of the following methods:
• Specify .OPTION AUTO[_SELECT] inside the netlist.
• Specify the -auto[_select] command line argument when invoking Eldo.
The weight of the following criteria is evaluated to decide which kernel to select automatically:
• Number of nodes
The more nodes the netlist contains, the more likely it is that Eldo Premier is selected. If
the netlist contains more than 1 million nodes, then Eldo Premier is always selected; if
the netlist contains less than 500 nodes, then Eldo Classic is always selected.
• Number of devices
64
Eldo® User's Manual, 15.3

Eldo Premier
Automatic Activation of Eldo Premier
The more devices the netlist contains, the more likely it is that Eldo Premier is selected.
If the netlist contains more than 3 million devices, then Eldo Premier is always selected;
if the netlist contains less than 1500 devices, then Eldo Classic is always selected.
• Highly connected netlist
For a given number of nodes, the more devices the netlist contains, the more likely it is
that Eldo Premier is selected.
• High proportion of transistors
If the netlist contains a high proportion of transistors then Eldo Premier is more likely to
be selected.
• Well-balanced hierarchy
Eldo Premier is more likely to be selected if the netlist is hierarchical than if the netlist is
flat.
• Transient analysis (.TRAN) in the netlist
If the netlist does not contain a .TRAN command, then Eldo Premier is less likely to be
selected.
• .OPTION PREMIER_MODE in the netlist
If the netlist contains option PREMIER_MODE with a value greater than or equal to 1,
then Eldo Premier is more likely to be selected.
Tip
See also “Eldo Premier Options” in the Eldo Reference Manual.
Limitations
• Eldo is able to detect when the netlist contains commands or devices not supported by
Eldo Premier and in such a case will never activate Eldo Premier, except for the
following limitation:
o
Eldo Premier does not support controlled devices controlled by anything other than
net voltage, voltage source current, or current through resistance. Eldo is not able to
detect this case and may activate Eldo Premier although this will cause Eldo Premier
to stop with an error. The workaround is to run the netlist with .OPTION CLASSIC
inside the netlist or use the -classic command line argument when invoking Eldo.
• Eldo does not check if the extra license needed to run Eldo Premier is available before
activating Eldo Premier. If the license is not available once Eldo Premier has been
activated, then Eldo Premier will stop with an error (except if the -queue flag is
specified). If you do not have enough licenses to run Eldo Premier, then do not attempt
to use .OPTION AUTO or the -auto command line argument.
Eldo® User's Manual, 15.3 65

Eldo Premier
Using Eldo Classic DC Solution
Related Topics
Using Eldo Classic DC Solution
Handling Matrix-Like Circuits
Solver Generation Methods
Eldo Premier Selectable Accuracy Option
Netlist Support
Using Eldo Classic DC Solution
To help speed up the DC solution, specify .OPTION PREMIER_FORCE_ELDO_DC. An Eldo
Classic DC solution is computed and saved into a .iic file. Eldo Premier is then activated and
uses this DC solution to run the simulation.
This option can be specified by default by placing it inside the eldo.ini file, see “Eldo
Initialization File” on page 51. It has no effect if a .USE or .RESTART command is present in
the netlist.
By default, if Eldo Premier finds an existing .iic file, generated during a previous run of the
same netlist, then it will reuse it. To force Eldo Premier to recompute the DC solution and
regenerate the .iic file, specify: .OPTION PREMIER_REUSE_AUTOSAVED_IIC_FILE=0.
To save the DC results in the .wdb file, specify the following commands in your netlist:
.PROBE DC ALL
By default when .OPTION PREMIER_FORCE_ELDO_DC is active, Eldo Premier uses the
DC computed by Eldo Classic as .NODESET commands and performs the .TRAN command as
specified in the netlist. To force Eldo Premier to use the DC computed by Eldo Classic as .IC
commands and perform a .TRAN UIC command, specify
.OPTION PREMIER_USE_IC_TRAN_UIC=1.
Tip
See also “Eldo Premier Options” in the Eldo Reference Manual.
Limitations
Using the Eldo Classic DC solution in Eldo Premier is not supported for the following:
• .TEMP commands in Questa ADMS Premier: a warning message is displayed and the
simulation is run for only the first temperature.
• .STEP, .ALTER, and .MPRUN commands.
• Eldo Control Language.
66
Eldo® User's Manual, 15.3

Eldo Premier
Handling Matrix-Like Circuits
Related Topics
Handling Matrix-Like Circuits
Overview of Eldo Premier
Eldo Premier Output
Netlist Support
Handling Matrix-Like Circuits
To activate dedicated Eldo Premier algorithms performing matrix processing for the simulation
of “matrix-like” circuits, specify .OPTION PREMIER_MATRIX. This is specifically adapted
to the simulation of circuits with a regular structure such as an array of pixels and with highly
connected power grids. Due to their particular matrix structure, display panel circuits (TFT,
OLED) belong to this category of circuits. This option is of no interest to regular circuits
without dense power networks.
This option removes the bottlenecks associated with parsing, elaboration, partitioning, solver
generation, and simulation. The simulation solution is fast, accurate, and handles all the
physical effects described in the circuit, for example: coupling between rows and columns, IR
drop due to ground and power networks, row and column access resistors. This option is useful
for matrix-like circuits that cannot be handled by Eldo Classic; using this option consumes less
memory.
If this option is specified and the circuit is considered matrix-like, matrix processing is enabled,
and the following note is displayed:
Matrix processing is on.
If this option is specified but the circuit is not matrix-like, Eldo Premier disables the matrix
processing and displays the following note:
Matrix option was set by user, but matrix processing has been disabled by
the simulator.
Tip
See also “Eldo Premier Options” in the Eldo Reference Manual.
Limitations
• Only display circuits (TFT, OLED) are handled.
• The total power dissipation at DC is not computed (0 W is displayed).
• If many waveforms are generated, it may be useful to increase the heap size for EZwave,
see “Troubleshooting Memory Issues” in the EZwave User’s and Reference Manual.
For example:
Eldo® User's Manual, 15.3 67

Eldo Premier
Solver Generation Methods
setenv AMS_JAVA_MEMORY_HEAP "-Xms100G -Xmx100G"
Related Topics
Overview of Eldo Premier
Eldo Premier Output
Netlist Support
Solver Generation Methods
By default, Eldo Premier uses a Just-In-Time (JIT) method for solver generation. The solver is
generated in memory instead of on hard disk. In case of issues with elaboration, disable this
method with option PREMIER_NOFASTGEN.
With this method disabled, to reduce the Eldo Premier elaboration time use the Linux built-in
RAM disk storage. Enable the RAM disk feature to perform solver generation and compilation
in either of the following ways:
• Command-line argument -premier_shm.
• Netlist option .OPTION PREMIER_SHM.
It is automatically disabled when the estimated generated code size exceeds the available space
in the RAM disk file system.
Tip
See also “Eldo Premier Options” in the Eldo Reference Manual.
Related Topics
Overview of Eldo Premier
Eldo Premier Output
Netlist Support
68
Eldo® User's Manual, 15.3

Eldo Premier
Eldo Premier Output
Eldo Premier Output
Normal Eldo commands are used to plot and/or probe signals. It supports the same waveform
output formats as Eldo, with .wdb being the default.
The simulation results of Eldo Premier are output to the .chi file in the same way as Eldo
Classic. It can also produce the usual Eldo output files, including .aex, .mt0, and so on; any postprocessing
scripts written for Eldo can be reused without modification.
Some Eldo Premier notes are generated in the transcript and .chi file providing information
about the simulation and flow:
• Parsing
• Generation
• Elaboration
• Solver generation
• DC
• Transient
Temporary Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Generic Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Forcing Elaboration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Temporary Files
To help speed up successive runs, Eldo Premier generates some specific temporary directories
and files:
• .res directory
Resolution library. Contains information to help speed-up the elaboration of the circuit
before simulation. Some resources in the .res directory are reused for consecutive
simulation runs of the same—or slightly modified—netlist, enabling a significant
reduction in elaboration time.
• .hbp file
Contains information related to the hierarchy structure of the design. The information is
reused for consecutive simulation runs of the same—or slightly modified—netlist,
enabling a significant reduction in elaboration time.
Eldo Premier simulations can sometimes generate huge temporary directories; it can be useful
to store output results and temporary files in different locations. To define the location where
Eldo Premier temporary files are generated, specify command line argument -tmpoutpath. By
Eldo® User's Manual, 15.3 69

Eldo Premier
Generic Outputs
default, temporary files are created in the same directory defined by the -outpath argument. If
neither -tmpoutpath nor -outpath are specified, temporary files are created in the same directory
as the .cir input file.
To remove the .res directory at the end of simulation, specify command line argument
-premier_remove_reslib or netlist option PREMIER_REMOVE_RESLIB.
Related Arguments
• -tmpoutpath in the Eldo Reference Manual
• -outpath in the Eldo Reference Manual
• -premier_remove_reslib in the Eldo Reference Manual
Generic Outputs
The syntax for probes, plots and extracts allows the user to write generic output requests, that
are expanded by the simulator to a set of outputs. For example:
.PROBE V
.PROBE I
.PROBE V(X1.*)
For performance reasons, it is not guaranteed that all outputs are available for such generic
output requests. When generic outputs are requested, some outputs may be missing (see
.removed for a listing) and the following warning message is displayed:
Warning 1021249: Due to elaboration optimizations, some outputs may not be
+ available.
+ This is related to the use of generic probes such as .PROBE V, .PROBE I
+ or the wildcard character.
+ The list of removed outputs is written to file ``.removed''.
+ Explicit probe can be used to enforce the availability of an output
+ voltage or current.
+ Option premier_keep_outputs can also be used to enforce the availability
+ of all outputs. However, this option may significantly slow down the
+ simulation.
You can specify explicit probes instead, as required. For backward compatibility, if you want to
generate all outputs, specify option PREMIER_KEEP_OUTPUTS. This may significantly slow
down the simulation, in which case a warning is displayed:
Warning 1021250: Option premier_keep_outputs may significantly slow down
+ the simulation.
+ It is recommended to use explicit probes instead of it, and as few
+ explicit probes as really needed.
70
Eldo® User's Manual, 15.3

Eldo Premier
Forcing Elaboration
Tip
See also “.OPTION PREMIER_KEEP_OUTPUTS” in the Eldo Reference Manual.
Forcing Elaboration
Eldo Premier stores results of the elaboration in the output directory. If the simulation is
restarted, Eldo Premier does not re-elaborate the circuit for parts of the netlist which have not
changed. Use option PREMIER_FORCE_GEN to force Eldo Premier to elaborate the whole
circuit instead of reusing the previous elaboration results.
This option may be necessary if there was an error during the first elaboration (for example disk
full, NFS error, data corrupted).
Tip
See also “Eldo Premier Options” in the Eldo Reference Manual.
Related Topics
Overview of Eldo Premier
Enabling Eldo Premier
Eldo Premier Selectable Accuracy Option
Netlist Support
Eldo Premier Selectable Accuracy Option
You can specify a global macro-option to control accuracy in Eldo Premier simulations.
It has an impact on the following:
• Accuracy tuning
• Device model optimization
• Small R and C simplification
• Reduction activation
The option PREMIER_MODE can be set to five distinct values; OFF and 1 to 4, where 1 is the
most accurate and slowest mode, and 4 is the least accurate and fastest. Syntax:
.OPTION PREMIER_MODE=OFF|1|2|3|4
The global macro-option, PREMIER_MODE, triggers specific combinations of actions
according to Table 3-1, enabling a gradual speed/accuracy trade-off with monotonous behavior.
Each individual action may be activated/deactivated through a specific option.
Eldo® User's Manual, 15.3 71

Eldo Premier
Eldo Premier Selectable Accuracy Option
Table 3-1. Option PREMIER_MODE Effect
PREMIER_MODE OFF 1 2 (Default) 3 4
Option
Tuning
(.OPTION TUNING)
Device Model
Optimization
(.OPTION
ELDO_MODEL_MOD
E)
Mininum R val
(.OPTION
MINRVAL.OPTION
RMMINRVAL)
Split C val
(.OPTION SPLITC)
Reduction
(.OPTION
ELDO_REDUCTION_
MODE)
The default value of option PREMIER_MODE is 2 for Eldo Premier, which provides a
balanced speed/accuracy trade-off. This option is equivalent to the Eldo command line
argument -premier_mode. This option is not available in Eldo Classic, it is deactivated.
The actions and associated options are as follows:
• Accuracy tuning
Default
(standard)
or
specified
Selects the default mode of operation of Eldo as regards to precision and speed.
• Device model optimization
Accurate
or
specified
Device models are optimized with an average speed-up of 30%, on the total transient
simulation time, compared to simulation with standard models. Device model
optimization is disabled in a circuit with high voltage (above 6V) sources detected.
• Removal of small linear resistors and floating capacitor simplification
Simulation is accelerated by removing linear resistors and simplifying floating
capacitors with values below a given threshold.
• Default activation of reduction in Eldo Premier
Default
(standard) or
specified
Default
(standard) or
specified
No Yes Yes Yes Yes
Fast or
specified
No 1 mΩ 1 mΩ 1 mΩ 1 mΩ
No 10 −18 F 10 −17 F 10 −16 F 10 −16 F
No No Frequency=
1/hmin
Analog=yes
Estimated
frequency
Analog=yes
Estimated
frequency
Analog=no
72
Eldo® User's Manual, 15.3

Netlist reduction is activated with the corresponding setup.
Related Topics
Eldo Premier
Eldo Premier Selectable Accuracy Option
Tip
For further information, see “.OPTION PREMIER_MODE” in the Eldo Reference
Manual.
Overview of Eldo Premier
Enabling Eldo Premier
Netlist Support
Eldo® User's Manual, 15.3 73

Eldo Premier
Netlist Support
Netlist Support
Eldo Premier supports a subset of the commands, options, and device models that the Eldo
kernel supports but, given Eldo Premier’s transient-centric nature, there are a number of
unsupported elements.
Supported Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Supported Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Supported Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Other Supported Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Miscellaneous Limitations of Devices and Features in Eldo Premier. . . . . . . . . . . . . . . 93
Supported Commands
Most Eldo commands are supported by Eldo Premier. Some unsupported commands are
ignored; others cause an automatic switch to Eldo Classic.
• For unsupported commands that are ignored, Eldo Premier displays a warning message
informing you the command is not supported.
• For unsupported commands causing an automatic switch to Eldo Classic, for example
.AC and .SST, Eldo Premier generates a warning informing you the command has
caused Eldo Premier to be deactivated.
Note
All Eldo RF commands are unsupported causing an automatic switch to Eldo
Classic.
Error and warning messages specific to Eldo Premier are listed in “Errors Related to Eldo
Premier” on page 1408 and “Warnings Related to Eldo Premier” on page 1450.
Table 3-2 lists all Eldo commands and shows which are supported by Eldo Premier. Links are
provided to the full syntax description for each in the Eldo Reference Manual.
Table 3-2. Eldo Analysis Command Support in Eldo Premier
Command
Eldo Premier
Support?
Command
Eldo Premier
Support?
.AC Switch to Eldo Classic .ACTIVITY Yes
.ADDLIB Yes .AGE Yes
.AGE_LIB Yes .AGE_SENSITIVITY Yes
.AGEMODEL Yes .ALTER Yes
74
Eldo® User's Manual, 15.3

Eldo Premier
Supported Commands
Table 3-2. Eldo Analysis Command Support in Eldo Premier (cont.)
Command
Eldo Premier
Support?
Command
Eldo Premier
Support?
.BIND Yes .BINDSCOPE Ignored
.CALL_TCL Yes .CHECKBUS Yes
.CHECKSOA Yes .CHRENT Yes
.CHRSIM Yes .COMCHAR Yes
.COMPAT Yes .CONNECT Yes
.CONSO Ignored .CORREL Switch to Eldo Classic
.CORREL EXPR Switch to Eldo Classic .DATA Yes (see .STEP /
.DATA / SWEEP
Limitations in Eldo
Premier)
.DC
Yes (See DC
Analysis in Eldo
Premier)
.DCHIZ
.DCMISMATCH Ignored .DEFAULT Yes
.DEFINE_GROUP Yes .DEFINE_TASK Yes
.DEFINE_TESTBENCH Yes .DEFMAC Yes
.DEFMOD Yes .DEFPARAM Yes
.DEFPLOTDIG Yes .DEFWAVE Yes
.DEL Yes .DEX Ignored
.DISCARD Yes .DISFLAT Ignored
.DISTRIB Ignored .DSP Yes
.DSPF_INCLUDE Yes .DSPMOD Ignored
.EIL Ignored .ELDO_CL_MPRUN Yes
.ELSE Yes .ELSEIF Yes
.END Yes .ENDCOMPAT Yes
.END_GROUP Yes .ENDIF Yes
.ENDINLINE Yes .ENDL Yes
.ENDS Yes .EQUIV Ignored
.EXTMOD Yes .EXTRACT Yes
.FFILE Ignored .FILTER Ignored
Yes
Eldo® User's Manual, 15.3 75

Eldo Premier
Supported Commands
Command
Table 3-2. Eldo Analysis Command Support in Eldo Premier (cont.)
.FORCE Ignored .FORMAT_STEP_LIMI
TERS
.FOUR Yes .FUNC Yes
.GLOBAL Yes .GUESS Yes
.HDL Ignored .HIER Yes
.HISTOGRAM Yes .HIZ Yes
.HIZ_CFG Yes .IC Yes
.IF Yes .IGNORE_DSPF_ON_
NODE
.INCLUDE Yes .INIT Yes
.INLINE Yes .IP_PROTECT Yes
.IPROBE Switch to Eldo Classic .LIB Yes
.LOAD Ignored .LOCALTOL Yes
.LOOP Ignored .LOTGROUP Ignored
.LSTB Switch to Eldo Classic .MALIAS Yes
.MAP_DSPF_NODE_N
AME
Yes
Yes
Ignored .MC Yes
.MCMOD Ignored .MEAS Yes
.MODEL Yes .MODLOGIC Yes
.MONITOR Yes .MPRUN Yes
.MSELECT Yes .NEWPAGE Yes
.NOCOM Yes .NODESET Yes
.NOISE Switch to Eldo Classic .NOISE_CORREL Ignored
.NOISETRAN
Eldo Premier
Support?
Yes (subset, see
Transient Noise
Analysis in Eldo
Premier)
Command
.NOTRC
.NOTRCMOD Yes .NWBLOCK Ignored
.OBJECTIVE Yes .OP Yess (see Operating
Point Analysis in Eldo
Premier for
limitations)
.OP_DISPLAY Yes .OPTFOUR Yes
Eldo Premier
Support?
Yes
76
Eldo® User's Manual, 15.3

Eldo Premier
Supported Commands
Table 3-2. Eldo Analysis Command Support in Eldo Premier (cont.)
Command
Eldo Premier
Support?
Command
Eldo Premier
Support?
.OPTIMIZE Yes .OPTION Yes
.OPTNOISE Ignored .OPTPWL Yes
.OPTWIND Yes .PARAM Yes
.PARAMDEX Ignored .PARAMOPT Switch to Eldo Classic
.PART Switch to Eldo Classic .PLOT Yes
.PLOTBUS Yes .PLOTWIND Yes
.POWER_ANALYSIS Yes .PRINT Yes
.PRINTBUS Yes .PRINTFILE Yes
.PROBE Yes .PROBEBUS Yes
.PROTECT Yes .PZ Ignored
.RAMP Yes .RAMP_SUPPLY Yes
.REDUCE
Yes (subset, see RC
Reduction in Eldo
Premier)
.REPORT_HEATING
.RESTART Yes .SAVE Yes
.SCALE Yes .SCOPE Yes
.SELECT_DSPF_ON_N
ODE
Ignored .SENS Switch to Eldo Classic
.SENS TRAN Switch to Eldo Classic .SENS AC Ignored
.SENSPARAM Ignored .SETBUS Yes
.SETKEY Yes .SETSOA Yes
.SIGBUS Yes .SINUS No
.SNF Switch to Eldo Classic .SOLVE Switch to Eldo Classic
.SPEF_INCLUDE Yes .START_TIME Yes
.STEP Yess (see .STEP /
.DATA / SWEEP
Limitations in Eldo
Premier)
.SUBCKT
.SUBDUP Switch to Eldo Classic .TABLE Yes
Yes
Yes
Eldo® User's Manual, 15.3 77

Eldo Premier
Supported Options
Table 3-2. Eldo Analysis Command Support in Eldo Premier (cont.)
Command
Eldo Premier
Support?
Command
Eldo Premier
Support?
.TCL_WAVE Yes .TEMP Yes (see
Temperature
expression
limitation)
.TEMPNODE Yes .TF Ignored
.TITLE Yes .TOPCELL Yes
.TRAN Yes .TSAVE Yes
.TVINCLUDE Yes .UNPROTECT Yes
.USE Yes .USEKEY Yes
.USE_TCL Yes .USE_VERILOGA Yes
.VEC Yes .VERILOG Yes
.WCASE Switch to Eldo Classic .WIDTH Yes
Related Topics
Overview of Eldo Premier
Enabling Eldo Premier
Eldo Premier Output
Netlist Support
Supported Options
Most Eldo options are supported by Eldo Premier. All unsupported options are ignored, and
Eldo Premier displays a warning message informing you the option is not supported.
Table 3-3 lists all Eldo options and shows which are supported by Eldo Premier, and which are
not (ignored). For full descriptions, see the “Simulator and Control Options” chapter in the Eldo
Reference Manual.
Table 3-3. Eldo Premier—Supported Options
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
ABSOLUTE_HMIN No ABSTOL Yes
ABSVAR Yes ACCSEMICOL Yes
78
Eldo® User's Manual, 15.3

Table 3-3. Eldo Premier—Supported Options (cont.)
Eldo Premier
Supported Options
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
ACDERFUNC No ACM Yes
ACNOISE_FILE No ACOUT No
ACSIMPROG No ADIT_CHECK Yes
ADJSTEPTRAN Yes ADMSBS No
ADMSMCDEVSEV - AEX Yes
AIDSTP No ALIGNEXT Yes
ALTCROSS - ALTER_ADDSTEP No
ALTER_NOMINAL_TEXT Yes ALTER_SUFFIX Yes
ALTERELDO Yes ALTINC Yes
AMMETER No ANALOG No
ASCII Yes ASCIIPLOT Yes
ASPEC Yes AUTO[_SELECT] Yes
AUTOCTYPE Yes AUTOSTOP Yes
AUTOSTOPBUS Yes AUTOSTOPMODULO Yes
BACKUP_ELDO_CL_NETLIS
TS
No BE Yes
BLK_SIZE No BLOCKS=IEM No
BLOCKS=NEWTON No BSIM3VER Yes
BSIMCMG_OPT Yes BSIM4SOI_OPT Yes
BSLASHCONT Yes CAPANW Yes
CAPTAB No CARLO_GAUSS No
CATMX No CATMX_REPORT -
CHECKDUPL No CHGTOL Yes
CKDCPATH No CLASSIC Yes
COLLAPSE_DSPF_OUTPUT No COMPAT Yes
COMPEXUP Yes COMPMOD Yes
COMPNET Yes CONTINUE_INCLUDE Yes
CONTINUOUS_FFT Yes COU Yes
CPTIME Yes CSDF Yes
Eldo® User's Manual, 15.3 79

Eldo Premier
Supported Options
Table 3-3. Eldo Premier—Supported Options (cont.)
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
CSHUNT Yes CTEPREC Yes
CTYPE Yes DCC_TUNING Yes
DCLOG No DCPART No
DCSIMPROG No DEFAD Yes
DEFAS Yes DEFAULTFALLTIME Yes
DEFAULTRISETIME Yes DEFL Yes
DEFNRD Yes DEFNRS Yes
DEFPD Yes DEFPS Yes
DEFPTNOM Yes DEFRMSNTR No
DEFW Yes DEPSRC_PWL_INTER Yes
DEPSRC_PWL_LOG Yes DICPRIO Yes
DIGITAL No DIS_EXP_LIM Yes
DISPLAY_CARLO No DOTNODE No
DPTRAN Yes DSCGLOB Yes
DSPF_LEVEL Yes DUMP_EXTRACT Yes
DUMP_FILE_LIST Yes DUMP_MCINFO No
DUMP_MCINFO_CONF No DUMP_MCINFO_SENS No
DVDT No DYND2ANALOG No
DYND2ANALOG2 No ELDO_MODEL_MODE Yes
ELDO_REDUCTION_MODE Yes ELDOMOS Yes
EMPTY_MCHISTO No ENGNOT Yes
EPS Yes EPSO Yes
ERR0DIV0 Yes ETMODE Yes
EXTCGS Yes EXTERR Yes
EXTFILE Yes EXTMKSA Yes
EXTMOD_GENWAVE Yes EXTRACT_EVAL_FINAL Yes
EXTRACT_VECT_AXIS Yes FALL_TIME Yes
FASTRLC Yes FLICKER_NOISE No
80
Eldo® User's Manual, 15.3

Table 3-3. Eldo Premier—Supported Options (cont.)
Eldo Premier
Supported Options
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
FLOATGATE0 Yes FLOATBULKCHECK No
FLOATBULKERR No FLOATFILE No
FLOATGATE0 Yes FLOATGATECHECK Yes
FLOATGATERR Yes FLUXTOL Yes
FNLEV No FORCE_GROUNDED_CAP No
FORCE_UPDATE - FORCE_WAVE_ALIASES Yes
FREQSMP Yes FROM_TO Yes
FS_PARTITION_DEBUG No FS_PARTITIONING No
FS_SOLVE_AMS_NODES No FSDB Yes
FSDB_SINGLE_FILE Yes FT Yes
GEAR Yes GENK Yes
GEOSHRINK Yes GMIN Yes
GMIN_BJT_SPICE Yes GMINDC Yes
GNODE No GRAMP Yes
GSHUNT Yes HACC No
HIER_SCALE No HIGHVOLTAGE Yes
HIGHVTH Yes HISTLIM Yes
HISTO_ZERO No HMAX Yes
HMIN Yes HRISEFALL Yes
IBIS_SEARCH_PATH No ICDC Yes
ICDEV No IEM No
IGNORE_CSHRC Yes IGNORE_LOCATION_MAP Yes
IGNORE_LVS_VARIABLE No IKF2 No
IMPLICIT_ISUB - INCLIB Yes
INFODEV No INFOMC No
INFOMOD No INGOLD Yes
INPUT Yes INTERP Yes
ITL1 Yes ITL3 Yes
Eldo® User's Manual, 15.3 81

Eldo Premier
Supported Options
Table 3-3. Eldo Premier—Supported Options (cont.)
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
ITL4 Yes ITL6 Yes
ITL7 Yes ITL8 Yes
ITOL Yes ITRPRT Yes
JTHNOISE No JWDB Yes
JWDB_ACTRAN_USE_TIME Yes JWDB_EVENT Yes
JWDB_EXTENSIONS Yes JWDB_PERCENT Yes
KEEP_DSPF_NODE No KEEP_ELDO_CL_TEMP_WAVE
S
Yes
KEEP_HMPFILE No KEEPDANGLING No
KEEPSHORTED No KLIM No
KWSCALE Yes LCAPOP Yes
LIBINC Yes LICN Yes
LIMIT_GROUNDED_CAP No LIMNWRMOS No
LIMPROBE Yes LIST No
LOCAL_MINRACC Yes LOCAL_NOWARN No
LOOPV0 Yes LOWVOLTAGE Yes
LOWVTH Yes LVLTIM No
M53
Switch to Eldo
Classic
MACMOD
Yes
MAX_CHECKBUS No MAX_DSPF_PLOT No
MAXADS No MAXL Yes
MAXNODEORD No MAXNODES No
MAXORD Yes MAXPDS No
MAXSTEP No MAXTOTWARN No
MAXTRAN No MAXV Yes
MAXW Yes MAXWARN Yes
MC_IGNORE_BINNING No MAX_NOMINAL_OP No
MEAS_TARGWHEN Yes MEASFILE Yes
MEASFORM Yes METHOD=GEAR Yes
82
Eldo® User's Manual, 15.3

Table 3-3. Eldo Premier—Supported Options (cont.)
Eldo Premier
Supported Options
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
MINADS Yes MINL Yes
MINPDS Yes MINRACC Yes
MINRESISTANCE Yes MINRVAL Yes
MINW Yes MIXEDSTEP Yes
MMSMOOTH Yes MMSMOOTHEPS Yes
MNUMER Yes MOD4PINS Yes
MODMONTE No MODWL Yes
MODWLDOT Yes MSGBIAS No
MSGNODE No MTFILE Yes
MULTITECH No NETLISTXN No
NETSIZE No NEWACCT Yes
NEWTON No NGATEDEF Yes
NGTOL No NMAXSIZE No
NO_FS_VA No NO_NOMINAL_ALTER Yes
NOACDERFUNC Yes NOACT0 No
NOADMSBS No NOAEX Yes
NOALTCROSS - NOALTINCEX Yes
NOASCII Yes NOASCIIPLOT Yes
NOAUTOCTYPE Yes NOBOUND_PHASE Yes
NOBSLASHCONT Yes NOCATMX N/A
NOCKRSTSAVE Yes NOCMPUNIX No
NOCONVASSIST Yes NOCOU Yes
NODCINFOTAB No NODCPART No
NODCPOWNEG No NODE No
NODEFNEWTON No NODEFRMSNTR No
NODUPINSTERR No NOELDOLOGIC No
NOELDOSWITCH No NOERR_VAPINSMISMATCH No
NOERR_XPINSMISMATCH Yes NOEXTRACTCOMPLEX No
Eldo® User's Manual, 15.3 83

Eldo Premier
Supported Options
Table 3-3. Eldo Premier—Supported Options (cont.)
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
NOFNSIEM No NOICNODE Yes
NOIICXNAME Yes NOINT No
NOISE_SGNCONV No NOISETRAN_TUNING Yes
NOJWDB Yes NOKEYWPARAMSST No
NOKWSCALE Yes NOLAT No
NOLICN Yes NOLTEDISC No
NOMALIAS_FOR_SOA Yes NOMATSING No
NOMEMMC - NOMEMSTP No
NOMOD Yes NOMODWL Yes
NONOISE No NONTRCNOMSTEP No
NONWRMOS Yes NOOP No
NOPAGE Yes NOPROBEOP Yes
NOQTRUNC Yes NORMOS No
NOSETBUSEXPAND Yes NOSIZECHK Yes
NOSMKMCWC No NOSSTKEYWORD No
NOSTATP No NOSTVER Yes
NOTHTOLSPI - NOTRC Yes
NOTRCLIB Yes NOVATOPOCHK No
NOWARN Yes NOWAVECOMPLEX No
NOXTABNOISE No NOZSINXX No
NSAFILE_FORMAT Yes NUMDGT Yes
NWRMOS Yes OLDACCT No
OPALLDC Yes OPSELDO_ABSTRACT No
OPSELDO_ALTER - OPSELDO_DETAIL No
OPSELDO_DISPLAY_GOALFI
TTING
No
OPSELDO_FORCE_GOALFITTI
NG
No
OPSELDO_JWDB_RUN No OPSELDO_NETLIST No
OPSELDO_NO_DUPLICATE No OPSELDO_NOGOALFITTING No
OPSELDO_OUTER No OPSELDO_OUTPUT No
84
Eldo® User's Manual, 15.3

Table 3-3. Eldo Premier—Supported Options (cont.)
Eldo Premier
Supported Options
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
OPSOA No OPTYP Yes
OSR No OUT_ABSTOL Yes
OUT_MCPARAM Yes OUT_REDUCE Yes
OUT_RELTOL Yes OUT_RESOL Yes
OUT_SMP Yes OUT_STEP Yes
PARAM_BEFORE_USE Yes PARAMETRIC_ACTRAN No
PARAMOPT_NOINITIAL No PARHIER Yes
PATTERN_MAX_ALLOWED_
COEFF
Yes PCS No
PCSPERIOD No PCSSIZE No
PEVFLY No PGATEDEF No
PIVCHECK No PIVREL No
PIVTOL No PODEV No
POST Yes POST_DOUBLE Yes
POWNEG0 No PREMIER Yes
PREMIER_FORCE_ELDO_DC Yes PREMIER_FORCE_GEN Yes
PREMIER_HISPEED Yes PREMIER_KEEP_OUTPUTS Yes
PREMIER_MATRIX Yes PREMIER_MODE Yes
PREMIER_NOFASTGEN Yes PREMIER_RCC Yes
PREMIER_REMOVE_RESLIB Yes PREMIER_REUSE_AUTOSAVE
D_IIC_FILE
Yes
PREMIER_SHM Yes PREMIER_USE_IC_TRAN_UIC Yes
PREVENT_TRUNCATE_EXPR
ESSION_REPRESENTATION
Yes PRINT_ACCT No
PRINT_ACOP No PRINT_DC No
PRINT_OPTION No PRINTFILE_STEP No
PRINTFILE_FREQ_STEP No PRINTFILE_TIME_STEP No
PRINTLG Yes PROBE Yes
PROBEOP Yes PROBEOP2 Yes
Eldo® User's Manual, 15.3 85

Eldo Premier
Supported Options
Table 3-3. Eldo Premier—Supported Options (cont.)
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
PROBEOPX Yes PROPAGATE_ELDO_CL_MAIN_
ARGS
Yes
PSF Yes PSF_ALL_FILES Yes
PSF_FULLNAME Yes PSF_NODEVICE_NOISE No
PSF_SCALARDC Yes PSF_VERSION Yes
PSF_WRITE_ALL Yes PSFASCII Yes
PSOSC No PSP_NOI_MOD Yes
PSTRAN Yes PWL1 -
QTRUNC Yes QUEUE_TIMEOUT Yes
QUOTREL Yes QUOTSTR Yes
RAILINDUCTANCE No RAILRESISTANCE No
RANDMC No RATPRINT No
REDUCE Yes REDUCE_KEEP_INST Yes
REDUCE_KEEP_NODE Yes REDUCE_KEEP_OUTPUTS Yes
REDUCE_MAX_CAP Yes REDUCE_MAX_IND Yes
REDUCE_MAX_RES Yes REDUCE_NETWORK_TYPE Yes
RELTOL Yes RELTRUNC Yes
RELVAR No REMOVE_ELDO_CL_TEMP_FIL
ES
Yes
RESET_MULTIPLE_RUN No RESNW No
RESTRICT_ELDO_CL_DECL
ARATIONS
Yes RGND Yes
RGNDI Yes RISE_TIME Yes
RMMINRVAL Yes RMOS Yes
RMPOWDC Yes RMUNBIASED -
RMV0 No RSMALL No
SAMPLE No SAVETIME Yes
SCALE Yes SCALEBSIM Yes
SCALM Yes SEARCH Yes
86
Eldo® User's Manual, 15.3

Table 3-3. Eldo Premier—Supported Options (cont.)
Eldo Premier
Supported Options
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
SELECTIVE_ELABORATION Yes SET_ELDO_CL_ARRAY_AUTO_
EXPAND
SET_ELDO_CL_MAX_PARA Yes SET_ELDO_CL_SIM_CHI_APPE
ND
Yes
Yes
SET_ELDO_CL_SIM_LOG_AP
PEND
Yes
SET_ELDO_CL_STRING_COMP
ARISON_CASE_SENSITIVE
Yes
SET_ELDO_CL_VERBOSE Yes SHRINK_FACTOR Yes
SIGTAIL No SIMUDIV Yes
SLASHCONT Yes SMOOTH Yes
SOA_EXCLUDE_LIMITS - SOA_HIER_RULE -
SOA_WAVE_FORMAT - SOIBACK No
SPI3ASC Yes SPI3BIN Yes
SPI3NOCOMPLEX Yes SPICEDC No
SPIOUT Yes SPLITC Yes
SPMODEL - SPMODLEV Yes
SPNNB Yes SPNRAT Yes
STARTSMP Yes STAT Yes
STATISTICAL No STD_OP -
STEP Yes STOPINFIRSTERROR Yes
STRICT No STVER Yes
SUBALEV Yes SUBFLAGPAR No
SWARN - TEMP_UNTI Yes
TEMPCOUK Yes THERMAL_NOISE No
THTOLSPI - TIMEDIV Yes
TIMESMP
Yes
TMAX Yes TMIPATH Yes
TNOM Yes TPIEEE No
TRAP Yes TRTOL Yes
TTHRESOL Yes TUNING Yes
Eldo® User's Manual, 15.3 87

Eldo Premier
Supported Options
Table 3-3. Eldo Premier—Supported Options (cont.)
Option
Eldo
PremierSupp
ort?
Option
Eldo
PremierSupp
ort?
UDRM_GET_DEVICE_SQUA
RE_M
Yes ULOGIC No
UNBOUND Yes UNFORCEDBULKCHECK No
UNFORCEDBULKERR No USE_ELDO_CL_SAFE_WAVE_C
P
Yes
USE_LAST_SUBCKT - USE_LOCATION_MAP Yes
USE_SPECTRE_CONSTANT Yes USEALLSTEP -
USEDEFAP Yes USEFIRSTDEF Yes
USELASTDEF Yes VALIDATE_ELDO_CL_CONCU
RRENCY
Yes
VAMAXEXP No VAMODEL -
VAOPTS - VARTEMP No
VBCSAT Yes VERBOSE No
VMAX Yes VMIN Yes
VNTOL Yes VOLTAGE_LOOP_SEVERITY Yes
VXPROBE No WARN Yes
WARN2ERR No WARNING_DEVPARAM No
WARNMAXV No WBULK No
WDB_IDELTA Yes WDB_NOSYNCHRO Yes
WDB_VDELTA Yes WDF -
WILDCARD_CORRELATION - WL Yes
WRITE_ALTER_NETLIST Yes XA Yes
XBYNAME No ZCHAR No
ZOOMTIME
Yes
Tip
For a list of the options specific to Eldo Premier, see “Eldo Premier Options” in the Eldo
Reference Manual.
Related Topics
Overview of Eldo Premier
88
Eldo® User's Manual, 15.3

Eldo Premier
Supported Models
Enabling Eldo Premier
Eldo Premier Output
Netlist Support
Supported Models
Eldo Premier supports the following models:
• All SPICE basic models (R, C, L, E, F, G, F, and so on).
• Eldo models (UDM and GUDM; charge controlled models only).
• Verilog-A (default flow only).
• VHDL models (when used inside Questa ADMS).
• Capacitive MOSFET models.
• A subset of Eldo built-in macromodels: all in the analog, digital, and mixed-signal
groups; Switch (Sxx) from the switched capacitor group.
Limitation: Eldo Premier does not plot the nodal current of macromodels, for example
I(Ymacro.2).
• Eldo S-domain (FNS) and Z-domain (FNZ) filters.
• S Parameters FBLOCK (block defined with frequency tabulated data in Touchstone
format).
• LDTL, W and U models (transmission line models).
• Ideal transmission line model (T element).
• Microstrip models.
• R, L, C elements defined with an expression (VALUE=) containing the FREQ
keyword.
• E and G of FREQ type (frequency dependent voltage-controlled voltage sources and
voltage-controlled current sources).
Other Supported Functionality
Eldo Premier supports the following, with some exceptions:
• All features of ECL except Simulation Dynamic Control, see “Eldo Control Language”
on page 801.
• Transient noise analysis subset, see “Transient Noise Analysis in Eldo Premier” on
page 90.
Eldo® User's Manual, 15.3 89

Eldo Premier
Other Supported Functionality
• RC reduction (TICER), see “RC Reduction in Eldo Premier” on page 90.
• .OP command, see “Operating Point Analysis in Eldo Premier” on page 92.
• .STEP/.DATA/SWEEP commands, see “.STEP / .DATA / SWEEP Limitations in Eldo
Premier” on page 92.
• Eldo UDRM, see “Reliability Simulation in Eldo Premier” on page 92.
Transient Noise Analysis in Eldo Premier
Eldo Premier supports a subset of the transient noise ( .NOISETRAN) analysis. This is to fulfill
the need of large circuits and long simulations. Transient noise analysis in Eldo Premier
supports optimized models, see .OPTION PREMIER_MODE. Only channel thermal noise and
flicker noise are handled. The supported configuration is a single noisy transient run without a
nominal run, with:
• nonom set
• nbrun set to 1 (single noisy transient run)
• mrun set (the single run algorithm is not used)
Command syntax and parameters available:
.NOISETRAN [fmin=val] fmax=val [nbf=val] [amp=val] [seed=val]
+ [nomod=val] [tstart=val] [tstop=val] [fmin_flicker=val]
Note
The setting of any other Eldo Classic parameters (for example all, nbbins) is ignored.
The noise related parameters specified on device instance lines (nonoise, fmin, fmax, nbf) are
supported.
The simulation results of the .NOISETRAN analysis in Eldo Premier is only one noisy run (per
plot). Any results related to multi-runs (rms and histogram) are not generated.
Verilog-A devices do not generate noise during transient noise analysis in Eldo Premier.
RC Reduction in Eldo Premier
Eldo Premier supports RC reduction as follows:
• .REDUCE command
o
o
The generic .REDUCE command is supported with all options: ANALOG,
FREQUENCY, TUNING, DELAY_ERROR, NOISE_ERROR, ENGINE.
The .REDUCE TICER command is supported with all options except
PORTMERGE.
90
Eldo® User's Manual, 15.3

o
Eldo Premier
Other Supported Functionality
The .REDUCE CC and .REDUCE RONLY commands are not supported.
• Reduction options
The following options are supported:
o
o
o
o
o
.OPTION REDUCE_KEEP_INST
.OPTION REDUCE_KEEP_NODE
.OPTION REDUCE_KEEP_OUTPUTS
.OPTION REDUCE_MAX_CAP
.OPTION REDUCE_MAX_RES
• Use .OPTION PREMIER_RCC to enable a number of RCC specific reduction options
to improve the performance while preserving accuracy on RCC parasitic post-layout
netlists.
Note
In addition to the support listed above, some modifications have been made to the default
values set by the PREMIER_MODE tuning option in Eldo Premier.
You can control the performance and accuracy of RC reduction in different ways, with the
following rules of precedence (from highest priority to lowest priority):
1. Manual setting, for example MINRVAL/SPLITC options.
2. .REDUCE TUNING=vhigh|accurate|standard|fast
3. .OPTION PREMIER_RCC
4. .OPTION PREMIER_MODE=OFF|1|2|3|4
Note
Mixing these options is not recommended as it may lead to unexpected results.
Limitations
• The TICER algorithm is supported with the following limitations:
Only R and C elements are reduced; L and K elements are not.
TICER reduction is less aggressive in Eldo Premier than in Eldo Classic, because some
optimizations (port merging and CC clumping) are not available.
• The following algorithms are not supported by Premier:
RONLY reduction, CC reduction.
• The following options are not supported:
Eldo® User's Manual, 15.3 91

Eldo Premier
Other Supported Functionality
o
o
.OPTION REDUCE_MAX_IND (not supported because inductors are not reduced:
see limitations below).
.OPTION REDUCE_NETWORK_TYPE (not supported: always set to RC, because
inductors are not reduced: see limitations below).
DC Analysis in Eldo Premier
Eldo Premier supports DC (.DC) analysis with the following limitation:
• Topology changes are not supported, that is, when a DC analysis adds or removes an
access resistor.
See also “Using Eldo Classic DC Solution” on page 66.
Operating Point Analysis in Eldo Premier
Eldo Premier supports operating point (.OP) analysis and the .OP_DISPLAY command with the
following limitations:
• OP info is not displayed for all linear devices (R, L, C, E, F, G and H). OP info is
displayed for some non-linear devices (R, L, C, E, F, G and H).
• Displayed information could be different compared with Eldo Classic due to different
optimizations (merged or simplified devices).
.STEP / .DATA / SWEEP Limitations in Eldo Premier
Eldo Premier supports .STEP/.DATA/SWEEP commands with the following limitation:
• Topology changes are not supported, that is when a .STEP adds or removes an access
resistor.
The outputs are consistent with Eldo Classic.
Reliability Simulation in Eldo Premier
Eldo Premier supports reliability simulation, Eldo UDRM, with the following limitations:
• Eldo UDRM enables the update of non-model parameter values (through regular
.PARAM commands). Because Eldo Premier does not keep the parameter dependencies,
this capability is not supported when using UDRM inside Eldo Premier.
Related Topics
Eldo UDRM Users Manual
Overview of Eldo Premier
Enabling Eldo Premier
92
Eldo® User's Manual, 15.3

Eldo Premier
Miscellaneous Limitations of Devices and Features in Eldo Premier
Eldo Premier Output
Netlist Support
Miscellaneous Limitations of Devices and Features
in Eldo Premier
The following devices and features are not supported by the Eldo Premier kernel:
• Magnetic and Switched Capacitor Eldo macromodels (except for the Sxx switch).
• IBIS models.
• Controlled devices using a function of frequency or time.
• Eldo Interactive mode.
• Merckel MOSFET models.
• Specifying a temperature expression as a parameter of the .TEMP command
(.TEMP ) produces incorrect simulation results for devices whose values
vary with temperature (expression depends on the TEMPER variable).
Workaround: Always use a numerical value instead of an expression as a parameter of
the .TEMP command.
When a model is not supported by Eldo Premier, a warning 93 is displayed causing an
automatic switch to Eldo Classic. For example:
Warning 93: Premier has been deactivated due to the unsupported model of
the object 'M1' (MERCK1).
Related Topics
Overview of Eldo Premier
Enabling Eldo Premier
Eldo Premier Output
Netlist Support
Eldo® User's Manual, 15.3 93

Eldo Premier
Miscellaneous Limitations of Devices and Features in Eldo Premier
94
Eldo® User's Manual, 15.3

Chapter 4
Eldo Netlist Setup
This chapter provides an overview of the circuit file (.cir) structure and describes general
aspects of the Eldo syntax used to specify all circuit descriptions and simulation commands in
the .cir file.
Full descriptions of the Eldo syntax for device, source and macromodel instantiations, and all of
the command set can be found in the Eldo Reference Manual.
Netlist Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Circuit Title. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Model Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Subcircuit Definitions and Calls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Element and Source Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Simulator Commands and Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
End Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
General Aspects of the Language Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Continuation Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Comment Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Parameter Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Case-Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Numerical Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Environment Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Functions, Operators and Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Arithmetic Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Directives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
IF, ELSE, ELSEIF, ENDIF Conditional Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
String Operator on If Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Directives Interpreted by the Eldo Parser (Default) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Directives to Postpone Block of Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Directives Interpreted using the C Pre-Processor (-E/-EE Arguments) . . . . . . . . . . . . . . . 126
Working With Subcircuits and Device Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Subcircuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Device Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Encrypting Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
encrypt_eldo Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Protection of Encrypted Libraries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Automatic Recognition of MOS Instantiations in TSMC Libraries . . . . . . . . . . . . . . . . 156
Eldo® User's Manual, 15.3 95

Eldo Netlist Setup
Running Multiple Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Merging Instances in Parallel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
96
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Eldo Netlist Setup
Netlist Structure
Netlist Structure
The Eldo .cir netlist file contains all the information necessary to run an Eldo simulation. The
Eldo structure and syntax is based on the SPICE language. However, Eldo provides many
additional features not available in SPICE.
Tip
You can display .cir files with the AMS Results Browser.
The circuit file example in Figure 4-1 shows the simple structure of an input circuit (.cir file).
Figure 4-1. Circuit File Example
The file is divided into the different sections labeled in the figure.
The example also contains full line and inline comments. The first line (circuit title) and last line
(.END) are the only ones that are order dependent. All other netlist lines are order independent.
Eldo® User's Manual, 15.3 97

Eldo Netlist Setup
Circuit Title
Tip
See also “General Aspects of the Language Syntax” on page 103.
Circuit Title . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Model Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Subcircuit Definitions and Calls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Element and Source Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Simulator Commands and Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
End Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Circuit Title
The first line of the netlist file is format free and always handled as comment, as in SPICE, and
is reserved for the title of the circuit file. The title is used for each section of output in the ASCII
file, and also in the waveforms database for viewing by the EZwave waveform viewer. This line
is mandatory.
Related Topics
Netlist Structure
General Aspects of the Language Syntax
Analyzing Simulation Results
Model Definitions
Use the .MODEL command to group sets of pre-defined parameters which may be used by one
or more devices. Models may be described directly in the input file or may be read from a
library file using .MODEL LIB or the .LIB and .ADDLIB commands.
Model Names
Model names cannot start with a numeric. This causes compilation of the netlist to be broken,
giving an error message.
Tip
See also “.MODEL” in the Eldo Reference Manual.
Related Topics
Netlist Structure
98
Eldo® User's Manual, 15.3

Subcircuit Definitions and Calls
Eldo Netlist Setup
Subcircuit Definitions and Calls
A subcircuit consists of a group of elements. To define a subcircuit within a circuit description
file, begin the subcircuit block with a .SUBCKT command and terminate it with the .ENDS
command.
Use the Xxx statement to instantiate a subcircuit previously defined using a .SUBCKT
command. All components and nodes used in the subcircuit definition are known only locally,
unless they have been globally defined via .GLOBAL or .PARAM commands. .MODEL
specifications inside the subcircuit are also known only locally. There is no limit to the size or
complexity of the subcircuit.
Tip
See “.SUBCKT,” “.ENDS” and “Subcircuit Instance” in the Eldo Reference Manual.
Related Topics
Netlist Structure
Working With Subcircuits and Device Libraries
Element and Source Definitions
The circuit connectivity (netlist) is described in the netlist file by element statements of devices
and sources.
Element statements provide:
• element name
• nodes the element is connected to
• parameter values
The first letter of the element name is a key letter indicating the element type, for example:
R for resistor, M for MOSFET, V for voltage source, and X for subcircuit instance.
Component Names
Component names start with the component reserved characters and continue with an arbitrary
sequence of alphanumeric characters, including %, $, #, _. Component names cannot be broken
at the end of a line.
Node Name Conventions
Node names may contain an arbitrary sequence of alphanumeric characters and some nonalphanumeric
characters including: !, $, #, _, [], , :, \, /, |, +, -, *, %.
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Eldo Netlist Setup
Simulator Commands and Options
The following characters are not allowed in node names: (), {}, ', =. Node names can not begin
with any of the following characters: *, +, -, &, |, ". Do not use the period character (.) in a node
name because it is reserved as a hierarchy separator between a subcircuit name and a node
name.
Node names cannot be broken at the end of a line.
Whenever Eldo sees a node name with suffix “.0”, Eldo assumes that node 0 was intended if the
name also begins with an X, for example, the following are identical:
C1 a XA.0 1p
C1 a 0 1p
Alternatively, with the following syntax, a node named a.0 is created as a regular node.
C1 a a.0 1p
Node Names Used Inside Subcircuits
The following example shows a legal node name used to access a node from a higher level of
hierarchy than the one in which it is defined:
X27.X113.N3
The node N3 is located within a subcircuit X113 which, in turn, is located inside another
subcircuit X27.
See Also
• Sources chapter in the Eldo Reference Manual
• Passive Device Elements chapter in the Eldo Reference Manual
• Diode Models chapter in the Eldo Reference Manual
• BJT Models chapter in the Eldo Reference Manual
• MOSFET Models chapter in the Eldo Reference Manual
Related Topics
Netlist Structure
General Aspects of the Language Syntax
Simulator Commands and Options
Simulator command statements include:
• Analysis commands to specify what type of analysis to run.
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Eldo Netlist Setup
Simulator Commands and Options
• Display commands to control the messages and outputs generated from simulation.
• Simulation control commands to modify general options for simulation.
• Circuit description commands to describe the attributes of the circuit.
Simulator control options, specified with the .OPTION command, to modify execution
behavior; netlist options are divided into the following groups:
Simulator compatibility
Simulation speed, accuracy, and efficiency
Model control
Noise analysis
Simulation output control
Eldo Control Language
Optimizer output control
Netlist parser control
Miscellaneous simulation control
RC reduction
Simulation display control
File generation
Mathematical algorithm
Mixed-mode
Multiple .OPTION commands can be used in a netlist. A single .OPTION statement can
contain multiple options. The order of definition is not usually important. In case of a
double definition, the last specified value is used.
• Output commands define which simulation results will be written to the output files for
display, and include:
o
o
.EXTRACT
Extracts waveform information using a combination of arithmetic expressions or
pre-defined functions (.MEAS is also supported as an alternative).
.PLOT
Specifies which simulation results have to be kept by the simulator for graphical
viewing and post-processing. Results are written to .wdb binary output files for postprocessing.
Related Topics
Tip
See also “Simulator Commands” and “Simulator and Control Options” in the
Eldo Reference Manual.
Netlist Structure
Output Commands Overview
Eldo® User's Manual, 15.3 101

Eldo Netlist Setup
End Statement
End Statement
Use the .END command to terminate the input description. Any text which follows it is ignored,
unless there is another .END statement; in which case, all lines between the preceding .END
and the current .END are treated as another circuit to simulate. This enables the possibility to
have several circuits in the same netlist file.
Tip
See “.END” in the Eldo Reference Manual.
Related Topics
Netlist Structure
General Aspects of the Language Syntax
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Eldo Netlist Setup
General Aspects of the Language Syntax
General Aspects of the Language Syntax
The following sections provide a summary of the Eldo language syntax. The Eldo Reference
Manual contains complete descriptions of all the devices, sources, macromodels and commands
listed in the following pages.
Tip
See “Documentation Syntax Conventions” on page 39 for a detailed description of the
meanings of the different fonts, brackets, and so on, used throughout this manual.
Continuation Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Comment Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Parameter Names. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Case-Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Numerical Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Environment Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Continuation Lines
The length of one input line is limited to 2000 characters. A line may be continued by using the
+ character at the beginning of the new line. In arithmetic expressions, this leading + sign will
be ignored arithmetically and handled as a continuation. Two + signs may be placed together to
both continue the line, and perform the addition operation.
Related Topics
Netlist Structure
General Aspects of the Language Syntax
Comment Lines
A new comment line must begin with the * or // characters.
If the comment follows an Eldo statement on the same line (inline comment), it must begin with
the ! (or, in some cases, the *) character. The inline comment character (! or *) must be
preceded by a white space. Otherwise, the ! or * character are handled as valid characters that
can, for example, be used in node names or be ignored in other cases. The * character is not
allowed as an inline comment on .EXTRACT, .DEFMAC, .DEFWAVE, .MEAS,
.OBJECTIVE, and .PARAM commands. Use the .COMCHAR command to specify different
inline comment characters.
*
!
Eldo® User's Manual, 15.3 103

Eldo Netlist Setup
Parameter Names
The inline comment character (! or *) must be preceded by a white space. If not, Eldo could
ignore it in the case of a parameter value, or consider it a valid character in node names. In the
example below, the first line is accepted, without any error or warning message, to be identical
to the second:
r1 1 2 5! 22
r2 2 0 5 22
“5!” is interpreted as the number 5 and the 22 is parsed as the TC1 temperature coefficient.
A set of comment lines can also be grouped together into a block as shown below:
#com
A block of
comment
#endcom
In these cases the * character is not needed.
Tip
See “.COMCHAR” in the Eldo Reference Manual.
Related Topics
Netlist Structure
General Aspects of the Language Syntax
Parameter Names
Parameter names may contain an arbitrary sequence of alphanumeric characters, including %, $,
#, _, !. Parameter names cannot be broken at the end of a line. Parameter names should not
contain boolean operators. Such a name can be quite ambiguous.
String Parameters
Eldo accepts quoted character strings as parameter values. These string values may be used for
model names and filenames. To use a string as a parameter, enclose the string within double
quotes, for example:
.param TT1="ResMod"
A string parameter can be defined on multiple lines if the string on each line is enclosed within
double quotes, for example:
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Eldo Netlist Setup
Case-Sensitivity
.SIGBUS mybus base=bin TFALL=3n TRISE=3n THOLD=20n TDELAY=50n VHI=5 VLO=0
+ pattern $(PAT)
.PARAM PAT= " 00000 00001 00010 00011 00100 00101 00110 00111 "
+ " 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 "
+ " 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 "
+ " 11100 11101 11110 11111 00000 00001 00010 00011 00100 00101 "
The space before the double quote at the right hand side is mandatory. Without it, Eldo will
generate an error.
The value of a string is retrieved by specifying the dollar sign ($) and parentheses ( ), for
example:
.param MOD="Pmos1"
m1 d g s b $(MOD) w=1u l=1u
.param STIMFILE='"Stim.txt"'
v1 1 0 pwl file=$(STIMFILE) R
String parameters can be used in .SIGBUS or pattern sources. A sweep (for example .STEP) can
also be made on string parameters.
Reserved Keywords
Some keywords should not be specified in a .PARAM command. If they are then errors will be
generated.
Tip
See “.PARAM” in the Eldo Reference Manual.
Related Topics
Netlist Structure
General Aspects of the Language Syntax
Assigning Parameter Values
Case-Sensitivity
Eldo supports case-sensitive netlist formats with the command-line argument -case. When
specified, all names (nodes, device instances, models, subcircuit definitions and instances,
labels) will be case-sensitive. Eldo commands remain case-insensitive.
Notes
• Running Eldo in -compat mode does not change the behavior of the netlist parser when
case-sensitivity is specified.
Eldo® User's Manual, 15.3 105

Eldo Netlist Setup
Case-Sensitivity
• Running Eldo with the -case argument applies case-sensitivity to the full netlist. If the
netlist contains different language parts then the argument is applied to all parts.
Examples
If you have the following netlist with case-sensitive model names (rLk and rlk):
test1.cir
.model rlk res level=4 RSH=1000
.model rLk res level=4 RSH=10000
Ibias1 0 N1 1mA
Rbig1 N1 0 rLk L=10u W=10u
Ibias2 0 N2 1mA
Rbig2 N2 0 rlk L=10u W=10u
.OP
.end
then you must run Eldo in case-sensitive mode:
eldo test1.cir -case
The voltage for node N1 will be 1V while voltage for node N2 it will be 10V. If you run Eldo in
default mode on this netlist, it will exit with the following error generated:
ERROR 504: In file "./test1.cir" line 3:
+ MODEL "RLK": is defined twice.
Here follows another example using case-sensitivity in nodes names (N1 and n1):
Test2.cir
Ibias1 0 N1 1mA
Rbig1 N1 0 1K
Ibias2 0 n1 1mA
Rbig2 n1 0 1k
.OP
.end
again you must run Eldo in case-sensitive mode:
eldo test2.cir -case
and the Eldo output will be:
DC:2 iterations FOR DC analysis
N1
1.0000E+00
n1
2.0000E+00
Running Eldo in default mode will output:
DC:2 iterations FOR DC analysis
N1
1.5000E+00
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Eldo Netlist Setup
Numerical Values
There is no error generated in this example but the results are different.
Tip
See the “-case” command line argument in the Eldo Reference Manual.
Related Topics
Netlist Structure
General Aspects of the Language Syntax
Numerical Values
Values are always handled as real numbers. They may be specified in exponential notation or
with scale factors with symbols.
See the scale factor symbols listed in Table 4-1:
Notes
Table 4-1. Scale Factors
Symbol Multiplier Name
A 1.0×10 −18 atto
F 1.0×10 −15 femto
P 1.0×10 −12 pico
N 1.0×10 −9 nano
U 1.0×10 −6 micro
M 1.0×10 −3 milli
K 1.0×10 3 kilo
MEG 1.0×10 6 Mega
G 1.0×10 9 Giga
T 1.0×10 12 Tera
• Letters which are not scale factors are ignored if they immediately follow a number.
Hence 10, 10V and 10Hz all represent the same number, 10. However, 10A will be
interpreted as 1.0e −17 , because of the atto scaling factor.
Eldo® User's Manual, 15.3 107

Eldo Netlist Setup
Environment Variables
• Letters immediately following a scale factor are ignored. Thus M, MA, MSEC, and
MMHOS all represent the same scale factor, M.
• The scale factor M represents 1×10 −3 or “milli” units. 1×10 6 or “mega” units are
specified using the MEG scale factor. This is commonly confused in SPICE syntax.
• Scale factors are not cumulative. KK is not MEG, but K, since the second letter is
ignored.
• M.K.S. units are used throughout the netlist.
• dB represents decibels.
Related Topics
Netlist Structure
General Aspects of the Language Syntax
Environment Variables
Eldo supports the syntaxes $(variable) and ${variable} to identify environment variables. For
example, if in the shell terminal you have an environment variable “var1” defined, you can use
it in commands that operate with pathnames:
.include test$(var1)lib/test.inc
.include test${var1}lib/test.inc
Related Topics
General Aspects of the Language Syntax
108
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Eldo Netlist Setup
Functions, Operators and Expressions
Functions, Operators and Expressions
This topic is divided into:
Arithmetic Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Arithmetic Functions
A set of arithmetic functions may be used in Eldo for the calculation of device parameters,
model parameters, new waves, and so on. These are divided into two groups:
• Functions for use without restriction in any “runtime” expression, see Table 4-2.
• Functions for use only in .EXTRACT, .DEFWAVE or .SETSOA, see Table 4-3.
Table 4-2. Arithmetic Functions and Operators
Function
Returns
ABS(val)
Absolute value of val: |val|
ACOS(val)
Arc cosine of val
ACOSH(val)
Arc hyperbolic cosine of val
ASIN(val)
Arc sine of val
ASINH(val)
Arc hyperbolic sine of val
ATAN(val)
Arc tangent of val
ATANH(val)
Arc hyperbolic tangent of val
BITOF(a, b) Returns “1” if bit b of the integer value of parameter a is a “1”.
Returns “0” if bit b of the integer value of parameter a is a
“0”.Returns “0” if bit b ≥ 32.
CEIL(val)
COS(val)
COSH(val)
DB(val)
Ceiling rounding function, returns the smallest integer value not
less than val. This is known as rounding up. For example ceil(1.25)
returns 2.0 and ceil(-1.25) returns -1.0.
Cosine of val, where val is defined in radians
Hyperbolic cosine of val
value in dBs of val (20×log 10 (val))
DDT(val)
DERIV(val)
EXP(val)
Returns the derivative of val
Returns the derivative of val
Exponent of val
Eldo® User's Manual, 15.3 109

Eldo Netlist Setup
Arithmetic Functions
Function
FLOOR(val)
IDT(val)
INTEG(val)
Table 4-2. Arithmetic Functions and Operators (cont.)
Returns
Floor rounding function, returns the largest integer value not
greater than val. This is known as rounding down. For example
floor(1.25) returns 1.0 and floor(-1.25) return -2.0.
Returns the integral of val
Returns the integral of val (equivalent to IDT). Value returned
does not depend on the current x-axis value.
INT(val)
LIMIT(a, b, c)
LOG(val)
LOG10(val)
MAX(val1,..., valn)
DMAX(val1,...,valn)
MIN(val1,..., valn)
DMIN(val1,...,valn)
MOD(x,y)
ONGRID([offset], step, value)
POW(val1, val2)
PWR(val1, val2)
PWL(xvalue, interp, x1, y1, ...
xn, yn)
PWL_CTE(xvalue, interp, x1,
y1, ... xn, yn)
Integer value of val (equivalent to TRUNC)
Returns b if a < b, returns c if a > c, returns a otherwise
Neperian logarithm of val
Decimal logarithm of val
Returns the maximum of val1 to valn. There is no limit to the
number of values that can be specified.
Returns the minimum of val1 to valn. There is no limit to the
number of values that can be specified.
Modulo operator. Floating-point remainder value function of
dividing x by y. Returns the value x − i × y, where i is the quotient
of x / y, rounded towards zero to an integer. An error is returned if
y is 0.
Returns 1 if value = offset + k×step where k is an integer value.
Otherwise it returns 0. Default value of offset is 0.0.
Returns the value of val1 to the power of the integer part of val2
Returns the absolute value of val1, raised to the power of val2,
with the sign of val1
Generates an interpolated output value from an input value xvalue,
provided as the first argument, using a PWL table described as a
series of x, y points passed as arguments to the function. interp=0|1
specifies whether the y value is interpolated linearly (1) or not (0).
xn and yn are used to calculate the equivalent output value.
Generates an interpolated output value from an input value xvalue,
provided as the first argument, using a PWL table described as a
series of x, y points passed as arguments to the function. interp=0|1
specifies whether the y value is interpolated linearly (1) or not (0).
xn and yn are used to calculate the equivalent output value. This
function will return y1 if the x value < x1, and will return yn if the
x value > xn.
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Eldo® User's Manual, 15.3

Function
PWL_LIN(xvalue, interp, x1,
y1, ... xn, yn)
ROUND(val)
SELECT(table_name, xvalue
[, LINEAR |
SAMPLE_HOLD |SPLINE])
SGN(val)
SIGMA()
SIGN(val)
SIGN(val1, val2)
SIN(val)
SINH(val)
SMABS(val, eps)
SMMAX(a, b, eps)
SMMIN(a, b, eps)
SMSGN(val, eps)
SMSIGN(val, eps)
SQRT(val)
STRMATCH(str, pat)
STRCMP(str1,str2)
Table 4-2. Arithmetic Functions and Operators (cont.)
Returns
Eldo Netlist Setup
Arithmetic Functions
Generates an interpolated output value from an input value xvalue,
provided as the first argument, using a PWL table described as a
series of x, y points passed as arguments to the function. interp=0|1
specifies whether the y value is interpolated linearly (1) or not (0).
xn and yn are used to calculate the equivalent output value. This
function linearly extrapolates the first value using the first two
points of the function if the x value < x1. The last value will also be
linearly extrapolated using the last two points if the x value > xn.
Rounded, to the nearest integer, value of val
Returns a value interpolated from an array of (x,y) values
according to a given x value. table_name is the name of an array of
(x,y) values defined with a .TABLE command, xvalue is the x
value for which y is requested, LINEAR | SAMPLE_HOLD |
SPLINE indicates the interpolation method to use to calculate the y
value. The default is SAMPLE_HOLD.
Returns the signum of val: +1 if val>0, 0 if val=0, -1 if val=0, -1 if val

Eldo Netlist Setup
Arithmetic Functions
Function
STRNCMP(str1,str2,n)
STRCASECMP(str1,str2)
STRNCASECMP(str1,str2,n)
TAN(val)
TANH(val)
TRUNC(val)
Table 4-2. Arithmetic Functions and Operators (cont.)
Returns
Compare the first n characters of two strings. Returns logical true
(1) if the first n characters of the strings str1 and str2 are the same,
and returns logical false (0) otherwise. Case sensitive.
Compare the strings str1 and str2, ignoring case, and returns
logical true (1) if the two are identical, and logical false (0)
otherwise.
Compare the first n characters of two strings, ignoring case.
Returns logical true (1) if the first n characters of the strings str1
and str2 are the same, and returns logical false (0) otherwise.
Tangent of val, where val is defined in radians
Hyperbolic tangent of val
Truncated value of val (integer part of real value)
WINTEG(wave [, t]) Returns the time or frequency integral of waveform wave at time t.
Value returned depends on the current x-axis value.
Table 4-3. Arithmetic Functions Used Only in .EXTRACT, .DEFWAVE,
.SETSOA
Function
Returns
COMPLEX(a, b) Returns a complex number using “a” as the real part and “b” as the
imaginary part
CONJ()
IMAG()
MAGNITUDE()
REAL()
STOSMITH(val)
YTOSMITH(val)
ZTOSMITH(val)
VALUEOF()
Returns the conjugate of a complex number
Returns the imaginary part of a complex number
Returns the magnitude of a complex number
Returns the real part of a complex number
Returns a normalized value of a complex quantity. These functions
can be used to convert complex functions (S/Y/Z parameters
generated by a .STEP analysis) so they can be correctly plotted in a
Smith chart; an “example” is given in the .PLOT command in the
Eldo Reference Manual.
Returns the current value of an extract. For example:.tcl_wave bar
= TEST("value_of_meas",valueof(meas(foo)))
112
Eldo® User's Manual, 15.3

Notes
Eldo Netlist Setup
Arithmetic Functions
• Where VAL is defined in the previous tables, it normally means a numeric value, but in
certain cases, the functions may also be applied to waves.
• The MAX and MIN functions are automatically converted into DMAX and DMIN
functions when necessary, for example: R1 1 2 {min(2,1,5)} is equivalent to: R1 1 2
{dmin(2,1,5)} which is also equivalent to: R1 1 2 1
There is no limit to the number of arguments that can be used in MAX, MIN, DMAX
and DMIN arguments.
• If three arguments are specified for MIN (that is, MIN(a,b,c)), this represents the MIN of
waveform a in the time window [b,c]. Use DMIN to return the minimum of a, b and c as
computed at each time step.
• The MIN/MAX/ABS/SGN/SIGN functions, when used in bias-dependent expression
(such as in R(V)), can cause non-convergence due to these operators making the
function non-derivable. Use option MMSMOOTH to make them derivable, to avoid
such problems. Alternatively use the SMMIN, SMMAX, SMABS, SMSGN and
SMSIGN operators.
• DDT(VAL) and IDT(VAL) can only be used on E & G elements, see the corresponding
descriptions for the Voltage Controlled Voltage Source and Voltage Controlled Current
Source. Expressions associated with R/L/C devices do not support DDT/IDT
operators.The DDT operator differs from the DERIV operator in the sense that DDT
utilizes the integration scheme used by Eldo, while the DERIV operator exclusively uses
the Backward-Euler algorithm.
• There can be differences between the DERIV operator of Eldo and the equivalent
operator (DRV) of EZwave. The formula used for the Eldo DERIV operator is
Backward-Euler (that is, deriv(f(t)) = (f(t) - f(t-h))/h) with t being the current time and h
being the time step, however the DRV operator of EZwave uses a more complex
formula based on f(t), f(t-h) and f(t+h). Eldo cannot use the EZwave “post-processor”
formulation, because it requires to know the value at t+h, which is not possible when the
simulator is running (Eldo at time t cannot know the value at t+h), but post-processor
formulation is usually smoother, hence both formulations are used.
• Nested COMPLEX() statements are forbidden, as well as using complex quantities for
the real or imaginary part. Corresponding errors are:
ERROR 3040: Nested complex(,) functions is not allowed.
ERROR 3041: Complex quantities can not be used inside complex(,)
function.
• If CEIL, ROUND, FLOOR cause convergence problems, Eldo will generate a warning
and invite the user to specify option NOLTEDISC to bypass LTE checks.
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Eldo Netlist Setup
Arithmetic Functions
-compat Argument
When the -compat argument is active, the following arithmetic function/operator rules apply:
• log(x) = sign(x) × log(abs(x)).
• log10(x) = sign(x) × log10(abs(x)).
• db(x) = sign(x) × 20.0×log10×abs(x)).
• sqrt(x) is −sqrt(abs(x)) if x is negative.
• x**y is computed as x ψ if x is positive, x ΙΝΤ(ψ) if x is negative, and 0 if x is 0.
• The power operator (^) has highest precedence (same as standard Eldo).
Related Topics
Operators
Note
In Eldo standard mode: sqrt(x) returns an error if x is negative; x**y is computed as
exp(y×log(x)) if x is strictly positive, 0 if x is 0, and returns an error if x is negative.
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Operators
Operators
This topic is divided into the following:
Operator Precedence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Arithmetic Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Boolean Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Bitwise Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Operator Precedence
The order of precedence and associativity of operators in Eldo affect the evaluation of
expressions. For example, in the expression a=2+b*3, which happens first? the addition or the
multiplication? Expressions with higher-precedence operators are evaluated first.
Table 4-4 summarizes the precedence from highest to lowest and associativity (the order in
which the operands are evaluated) of Eldo operators. Where several operators appear together,
they have equal precedence and are evaluated according to their associativity.
Table 4-4. Operator Precedence
Operator Description Associativity
() function call left-to-right
! - logical NOT, unary negation right-to-left
** ^ power, power (synonym) left-to-right
* / multiply, divide left-to-right
+ - add, subtract left-to-right
> bitwise left shift, bitwise right shift left-to-right
< >= less than, less than or equal, greater than, left-to-right
greater than or equal
== != equal, not equal left-to-right
& bitwise AND left-to-right
| bitwise OR left-to-right
&& logical AND left-to-right
|| logical OR left-to-right
Related Topics
Arithmetic Operators
Operators
Eldo® User's Manual, 15.3 115

Eldo Netlist Setup
Operators
Arithmetic Operators
The arithmetic operators available are +, -, *, / and ^ (or **) for power.
Note
The power operator (^) has the highest precedence. For example:
1+4^2 gives the result: 17
2*3^2 gives the result: 18
x^y or x**y is computed as exp(y*log(x)) if x is strictly positive, 0 if x=0, and returns an error
if x is negative. Specify option POWNEG0 to allow a negative x value in power expressions:
the expression will return 0. In versions of Eldo prior to v6.6, a negative x value was allowed.
Related Topics
Boolean Operators
Operators
Boolean Operators
The following boolean expressions/operators are available:
Table 4-5. Boolean Operators
Operator Meaning
!= not equal to
== equal to
< less than
greater than
>= greater than or equal to
|| OR operator
&&
AND operator
Related Topics
Bitwise Operators
Operators
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Eldo Netlist Setup
Operators
Bitwise Operators
The following Bitwise operators are available:
Related Topics
Expressions
Operators
Table 4-6. Bitwise Operators
Operator Meaning
&
Bitwise AND operator
| Bitwise OR operator
> Bitwise shift right
operator
Eldo® User's Manual, 15.3 117

Eldo Netlist Setup
Expressions
Expressions
Expressions can be used in a netlist with the following restrictions.
• Numerical expressions must be contained within braces, { and }, single quotes, ' and ', or
parentheses, ( and ).
• String expressions should be contained in double quotes, " and ".
• Mathematical grouping within expressions must be done using normal parentheses, (
and ).
• Constants and parameters may be used in expressions, together with the built-in
functions (see “Arithmetic Functions” on page 109) and operators (see “Operators” on
page 115).
Expressions may be used in the following situations:
• Parameters in the calculation of MOS geometries and R, C and L values.
• Parameter values in the .MODEL command.
• Time point values in the signal descriptions PULSE, PWL, SFFM, SIN and EXP.
• Parameters values in the .SIGBUS command.
• Voltage and current source values.
• S and Z transform (FNS and FNZ) devices.
• .PARAM, .EXTRACT and .DEFWAVE commands.
• E and G sources described by functions or tables.
• R, C and L devices described by functions.
Examples:
Tip
Some parameters may appear in expressions but will cause an error if used in a
.PARAM command. For more information on these see “.PARAM” in the Eldo
Reference Manual.
r1 1 2 {3.0*p1-4k}
.model nn nmos vt0={p2-p2/2.0}
e1 1 2 value={15v*sqrt(v(3,2))}
.defwave pow=v(a)*i(b)
.param x1={2*sqrt(a)}
Note
By default, double quotes are used to specify a parameter string. However, in -compat
mode, double quotes are interpreted as single quotes.
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Expressions
Specifying the Simulation Time in Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Conditional Evaluation of Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Specifying the Simulation Time in Expressions
The current simulation time can be specified inside expressions using the TIME keyword.
TIME is a variable returned by the simulator which gives the value of the current simulation
time and may be used in subsequent calculations. The TIME variable may be used in the
formulation of time-dependent expressions.
The TIME variable may be used in conjunction with VALUE={EXPR} in resistors, capacitors,
inductors, and E and G sources to specify devices/sources whose values vary with time.
g1 1 0 value={TIME * 1u}
r1 1 0 1
.tran 1 10
.print tran v(1)
.end
This specifies a voltage controlled current source between nodes 1 and 0. The current through
g1 from node 1 to node 2 is equal to the current simulation time (TIME) multiplied by 1×10 −6 .
Related Topics
Expressions
Conditional Evaluation of Expressions
Conditional Evaluation of Expressions
Parameters or source values can be evaluated in expressions containing conditional statements.
Syntax
VALIF(CONDITION,expression1,expression2)
EVAL(CONDITION?expression1:expression2)
If CONDITION is TRUE, then VALIF (or EVAL) returns expression1 else it returns
expression2. The keyword VALIF (or EVAL) can be used in any expression. The VALIF
operator also accepts strings in .PARAM statements. This is useful for selecting models
according to parameter values.
Examples
.param p1 = 1.0
.param p2 = 2.0
.param p3 = valif(p1>p2,p1+1.5,p2+1.5)
Here, P3 will be assigned the value 3.5.
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Eldo Netlist Setup
Expressions
.param p1 =1
.param p2 = 2
.param pu = valif(p1 > p2,"r1","r2")
.model r1 r r = 1
.model r2 r r = 2
i1 1 0 1
r1 1 0 $(pu) 1
This examples shows the use of strings. Here, model r2 will be used because condition p1 > p2
is false.
Note
The EVAL syntax is closer to ‘C’ language, and may be more convenient for some users.
Related Topics
Expressions
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Eldo Netlist Setup
Directives
Directives
Directives can be used to simulate variations of circuits.
IF, ELSE, ELSEIF, ENDIF Conditional Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
String Operator on If Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Directives Interpreted by the Eldo Parser (Default) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Directives to Postpone Block of Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Directives Interpreted using the C Pre-Processor (-E/-EE Arguments). . . . . . . . . . . . . 126
IF, ELSE, ELSEIF, ENDIF Conditional Statements
IF, ELSE, ELSEIF, and ENDIF conditional statements can be used inside the Eldo netlist and
can be used to instantiate devices depending on parameter size. ELIF and ELSIF keywords are
also accepted as the ELSEIF condition.
• The IF, ELSE, ELSEIF, ENDIF section must not contain any command, otherwise
unexpected results can be obtained. Warnings are issued in this case.
• The parameters used in expressions of if statements are evaluated during the parsing of
the design only, even if these parameters are changed at run time (because of .STEP, for
instance), then the design will not be changed, a message will be issued that the
operation cannot be taken into account. The .ALTER mechanism should be preferred
here.
Example of usage:
.subckt foo 1 param: p1 = 1
if (p1 >= 1.5)
r1 1 0 '2*p1'
else
r1 1 0 '3*p1'
endif
.ends
i1 1 0 3
x1 1 foo p1 = 3
.op
.end
In this example, the value of resistor r1 will be 6 Ω.
Note
Errors are issued if ADMS is used, or if X or Y statements are present inside if-endif blocks.
Tip
See “.IF, .ELSE, .ELSEIF, .ENDIF” in the Eldo Reference Manual.
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Eldo Netlist Setup
String Operator on If Expressions
Related Topics
Directives
String Operator on If Expressions
String Operator on If Expressions
It is possible to use C-like functions strcmp and strncmp inside if statements used for netlist
configuration. strcmp and strncmp return “0” when the string matches, “not 0” otherwise.
Examples:
.param p1 = "myp1"
if (strcmp(p1,"myp1") == 0)
i1 1 0 1
else
i1 1 0 2
endif
r1 1 0 1
Here, i1 will be 1A.
if (strcmp($(p1),"myp1") == 0)
i1 2 0 3
else
i1 2 0 4
endif
r1 2 0 1
Similarly, i1 will be 3A because the if statement is true.
Related Topics
Directives
Directives Interpreted by the Eldo Parser (Default)
Directives Interpreted by the Eldo Parser (Default)
By default, (without the -E or -EE argument) Eldo understands the following simple preprocessor
commands: #if, #define , #undef , #ifdef , #ifndef
#else, #endif. These can be used as conditional statements to select a part of the netlist.
For example:
#define NO_RESISTOR
...
#ifndef NO_RESISTOR
R1 A B 1k
#endif
...
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Eldo Netlist Setup
Directives Interpreted by the Eldo Parser (Default)
A definition can be specified in two ways:
• when invoking Eldo with:
eldo -define
• in the netlist with:
#define
...
For example, -define foo on the command line is equivalent to #define foo in the netlist. For
both methods, the netlist statement #ifdef foo will be true.
The #if statement can be used for making complex conditional statements using logical
operators: OR ||, AND &&; and comparison operators: not equal to !=, equal to ==. For
example:
#if (defined(U) || defined(A))
The #if directive can also be used in conjunction with the defined function, that is, if a #define
is active, defined() returns 1 whatever value is assigned to .
Pre-processor commands are position dependent; Eldo behaves like C: the #define is acted upon
only when encountered. In an Eldo (or Questa ADMS mixed-signal) netlist there are normal
SPICE commands and/or netlist pre-processor commands that work completely differently.
SPICE commands are usually position-independent but pre-processor commands beginning
with the # character are position-dependent according to C language.
Examples
V1 1 0 1
#define U 0
#if (defined(U) || defined(A))
R1 1 0 1
#else
R1 1 0 2
#endif
.end
Because U is defined in the above example, defined(U) will return 1. The #if statement is true
and R1 will be set to 1. When the #if statement is substituted with: #if (defined(U) &&
defined(A)), the #if statement will no longer be true because A is not defined. R1 would
therefore be set to 2.
An example of position dependency:
If Eldo is invoked with “a” defined (eldo netlist.cir -define a), in the following:
Eldo® User's Manual, 15.3 123

Eldo Netlist Setup
Directives Interpreted by the Eldo Parser (Default)
#ifdef b
c1 1 0 1
#endif
#ifdef a
#define b
l1 2 0 1
#endif
the first #ifdef block is ignored because identifier b is not defined until the next #ifdef block.
The correct order for identifier b to be taken into account in this example is as follows:
#ifdef a
#define b
l1 2 0 1
#endif
#ifdef b
c1 1 0 1
#endif
AMS_VERSION
You can make use of the predefined name AMS_VERSION in directive statements.
AMS_VERSION is accepted in two formats:
• The year followed by the index number, for example 2010.1 or 2012.2 (for the 12.2
release).
• The release version, for example 12.2.
For lettered releases, specify the letter to be taken into account, for example 2012.2a or 12.2a
for the 12.2a release.
Note
This feature only works in a netlist being run by AMS2010.1 or newer.
Using a version testing pragma such as this enables using and maintaining a single library with
multiple releases of Eldo.
Examples
An example of using predefined name AMS_VERSION in #define statements:
#if ( AMS_VERSION >= 2010.2)
.lstb vd1 vd2
#else
*versions prior to 2010.2 do not support differential LSTB
.lstb vstb
#endif
Another example using predefined name AMS_VERSION shows you can specify different
options/settings depending on the version of Eldo you are using.
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Eldo Netlist Setup
Directives to Postpone Block of Commands
#if (AMS_VERSION >= 2012.1)
.param p1 = 1
#else
.param p1 = 2
#endif
i1 1 0 p1
r1 1 0 1
.dc
.end
Related Topics
Directives
Directives to Postpone Block of Commands
Directives to Postpone Block of Commands
Every line declared between these two directives is postponed until the end of the netlist
(.END). This could be used, for example, to enable a .ALTER definition anywhere in the netlist.
If multiple #NETLIST_END/#END_NETLIST_END blocks are declared, they are handled
according to their order in the design. These blocks can be defined in the top netlist or any
included files. Nested #NETLIST_END/#END_NETLIST_END directives are ignored.
Syntax
#NETLIST_END
...
#END_NETLIST_END
Example
i1 1 0 dc 'p1'
.dc
#netlist_end
.alter
.param p1=3m
#end_netlist_end
.param p1=1m
r1 1 0 1
.extract dc v(1)
.alter
.param p1=2m
.end
In this example, three DC analyses will be performed: the first one using p1=1m, the second one
using p1=2m, and the last one using p1=3m which is defined in a #netlist_end/#end_netlist_end
block.
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Eldo Netlist Setup
Directives Interpreted using the C Pre-Processor (-E/-EE Arguments)
Related Topics
Directives
Directives Interpreted using the C Pre-Processor (-E/-EE Arguments)
Directives Interpreted using the C Pre-Processor
(-E/-EE Arguments)
For an extended use of pre-processor commands to define macros and replace them inside the
netlist (see the example below), the -E or -EE argument needs to be specified. These are not the
Eldo default because the parsing of large circuits may be significantly slower.
The -E argument forces Eldo to provide only the main netlist to the C pre-processor, whereas
-EE ensures that all #include filename statements will be pre-processed before parsing. The
.INCLUDE/.LIB statements, which are SPICE commands, are not understood by the C preprocessor
and so will not be pre-processed.
The #include directive can only be used when the -E/-EE arguments are specified.
Note: The C pre-processor analyses files independently. Therefore #define statements are only
known to the file they are defined in.
The -define argument can also be specified on the command line, and it will have the same
effect as without the -E/-EE arguments. To use #define in Eldo in the same way you define
macros in the C language, the syntax is as follows:
#define macro(args) expression
When the macro is encountered in the netlist, it is replaced by the expression. Arguments of the
macro will be replaced by the literals in the macro call. For example:
#define sat_margin(device) abs(vds(device)-vdss(device))
.extract sat_margin(XM0.M1)
will be replaced by:
.extract abs(vds(XM0.M1)-vdss(XM0.M1))
Note
Because -E/-EE uses the C pre-processor, you must ensure there is a carriage return
proceeding the directive in the file to avoid problems. Uppercase function names are not
accepted. Using comments defined with #com and #endcom are not compatible with -E/-EE.
Related Topics
Directives
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Eldo Netlist Setup
Working With Subcircuits and Device Libraries
Working With Subcircuits and Device Libraries
This topic is divided into:
Subcircuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Device Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Subcircuits
Subcircuits can be used to simplify netlists because once defined they can be instantiated
multiple times in the netlist. Subcircuit definitions and instances can be nested. The inner
subcircuit definitions are local to the subcircuit definition in which they are defined, that is, they
are not valid outside of it. Parameters contained in a subcircuit can be assigned explicitly or via
the .PARAM command.
Subcircuits may be parameterized. Symbols may be used as values within the subcircuit body
which may be assigned values when the subcircuit is instantiated. A subcircuit may be stored in
a library file, in which case the .SUBCKT LIB syntax should be used together with .LIB or
.ADDLIB.
A subcircuit may optionally be simulated using the differentiated accuracy system. The iteration
technique used to process the subcircuit is chosen by the (ANALOG) optional keyword.
Usually, a circuit with (ANALOG) specified indicates ‘high accuracy’.
By default, when Eldo encounters multiple definitions of .SUBCKT statements an error is
reported and the simulation is stopped. To enable the simulation to proceed you can force Eldo
to only use the first definition by specifying option USEFIRSTDEF at the beginning of the
netlist (any further definitions are ignored); or to only use the last definition specify option
USE_LAST_SUBCKT or USELASTDEF (any previous definitions are ignored). The last
definition takes into account contents included from library files.
Order of Precedence of Subcircuit Parameter Assignments
Parameters used within a subcircuit may be defined in several ways.
• In the subcircuit instantiation:
X1 N1 N2 N3 MY_SUBCIRCUIT P3=10
• Internally, within the subcircuit:
.SUBCKT MY_SUBCIRCUIT
.PARAM p3=20
.ENDS
• In the subcircuit declaration:
.SUBCKT MY_SUBCIRCUIT P1 P2 P3 PARAM: p3=2
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Eldo Netlist Setup
Subcircuits
• Or globally in the top level netlist:
.PARAM p3=5
X1 N1 N2 N3 MY_SUBCIRCUIT
The precedence of these parameter assignment methods is, in descending order, subcircuit
instantiation, internal subcircuit, subcircuit declaration which acts as a default only, and finally
global declaration.
Use option PARHIER to control the priorities for parameters.
Note
.PARAM assignments are order dependent within the netlist. Thus, a parameter value
assigned using the .PARAM command will only apply to subcircuits instantiated after this
.PARAM command. Therefore, for the below:
.SUBCKT INV
.PARAM p1=v0
.ENDSx1 ... inv
.param p1=v1
This is accepted, and p1 retains the value of v0 within x1 (when option PARHIER is set to
local).
Accessing Nodes Inside Subcircuit Instances from Outside
The following example illustrates how inner nodes may be accessed from outside of a subcircuit
instance in which they are defined.
.subckt inner n1 n2 n3
r1 n1 n3 1k
r2 n3 n8 4k
q27 n1 n7 n8 nbip
*...
.ends inner
.subckt outer n1 n2 n3 n4
q1 n1 n5 n6 pbip
*...
x1 n10 n12 vdd inner
*...
.ends outer
x13 n21 n25 n30 vdd outer
cmill1 x13.n1 x13.n5 1.2p
cmill2 x13.x1.n1 x13.x1.n5 0.9p
Where cmill1 is the Miller Capacitance of q1 located inside the subcircuit x13 and cmill2 is the
Miller Capacitance of q27 located inside x1 which in turn is located inside x13. Note that in this
example, the capacitances are declared from outside of the subcircuit definitions.
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Eldo Netlist Setup
Subcircuits
Specifying Noise in Subcircuits
By default, devices present noise contributions when a noise analysis is specified. The
NONOISE parameter on a device model or instance can be specified so that no noise model will
be used for the device when performing a noise analysis. The specification of noise on a device
or subcircuit instance overrides any specification in the model definition (.MODEL statement).
Noise can also be controlled at the subcircuit level in the following ways to specify that devices
present no noise contribution to the noise analysis:
• On the subcircuit definition (.SUBCKT statement) specify the (NONOISE) parameter.
This parameter must be specified before the PARAM: or PAR=VAL specifications, if
any.
• On the subcircuit instance (X statement) specify the (NONOISE) or NOISE=0
parameter. This parameter must be specified after the PARAM: or PAR=VAL
specifications, if any.
Local specification takes precedence. The specification of noise in the subcircuit overrides any
specification in the parent subcircuit instance. In the following example:
.subckt top1 in out (nonoise)
Xinv1 in out inv wn=17u noise=1
.ends
XTOP in out top1 (nonoise)
A noise analysis will run even though (NONOISE) is specified in the XTOP instance; this is
because NOISE=1 is specified inside the subcircuit definition of top1.
(INLINE) Keyword Example
The following example illustrates how the (INLINE) keyword can be specified on the
.SUBCKT instance, so that Eldo will not print the full hierarchical name of the device which has
the same name as the .SUBCKT.
X1 ... MFOO
X2 ... MFOO
.SUBCKT MFOO ... (INLINE)
M1 ...
MFOO
M2
...
.ENDS
In the OP table, it will not be X1.MFOO and X2.MFOO which appear, but simply X1 and X2.
The other names, X1.M1, X2.M1, X1.M2 and X2.M2, will be printed out unaffected.
DSCGLOB Option Example
Nodes which appear in subcircuit definitions have priority over the nodes defined with
.GLOBAL statements. Option DSCGLOB can be used to change this behavior. For example:
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Eldo Netlist Setup
Subcircuits
.GLOBAL QWE
VG QWE 0 DC 3
*.SUBCKT with a global node name in argument list
.SUBCKT B QWE
R1 QWE 0 1K
.ENDS
V2 PIN2 0 DC 2
X2 PIN2 B
By default, Eldo will connect R1 between PIN2 and 0 because the symbolic subckt pin QWE is
related to real node PIN2.
When option DSCGLOB=GLOBAL is specified Eldo will connect R1 between global node
QWE and 0.
Multiplication (M) Factor
The M factor is an element multiplier, simulating the effect of multiple elements in parallel. The
M factor can be specified as a subcircuit parameter and applies to all elements.
For example, if you have a subcircuit defined and instantiated as follows:
.SUBCKT MYRSUB IN OUT
R1 IN 1 1000 M=4
R2 1 OUT 1000
.ENDS MYRSUB
X1 IN OUT MYRSUB M=2
By default, the resistances of X1.R1 and X1.R2 will be 125 Ω and 500 Ω respectively. It is
simulated as if there are eight X1.R1 devices in parallel and two X1.R2 devices in parallel. As
can be seen in the example, the M factor works through the hierarchy. When it is specified on a
subcircuit instance (X instance), every element defined in the subcircuit will be duplicated by
this multiplication factor.
You should not specify an M factor value less than 1 on devices as this could lead to simulating
devices that cannot be physically realized. However, specifying M=0 on a subcircuit instance
means the M factor is ignored for that subcircuit.
To change the M factor behavior, so that the M=val factor of a subcircuit instance is handled as
a user-defined parameter instead of a multiplication factor, specify the M53 option. In the
previous example, with M53 specified, the final resistances of X1.R1 and X1.R2 will be 250 Ω
and 1000 Ω, respectively. It is simulated as if there are four X1.R1 devices in parallel.
See Also
• Subcircuit Instance in the Eldo Reference Manual
• .SUBCKT in the Eldo Reference Manual
• .GLOBAL in the Eldo Reference Manual
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Subcircuits
Related Topics
Subcircuit Definitions and Calls
Element and Source Definitions
Device Libraries
Eldo® User's Manual, 15.3 131

Eldo Netlist Setup
Device Libraries
Device Libraries
To include model or subcircuit definitions from library files into the current input netlist the
following statements are available. Eldo includes the whole contents of the file specified.
• .INCLUDE
Inserts the contents of a file into a .cir file. For example:
.INCLUDE circuit_addon.inc
Specifies that the contents of the circuit_addon.inc file be included in the circuit
description file (netlist). In this case, the included file is resident in the same directory as
the netlist.
See “.INCLUDE” in the Eldo Reference Manual.
• .LIB
Inserts model or subcircuit definitions into an input netlist from a library file. For
example:
.LIB models.lib
Specifies that any model and subcircuit information missing in the input netlist should
be taken from the file models.lib. The models.lib file could contain model definitions for
example:
*BJT model definition
.model qmod npn bf=160 rb=100 cjs=2p
+ tf=0.3n tr=6n cje=3p cjc=2p vaf=100
*...
The input netlist could contain the following reference to the model defined:
*main circuit
q23 10 24 13 qmod
Specifies the bipolar transistor q23 of model type qmod.
See “.LIB” in the Eldo Reference Manual.
• .ADDLIB
Searches a directory for files with extensions .mod, .ckt, .sub and include in the .cir file
the contents of files with names corresponding to referenced model and subcircuit
definitions. For example:
mn1 a b c d mna w=w l=l
*...
.ADDLIB 2 /users/examples/
.ADDLIB 1 /users/models/
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Specifies that all models and subcircuits missing in the input netlist should be searched
for and extracted from .mod, .ckt, .sub or .cir files contained in the directories /users/
models/ and /users/examples/ in this order. The file containing the model mna must be
named mna.mod.
See “.ADDLIB” in the Eldo Reference Manual.
See also “Search Rules and Naming Conventions for Adding Libraries” on page 136.
• .SCOPE
See also:
Associates a library to a set of instances, using a library identifier (key). For example:
.LIB key=dk1 models1.lib foo
.LIB key=dk2 models2.lib foo
x1 a b foo
x2 a b foo
.SCOPE key=dk1 inst=x1
.SCOPE key=dk2 inst=x2
In this example, models1.lib and models2.lib both contain a definition of subcircuit foo.
Each library is specified a different key, which is used to select the version of foo during
instantiation. The .SCOPE commands attach a specific library to a specific instance with
the key identifier. Here instance x1 is associated to the models1.lib library file, and
instance x2 is associated to the models2.lib library file.
See .SCOPE in the Eldo Reference Manual.
• “Search Path Priorities” on page 133
• “Library Variant Management” on page 134
• “Deleting a Library” on page 136
Search Path Priorities
The order of directories in which include and library files are searched for is:
1. Absolute path.
2. Parent directory — Directories of the files in the calling hierarchy (files which contain
the .INCLUDE/.LIB statement), the directory of the last calling file being searched first.
3. Current directory — Directory from which Eldo was started.
4. Search path — Specified using the -searchpath argument or .OPTION SEARCH=path
within the netlist. If both are specified, then the contents of -searchpath is searched first.
Eldo® User's Manual, 15.3 133

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Device Libraries
Search Path Priorities Example
The following example is related to search path priorities and shows the order in which
directories are searched. If you have the following command in a netlist file:
.LIB ./foo/myfile.lib
and if in the library file myfile.lib, you have:
.LIB toto
then if file toto is not found in the netlist directory or parent directory, it is searched for in the
current directory from which Eldo was started.
In the case of a nested .LIB or .INCLUDE, the directory of the library file containing the .LIB or
.INCLUDE statement is searched.
Tip
See “.OPTION SEARCH” and the “-searchpath” command-line argument in the Eldo
Reference Manual.
Related Topics
Device Libraries
Library Variant Management
The .LIB command can be used to manage library variants such as “best,” “worst,” and
“typical” process variations, also called device corners. Within the library, you must have
sections defined by library variant blocks using the syntax:
.LIB libtype
* device corner specification
.ENDL
An example library file, mos_corners.lib, containing the device corners follows:
lib case management
.lib best
.model MN nmos level=3 vt0=0.5
.endl best
.lib typ
.model MN nmos level=3 vt0=0.75
.endl typ
.lib worst
.model MN nmos level=3 vt0=1.0
.endl worst
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Device Libraries
The device corner variants are the different threshold voltages. In the main netlist, you specify
the library filename together with the name of a library variant to be used, for example the
following specifies the “typ” device corner is to be used from the library file mos_corners.lib:
lib case management
.lib mos_corners.lib typ
m1 vdd g 0 0 MN l=1.2U w=5U
vdd vdd 0 5
vg g 0 0.8
.op
.end
Tip
See “.LIB” and “.ENDL” in the Eldo Reference Manual.
Related Topics
Device Libraries
Library Nesting
Eldo libraries may themselves contain other libraries.
For example, consider a library lib.lib:
.lib best
.lib mos.lib best
.lib bip.lib best
.endl best
.lib typ
.lib mos.lib typ
.lib bip.lib typ
.endl typ
If a netlist contains the command:
.LIB lib.lib best
then Eldo will browse the mos.lib and bip.lib which are surrounded by .LIB best and
.ENDL best.
Tip
See “.LIB” and “.ENDL” in the Eldo Reference Manual.
Related Topics
Device Libraries
Eldo® User's Manual, 15.3 135

Eldo Netlist Setup
Device Libraries
Deleting a Library
Use the .DEL LIB command to remove a library name used in a previous run from the nominal
description. Next time a simulation is run, the .DEL LIB statement removes the corresponding
.LIB statement and a new library can be specified. It can be used in conjunction with the
.ALTER command to create modifications within the netlist before re-runs.
This example demonstrates how a library file can be replaced after a first run. delib1.lib is
removed and delib2.lib is put in its place:
v1 1 0 1
x1 1 2 r
r2 2 0 1
.dc
.extract dc v(2)
.lib delib1.lib
.alter
.del lib delib1.lib
.lib delib2.lib
.end
Tip
See “.DEL LIB” and “.LIB” in the Eldo Reference Manual.
Related Topics
Device Libraries
Search Rules and Naming Conventions for Adding
Libraries
Search rules and uppercase/lowercase character naming conventions for the .ADDLIB
command are as follows:
• A filename must be in all uppercase or all lowercase and appended with a lowercase
.mod, .ckt, .sub, or .cir.
.mod for models only
.sub, .ckt or .cir for subcircuits only
• Files with uppercase are searched first. For example:
My_2N2222a.mod (not searched)
MY_2N2222A.mod (searched first)
my_2n2222a.mod (searched last)
• For subcircuits .ckt extension is searched first, then .sub is searched, .cir is searched last.
For example:
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Device Libraries
op11A.ckt (not searched)
OP11A.ckt (searched first)
op11a.ckt (searched second)
OP11A.sub (searched third)
op11a.sub (searched fourth)
OP11A.cir (searched fifth)
op11a.cir (searched last)
Related Topics
Device Libraries
Tip
See “.ADDLIB” in the Eldo Reference Manual.
Using Libraries in Eldo Interactive Mode
It is possible to use the .LIB mechanism in Eldo interactive mode. The netlist must contain one
or several lines of type:
.LIB KEY=kname FNAME [LIBTYPE]
In interactive mode, the following commands can be issued:
.LIB key=toto mymod.tech nominal
.LIB key=toto mymod.tech worst
.LIB key=toto mymod2.tech
Eldo will search for the kname to identify which library must be replaced. Limitations of the
.LIB command when issued in interactive mode are as follows:
• Subcircuits are not replaced.
When .LIB is specified in the input file, it can be used to select a subcircuit to be
included in the design. Since taking a subcircuit from another library than the library
specified in the input file could result in a change of topology (and changing topology of
the current design is strictly impossible), Eldo would issue an error whenever the user
attempts to substitute one subcircuit for another.
• Switching between GUDM and non-GUDM models is prohibited. Similarly, switching
between GUDM models is prohibited.
• Only MOS, BJT, DIODE, JFET, R, L and C .MODEL commands can be substituted.
Attempting to substitute other kinds of models will lead to an error.
Tip
See “.LIB” in the Eldo Reference Manual.
Eldo® User's Manual, 15.3 137

Eldo Netlist Setup
Device Libraries
Related Topics
Device Libraries
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Encrypting Libraries
Encrypting Libraries
This topic describes the encryption tool available in Eldo, used to encrypt libraries.
• See “encrypt_eldo Tool” on page 140 for details of the tool syntax and arguments.
• See “Protection of Encrypted Libraries” on page 144 for details of the IP protection
system.
Eldo® User's Manual, 15.3 139

Eldo Netlist Setup
encrypt_eldo Tool
encrypt_eldo Tool
Use the encrypt_eldo tool to encrypt the libraries containing .SUBCKT definitions, .MODEL/
.PARAM cards, .PROTECT/.UNPROTECT blocks, and Verilog-A source files. It uses DES
encryption with an internal 56-bit key. The file will be automatically decrypted by Eldo at run
time, but no encrypted information is displayed in any output files generated by Eldo, such as
the ASCII output file (.chi). This guarantees the confidentiality of the data.
Usage
encrypt_eldo -i input_file [-o output_file] [-semi] [-nosemi]
[-compat|-veriloga] [-v]
Arguments
• -i input_file
Input filename. The file can contain model cards, parameter cards, subcircuit definitions,
and protected blocks for encryption.
• -o output_file
Output filename. If this is not specified, the filename will be input_file.crypt.
• -semi
Enables semi-transparency for encrypted blocks generated from subcircuit definitions and
.PROTECT/.UNPROTECT blocks. See “Semi-Transparent Encryption” on page 147.
• -nosemi
Disables semi-transparency for encrypted blocks, discarding any user annotation.
Equivalent to removing all .SEMITRANSPARENT commands from the input file before
encryption. See “Semi-Transparent Encryption” on page 147.
• -compat
Simulator compatibility argument, to encrypt HSPICE source files. When specified only
.PROTECT/.UNPROTECT blocks will be encrypted.
• -veriloga
Encrypt Verilog-A source files.
• -v
Returns the software version number. No encryption is performed.
Description
Notes for Verilog-A Usage
• When running the simulation multiple times, Eldo will not decrypt and recompile the
Verilog-A file each time if the file or the launching parameters are unchanged.
• .PROTECT/.UNPROTECT blocks have no effect with the -veriloga argument.
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encrypt_eldo Tool
• .INLINE/.ENDINLINE act as .SUBCKT/.ENDS. The inline block is encrypted in the
same way as subcircuits; it does not require the -veriloga argument.
• For partial encyrption, use the Verilog-A source code directives `pragma protect begin
\ `pragma protect end, `protect \ `endprotect, or `protect begin \ `protect end, to
specify the blocks for protection inside the Verilog-A model file.
• By default -veriloga encrypts the complete file, except the lines containing the keywords
module, macromodule, endmacromodule, endmodule.
Examples
1. Unencrypted netlist (diode.lib):
.model DNPPSJU
+ d level=8 diolev=9 tr=27 tnom=27
+ vr=0 cjbr=0.00072727 cjsr=8.649e-12
+ cjgr=3.946e-10 jsdbr=3.5987e-07 jsdsr=3.4372e-12
+ jsdgr=6.9543e-14 jsgbr=6.0153e-06 jsgsr=1.0506e-09
+ jsggr=6.4326e-10 vdbr=0.55572 vdsr=0.49482
+ vdgr=0.79381 pb=0.44466 ps=0.99
+ pg=0.43889 nbj=1 nsj=1.2
+ ngj=1
.subckt diode A B
.model my_diode D diolev=9 tr=27
tnom=27
+ vr=0 cjbr=0.00072727 cjsr=8.649e-12
+ cjgr=3.946e-10 jsdbr=3.5987e-07 jsdsr=3.4372e-12
R1 A A1 1k
D1 A1 B1 my_diode
R2 B1 B 1k
.ends
2. Command for encrypting this netlist with the Eldo license:
encrypt_eldo -i diode.lib -o diode_crypt.lib
3. Output file generated (diode_crypt.lib):
Eldo® User's Manual, 15.3 141

Eldo Netlist Setup
encrypt_eldo Tool
%.model DNPPSJU
%6A41CAC8CE3D50CB0B85F0126F6D1CCF23E5CA9C3BD0E7F21716251CB19DA7
%36FBBF69EF23E826A0478CA39376DCC8C4B7DBCD4A5A61CD26999C7F74FA2C
%75D9133AD4A91885751DDCE235FB1D944B96A4491CE3EDC5247588A7697FA1
%F912ED3488C832AB598321B58D3F25D176D794F6376924596B7948A4068996
%35363770AA370F3C10331A8FC0B5822FFDA963774FFFC74F1FFA3021EA693F
%D88A1A3E8DDBC62012F317FE3BF379A999B6638BFE8A7A97E6B46C6E1E2B60
%A2A9362162265083A1A898E5CF8EF5A5F6FF420A52C2E23FB9364E2BC13F29
%6F79757FF86BB080DCBAA2B4FC7EBF863B3B0C7C896BAF6525DF00901CD9E1
%6FC7E1BD4E691E6B006451AAE3302D64AD912114D5AC4F3D436BB1AAE5582F
%1A
.subckt diode A B
%A40ACD98849922AC04809D607E2424D4255F6765FF779A2EF49C24DC0
%483152A2024CA2B0C2E975EE8E41C1DCD2098C152082EA626C990AE64
%7B7F38B8FFEA9868E28164C55E19139F8378A9FF6BB9946CC7448D744
%127ADEA26B511101C631E3D455880E6E56EFBFEBC481964A7300C9FBF
%5B57245A6CC15D2A72BC833D8437DCF53D85F1B017366485676443756
%2BFFAC6DFEB58B5A43ACD64C30ECA1F7491380ED4F8777FBDF2BF6DA1
%287BD1F4C86D96B25ABA5164851F196324189F42BFC67116235368287
%5
.ends
4. Input file (test.cir)
* example for encryption netlist
.lib diode_crypt.lib
v1 1 0 1
d1 1 2 DNPPSJU
x1 2 0 diode
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Eldo Netlist Setup
encrypt_eldo Tool
.op
.end
5. Invoking Eldo.
eldo test.cir
Results
The netlist is not displayed inside the Eldo output (.chi) file, as shown below:
.MODEL DNPPSJU
----> the lines 4 to 13 are not displayed here.
.SUBCKT DIODE A B
-> the lines 16 to 23 are not here.
Warning 902: "DIOLEV in model DIODE.MY_DIODE": Model parameter ignored.
Warning 902: "TR in model DIODE.MY_DIODE": Model parameter ignored.
Warning 902: "VR in model DIODE.MY_DIODE": Model parameter ignored.
Warning 902: "CJBR in model DIODE.MY_DIODE": Model parameter ignored.
Warning 902: "CJSR in model DIODE.MY_DIODE": Model parameter ignored.
Warning 902: "CJGR in model DIODE.MY_DIODE": Model parameter ignored.
Warning 902: "JSDBR in model DIODE.MY_DIODE": Model parameter ignored.
Warning 902: "JSDSR in model DIODE.MY_DIODE": Model parameter ignored.
.ENDS
V1 1 0 1
D1 1 2DNPPSJU
X1 2 1 DIODE
The encrypted model parameters are not displayed inside the Eldo output .chi file.
Tip
See “.PROTECT” and “.UNPROTECT” in the Eldo Reference Manual.
Related Topics
Protection of Encrypted Libraries
Running Eldo
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Eldo Netlist Setup
Protection of Encrypted Libraries
Protection of Encrypted Libraries
An improved IP protection system is available for IP providers, providing an additional level of
protection compared to simple encryption available through the encrypt_eldo utility. The device
model libraries provided by IP providers (typically foundries) often contain process sensitive
information such as SPICE device models, equations, technology parameters, and so on. These
may be encrypted, but there is no easy way to restrict the usage of these encrypted model
libraries. In particular, there is no way to restrict the allowed duration of usage.
The purpose of the enhanced IP protection system is to enable an IP provider to ship encrypted
and licensed model libraries to their customers, independent of Mentor Graphics. The licensing
mechanism might be a standard commercial license managing system. Using the system, the IP
provider can control the usage of its model libraries in exactly the same way that any
commercial software is controlled, using features, license files, expiration dates, and so on. The
system is designed in such a way that Mentor Graphics does not have to know the final endusers,
nor generate any keys nor licenses. The IP provider creates and provides both the
encrypted IP (the model libraries) and an “IP access library.” The IP access library is a dynamic
load library (compiled C code). Mentor Graphics does not interfere with the encryption process,
nor the license generation, maintenance, renewals, and so on, which are the entire responsibility
of the IP provider.
Preparing and Installing a Protected Library
Lists the steps involved in preparing and installing a vendor-specific protected/encrypted
library.
Procedure
1. The vendor, or IP provider, prepares a single IP access library. This is a dynamic load
library coded in C.
2. The vendor then prepares and encrypts the Eldo library source for each library the
vendor wishes to distribute.
3. The user installs the vendor-specific IP access library and the vendor protected/
encrypted libraries.
4. The user then installs the licensing software and keys provided by the IP vendor.
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Eldo Netlist Setup
Protection of Encrypted Libraries
Figure 4-2. IP Protection
Related Topics
encrypt_eldo Tool
Coding and Encrypting a Protected Library
Description of the Loading and Control Process
Creating the IP Access Library
Installing a Protected Library
Eldo® User's Manual, 15.3 145

Eldo Netlist Setup
Protection of Encrypted Libraries
Coding and Encrypting a Protected Library
If you are an IP provider wishing to protect a library, you must include the .IP_protect command
in your library file (.lib).
Usage
.IP_protect IP_provider=NameOfTheIPProvider
+ IP_access_lib=NameOfTheAccessLibrary feature=NameOfTheFeature
+ ixl=ixl_crc ixl64=ixl64_crc
Arguments
• IP_provider=NameOfTheIPProvider
The name of the IP provider, as it will appear in messages. Use a simple string comprising
only letters (A-Z) and numbers (0-9). Do not use blanks.
• IP_access_lib=NameOfTheAccessLibrary
The name of the dynamic load library which communicates between Eldo and the actual
license manager. Note that NameOfTheAccessLibrary must be given without its extension.
Eldo will add the correct extension (such as “.so”) according to the platform. This library
will have to be located in a path listed in the LD_LIBRARY_PATH environment variable.
• feature=NameOfTheFeature
The feature name which will be checked-out to grant access to the protected library.
• ixl=ixl_crc, ixl_64=ixl64_crc
These are CRC values of the IP access libraries, as returned by the eldo_checksum.exe
utility provided in the AMS distribution. These CRC values must be provided, and are
checked by Eldo to verify the integrity of the IP access library. The eldo_checksum.exe
utility must be run once per physical platform.
Description
The .IP_protect command must be written inside a .PROTECT/.UNPROTECT area of the
device model library (.LIB). The device model library then has to be encrypted using the
standard eldo encryption tool, encrypt_eldo, which is provided with the AMS distribution. As
the .IP_protect command is inside a .PROTECT/.UNPROTECT area, it is encrypted as well,
and therefore cannot be read nor changed by the final user.
Tip
See “.IP_PROTECT”, “.PROTECT” and “.UNPROTECT” in the Eldo Reference Manual.
Related Topics
encrypt_eldo Tool
Description of the Loading and Control Process
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Eldo Netlist Setup
Protection of Encrypted Libraries
Creating the IP Access Library
Installing a Protected Library
List of Encryption Errors and Warnings
Semi-Transparent Encryption
Semi-transparent encryption enables an encrypted part of the circuit to behave as if it was
protected by a .PROTECT/.UNPROTECT block.
By default, non-semi-transparent encryption blocks are not printed in the output file nor
accessible through various plotting and extracting functions of Eldo. However, commands and
devices that are not encrypted but appear in a protected block are not printed in the output file,
but it is still possible to plot or extract nodes and devices.
Semi-transparent encryption avoids encrypted content from being printed in the output file, but
enables that content to be plotted or extracted.
• Semi-transparent encryption with the encrypt_eldo utility
Specify encrypt_eldo command line argument -semi to activate semi-transparency for
encrypted blocks generated from subcircuit definitions and .PROTECT/.UNPROTECT
blocks.
• Semi-transparent encrypted blocks
An encrypted block in a circuit netlist appears as consecutive lines made of a heading %
sign followed by a string of hexadecimal characters of an arbitrary length, for example:
%886B59DED5CEB36FC3D6EE8D90E8048F
%BB6460E7E01502C4F0D03A632D324F2D
Eldo deciphers the block into a list of original text lines:
.INCLUDE r.inc
V1 0 1 10
A semi-transparent encrypted block looks exactly like a normal encrypted block, but
once deciphered, the first command is .SEMITRANSPARENT. If the command appears
anywhere but at the beginning of the deciphered lines, it is discarded. For example, if an
encrypted block is deciphered into the following original text lines, then these lines are
handled as semi-transparently encrypted:
.SEMITRANSPARENT
.INCLUDE r.inc
V1 0 1 10
When encrypt_eldo command line argument -semi is specified, it produces encrypted
blocks starting with the .SEMITRANSPARENT command (for encrypted blocks
generated by subcircuit definitions and the .PROTECT/.UNPROTECT blocks).
Eldo® User's Manual, 15.3 147

Eldo Netlist Setup
Protection of Encrypted Libraries
• Safety guarantee
The .SEMITRANSPARENT command is effective only if it is found at the beginning of
the deciphered content of an encrypted block. The semi-transparency property only
applies to the content of the very same encrypted block. This constraint guarantees that
it is not possible to transfer the semi-transparency property to encrypted blocks that were
not semi-transparently encrypted. The Eldo encryption scheme guarantees that there is
no way for an attacker to decipher or modify the content of an existing encrypted block
without computing the Eldo key. There is no way for an attacker to prepend
.SEMITRANSPARENT to the content of an encrypted block in order to make it semitransparent.
• User-defined semi-transparent encrypted block
You can manually insert .SEMITRANSPARENT as the first command of a subcircuit
definition or a protected block. As long as the command is in plain-text it is discarded by
Eldo. But once the circuit netlist is encrypted (using the encrypt_eldo utility), the
commands are processed by Eldo as if they appear at the proper location. If you specify
the encrypt_eldo utility without the -semi argument, then the only semi-transparent
blocks generated are those you manually annotated.
The additional encrypt_eldo utility -nosemi argument produces non-semi-transparent
encrypted blocks, discarding any user annotation. It is equivalent to removing every
.SEMITRANSPARENT command from the input file before encrypting it.
• Semi-transparent encryption of Verilog-A blocks.
Examples
Verilog-A modules embedded in a SPICE netlist, using the .INLINE command or
described in a separate file, can be encrypted using the same mechanism above. Module
internal nodes and variables are given public visibility while keeping the
implementation private. To encrypt a Verilog-A file, specify the encrypt_eldo utility
with the -veriloga argument.
Only protected modules that have the Verilog `pragma protect viewport compiler
directive defined before the `pragma protect begin directives, will be encrypted in a
semi-transparent way. The other modules that do not have this directive before the
`pragma protect begin are encrypted in a standard way. The encrypt_eldo utility -semi
argument is not mandatory to achieve semi-transparent encryption of Verilog-A
modules. If this argument is specified then all modules to be encrypted in a file are done
so in a semi-transparent way.
The .SEMITRANSPARENT command is optional if the encrypt_eldo utility is specified with
the -semi argument. .MODEL commands must be included inside a .PROTECT or a .SUBCKT
statement in order for them to be semi-transparently encrypted. For example, to encrypt a model
semi-transparently, pass the following commands to the encrypt_eldo utility:
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Protection of Encrypted Libraries
.PROTECT
.SEMITRANSPARENT
.MODEL ...
.MODEL ...
.UNPROTECT
This example shows a Verilog-A with partial protection and viewport directives:
`include "disciplines.vams"
`timescale 1ns / 100ps
module circuit (out);
output out;
wire in, out;
parameter integer frequency=20000000;
multiplier mltp1 (in, out);
stimulus #(.fr(frequency)) stim1(in);
endmodule // circuit
`pragma protect viewport
`pragma protect begin
module multiplier (in, out);
input in;
output out;
electrical in, out;
parameter mult = 2;
analog begin
V(out)

Eldo Netlist Setup
Protection of Encrypted Libraries
`include "disciplines.vams"
`timescale 1ns / 100ps
module circuit (out);
output out;
wire in, out;
parameter integer frequency=20000000;
multiplier mltp1 (in, out);
stimulus #(.fr(frequency)) stim1(in);
endmodule // circuit
`pragma protect begin
module multiplier (in, out);
input in;
output out;
electrical in, out;
parameter mult = 2;
analog begin
V(out)

Eldo Netlist Setup
Protection of Encrypted Libraries
encrypted library, the .LIB command in the netlist is a regular .LIB command (that is, whether
the device model library is encrypted or not does not change the usage).
Eldo decides if access is granted or denied by calling a function in the IP access library. This
function must be coded by the IP provider, and it is in charge of interrogating the provider’s
license daemon to grant/deny access to the necessary feature. See “Creating the IP Access
Library” on page 151.
As it would be too easy to fool this system by replacing the IP access library by another
dynamic library which always returns ‘ALLOWED’, Eldo verifies that the checksum of the
loaded library is the same as the one specified in the .IP_protect command. That means that if a
new IP access library is compiled, the .IP_protect command must be rebuilt, and the model
library re-encrypted, as the CRC will have changed. Note that a CRC is platform dependent, and
therefore several CRCs must be provided in the .IP_protect command to accommodate the
various targeted platforms (ixl and so on).
The standalone executable, eldo_checksum.exe, generates the CRC of the library. This is
available in the standard AMS distribution, located in the $MGC_AMS_HOME/$VCO/bin
directory.
For example, run:
$MGC_AMS_HOME/$VCO/bin/eldo_checksum.exe
where NameOfTheAccessLibrary is a .so file on Linux. Specify this name without its extension.
The utility returns a CRC value which must be provided to the .IP_protect command. It must be
run once for each platform.
The NameOfTheIPprovider character string is used to display correct messages to the final user
if there is a problem during the license check-out.
Related Topics
Coding and Encrypting a Protected Library
Creating the IP Access Library
Installing a Protected Library
List of Encryption Errors and Warnings
Creating the IP Access Library
The required Eldo interface of the IP access library must contain two functions:
ty_lib_status * get_license_third_party(char *feature);
ty_lib_status * release_license_third_party(char *feature);
Eldo® User's Manual, 15.3 151

Eldo Netlist Setup
Protection of Encrypted Libraries
The ty_lib_status type and the function prototypes are defined in the eldo_ipprotect.h include
file, shown below. This is provided in the $MGC_AMS_HOME/include folder. The various
return values and their meanings are explained in the comments.
The compilation command for the shared library is as follows:
gcc -I$MGC_AMS_HOME/include (...other include folders...)
-o -shared
This library does not need to be recompiled with each new version of Eldo unless this is
explicitly stated in the release notes of a new version.
Contents of eldo_ipprotect.h Include File
typedef enum
{
/*! The license manager has successfully checked out the feature,
* nothing special to do */
getFeatureOk,
/*! The license manager failed to check out the feature.
* An error message will be printed and the simulation will stops.*/
getFeatureNOk,
/*! The license manager has checked out the feature, but a warning
* should be printed
* (for example: if the license is about to expire soon) */
getFeatureOkWarn,
/*! The license manager has released the feature, nothing special to do
*/
releaseFeatureOk,
/*! The license manager failed to release the feature. A warning message
* will be printed and the simulation will continue.*/
releaseFeatureNOk,
/*! The license manager has released the feature, but a warning
* should be printed */
releaseFeatureOkWarn
} en_ipstatus;
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Eldo Netlist Setup
Protection of Encrypted Libraries
/**
* This structure is used by eldo to check the result of the license
* request.
*/
typedef struct
{
/* The status of the request. According to it some actions will be
done.*/
en_ipstatus status;
/* The message that eldo must print. Once the message is printed, eldo
* will free the memory allocated for the message.
*/
char *message;
} ty_lib_status;
/**
* \brief This function is used to check that the feature given in
* argument is available. Eldo doesn't manage the possible queue
* systems. It is up to the library loaded by eldo to do that job.
*
* \param feature is the feature name (as it appears in the license file)
* needed to continue to parse the design
*
* \returns the status of the license check-out.
* If the license check-out failed, eldo will print the attached
* message as an error, will free it just after,
* and will abort the simulation. It will work the same way
* if the status is getFeatureOkWarn but the printed message
* will be a warning and it will not abort the simulation.
*/
ty_lib_status * get_license_thrd_party(char *feature);
/**
* \brief That function is used to release the feature given in argument.
* Eldo doesn't manage the possible queue systems. It is up to the
* library loaded by eldo to do that job.
*
* \param feature is the feature name that has been previously checked out
* and that must be released.
*
* \returns the status of the license checkin.
* If the license checkin failed, eldo will print the attached
* message as a warning and will free the message just after.
* The simulation will not be aborted. It will work the same way
* if the status is releaseFeatureOkWarn.
*/
ty_lib_status * release_license_thrd_party(char *feature);
Eldo® User's Manual, 15.3 153

Eldo Netlist Setup
Protection of Encrypted Libraries
Related Topics
Coding and Encrypting a Protected Library
Description of the Loading and Control Process
Installing a Protected Library
List of Encryption Errors and Warnings
Installing a Protected Library
For Eldo to be able lo load a protected library, the IP access library (a .so file on Linux) must be
located in a directory named .../ixl and so on, depending on its binary origin (Linux and so on).
The parent of that directory must be specified in the standard LD_LIBRARY_PATH variable.
Example
Having received the foo.so library (for Linux 32-bit) from your provider IpProvider, you want
to put that library under the common shared folder /shared/common/thirdPartyLibs. You must
create a specific folder according to the platform of the foo.so library. In this example it is a
Linux 32-bit library so put the file under /shared/common/thirdPartyLibs/ixl.
The path to include in the LD_LIBRARY_PATH variable is /shared/common/thirdPartyLibs.
Eldo will automatically search under the ixl folder if it is run on the Linux 32-bit system.
Related Topics
Coding and Encrypting a Protected Library
Description of the Loading and Control Process
Creating the IP Access Library
List of Encryption Errors and Warnings
List of Encryption Errors and Warnings
In the list of messages below, “%s” is a place-holder for the actual name of the library, name,
and so on.
ERROR 1608: Wrong vendor library, found at:\n+ %s\n+ The CRC of that
library is not the expected one. Please contact your %s office.
The checksum made on the found library does not match the one specified in the netlist.
ERROR 1609: Unable to find the %s%s dynamic library provided by %s.\n+
Check first your LD_LIBRARY_PATH. It must contain the path to %s/%s%s.\n+
If you don’t have that library, please contact your %s office to get one.
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Eldo was not able to find the requested library through the folder given in the
LD_LIBRARY_PATH variable (with respect to the rule specified above).
Eldo Netlist Setup
Protection of Encrypted Libraries
ERROR 1610: The protected part of the %s design requires a license to be
used. Eldo is unable to get a valid license feature %s\n+ %s”
Checkout of the license has failed.
ERROR 1611: Shared library %s%s was found but an error occured during its
loading.\n+ Please contact %s office.
An unexpected error has occurred (there was a missing function, the simulation was aborted
before, the crc has been changed, and so on).
ERROR 1612: Wrong vendor library %s%s found. The CRC of that library is
not the expected one. Please contact your %s office.
The checksum made on the found library does not match the one specified in the netlist.
ERROR 1616: In command .IP_Protect, missing %s parameter or parameter
value.
The command contains one or several parameters that have no value, or a mandatory parameter
has been forgotten.
ERROR 1618: Command .IP_Protect is not supported on that platform.
You have tried to run a circuit protected by ip_protect on a Windows platform. (Windows is not
supported.)
ERROR 1619: Errors occur during command .IP_Protect: aborting the
simulation.
This appears at the end of the command if an error occurred before.
ERROR 1620: Fatal error while %s license %s from provider %s.\n+ Please
contact your provider for more details.
Eldo is unable to get a proper return value when trying to check-out or check-in the license.
ERROR 1621: Fatal error while loading shared library %s%s.\n+ Please
contact %s office.”
Eldo is unable to load the dynamic library.
Warning 1447: Unable to release %s license, feature %s\n+ %s
The license check-in failed.
Warning 1476: License message from Provider: %s – Feature: %s\n+
&quot;%s&quot;
Eldo® User's Manual, 15.3 155

Eldo Netlist Setup
Automatic Recognition of MOS Instantiations in TSMC Libraries
The license tool has a specific message to deliver to the end user.
Related Topics
encrypt_eldo Tool
Protection of Encrypted Libraries
Automatic Recognition of MOS Instantiations
in TSMC Libraries
Eldo accepts MOS devices instantiated in TSMC libraries using subcircuit instantiations.
TSMC provides two sets of libraries:
• MACRO library—where MOS devices are represented by subcircuits, and hence uses
the letter ‘X’ in the netlist for instantiation. This is the MACRO approach.
• TSMC Modeling Interface (TMI) library—where MOS devices are instantiated
normally as MOS devices.
The same netlists can be used when switching from one library to another. If Eldo cannot find a
subcircuit definition with the expected name, but finds a .MODEL definition, it converts the ‘X’
instance into a normal MOS instance.
Related Topics
Model Definitions
Subcircuit Definitions and Calls
Running Multiple Runs
The .MPRUN command runs multiple simulations on one multi-processor machine, or on many
machines.
Notes
• When the simulation of the netlist is very short (for example less than 1s), the .MPRUN
feature is not suitable because most of the simulation time is spent collecting results.
One solution is to use USE_LOCAL_HOST=NO, but for very short simulations this is
not enough, and total simulation times are similar with or without the .MPRUN
command.
• In all cases, Eldo will warn you if a host cannot be used.
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Eldo Netlist Setup
Running Multiple Runs
This will happen when you do not have the permissions to see the machine and/or to
write in the working directory. This error must be fixed by the system administrator
before the .MPRUN command can be used.
• The netlist must be in a shared directory (a place visible from the other machines on the
network).
• If using local installations of Eldo, the installation patches (not the binaries) must be
strictly identical on all machines.
• Users need to be able to login remotely to other machines without supplying a password.
If a user needs a password to login remotely to other servers, Eldo will be unable to
access systems on those servers to launch tasks, because the other machines require
passwords and Eldo cannot supply them.
• The result of a .CALL_TCL command used with .MPRUN is unpredictable since the
behavior of the Tcl function is unknown to Eldo. It does not know if the command opens
output files or returns a waveform.
• .MPRUN cannot be specified inside a .ALTER section.
• If you set QUEUE=YES on the .MPRUN command, Eldo adds -queue on the command
line of the remote processes. The local process does not queue license requests. If you
simulate a netlist with -queue, both the main process and the remote processes can queue
license requests.
Usage
Before performing a run on a remote host, the .MPRUN command must initialize the remote
environment. By default, Eldo does the following before running a simulation:
cd
setenv MGC_AMS_HOME ...
setenv MGLS_LICENSE_FILE ...
If you specify INIT_FILE=filename, the sequence becomes:
cd
source
setenv MGC_AMS_HOME ...
setenv MGLS_LICENSE_FILE ...
and if you also specify DEFAULT_INIT=NO, the sequence becomes:
cd
source
and if you remove the INIT_FILE=filename, the sequence becomes:
cd
See Also
• .MPRUN in the Eldo Reference Manual
Eldo® User's Manual, 15.3 157

Eldo Netlist Setup
Merging Instances in Parallel
• -queue in the Eldo Reference Manual
Merging Instances in Parallel
By default, Eldo merges instances connected in parallel into a single instance. The parallel
instances must have the same set of parameters, and follow each other consecutively.
The multiple instances are reduced into a single instance by Eldo with the M parameter, for
example:
X1 1 2 FOO A=1 B=1
X2 1 2 FOO A=1 B=1
X3 1 2 FOO A=1.0 B=1
X4 1 2 FOO A=1 B=1
Here, X3 remains as it is because the character string for A does not match, X4 remains as it is
because it does not follow the other instances to be merged (X3 has broken the merge
sequence). Merging is done for X instances X1 and X2; they will be replaced by:
X1 1 2 FOO A=1 B=1 M=2
An example showing the merging of parallel instances with different instances between:
X1 A B INV1 W=0.8U L=0.35U
xr1 B 0 RES
X2 A B INV1 W=0.8U L=0.35U
xr2 B 0 RES
Merging is done for X instances X1 and X2, and also X instances xr1 and xr2. They will be
replaced by:
X1 A B INV1 W=0.8U L=0.35U M=2
xr1 B 0 RES M=2
This behavior applies to:
• Resistors
• Diodes
• BJTs
• MOSFETs
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Eldo Netlist Setup
Merging Instances in Parallel
• Subcircuit instances
The ASCII .chi output file lists the number of devices and subcircuit instances merged. For
example:
Number of X instances merged 3
Number of devices merged 5
To report all of the merged elements specify option CATMX_REPORT. In this case, the ASCII
.chi output file contains the instances that have been merged. For example:
X4 merged with X1
X3 merged with X1
X2 merged with X1
R6 merged with R1
R5 merged with R1
R4 merged with R1
R3 merged with R1
R2 merged with R1
The merging is done to speed-up simulations. However, this may also result in unexpected
warnings in the following situations:
• If an instance name is specified in a .PRINT/.PLOT/.EXTRACT, and if this instance is
merged with another, Eldo issues a warning that the instance is not found. For example,
with .PRINT dc ix(x2.1) Eldo issues a warning that instance x2 is not found.
• The output may take into account the M factor. For example, .PRINT IX(X1.1) will
return twice the number values obtained compared with if the instances had not been
merged. For MOS instances, if the M factor specification is not equal to 1 (default) the
merging of devices is not performed.
• If option MINRAVL is specified, and if there are resistors inside some X instances
which are merged, the working resistance of the device is R/M, where M is the number
of items in parallel. R/M can become < MINRVAL when R was > MINRVAL. This
should have limited impact on the results.
• When using high impedance (Hi-Z) checking commands, impedance is not computed on
the internal nodes of merged instances. Eldo issues a warning in this case to disable
merging instances in parallel so it can compute the impedance of those nodes.
To disable merging instances in parallel, specify option NOCATMX or invoke Eldo with the
-nocatmx argument.
Eldo® User's Manual, 15.3 159

Eldo Netlist Setup
Merging Instances in Parallel
Notes
• Merging instances in parallel (with or without device multiplier M=val specified) is
disabled when a Monte Carlo analysis is specified.
• Merging instances in parallel is disabled in interactive mode.
• Merging instances in parallel is disabled when a .DSPF_INCLUDE command is inside
the netlist.
• Instances inside Verilog-A instances are never merged.
See Also
• Combining Identical Resistors in the Eldo Reference Manual
• Combining Identical Diodes in the Eldo Reference Manual
• Combining Identical BJTs in the Eldo Reference Manual
• Combining Identical MOSFETs in the Eldo Reference Manual
• Combining Identical Subcircuits in the Eldo Reference Manual
• Option CATMX_REPORT in the Eldo Reference Manual
• Option NOCATMX in the Eldo Reference Manual
160
Eldo® User's Manual, 15.3

Chapter 5
Simulator Compatibility
Eldo provides compatibility with different simulators. Eldo can use an external simulator netlist
as input, accepting the different constructs and syntax used by such simulators. This chapter
shows the compatibility available.
HSPICE Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Hybrid Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Compat Mode Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Devices in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Sources in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Commands in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Options in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Netlist in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Arithmetic Functions and Operators in Compat Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Output Format in Compat Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Spectre Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Spectre Compatibility Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Spectre Compatibility Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Working with Multiple Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Troubleshooting the Spectre to Eldo Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Spectre to Eldo Converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
spect2el Command Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Eldo® User's Manual, 15.3 161

Simulator Compatibility
HSPICE Compatibility
HSPICE Compatibility
Eldo provides partial compatibility with HSPICE ®1 . You can use an HSPICE netlist as an Eldo
input. The main effect of compat mode is that it accepts some HSPICE constructs and syntax.
Eldo HSPICE compatibility is invoked as follows:
eldo -compat ... cir_file_name
or by adding in the netlist the following option (must be set at the top of the design):
.OPTION COMPAT
Note
Argument -compat is equivalent to setting both -compmod and -compnet arguments.
The different effects of HSPICE compatibility mode are divided into the following:
Hybrid Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Compat Mode Flexibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Devices in Compat Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Sources in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Commands in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Options in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Netlist in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Arithmetic Functions and Operators in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Output Format in Compat Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Hybrid Compat Mode
You can select a portion of the design for compat mode to be applied, and leave the rest of the
design in native Eldo mode (an alternative to options COMPAT, COMPMOD, and
COMPNET). This is done by encapsulating the section of the circuit inside .COMPAT and
.ENDCOMPAT commands.
For example:
1.HSPICE is a registered trademark of Synopsys, Inc.
162
Eldo® User's Manual, 15.3

Simulator Compatibility
Hybrid Compat Mode
My netlist
.compat
.subckt fooh 1
r1 1 0 '-1.0*sqrt(-4)' $ comment
i1 1 0 1m
.ends
.endcompat
.subckt foo 1
r1 1 0 'sqrt(4.0)' ! comm
i1 1 0 1m
.ends
x1 1 foo
x2 2 fooh
.op
.extract dc v(1)
.extract dc v(2)
.end
In this example, the subcircuit fooh is run in compatibility mode. The remainder of the circuit is
run in native Eldo mode.
Files that are included with .LIB or .INCLUDE between .COMPAT and .ENDCOMPAT are
handled in compat mode. In the following example, the content of the included files, file2 and
file3, are handled in compat mode:
.compat
.include file2
.lib file3 TT
.endcompat
You can use hybrid compat mode (.COMPAT/.ENDCOMPAT blocks) together with -
compmod or -compnet arguments (or equivalent options). Locally inside the block the
compatibility mode applies to both models and syntax, and outside the block it applies only to
models or syntax respectively.
Note
If hybrid compat mode (.COMPAT/.ENDCOMPAT blocks) is used together with the -
compat argument (or equivalent option) Eldo outputs a warning notifying that the
.COMPAT command has been specified even though compat mode is already enabled.
Limitations
• The commands .COMPAT and .ENDCOMPAT can not be specified inside .ALTER
sections.
• In compat mode, analyses are run in the sequence they are listed in the .cir file. However
this is not the case for analysis commands inside .COMPAT/.ENDCOMPAT blocks.
For example:
.tran 1n 10n
.tran 1n 20n
Eldo® User's Manual, 15.3 163

Simulator Compatibility
Compat Mode Flexibility
In this example, two analyses would be performed in standard compat mode, but if the
commands were inside a .COMPAT/.ENDCOMPAT block only one transient analysis
of 20n would be performed.
• Hybrid compat mode, with .COMPAT/.ENDCOMPAT blocks, impacts only model/
device parameters, not the way analyses are performed.
• In hybrid compat mode, the default temperature of devices inside .COMPAT/
.ENDCOMPAT blocks is 27°C, the same as the Eldo default mode. This temperature is
applied across the entire design. In compat mode, the default temperature is 25°C.
Tip
See “.COMPAT” in the Eldo Reference Manual.
Compat Mode Flexibility
Instead of using -compat (or .OPTION COMPAT) to read an HSPICE netlist, the -compmod
and -compnet arguments (or .OPTION COMPMOD and .OPTION COMPNET) can be set.
The effects of these arguments are:
• -compat — Interprets the netlist and the models as HSPICE format.
• -compmod — Triggers only the automatic conversion of models, not the netlist syntax.
Can alternatively be set with .OPTION COMPMOD. Only models referenced in the
topic “Devices in Compat Mode” on page 165 will be converted.
Note
-compmod only effects the model selection, not the parameters of a library. If you
have a HSPICE library that you want to be fully handled as such you should enclose
the .LIB command with .COMPAT and .ENDCOMPAT commands for “Hybrid
Compat Mode” on page 162. A library which contains no model, but only a subcircuit
with parameters will not be converted. -compnet must be used instead of -compmod in
this particular case.
• -compnet — Causes the netlist to be interpreted as compatible format, but the device
models are handled as Eldo SPICE models. This assumes the models are selected with
the Eldo model levels (for example, to select the BSIM3v3 model you must specify level
53, not 49). -compnet can alternatively be set with .OPTION COMPNET.
The -compnet and -compmod arguments apply to the entire netlist, including library files. For
example, when -compnet is set, even the statements in the library file, including those of model
library files, are interpreted in compat mode.
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Simulator Compatibility
Devices in Compat Mode
Note
See also the command line arguments “-compat,” “-compmod” and “-compnet” in the Eldo
Reference Manual
Related Topics
HSPICE Compatibility
Devices in Compat Mode
The following tables show the model level mapping when in compat mode. For example,
specifying LEVEL=70 in compat mode selects the BSIMSOIv4 model, but in Eldo standard
mode it selects the Philips PSP model. Any models not listed are handled as standard Eldo
models.
Eldo Device Levels
The following Eldo Levels are set in compat mode:
Table 5-1. MOS Levels with -compat
HSPICE Model Name
Eldo LEVEL
LEVEL
2 Eldo2 12
3 Eldo3 13
6 Modified Lattin-Jenkins Grove 16
8 Enhanced Berkeley LEVEL 2 17
13 Berkeley BSIM1 8
39 Berkeley BSIM2 11
49 Berkeley BSIM3v3.0 & BSIM3v3.1 53
50 Philips MOS Model 9 59
54 Berkeley BSIM4 60
57 Berkeley BSIMSOI3v2 PD 56, SOIMOD=1
59 Berkeley BSIMSOI3v2 FD 56, SOIMOD=3
64 HiSIM 66
68 HiSIM 66
69 Philips PSP 70
70 BSIMSOIv4 72
Eldo® User's Manual, 15.3 165

Simulator Compatibility
Devices in Compat Mode
HSPICE
LEVEL
Table 5-1. MOS Levels with -compat (cont.)
Model Name
73 HiSIM-LDMOS (HiSIM-HV) v1 73
HiSIM-LDMOS (HiSIM-HV) v2 83
77 Berkeley BSIM6 82
See “MOSFET Models” in the Eldo Reference Manual.
Eldo LEVEL
Table 5-2. BJT Models with -compat
HSPICE Model Name
Eldo LEVEL
LEVEL
2 Improved Berkeley 5
3 STMicroelectronics LEVEL 1 2
4 VBIC v1.2 8
(VERSION=1.15) VBIC v1.1.5 8
6 Philips Mextram 503.2 4
8 HICUM 9
9 VBIC v1.2 8
(VERSION=1.15) VBIC v1.1.5 8
See “BJT Models” in the Eldo Reference Manual.
Table 5-3. Diode Models with -compat
HSPICE Model Name (Eldo Level)
Eldo LEVEL
LEVEL
2 Fowler-Nordheim 3
3 Berkeley Level 1 1, SCALEV=3
4 JUNCAP Diode 8, DIOLEV=9
6 JUNCAP2 Diode 8, DIOLEV=11
See “Diode Models” in the Eldo Reference Manual.
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Simulator Compatibility
Devices in Compat Mode
Table 5-4. Resistor Level with -compat
HSPICE Model Name
Eldo LEVEL
LEVEL
1 RC Wire 3
See “RC Wire Model Syntax” in the Eldo Reference Manual.
PNP and NPN Devices
Compat mode affects the default type for PNP and NPN devices. SUBS defines the type of BJT.
By default, NPN and PNP are vertical:
• If SUBS is -1, BJT is lateral.If SUBS is 1, BJT is vertical.
• If -compat is set, NPN are vertical, PNP are lateral.
See “BJT Model Syntax” in the Eldo Reference Manual.
Resistor and Capacitor Model Syntax
.MODEL R or C: SCALE equivalent to Eldo R or C.
In compat mode (-compat or -compmod) R is not allowed as a parameter for a resistor model
and C is not allowed as a parameter for a capacitor model. Use the SCALE parameter instead.
Capacitor CTYPE Parameter
In compat mode, CTYPE will always default to 0 for C(V) and VCCAP devices, and
AUTOCTYPE is disabled. The default CTYPE can be globally set to 1 using .option
CTYPE=1. AUTOCTYPE can be activated using .option AUTOCTYPE.
Element Output
In compat mode, LV1 represents the channel length for the BSIM4 MOS model, and the
effective channel length (default) for all other MOS models.
In compat mode, LV2 represents the channel width for the BSIM4 MOS model, and the
effective channel width (default) for all other MOS models.
See “Element Output” in the Eldo Reference Manual.
Group Delay
VT is equivalent to VGD, and IT is equivalent to IGD (Group Delay on voltage or current). For
more information, see “VXxx(devname.posi)” in the Eldo Reference Manual.
Eldo® User's Manual, 15.3 167

Simulator Compatibility
Sources in Compat Mode
Node GROUND/GND/GND!
Node GROUND, GND and GND! are assumed to be the global node 0.
Value “x”
“x” is equivalent to “meg”, that is, in compat mode:
R1 1 0 1x
is equivalent to:
R1 1 0 1meg
Otherwise, 1x corresponds to 1.0.
S Parameter (SP) Model
In compat mode, a subset of the small-signal parameter data frequency table model (SP model)
is supported. The options and parameters supported are: S param data directly written in netlist,
FBASE, FMAX, TYPE=Y, VALTYPE, DATA. The VALTYPE parameter is optional; if not
specified, the default value is cartesian. Resistance is 50 Ω by default.
See “Lossy Transmission Line W Sampled Matrix Model” in the Eldo Reference Manual.
Related Topics
HSPICE Compatibility
Sources in Compat Mode
The LFSR source syntax is different in compat mode:
LFSR [(] vlow vhigh tdelay trise tfall rate seed
+ [taps] [rout=val] [ENCODE=DW8b10b] [RD_INIT=1|2] [)]
Related Topics
HSPICE Compatibility
Commands in Compat Mode
Some commands have different behavior in HSPICE compatibility mode.
• .ALTER
This command is cumulative. For example:
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Simulator Compatibility
Commands in Compat Mode
r1 1 0 1
r2 2 0 1
.alter 1
r1 1 0 2
.alter 2
r2 2 0 2
The second “alter” simulation will be run with both r1 set to 2 (inheritance from later
number 1), and r2 set to 2. In default Eldo mode without the -compat argument, the
second “alter” simulation will be run with r1 set to 1 (original netlist) and r2 set to 2.
Option COMPAT can be placed anywhere in the netlist; it is not order-dependent.
However, if the netlist contains .ALTER statements, and the option is placed in the
.ALTER block then it will not be taken into account in the nominal run, only the
.ALTER run. Then it will remain active for any further .ALTER runs. For example, if
the netlist contains:
title
netlist
.alter 1
.option compat
.alter 2
*...
.end
v1 1 0 1
r1 1 0 1
.dc
.end
Here, the nominal run will not recognize the COMPAT option, the first .ALTER will,
and the second .ALTER will also. The statements between the last two .END statements,
which correspond to the simulation of yet another circuit, will still treat COMPAT as
active. Once activated, compat cannot be deactivated.
See the “.ALTER command” in the Eldo Reference Manual.
• .DC
When only a DC analysis is specified in compat mode, by default the initial transient
value is used.
For .DC with .OP, a DC sweep is done before any OP calculations. The Eldo default
behavior, and in hybrid compat mode (with .COMPAT/.ENDCOMPAT blocks but
without .OPTION COMPAT), is to perform the OP around the first point of the DC
sweep.
See the “.DC command” in the Eldo Reference Manual.
• .EXTRACT RMS()
In compat mode, this extract returns the root mean square value of a waveform for
transient analysis, computed as:
Eldo® User's Manual, 15.3 169

Simulator Compatibility
Commands in Compat Mode
For example, if your netlist has the following AC analysis, then the frequency interval
used is: x_start=0.1 (fmin) and x_end=10e6 (fmax).
.ac dec 100 0.1 10e6
Note
EZwave is not instructed that compat mode has been used during the .wdb file
generation, so you can incorrectly select rms_ac or rms_noise in the measurement
tool. In this case, only rms_tran must be used to be consistent with compat mode.
See the “.EXTRACT RMS command” in the Eldo Reference Manual.
• .HDL
The syntax is different in compat mode:
.HDL "filename" [module_name] [module_alias]
See the “.HDL command” in the Eldo Reference Manual.
• .LIB
.LIB behaves as .INCLUDE.
See the “.LIB command” in the Eldo Reference Manual.
• .LIN
There are some limitations when using the .LIN command in compat mode:
o
o
o
o
Parameter modelname is not used by Eldo, if specified it is ignored.
Only format=touchstone is supported. It is set by default, if another format is
specified an error will be displayed.
Parameter noisecalc is not supported in Multiport syntax, only Two-Port syntax.
Parameters gdcalc, FREQDIGIT, SPARDIGIT, listfreq, listcount, listfloor, and
listsources are not supported.
See the “.LIN command” in the Eldo Reference Manual.
• .PLOT/.PRINT
The sign convention of Ix is that the current is positive when it enters the device by pin
x. However, when -compat is set, then the following apply:For R/L/C/E/F/G/H/I/V/D
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Simulator Compatibility
Commands in Compat Mode
devices, I2 returns the same value as I1.For M/B/J devices, I3 is positive when current
leaves the object by pin number 3.
See the “.PLOT” and “.PRINT” commands in the Eldo Reference Manual.
• .PROBE
The Eldo .PROBE command is emulated; all node voltages are dumped in the binary
output file (.wdb). To only dump those items specified in .PLOT/.PROBE in the output
file, add .OPTION PROBE.
When .PROBE I is specified with .OPTION POST, only currents through dipoles are
plotted, MOS current pins are not.
See the “.PROBE command” in the Eldo Reference Manual.
• .SAVE
In compat mode, generates a .ic0 file.
See the “.SAVE command” in the Eldo Reference Manual.
• .SUBCKT
When GLOBAL node names are used in the .SUBCKT definition node list, Eldo will
check the node names in the subcircuit list definition prior to the global node list.
See the “.SUBCKT command” in the Eldo Reference Manual.
• .TEMP
The model parameter TREF can be specified. This is equivalent to the parameter TNOM
when the .TEMP command is used to apply temperature effects. When TREF is
specified, TNOM will be ignored.
o
.PARAM TEMP
In compat mode, you must use the TEMPER variable to return the current
simulation temperature set by the .TEMP command. The TEMP variable is not
supported in compat mode.
See the “.TEMP command” in the Eldo Reference Manual.
• .TRAN
If the .TRAN command has four parameters, for example:
.TRAN tprint tstop tstart hmax
o
If value4 (hmax) < value2 (tstop), it is handled as in Eldo standard mode:
.TRAN tprint tstop tstart hmax
o
If value4 (hmax) ≥ value2 (tstop), it is handled as a list of INCRn Tn values:
Eldo® User's Manual, 15.3 171

Simulator Compatibility
Options in Compat Mode
.TRAN INCR1 T1 [{INCRn Tn}] [TSTART=val] [UIC]
See the “.TRAN command” in the Eldo Reference Manual.
Related Topics
HSPICE Compatibility
Options in Compat Mode
Some options have different behavior in HSPICE compatibility mode.
• ACDERFUNC
This option is automatically unset in compat mode.
• ACM
This option is automatically set in compat mode.
• ACOUT=VAL
ACOUT defaults to 1.
1 — Vx(a,b) or Ix(a,b) are computed from the complex value Vx(a,0)-Vx(b,0) or from
Ix(a,0)-Ix(b,0).
• DEFPTNOM
This option is automatically set in compat mode. Enables a parameter to be defined with
the name TNOM. In such a case, this value will be used inside parameter expressions,
instead of the default TNOM or the value set using option TNOM=val.
• ICDC and ICDEV
These options are automatically set in compat mode. This means that IC specifications
given on devices are taken into account for the DC which is performed prior to TRAN.
When -compat is not set, and neither are the ICDC and ICDEV options, then IC
specifications given on devices are ignored, unless the UIC keyword is specified on the
.TRAN card.
• GENK
This option is automatically set in compat mode. It forces Eldo to generate second order
mutual inductors. It is used together with the KLIM option.
• (NO)KWSCALE
This option is automatically set in compat mode. Therefore, SCALE is not treated as a
keyword and can be used as a parameter.
• LIBINC
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Simulator Compatibility
Options in Compat Mode
This option is automatically set in compat mode. It specifies that all the libraries (.LIB)
should be included without filtering the objects (model, card or subcircuit) that are not
used in the specific netlist.
• LICN
This option is automatically set in compat mode. Causes the last initial condition (.IC)
specification to have precedence over previous IC specifications.
• MODWLDOT
This option is automatically set in compat mode. It is used for binned models.
• NOELDOLOGIC
This option is automatically set in compat mode.
• NOELDOSWITCH
When specified in compat mode, it informs Eldo that devices beginning with an S are
not switches (Eldo default) but S-parameter block instantiations.
• NOINIT
Set for cases where UIC is set on the .TRAN card.
• OPSELDO_DETAIL
If this option is not set, Eldo enables a variation of SILENT mode. Nothing is written in
the .wdb and .aex files, but the last run is saved in the .chi file.
• PARHIER=local|global
Default is set to global. Global “parent” values have precedence. Example:
.SUBCKT R1 1 2
R1 1 2 a
.ends
X1 in out R1 a=2
.param a=3
When parhier is local, X1.R1 will be 2, while when parhier is global, X1.R1 is 3. See the
“PARHIER” option in the Eldo Reference Manual.
• PROBE
.PROBE command is emulated, that is, all node voltages are dumped in the binary
output file (.wdb). To dump only those items specified in .PLOT/.PROBE in the output
file, add .OPTION PROBE.
• QUOTREL
This option is automatically set in compat mode.
• SLASHCONT
Eldo® User's Manual, 15.3 173

Simulator Compatibility
Options in Compat Mode
This option is automatically set in compat mode. It enables a single backslash to be used
for the continuation of the line. Example:
.OPTION SLASHCONT
R1 1 2 \
3k
R2 1 2 1k
R1 will be set to 3K. Disable this option by specifying .OPTION NOBSLASHCONT.
• SWARN
This option is automatically set in compat mode. It activates TSMC SOA checks.
• TNOM
TNOM defaults to 25°C instead of 27°C. For more information see “Temperature
Handling” on page 287.
Options Only Available in Compat Mode
The following options are only available in compat mode:
• ALTERELDO
Changes the way the .ALTER re-run feature works in compat mode. In compat mode,
for alter index ‘n’, Eldo revisits the ‘n-1’ alter looking for substitution. In default Eldo
mode, for alter index ‘n’, Eldo only deals with the nominal and the alter ‘n’; it ignores
the ‘n-1’ alter. In other words, in compat mode, alters are cumulative, but not in Eldo
default mode. Specify ALTERELDO to activate the default Eldo mode behavior when
in compat mode.
• CKDCPATH
Forces Eldo to issue a warning instead of an error when a dangling node (no DC path to
ground) is encountered on a current source. The source is then disabled and the node
connected to ground. This option is only used in compat mode.
• COMPEXUP
Forces Eldo to keep the name of the extraction results (from .EXTRACT and .MEAS
statements) in uppercase. This option is only used in compat mode.
• NOBSLASHCONT
Disables option SLASHCONT which is set by default in compat mode.
Related Topics
HSPICE Compatibility
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Eldo® User's Manual, 15.3

Netlist in Compat Mode
Some aspects of the netlist syntax are different in HSPICE compatibility mode.
Comment Character
Dollar $ is used as the comment character in the netlist line instead of !.
Simulator Compatibility
Netlist in Compat Mode
The comment character is usually treated as such only if the preceding character is a blank space
or if the comment is at the beginning of a line. In -compat mode with the comment character $,
then the above rule still applies; additionally, the $ character is a comment character if:
• the preceding character is not a white space, and
• the first character of the string is ‘, ’, “, a number, or a period (.)
If you want to reference an environment variable using the $ character, for example to specify a
file path, surround the path and filename in quotes.
Examples:
• Circumstances where $ is treated as a comment:
o $ is treated a comment because the string begins with the digit 0:
M1... l=0.1u$
o
$ is treated a comment because the preceding character is a blank space:
M1... l=0.1u $
.INCLUDE $HERE/myfile.txt
o
$ is treated a comment because the first character is a number:
M1 1$ d g s b nmos w=1u l=3
• Circumstances where $ is not treated as a comment:
Wildcard Support
M1 a1$ d g s b...
M2 ‘1$’ d g s b ...
.INCLUDE "$HERE/myfile.txt"
The “?” wildcard character matches a single character in compat mode; it is not supported in
default Eldo unless a “*” wildcard character is also specified.
Eldo® User's Manual, 15.3 175

Simulator Compatibility
Netlist in Compat Mode
Parameters
Multiple assignment of parameters which can be overwritten sequentially is allowed.
In model instantiations, Eldo checks whether there is a .MODEL with the same name as the
string after the nodes in a model declaration. If not, it looks for a parameter name.
In .PARAM statements, LOT and DEV are not treated as keywords, however LOT/GAUSS,
DEV/GAUSS, LOT/, and DEV/ are.
Quotes
Double quotes are treated as single quotes. (In standard Eldo mode, double quotes are used to
specify a parameter string.) Use option QUOTSTR to treat double quotes as a parameter string
delimiter.
Order of Analyses
Analyses are performed in the order specified in the netlist. The order in which analyses are
performed can then differ from the original Eldo order, and there can be multiple analyses of the
same type to be run sequentially. In addition, .PRINT/.PLOT/.EXTRACT/.MEAS commands
are seen only by the preceding command. Example:
.tran 1n 10n
.print tran v(1)
.tran 1n 50n
.print tran v(2)
.end
In compat mode, the first .tran command forces Eldo to do a transient simulation between 0 and
10n. Only v(1) will be displayed. The second .tran command forces Eldo to do a transient
simulation between 0 and 50n. Only v(2) will be displayed for that simulation.
Order of Analyses—AC in the Middle of a .TRAN
AC in the middle of transient is handled with respect to the compat mode ordering rule (as
described above). Whenever a .AC command, a .TRAN command, and a .OP command
containing time specifications are specified in the .cir file, then the results will be:
• .ac followed by .tran
AC will be performed during the transient because .ac appears before .tran
• .tran followed by .ac
AC will be performed after the transient, and not inside it. A warning is issued:
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Simulator Compatibility
Arithmetic Functions and Operators in Compat Mode
Warning 1484: AC analysis will not be performed during transient
because of the commands ordering.
• .tran followed by .ac followed by another .tran
The first transient is performed, then AC + transient as in the first case
Related Topics
HSPICE Compatibility
Arithmetic Functions and Operators in Compat
Mode
Some arithmetic functions/operators have different behavior in HSPICE compatibility mode.
The following rules apply:
log(x) = sign(x) * log(abs(x))
log10(x) = sign(x) * log10(abs(x))
db(x) = sign(x) * 20.0*log10*abs(x))
sqrt(x) is -sqrt(abs(x)) if x is negative.
x**n is computed as x**n if x is positive, x**(INT(n)) if x is negative, and 0 if x is 0.
The power operator (^) has highest precedence (same as standard Eldo).
Note
In Eldo standard mode:
sqrt(x) returns an error if x is negative.
x**n is computed as exp(n*log(x)) if x is strictly positive, 0 otherwise.
EVAL Keyword
When the -compat argument is active, the function keyword EVAL is not required in
conditional expressions. For example:
r1 1 2 '(p1 > p2 ? p2: p1)'
Will be the equivalent of:
r1 1 2 'eval(p1 > p2 ? p2: p1)'
Related Topics
Arithmetic Functions
Eldo® User's Manual, 15.3 177

Simulator Compatibility
Output Format in Compat Mode
Output Format in Compat Mode
Some different output files are generated in HSPICE compatibility mode.
The following types of output files are generated in compat mode:
• If option POST=1 or POST=2, Eldo generates only .tr0 output files, no .wdb file is
generated.
• Without specifying option POST, Eldo generates only .wdb output files.
When running in compat mode (-compat) three types of files can be created:
• .trX files for analysis in the time domain (transient, noisetran, tsst, tmodsst, and so on).
• .acX files for analysis in the frequency domain (ac, fsst, fmodsst, and so on).
• .swX files for dcsweep analysis.
As a consequence, when loaded inside EZwave or converted into .wdb, the results are stored
inside folders TRAN, AC and DC respectively.
Note
In compat mode, .SAVE generates a .ic0 file.
Related Topics
HSPICE Compatibility
178
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Simulator Compatibility
Spectre Compatibility
Spectre Compatibility
Eldo can use a Spectre netlist as input.
There are two flows to simulate a Spectre netlist in Eldo:
• Spectre Compatibility Flow
Run Eldo on the Spectre netlist. Eldo will call the spect2el script to convert netlists from
Spectre format (Spectre language syntax) into Eldo format (Eldo syntax). Additionally,
spect2el generates several files that will be used to map the Spectre name to a SPICE
name, and to avoid the reconversion of the Spectre files if nothing has changed in them.
This flow is more straightforward and more efficient. This is the preferred approach.
• Spectre to Eldo Converter Flow
This flow is based on the spect2el script that converts libraries and netlists from Spectre
format (Spectre language syntax) into Eldo format (Eldo syntax). You then run Eldo on
the converted netlist. This flow offers more flexibility, in particular if manual
modifications are necessary to workaround unexpected conversion issues. See Spectre
to Eldo Converter for more information on the spect2el script.
Spectre Compatibility Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Spectre Compatibility Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Working with Multiple Languages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Troubleshooting the Spectre to Eldo Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Spectre to Eldo Converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
spect2el Command Reference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Eldo® User's Manual, 15.3 179

Simulator Compatibility
Spectre Compatibility Flow
Spectre Compatibility Flow
Run an Eldo simulation on a Spectre netlist with the eldo -sp command line argument.
Syntax
eldo -sp spectre_file [-i spice_command_file] [-clean_sp]
[-spectre_out pathname] [-sp_plot 2|1|0] [-css 1|0]
Arguments
• -sp spectre_file
The filename of the Spectre format netlist to be used as input for Eldo. spectre_file must be
specified with an extension. No guess is made on the possible extension. If the filename is
specified without its extension an error is generated. Required.
• -i spice_command_file
The filename of the Eldo/SPICE command file to be used in association with the Spectre
netlist. Optional. Used with the -sp argument when a Spectre netlist is the input.
spice_command_file must be specified with an extension. No guess is made on the possible
extension. If the filename is specified without its extension an error is generated. The
spice_command_file must not include the spectre_file. Eldo automatically performs the link
between these files. Including the Spectre file will not work and the simulation will stop.
• -clean_sp
Removes all the files generated by spect2el. As a consequence, if you want to relaunch the
simulation on that design, the converter will reproduce the work. This increases the overall
simulation time. Optional. Used with the -sp argument when a Spectre netlist is the input.
• -spectre_out pathname
Define the path in which the files generated by spect2el reside. Optional. Used with the -sp
argument when a Spectre netlist is the input. Eldo creates pathname automatically if it does
not exist. If –clean_sp is also specified, Eldo clears the files/subdirectories under pathname,
while pathname itself is not removed after simulation. By default, pathname is identical to
the one specified by –outpath.
• -sp_plot 2|1|0
Controls the conversion of Spectre save statements into Eldo .PRINT, .PLOT and .PROBE
commands as below:
0
The save statement is converted into .PRINT (default).
1
The save statement is converted into .PLOT.
2
The save statement is converted into .PROBE.
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Simulator Compatibility
Spectre Compatibility Description
• -css 1|0
Convert all or just the selected sections of your library. Set to 0 to convert all sections. Set to
1 (default) to convert only selected sections. If a file is included in an unselected section,
then this file is ignored even if it does not exist in the path of the include statement. When
css=1, a missing file error is only generated if the file is called, otherwise a warning is
printed in spect2el.log.
Description
If errors occur, a file named spect2el.error is generated clearly describing the errors.
Note
Eldo launches spect2el with the following options:
-do_va 1 -netlist_converter 1
You cannot change these options when running from the Eldo command line.
Tip
See the “-sp” command line argument in the Eldo Reference Manual.
Related Topics
Spectre Compatibility Description
Working with Multiple Languages
Troubleshooting the Spectre to Eldo Flow
Spectre to Eldo Converter
spect2el Command Reference
Spectre Compatibility Description
spectre_file and spice_command_file must be specified with their extensions. No attempt is
made by Eldo to surmise the possible extension. If the filename is specified without its
extension an error is generated.
See Table 5-6 for example error messages.
The convention for the generated files is as follows:
• The converted SPICE files are written to the folder named [outpath].spectre_file_dir/.
• The files generated for name mapping purpose are written to the folder named
[outpath].spectre_file_map_dir/.
• The files generated to avoid the (re)conversion of the Spectre files, when it is not
necessary, are written to the folder named [outpath].spectre_file_db_dir/.
Eldo® User's Manual, 15.3 181

Simulator Compatibility
Spectre Compatibility Description
You can manually remove these folders if they are no longer required. Specify an alternative
output directory with the -spectre_out pathname argument.
The spice_command_file must not include the spectre_file. Eldo automatically performs the
link between these files. Attempting to include the Spectre file will not function, and the
simulation will stop. For examples, see Include Files in “Troubleshooting the Spectre to Eldo
Flow” on page 186.
All SPICE commands (.PLOT/.PROBE/.STEP/.EXTRACT, and so on) can be used except for
the .ALTER command, where the mapping is not handled. When specifying a name for the
.PLOT command, the Spectre names can be used.
Here follows a simple example:
spectre_file.sp:
simulator lang=spectre
subckt foo a b
Aresfoo a b resistor r=1k
ends
subckt bar a b
Aresbar a b resistor r=1k
myInstance a b foo
ends
anotherInstance 1 0 bar
spice_command_file.cir:
*first line
c1 1 0 1p
I1 1 0 1
.plot tran I(anotherInstance.*)
.plot tran v(c1)
.tran 1n 10n
.end
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Eldo can be launched on the Spectre design by entering the following:
eldo -sp spectre_file.sp -i spice_command_file.cir
Simulator Compatibility
Spectre Compatibility Description
In the .wdb output file, the name of the plotted elements are as defined in the Spectre design. In
this example, I(ANOTHERINSTANCE.ARESBAR) is plotted.
Note
By default, every device name or node name is case-insensitive because SPICE language is
being used. Specify -case to parse the netlist in case-sensitive mode. Spectre is casesensitive
by default.
For example, if the Spectre design contains:
aRes n1 n2 resistor r=1k
ares n1 n2 resistor r=2k
Eldo (SPICE) is case-insensitive, so it considers resistor “ares” has been defined twice. Spectre
is case-sensitive so differentiates between “aRes” and “ares.” Run the Spectre to Eldo converter
with the -case argument to enable the differentiation between “aRes” and “ares.”
Spectre Default Constants and Functions
When using Eldo with the command line argument -sp, or if option
USE_SPECTRE_CONSTANT is specified in the SPICE netlist, Eldo understands a number of
Spectre default parameters, constants, and functions as follows:
• Spectre instance parameter trise is handled as an alias to dtemp for all instances.
• Spectre instance parameter perim is handled as an alias to peri for diode instances.
• Spectre default constants and functions as listed in Table 5-5 are allowed:
Table 5-5. Spectre Constants and Functions
Constant/Function Value
m_e 2.7182818284590452354
m_log2e 1.4426950408889634074
m_log10e 0.43429448190325182765
m_ln2 0.69314718055994530942
m_ln10 2.30258509299404568402
m_pi 3.14159265358979323846
m_two_pi 6.28318530717958647652
Eldo® User's Manual, 15.3 183

Simulator Compatibility
Spectre Compatibility Description
Table 5-5. Spectre Constants and Functions (cont.)
Constant/Function Value
m_pi_2 1.57079632679489661923
m_pi_4 0.78539816339744830962
m_1_pi 0.31830988618379067154
m_2_pi 0.63661977236758134308
m_2_sqrtpi 1.12837916709551257390
m_sqrt2 1.41421356237309504880
m_sqrt1_2 0.70710678118654752440
m_degperrad 57.2957795130823208772
p_q
1.6021918×10 −19
p_c 2.997924562×10 8
p_k
p_h
p_eps0
These constants can be used inside all expressions.
Limitations
• The .ALTER command is not supported.
• When Eldo is using a Spectre netlist as input, and the netlist contains an internal node
and a device with the same name, it is impossible for Eldo to distinguish between these.
When Eldo analyses a subcircuit in the Spectre netlist, each element is attempted to be
converted, without knowing if it is a node name or a device name. This can lead to plots
not being performed as expected, because Eldo does not know what kind of plot is
required (I or V for example). For examples, see Spectre Node and Device Names in
“Troubleshooting the Spectre to Eldo Flow” on page 186.
• Spectre RF commands are not supported.
1.3806226×10 −23
6.6260755×10 −34
8.85418792394420013968×10 −12
p_u0
m_pi×4.0×10 −7
p_celsius0 273.15
f_mod(a,b)
{a-b×int((a+0.5)/b)}
atan2(a,b)
{atan(a/b)}
hypot(a,b)
{sqrt(a×a + b×b)}
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Working with Multiple Languages
Related Topics
Spectre Compatibility Flow
Working with Multiple Languages
Troubleshooting the Spectre to Eldo Flow
Spectre to Eldo Converter
Working with Multiple Languages
The Spectre to Eldo converter supports multiple languages (Eldo, Spectre, SPICE) inside the
same netlist. To switch between the different language modes, use one of the following methods
provided:
• To encapsulate portions of different languages specify start and end lines with the
syntax:
Simulator lang=ELDO|SPECTRE|SPICE
...
...
End lang=ELDO|SPECTRE|SPICE
• To encapsulate the language of included files (within the encapsulated lines) to be the
same as the parent file specify start and end lines. This avoids any need to specify
Simulator lang at the beginning of the called files.
Included lang=ELDO|SPECTRE|SPICE
...
...
End lang=ELDO|SPECTRE|SPICE
Specify End lang to return the simulation language to the default one.
Note
To keep compatibility with Spectre behavior, the language of the included file can
be determined using the “Priority Rules” on page 186, in other words, the included
file does not have to be in the same language as its parent file.
• To change the default language, invoke the Spectre to Eldo converter with the -lang
keyword argument.
spect2el -lang eldo|spectre|spice
By default the Spectre to Eldo converter assumes Spectre syntax for the main file
specified by the -file_list argument in the specte2el command line. Otherwise, all
included files are assumed to be in Spice syntax by default to match Spectre behavior.
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Troubleshooting the Spectre to Eldo Flow
Priority Rules
The language of any file is determined based on the rules prioritized below (where
XYZ=SPECTRE | ELDO | SPICE). The first applied rule determines the file’s language without
any further rule checking.
1. If “simulator lang=XYZ” is specified inside the file, then the language of the file is
XYZ.
2. If “included lang=XYZ” is specified before a .include file statement, then the language
of this included file is XYZ, and the language within “included lang=XYZ … end
lang=XYZ” should also be XYZ.
3. If “-i ” is specified in the command line of spect2el, then the language of file
is Eldo.
4. If the file extension is “.scs”, then its language is Spectre.
5. If the file extension is “.sp”, then its language is SPICE.
6. If “-lang XYZ” is specified in the command line of spect2el, then the language of all
remaining files is XYZ (these files are not included in any of the above cases).
7. If none of the above rules are applied, then the language of the file is SPICE.
This applies to the standalone converter and also the Spectre compatibility flow (invoking Eldo
with the command eldo -sp).
Related Topics
Spectre Compatibility Flow
Troubleshooting the Spectre to Eldo Flow
Spectre to Eldo Converter
Troubleshooting the Spectre to Eldo Flow
Some tips on troubleshooting the Spectre to Eldo flow.
Include Files
The spice_command_file must not include the spectre_file, and vice versa. Eldo automatically
performs the link between these files. Attempting to include the Spectre file will not function,
and the simulation will stop.
• The SPICE file includes the Spectre file.
Eldo will not be able to parse the Spectre file, leading to the following syntax error
message (example):
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Troubleshooting the Spectre to Eldo Flow
ERROR 208: In file "./t1.sp" line 5:
+ OBJECT "AOP": Unrecognized character or word A
In this example, Eldo considers that “Aresfoo” in line 5 is requesting an aop (opamp).
• The Spectre file includes the SPICE file.
If you have the following top Spectre file, where t1.cir should be the
spice_command_file:
simulator lang=spectre
subckt foo a b
ends
Aresfoo a b resistor r=2k
subckt bar a b
Aresbar a b resistor r=1k
myInstance a b foo
ends
anotherInstance 1 0 bar
simulator lang=spice
.include "t1.cir"
The Spectre to Eldo converter does not understand the .INCLUDE statement and so will
not change its path nor copy the t1.cir file into the .t1.sp_dir folder. Eldo might find it,
and proceed with the include, however it could also fail to find it and raise an error
message.
Moreover if the file is both included and specified using the -i command line option, you
will have duplicate definitions, as the file is effectively included twice.
Spectre does not understand SPICE syntax, which means only a full Spectre design can
be used. However spectre_file could contain subcircuit definitions and Spectre library
inclusion, and have its full design in the spice_command_file which may include some
SPICE libraries.
To summarize, from one side a full Spectre tree is allowed and from the other a full
SPICE tree. This enables you to specify complex designs mixing both SPICE and
Spectre.
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Troubleshooting the Spectre to Eldo Flow
Spectre Node and Device Names
When Eldo is using a Spectre netlist as input, and the netlist contains an internal node and a
device with the same name, it is impossible for Eldo to distinguish between these. When Eldo
analyses a subcircuit in the Spectre netlist, each element is attempted to be converted, without
knowing if it is a node name or a device name. This can lead to plots not being performed as
expected, because Eldo does not know what kind of plot is required (I or V for example).
If topsp, the Spectre input file, contains a subcircuit instance named x1, and the SPICE
command file, cmd.cir, contains:
.plot dc v(x1.c1)
then c1 must be an internal node name as a voltage plot is requested.
However, if cmd.cir contains:
.plot dc I(x1.c1)
then c1 must be a device name as a current plot is requested.
When Eldo is using a Spectre netlist as input, Eldo does not initially know the kind of plot
requested (I or V). Therefore, when Eldo analyses x1.c1, each element is attempted to be
converted; x1.c1 is mapped to xx1.yy, where yy can be cc1 if there was a capacitor named c1 in
that subcircuit in the Spectre design, or c1 if there was no capacitor named c1.
So if the following is specified:
.plot dc v(x1.c1)
it is equivalent to .plot dc v(xx1.cc1) if c1 is defined as a device, no matter if it is a node name
or not. In this case, the plot is not performed.
Error Messages
The Spectre to Eldo converter logs the line number where a conversion error occurs. Some
example error messages and full descriptions are provided in Table 5-6.
Table 5-6. Spectre Conversion Error Messages
Error Message
Code
5 Unable to open the temporary file
“a_name”.
Description
Eldo cannot create a temporary file
required to process the simulation. The file
contains the converted Spectre design and
the SPICE command file, if there is one.
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Error
Code
Related Topics
Spectre Compatibility Flow
Spectre Compatibility Description
Working with Multiple Languages
Spectre to Eldo Converter
Simulator Compatibility
Troubleshooting the Spectre to Eldo Flow
Table 5-6. Spectre Conversion Error Messages (cont.)
Message
33 Spectre file not specified. Option -sp has been specified without a
filename (eldo -sp).
1602 outpath not specified. Option -outpath has been specified without
a filename (eldo -sp topsp.sp -outpath).
1603 Spectre input file is a directory. The specified Spectre file is in fact a
directory name.
1604 Spectre input file “a_name”
doesn’t exist.
1605 Error: Unable to create the
directory “a_name”. Either you
don’t have write access or there is
not enough space left on device.
1606 preprocessing of the Spectre files
failed.
Please refer to /spect2el.log
file for more details.
1606 preprocessing of the Spectre files
failed.
Please refer to spect2el.log file for
more details.
Description
Eldo cannot find the specified Spectre file.
For example, if the file extension was not
specified or if the file does not exist.
spect2el cannot create the directory that
will contain the converted design.
spect2el did not convert the Spectre design
properly. Some missed cases may remain
(when using the alterblock in Spectre for
example).
As above but with file and path
information displayed.
As above but when the Eldo -outpath
argument is not specified.
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Spectre to Eldo Converter
Spectre to Eldo Converter
The Spectre to Eldo converter is a tool script that converts from Spectre format (Spectre
language syntax) into Eldo format (Eldo syntax). The script is named spect2el.
For libraries including mixed-language syntax (Spectre and SPICE), Spectre to Eldo assumes
SPICE input mode when it opens an include file. All included files, except top-level files and
those with a .scs extension, that use the Spectre native language must begin with the statement:
simulator lang=spectre. Exceptions are top-level files and files that end with a .scs extension
which are read in Spectre input mode.
Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Installing a Patch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Supported Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Netlist Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Prerequisites
Prerequisites for the Spectre to Eldo converter.
• Korn shell must be installed under the /bin directory. The tool is not able to run if /bin/
ksh cannot be invoked.
• The “gawk” utility. This is provided along with the tool.
• The dos2unix utility must be installed on the running machine. The tool generates a
warning and produce an inaccurate conversion or remain in hanged state if dos2unix
cannot be invoked.
Installing a Patch
When an urgent fix is required, Mentor Graphics may provide a specific Spectre to Eldo
converter patch mechanism to enable the fixed version of the converter to be used with an
existing AMS installation. The patch is provided through a tar file.
Follow the instructions below to patch an older AMS tree version with a newer Spectre to Eldo
converter.
Procedure
1. Untar the patch tar file into an empty directory.
2. Run the script patchs2e that has been extracted to the directory.
3. Enter the full path of the output directory as requested by the script (must be existing
prior to running the script, the script will not create a missing directory).
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4. The script runs through the patch installation, and upon completion requests two settings
to be added to your .cshrc (or equivalent) file:
• Set the patch environment variable:
setenv S2E_PATCH out_dir
(where out_dir is the full path of the output directory as you entered in step 3)
• Add $S2E_PATCH/bin to your PATH environment variable:
setenv PATH $S2E_PATCH/bin :$PATH
5. In a new shell, or sourcing the .cshrc, you will be able to use the new Spectre to Eldo
converter.
Supported Features
The Spectre to Eldo converter can convert Spectre syntax to guarantee compatible results for:
• Basic component instantiations.
• Device models and instances.
• Subcircuit definitions and instances.
• nport instances.
• Controlled sources.
• Functions and “if” statements.
• Statistics.
• Conversion of some of the device models written with SPICE syntax (simulator
lang=SPICE). These models are:
MOSFET models (nmos and pmos) MOS1, MOS2, MOS3, BSIM1, BSIM2, BSIM3,
BSIM3v3, BSIM4, and BSIM-CMG (SPICE levels 1, 2, 3, 4, 5, 10, 11, 54, and 72
respectively); BJT model (npn, pnp, lnpn, and lpnp), SPICE BJT (equivalent to Eldo
level 1 as SPICE does not support level for BJT); Diode model (SPICE levels 1 and 3).
The Spectre to Eldo converter can handle libraries with nested includes for any number of levels
and for any directory structure.
The following Spectre device models are supported:
• BSIM3v3 MOS model.
• BSIM-CMG MOS model.
• Philips PSP 102 MOS model.
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Simulator Compatibility
Spectre to Eldo Converter
Notes
The following models are supported: psp1010, psp1020, pspnqs1020, psp1011,
psp1021, pspnqs1021, psp101, psp102e, and pspnqs102e.
• Philips PSP 103 MOS model.
• Philips MOS Model 11 Level 1102.
The following models are supported by the converter as Eldo Level 69: mos 11021,
mos11021t, mos11020, mos11020t, mos1102e, and mos1102et.
• Philips MOS Model 11 Level 11010.
• HISIM MOS model (Eldo level 66).
• HISIM-LDMOS MOS model (Eldo level 73).
• VBIC bipolar model.
• HICUM bipolar model.
• BJT level one model (Gummel Poon).
• Diode level one model.
• JFET level one model.
• MOS1 model.
• Polynomial models for R, L, and C.
• Geometric Resistor model.
• Physical Resistor model (phyres).
• R3_cmc resistor model.
• MOS0 model.
However, since this model has no equivalent in Eldo, it is mapped to the MOS level=1
model of Eldo. Full compatibility is not guaranteed.
• Bsource instances (r, l, c, i, v, q, g, and phi sources).
• Other device models are converted from the syntax point of view only with primary
compatibility testing.
The list includes: BSIM4, DP500, MOS2, MOS3, BSIM1, BSIM2, BSIM3v2, EKV,
BSIMSOI3 PD, BSIMSOI4, GAAS, TOM2, BJT504, BJT504t, JFET level 2, JFET
level 4, PSP, TFT Polysilicon, TFT Amorphous, Mextram504, HICUM Level0,
MOS2002, JUNCAP, JUNCAP2, JUNCAP_ELDO.
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• For proper conversion of netlists or libraries, all the included files should exist. If any
instance in the input library or netlist refers to a model, a subcircuit, or a Verilog-A
module, which is not defined in the input library/netlist or one of its included files, this
instance cannot be recognized or converted and a warning message is displayed in the
running terminal. The conversion continues if running the tool in standalone mode.
However, if running the tool from inside Eldo, the converter exits with error code 10
informing that this line is not converted and the conversion process will not continue
until this error is corrected. A file named spect2el.error is generated clearly describing
the errors.
• If model parameters wdexp and ldexp are not specified in the Spectre resistor model,
then the converter prints them with a default value equal to 1. If model parameter AF is
not specified in the Spectre resistor model, then the converter prints it with a default
value equal to 2. In the case of a resistor instance, the converter ignores the printing of
{wdexp, ldexp, weexp, leexp}.
Netlist Conversion
The netlist conversion features come with the spect2el tool. This feature automates the netlists
conversion process from Spectre syntax to Eldo syntax. The following features are supported:
Analyses
• AC analysis
• DC analysis
• Transient analysis
• S parameters analysis
• Monte Carlo analysis
• Sweep analysis
• Noise analysis
• Sensitivity analysis
• Transfer function analysis
• Stability analysis
Note
The above analyses types are partially supported. There are some combinations that
are not yet supported.
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Simulator Compatibility
Spectre to Eldo Converter
Control Statements
• Option statements:
• Paramset statement
• Save statement
Reltol Vabstol Iabstol Temp
Tnom Scalem Scale Gmin
Digits Pivrel Pivab
• Assert statement
With the assert statement, you can set custom characterization checks to specify the safe
operating conditions for your circuit. The Spectre circuit simulator then issues messages
telling you when parameters move outside the safe operating area and, conversely, when
the parameters return to the safe area.
Using model types as a primitive with the assert statement like below is not yet
supported:
check assert primitive=bsim3v3 param=l min=10u max=100u
• Simple combinations of alter and set statements
• Include statement
Any include statement between corner markers {//corner to //endcorner} are commented
in the Eldo output, and included files in this area are converted in the /out_dir/corner/
directory. Note that corner and endcorner are case-insensitive.
o
included lang=eldo|spice|spectre
Specifying the statement included lang=eldo|spice|spectre instead of simulator lang
behaves exactly like simulator lang, but in addition forces included files (included
within included lang and end lang statements) to be in the same language as
specified after included lang=. This avoids any need to specify simulator
lang=eldo|spice|spectre at the beginning of the called files. It forces the language of
included files to be controlled by the parent file. Specify end lang=eldo|spice|spectre
to return the simulation language to the default one.
Sources
• Independent Sources:
o
o
Isource
Vsource
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Simulator Compatibility
Spectre to Eldo Converter
• Controlled Sources:
o
o
o
o
VCVS
VCCS
CCVS
CCCS
• Polynomial Controlled Sources:
o
o
o
o
Pcccs
Pccvs
Pvccs
Pvcvs
Components
• Primitive components (resistor, capacitor, diode, inductor, mutual inductor)
• MOSFET, JFET, Bipolar transistors
• Relay
The four-terminal relay is a voltage controlled relay tied between terminals t1 and t2.
The voltage between terminals ps and ns controls the relay resistance. The relay
resistance varies nonlinearly between ropen and rclosed, the open relay resistance and
closed relay resistance, respectively. These resistance values correspond to control
voltages of vt1 and vt2 respectively.
• Ideal switch
Single-pole multiple-throw switch with infinite off resistance and zero on resistance.
The switch is provided to enable you to reconfigure your circuit between analyses.
When the switch is set to position 0, it is open. In other words, no terminal is connected
to any other. When the switch is set to position 1, terminal 1 is connected to terminal 0,
and all others are unconnected. When the position is set to position 2, terminal 2 is
connected to terminal 0, and so on.
The switch can change its position based on which analysis type is being performed
using the xxx_position parameters.
• Transformer
• Delay Line
The delay line model is a four-terminal device with zero output impedance and infinite
input impedance. The output between nodes p and n is the input voltage between nodes
ps and ns, delayed by the time delay td and scaled by gain.
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Simulator Compatibility
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• A2D
The analog-to-logic converter transfers analog waveforms to a logic simulator.
• D2A
The logic-to-analog converter converts a binary signal from a logic simulator to an
analog waveform.
• Verilog-A instances
• Current probe (iprobe)
• Independent resistive source (port)
Limitations
• The following features cannot be converted with the tool. They require some manual
modifications.
o
o
o
o
o
Related Topics
Nested sweeps that sweeps more than one paramset. For example:
sweep1 sweep paramset=paramset1 {
sweep2 sweep paramset=paramset2 {
}
}
....
Complicated combinations of the alter set statements.
In the PWL definition, a maximum of 500,000 pairs are accepted. If this number is
exceeded, the conversion will fail.
Long lines, it is advisable that any line should not be longer than 2,000 characters,
usage of line continuation is strongly advised in the original netlist.
Immediate set options and deferred set options are partially covered.
Spectre to Eldo Converter
spect2el Command Reference
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spect2el Command Reference
Simulator Compatibility
spect2el Command Reference
Runs the Spectre to Eldo converter script that converts from Spectre format into Eldo format.
Syntax
spect2el
-in_dir [-file_list ] [-i ] [-lang eldo|spectre|spice]
[-out_dir ] [-log ] [-remove_param 1|0] [-remove_param_warn 1|0]
[-do_va 1|0] [-inline_warnings 1|0] [-netlist_converter 1|0] [-devx 1|0] [-scs2lib 1|0]
[-condition 2|1|0] [-use_database 2|1|0] [-clr_database 1|0] [-sp_plot 2|1|0] [-css 1|0]
[-case 1|0] [-p | -searchpath ] [-v]
Arguments
• -in_dir dir1
Input directory where the library/netlist to be converted reside. This could be a full path or a
relative path, relative to where the tool is initiated. Required.
• -file_list list
File list to be converted. It defaults to all files in the given directory if not specified. Default
‘*’.
The file list should only include the library main file(s), which is to be directly included in
the netlist in case of library conversion, or only the netlist file in case of netlist conversion.
Other files, which are included from within those main file(s) are handled automatically. In
other words, each file in the file list should not be included in any other file in the file list.
Each file in the file list should be a standalone file. It should not depend on any other file in
the file list. That is, it should not use any model, parameter, or subcircuit, which is not
defined in it or in any of the files it includes.
• -i eldo_file
Defines a single Eldo syntax file to be used in association with the Spectre netlist. This Eldo
file and any included files from within is handled as Eldo syntax unless the statement
simulator lang=spectre|spice is specified inside.
• -lang eldo|spectre|spice
Changes the default language syntax of the Spectre to Eldo converter. The default syntax is
Spectre.
Specify -lang eldo to set the default language syntax to Eldo. This avoids any need to
specify simulator lang=eldo at the beginning of Eldo files.
Specify -lang spice to set the default language syntax to SPICE. This avoids any need to
specify simulator lang=eldo at the beginning of SPICE files.
• -out_dir dir2
Output directory where the converted files are to be written. This could be a directory name
or a path. This directory is created by the tool. If this directory already exists a warning
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spect2el Command Reference
message is issued. If not specified, it defaults to the same name as the input directory name
but with a suffix “_converted.” Default ./{in_dir}_converted for output name.
• -log file
Specifies the log file that contains a brief report about the conversion process including any
error or warning messages appearing during the conversion. If not specified, it defaults to a
file named spect2el.log in the current working directory. The file can be specified by name,
or by full path, or relative path to the current working directory.
• -remove_param 1|0
If set to 1, some model card parameters not supported by Eldo are removed. Default is 1
(set). If set, parameters removed are: “dope” for Diode level 1. “meto” and “wnoi” for
BSIM3v3.
• -remove_param_warn 1|0
If set to 1, a warning is issued each time one of the above parameters is removed. This works
only if -remove_param is set. Default is 0 (not set).
• -do_va 1|0
If set to 1, attempts to convert Verilog-A instances used inside SPICE netlists. Default is 1
(set).
Note
This argument is not guaranteed. Its success is dependent on the syntax of the
Verilog files included. Any unusual syntax in the Verilog file may cause this feature
to fail. Any issue regarding Verilog syntax is beyond the scope of this converter.
• -inline_warnings 1|0
If set to 1, useful converter warnings are printed inline as comments in the converted netlist
to ease any required manual conversion work. Default is 0 (not set).
• -netlist_converter 1|0
If set to 1, enables the netlist conversion feature. Default is 1 (set).
• -devx 1|0
Control whether the mismatch variation (for Monte-Carlo analysis) in Spectre would be
converted to devx variation (set to 1) or dev variation (set to 0) in Eldo. Default is 1 which
means that it would be converted to devx.
• -scs2lib 1|0
If set to 1, all files with extension .scs are converted to the extension .lib. This also handles
all include statements. Default is 0 (not set).
• -condition 2|1|0
Controls the conversion of Spectre statements that include the conditional operator “?” as
below:
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spect2el Command Reference
0
The converter parses the conditional statement as is (default).
1
The converter uses keyword eval in the conversion (pre-2008.2 behavior).
2
The converter uses keyword valif in the conversion.
• -use_database 2|1|0
0
Disables this argument. Set to 0 if the user’s home directory quota is reached, to
deactivate the database creation.
1
Default. Enables you to make use of a library that has been converted before and is
included in your netlist instead of having to convert it again for each design or for
each time you modify your design. This is achieved by saving a database for the
library when it is first converted, and then reading this database later to convert the
netlists using this library. The converter checks for every file if it has an entry in this
database or not. If a file has an entry it is not converted but retrieved from the
database instead. Otherwise, if the file does not have an entry in the database (or is
more recent than the entry), this file is converted and saved to the database. The
database is created in your home directory with the minimum needed size.
Unmodified files are copied from the last path they were converted to.
2
The outer level included files are not converted to the external_files directory. Netlist
include statements with those files specified point directly to the pre-converted files.
It is important to ensure that these outer level files have previously been converted,
otherwise the files are converted and written to the external_files directory.
Note
Spectre to Eldo requires enough disk space on the user’s home area to save the
database.
• -clr_database 1|0
If set to 1, enables you to remove the database of converted libraries. Note that this option
removes all databases at once. Default is 0 (not set).
• -sp_plot 2|1|0
Controls the conversion of Spectre save statements into Eldo .PRINT, .PLOT and .PROBE
commands as below:
0
The save statement is converted into .PRINT (default).
1
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spect2el Command Reference
The save statement is converted into .PLOT.
2
The save statement is converted into .PROBE.
• -css 1|0
Convert all or just the selected sections of your library. Set to 0 to convert all sections. Set to
1 (default) to convert only selected sections. If a file is included in an unselected section,
then this file is ignored even if it does not exist in the path of the include statement. When
css=1, a missing file error is only generated if the file is called, otherwise a warning is
printed in spect2el.log.
• -case 1|0
Set to 1 for the converter to be case-sensitive for all names (nodes, devices instances,
models, subcircuit definitions and instances). Default is 0 (not set) which means that the
converter is case-insensitive.
• -p dir | -searchpath dir
Specifies a directory where include files are located. If any included file from inside the
netlist is not found, the converter looks for it in the location specified by ref_dir. If ref_dir is
not a full path, it is generated relative to in_dir. Default is in_dir. See the usage examples.
• -h
Display the tool usage.
• -v
Display the Spectre to Eldo version, release, and build date.
Description
If errors occur, a file named spect2el.error is generated clearly describing the errors.
All the above arguments are optional except for -in_dir.
Examples
The following is an example of converting a design including the library:
spect2el -in_dir . -out_dir ./out -file_list netlist.scs -sp_plot 2
The following is an example of converting a library:
spect2el -in_dir . -out_dir ./out -file_list allModels.scs -scs2lib 1
In both cases, the output directory out is created if it does not already exist. A directory named
external_files is created in the directory out for converted .LIB/.INCLUDE files.
The following shows an example of specifying a directory for the location of include files:
200
Eldo® User's Manual, 15.3

Simulator Compatibility
spect2el Command Reference
spect2el -in_dir spectre -out_dir eldo -file_list test.scs
-p ../general_include
Related Topics
Spectre to Eldo Converter
Spectre Compatibility
Eldo® User's Manual, 15.3 201

Simulator Compatibility
spect2el Command Reference
202
Eldo® User's Manual, 15.3

Chapter 6
Setting Up An Analysis
This chapter describes how to set up the following types of analysis for simulation in Eldo and
the expected outputs.
DC and Operating Point Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
DC Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Performing a DC Analysis During Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Operating Point Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
Differences Between DC and OP Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
DC Convergence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Improving DC Convergence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
DC Convergence Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Saving and Restarting DC Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Transient Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Saving and Restarting Transient Simulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
AC Related Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
AC Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Adaptive AC Analysis Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Performing an AC Analysis During Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Saving and Restarting AC Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Loop Stability Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Pole Zero Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Transfer Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Noise Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Noise Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Transient Noise Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Statistical and Sensitivity Related Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Worst Case Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
DC Mismatch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
DC Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Transient Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
AC Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Sensitivity Analysis of Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Design of Experiments Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
Other Miscellaneous Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
Aging and Reliability Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
Eldo® User's Manual, 15.3 203

Setting Up An Analysis
Check Safe Operating Area Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
High Impedance Node Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Power Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Viewing Power Analysis Results Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Electrothermal Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
RF Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
204
Eldo® User's Manual, 15.3

DC and Operating Point Analyses
The DC related analyses are:
• “DC Analysis” on page 205
• “Operating Point Analysis” on page 208
DC Analysis
Setting Up An Analysis
DC and Operating Point Analyses
The .DC command performs a DC analysis to determine the quiescent state or DC operating
point (OP) of the circuit. The operating point of the circuit is computed with capacitances
opened and inductances short-circuited. A DC analysis may be requested to determine the stable
initial condition of an analog circuit prior to a transient or AC analysis.
Tip
See “.DC” in the Eldo Reference Manual.
There are seven different types of DC analysis available as shown below:
• .DC with no further parameters results in a single analysis of the circuit’s quiescent
state.
• .DC followed by a component name, CNAM, results in a variation of the element size or
value. The variation sweeps from the value START to the value STOP with the
incremental step INCR. The quiescent state is calculated for each incremental step.
• .DC followed by a voltage or current source, SNAM, results in a voltage or current
sweep of the specified source from START to STOP in increments INCR. The quiescent
state is calculated for each incremental step. A second source SNAM2 may optionally
be specified with associated sweep parameters. In this case, the first source is swept over
its range for each value of the second source.
• .DC followed by the TEMP keyword results in a variation of temperature. The
temperature sweeps from the value of START to the value of STOP with the
incremental step INCR. The quiescent state is calculated for each incremental step.
• .DC followed by the PARAM keyword results in a variation of the value of a globally
declared parameter PARAM_NAME. The variation sweeps from the value of START to
the value of STOP with the incremental step INCR. The quiescent state is calculated for
each incremental step.
• .DC followed by the parameter, DATA=dataname, results in a sweep of the values predefined
in the .DATA command. The quiescent state is calculated for each incremental
step.
Eldo® User's Manual, 15.3 205

Setting Up An Analysis
DC Analysis
• .DC followed by the parameter TIME={time} performs a DC analysis during a transient
analysis. The transient analysis is stopped at each time specification, a true DC analysis
is performed, then the transient analysis continues.
DC sweeps can be nested up to three levels deep. For each value of the third level variable, the
second level variable is swept through its specified range. For each value of the second level
variable, the first level variable is swept through its specified range.
DC Analysis Results
For DC sweeps, the simulation output will contain tables of DC transfer voltages and currents
available in the ASCII .chi file or binary waveform output.
Example output in the .chi file from a .PRINT statement:
0**** DC TRANSFER CURVES TEMPERATURE = 27.000 DEG C
0************************************************************************
V1 V(1) V(2) V(3)
1.0000E+00 1.0000E+00 2.0000E+00 3.0000E+00
1.5000E+00 1.5000E+00 2.0000E+00 3.0000E+00
2.0000E+00 2.0000E+00 2.0000E+00 3.0000E+00
1.0000E+00 1.0000E+00 2.5000E+00 3.0000E+00
1.5000E+00 1.5000E+00 2.5000E+00 3.0000E+00
2.0000E+00 2.0000E+00 2.5000E+00 3.0000E+00
1.0000E+00 1.0000E+00 3.0000E+00 3.0000E+00
1.5000E+00 1.5000E+00 3.0000E+00 3.0000E+00
2.0000E+00 2.0000E+00 3.0000E+00 3.0000E+00
1.0000E+00 1.0000E+00 2.0000E+00 3.5000E+00
1.5000E+00 1.5000E+00 2.0000E+00 3.5000E+00
2.0000E+00 2.0000E+00 2.0000E+00 3.5000E+00
1.0000E+00 1.0000E+00 2.5000E+00 3.5000E+00
1.5000E+00 1.5000E+00 2.5000E+00 3.5000E+00
2.0000E+00 2.0000E+00 2.5000E+00 3.5000E+00
1.0000E+00 1.0000E+00 3.0000E+00 3.5000E+00
1.5000E+00 1.5000E+00 3.0000E+00 3.5000E+00
2.0000E+00 2.0000E+00 3.0000E+00 3.5000E+00
1.0000E+00 1.0000E+00 2.0000E+00 4.0000E+00
1.5000E+00 1.5000E+00 2.0000E+00 4.0000E+00
2.0000E+00 2.0000E+00 2.0000E+00 4.0000E+00
1.0000E+00 1.0000E+00 2.5000E+00 4.0000E+00
1.5000E+00 1.5000E+00 2.5000E+00 4.0000E+00
2.0000E+00 2.0000E+00 2.5000E+00 4.0000E+00
1.0000E+00 1.0000E+00 3.0000E+00 4.0000E+00
1.5000E+00 1.5000E+00 3.0000E+00 4.0000E+00
2.0000E+00 2.0000E+00 3.0000E+00 4.0000E+00
Figure 6-1 shows an example waveform output from a .PLOT statement:
206
Eldo® User's Manual, 15.3

Setting Up An Analysis
Performing a DC Analysis During Transient Analysis
Figure 6-1. DC Device Characteristics
Related Topics
Performing a DC Analysis During Transient Analysis
Operating Point Analysis
Differences Between DC and OP Analyses
DC Convergence
Improving DC Convergence
DC Convergence Troubleshooting
Performing a DC Analysis During Transient
Analysis
It is possible to perform a true DC analysis during a transient analysis. This can be useful in
cases where the circuit is brought to a certain state through transient patterns and simulation, for
example digitally programmed circuits. Specifying .DC with time specifications enables you to
stop the transient, perform a true DC analysis, and continue the transient analysis. The true DC
analysis is initialized with the transient state of the circuit at that time, and might converge to a
slightly different state, due to the fact that any residual dynamic current will be eliminated (true
DC analysis searches for a solution with static currents only). Also, when restarting, the
dynamic currents are lost, so the occurrence of a DC analysis during a transient analysis
potentially perturbates the exact transient trajectory. It is recommended to specify the DC
analysis during transient analysis at times where the circuit is stabilized: in a state with no or
very small residual dynamic currents.
Eldo® User's Manual, 15.3 207

Setting Up An Analysis
Operating Point Analysis
In the following example Eldo performs a DC analysis at times 20ns and 40ns during a transient
analysis from 0 to 100ns.
.DC TIME=20n 40n
.TRAN 1n 100n
The results of DC analysis during transient analysis are output using:
.EXTRACT DC TIME=...
Limitations:
• Only one .DC command with time specifications is allowed: subsequent commands are
ignored.
• Not supported for Questa ADMS, SST/MODSST analysis, and NOISETRAN analysis.
See Also
• .DC in the Eldo Reference Manual
• .EXTRACT in the Eldo Reference Manual
• .TRAN in the Eldo Reference Manual
Related Topics
DC Analysis
Operating Point Analysis
The .OP command determines the DC Operating Point (DCOP) of the circuit with inductors
short-circuited and capacitors opened. If either the specified simulation time is reached or one
of the conditions described in the “optional parameters” is fulfilled, the DC operating point is
saved to the .chi file.
If no parameter is specified, the operating point information is saved for DC prior to AC, or first
DC analysis in the case of a DC sweep.
.OP analysis is automatically performed before an .AC analyses.
Tip
See “.OP” in the Eldo Reference Manual.
DC Operating Point Calculation for RF
The DC operating point calculation for Eldo RF differs from the Eldo .OP command by using
an average value of the source, even if a DC value is specified.
208
Eldo® User's Manual, 15.3

Setting Up An Analysis
Operating Point Analysis
See “.OP RF” in the Eldo RF User’s Manual for more information.
Operating Point Analysis Results
The DC operating point is saved to the .chi file. Information concerning the operating points
such as power dissipation, node voltages, and source currents are output to the .chi file.
Example results:
0**** DC OPERATING POINT TEMPERATURE = 27.000 DEG C
0************************************************************************
NODE VOLTAGE NODE VOLTAGE NODE VOLTAGE
D 2.0000E+000 G 5.0000E-001 S 0.0
VOLTAGE SOURCE CURRENT
NAME CURRENT VOLTAGE POWER
VD -7.7327E-013 2.0000E+000 -1.5465E-012
VG 0.0 5.0000E-001 0.0
VS 0.0 0.0 0.0
TOTAL POWER DISSIPATION: 1.5465E-012 WATTS
0**** OPERATING POINT INFORMATION TEMPERATURE = 27.000 DEG C
0************************************************************************
MN1
MODEL
MN
ID
7.7327E-013
VGS
5.0000E-001
VDS
2.0000E+000
VBS 0.0
VTH
5.0000E-001
VDSAT 0.0
GM
5.1797E-008
GDS 0.0
RON
-1.0000E+030
GMB 0.0
CBD 0.0
CBS 0.0
CGS
4.6042E-014
CGD 0.0
CGB 0.0
Region
saturation
VTH_D 0.0
Related Topics
Differences Between DC and OP Analyses
DC Convergence
Improving DC Convergence
Eldo® User's Manual, 15.3 209

Setting Up An Analysis
Differences Between DC and OP Analyses
DC Convergence Troubleshooting
Differences Between DC and OP Analyses
The .DC and .OP commands (without any parameters specified) both determine the quiescent
state or DC Operating Point (DCOP) of the circuit. The operating point of the circuit is
computed with capacitances opened and inductances short-circuited.
Tip
See “.DC” and “.OP” in the Eldo Reference Manual.
The main difference between the commands is the information output to the .chi file:
• The .DC command only prints DC Operating Point information related to the node
voltages, source currents, and power dissipation. Look for the DC OPERATING POINT
section in the .chi file.
• The .OP command prints DC Operating Point information related to the node voltages,
source currents, and power dissipation, as well as the Operating Point table information
related to device bias. Look for the DC OPERATING POINT and OPERATING POINT
INFORMATION sections in the .chi file. The items in the OP table can also be
extracted, plotted, and printed.
When sweeping parameters (for example .STEP), with a .DC or .OP command specified with
no other analysis, a continuous waveform is generated when DC plots are requested. When
another analysis (for example .AC) is requested during a sweep together with .DC, Eldo
generates a single point waveform for each run and EZwave displays them as a compound
waveform. If a .OP command is specified instead of the .DC command, no DC plots are
generated.
Eldo automatically determines the DC Operating Point before performing the following
analyses:
• .AC without UIC parameter specified—a .OP is first performed, the SMALL SIGNAL
BIAS SOLUTION and OPERATING POINT INFORMATION are output to the .chi
file.
• .TRAN without UIC parameter specified—a .DC is first performed, no operating point
information is output to the .chi file.
• .DC sweep specified—a .DC is performed at each point of the DC sweep, no operating
point information is output to the .chi file.
Note
The SMALL SIGNAL BIAS SOLUTION is equivalent to the DC OPERATING
POINT information in the .chi file, just the label is different.
210
Eldo® User's Manual, 15.3

Setting Up An Analysis
DC Convergence
Related Topics
DC Analysis
Operating Point Analysis
DC Convergence
DC Convergence
Eldo partitions the circuit in one block or several blocks (especially in the case of large circuits
with MOS). Partitioning iterations are used to find DC convergence. Partitioning iterations can
be disabled by specifying either of the following options:
• .OPTION NODCPART
• .OPTION DCPART=0 (default values is 5)
For DC Analysis, only the Newton Raphson algorithm is used to compute DC.
Tip
See “.OPTION NODCPART” and “.OPTION DCPART” in the Eldo Reference Manual.
Related Topics
Improving DC Convergence
DC Convergence Troubleshooting
Improving DC Convergence
Before any kind of analysis is carried out by Eldo, a DC or operating point for the circuit in
question is usually carried out, unless the UIC parameter is present in the .AC or .TRAN
command.
DC and operating point convergence times can vary greatly, depending on the type of circuit
simulated. Eldo provides some commands that may be used to speed up the convergence
process:
.IC V=value
When used, Eldo fixes the specified node voltages for the duration of the DC analysis. If the
UIC parameter is also present (for example in the .TRAN command), no DC analysis is
performed and the voltages are initialized as defined in the .IC command. All other voltages on
nodes not initialized in the .IC command are determined by Eldo. During subsequent analysis
(transient), the node voltages are freed of their initial values, and may therefore assume different
values.
Eldo® User's Manual, 15.3 211

Setting Up An Analysis
Improving DC Convergence
.NODESET V=value
Used to help calculate the DC operating point by initializing selected nodes during the first DC
operating point calculation. After the first calculation has been completed, the node values are
released, and a second DC operating point calculation is started. This command is useful when
the whereabouts of the DC operating point is known, enabling Eldo to converge directly to it,
and also for bistable circuits or circuits with more than one operating point.
.GUESS V=value
Enables you to set the initial voltages to specific nodes for the first iteration of a DC operating
point run. This differs from the .NODESET command where the node voltages are fixed for the
duration of the first DC operating point calculation.
.RAMP
This command can be used when no DC operating point has been found using the above
methods. Two ramping facilities are provided: DC ramping and transient ramping.
DC convergence algorithms are automatically used by Eldo when the standard DC algorithm
fails to converge. The sequence of algorithms used is as follows: Newton, Gmin ramping, DC
ramping, Transient ramping, PSTRAN, T° ramping, and DPTRAN. The DPTRAN algorithm is
used as a last attempt at convergence. To disable the automatic convergence aid mechanism,
specify option NOCONVASSIST.
.RAMP_SUPPLY
This command provides a power supply ramping analysis as an alternative to the .RAMP
command. It slowly applies the power range over the specified time value, or over a percentage
of the total simulation duration if the simulation duration is known. This can be used as an
alternative solution when .TRAN UIC is specified.
.OPTION VMIN, VMAX
By default, Eldo looks for the DC operating point within the limits of the circuit power supply.
In the case of a circuit that contains elements that create energy, such as voltage- or currentcontrolled
sources, it is possible that Eldo can look for solutions outside the expected bounds. If
so, Eldo displays the message:
Searching operating point between [x1,x2]
You can control the x1 and x2 limits to speed up the DC convergence process using the VMIN
and VMAX parameters. It must be stressed, however, that unrealistic limits can also cause
convergence problems.
Related Commands
• .GUESS in the Eldo Reference Manual
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Eldo® User's Manual, 15.3

Setting Up An Analysis
DC Convergence Troubleshooting
• .IC in the Eldo Reference Manual
• .NODESET in the Eldo Reference Manual
• .RAMP in the Eldo Reference Manual
• .RAMP_SUPPLY in the Eldo Reference Manual
• Options GRAMP, PSTRAN, DPTRAN, and NOCONVASSIST in the Eldo Reference
Manual
• Options VMIN and VMAX in the Eldo Reference Manual
Related Topics
DC Convergence Troubleshooting
DC Convergence Troubleshooting
This topic describes some basic steps you can perform to help troubleshoot common DC
operating point (DCOP) convergence problems in Eldo.
Causes
Most convergence problems are related to one of the following:
• Devices and device models.
• Circuit topology (open loop, closed loop, hierarchical).
• Simulator setup (usually through simulation commands and options).
In DC analysis, the main causes of convergence failure are:
Solution
• Model discontinuities.
• Absence of (or insufficient) initial conditions.
• Instability in the circuit, bistable circuit blocks, and so on.
• Unpractical impedance levels (also check the units are correct: m is milli).
To improve DC convergence, do at least one of the following:
• Check circuit connections, especially for nodes with two connections or floating nets.
• Use initial conditions for important nodes:
.IC V(node)=...
• Increase ITL1 to 200, 300, or even 400; this increases the number of allowed DC
iterations before the simulator gives up:
Eldo® User's Manual, 15.3 213

Setting Up An Analysis
DC Convergence Troubleshooting
.OPTION ITL1=200
• Use ramping and related options to change DC bias incrementally to full bias, for
example:
.OPTION GRAMP=9
• Add large shunt resistors and the keyword OFF to diodes, and so on, for example:
D5 5 6 DMOD OFF
RD5 5 6 100MEG
For large circuits, it is advisable to save the entire DCOP data so that DC analysis will have to
be done once and the results reused again and again as long as the design does not change.
Follow these steps to do this:
For an initial simulation (DCOP):
• Use the suggestions above until a successful convergence is achieved.
• Make sure you have the following commands in the simulation file:
.OP
.SAVE /filename.iic DC
For subsequent simulations (AC, Transient), DC analysis will be skipped thus saving valuable
CPU time. Do the following:
• Remove the commands .OP and .SAVE from the simulation file.
• Add a command to use the initial conditions captured for the whole circuit:
.USE /filename.iic IC
where IC is a keyword for Initial Conditions.
• Modify the .TRAN statement to make use of the initial conditions:
.TRAN tprint tstop [tstart [Hmax]] UIC
where UIC is a keyword for Use Initial Conditions. This makes a big difference
especially when DCOP data is available.
• Modify the .AC statement in a similar way, by adding UIC at the end.
These steps will solve most convergence problems without going into the guesswork of tuning
simulator options. For troublesome designs, more advanced steps will need to be taken.
When initial conditions are used (UIC parameter) Eldo performs a logical initialization prior to
the Transient run (that is, no DC analysis to be performed). Specify option NOINIT to disable
214
Eldo® User's Manual, 15.3

Setting Up An Analysis
Saving and Restarting DC Simulations
this logical initialization; Eldo still considers .NODESET and .IC statements, but all other node
voltages start at zero.
Tip
See “.DC” and “.OPTION NOINIT” in the Eldo Reference Manual.
Related Topics
DC Analysis
Saving and Restarting DC Simulations
A circuit may need to be simulated several times. In each case, the operating point must be
determined, although it may be the same for each run or may be only slightly different; in any
case a large change of operating point is unlikely. To avoid the wasteful recalculation of the
operating point, a system is provided to store and reload the result of the DC analysis from Eldo;
this significantly increases performance, as operating point calculation time is reduced.
.SAVE DC in Combination with .RESTART
The DC or operating point values for a circuit can be saved to a file and used later to greatly
shorten this part of the analysis when the circuit is resimulated. This is achieved by employing
the .SAVE DC and .RESTART commands, provided the circuit node names remain the same.
To restart the simulation, you must modify the circuit description file. Remove the original
.SAVE command, and include a .RESTART command in the circuit description file:
.RESTART
.SAVE DC in Combination with .USE
The DC or operating point values for a circuit can be saved to a file and used later to greatly
shorten this part of the analysis when the circuit is resimulated.This is achieved by employing
the .SAVE DC and .USE commands, provided the circuit node names remain the same. The
following steps are used, assuming that the circuit is stored in the circuit description file
.cir.
1. Add the following line to the circuit description file:
.SAVE DC
If no filename fname is given, the default used is .iic.
2. Run the simulation to find the operating point of the circuit. This is stored in the file as
specified in the .SAVE command.
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Setting Up An Analysis
Saving and Restarting DC Simulations
3. Change the circuit description file to include any other analysis required. Do not specify
DC, UIC or operating point calculation. Add to the circuit description file one of the
lines:
.USE IC
.USE NODESET
.USE GUESS
! to use .IC
! to use .NODESET
! to use .GUESS
Rerun the simulation. Eldo will attempt to use the operating point information stored in
the file.
Eldo provides a system of combining the DC values of parts of a circuit to speed up the
operating point calculation of the complete circuit. The DC state of the circuit sections that are
available are stored in separate files. Such circuit parts may be whole subcircuits. In the general
case, the DC data will be available in several files, called here OPDATA_SS. To use such data
for the DC calculation of a complete circuit, add one of the following lines to the circuit
description file, and for each OPDATA_SS file:
• for usage with the .IC command:
.USE IC
• for usage with the .NODESET command:
.USE NODESET
• for usage with the .GUESS command:
.USE GUESS
Eldo will attempt to use the operating point information stored in all the OPDATA files.
Note
As a guide to choosing the appropriate command, .IC has more constraints than
.NODESET, which has more constraints than .GUESS.
Related Commands
• .USE in the Eldo Reference Manual
Related Topics
DC Analysis
Improving DC Convergence
Saving and Restarting Transient Simulations
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Setting Up An Analysis
Transient Analyses
Transient Analyses
The transient related analyses are:
• “Transient Analysis” on page 217
• “Transient Noise Analysis” on page 241
Transient Analysis
Transient analysis (.TRAN command) is a simulation over a specified time, also called a timedomain
analysis.
Transient output variables (that is, those variables contained within .PRINT and .PLOT
commands in the input description file) are calculated as a function of time over a userspecified
time interval. The initial conditions are automatically determined by a DC analysis
(unless the UIC parameter is specified) with all sources that are not time-dependent being set to
their DC values.
Different types of transient analysis can be specified:
• Point-driven analysis—In the basic form of transient analysis you specify the analysis
duration and the time interval for printing or plotting transient analysis results.
• Parameter-driven analysis—The transient analysis can be performed while sweeping a
parameter or device.
• Data-driven analysis—As an alternative to constant timesteps, you can specify predefined
timestep values in a .DATA command.
Results of a previous simulation can be used as the input to the current simulation by using the
.CHRSIM command.
Multi-threading can be activated for a single DC or transient simulation; Eldo shares computer
resources on a multi-processor machine.
For transient analysis, Eldo analyzes the design by applying the time-domain behavior that you
have specified for all stimulus models (such as voltage sources). To do this, Eldo calculates the
behavior of all models a certain number of times for the duration of the analysis.
Eldo provides sources or stimuli generators. Independent sources can be assigned a time
dependent value for transient analysis. Time dependent functions provided are:
Amplitude Modulation Function
Exponential Function
AM
EXP
Eldo® User's Manual, 15.3 217

Setting Up An Analysis
Transient Analysis
Noise Function
Noise Table Function
Pattern Function
Pulse Function
Piece Wise Linear Function
Single Frequency FM Function
Sine Function
Trapezoidal Pulse With Bit Pattern Function
Exponential Pulse With Bit Pattern Function
Linear Feedback Shift Register (LFSR) Function
Circuit-level transient simulation is the numerical resolution of an algebraic differential system
of equations; as such, it is not an exact procedure (unlike the linear AC or NOISE analyses), and
many ‘switches’ can be used to control the accuracy of the results. Typically, improved
accuracy comes with an increased CPU time. The trade-off between speed and accuracy is the
primary concern of users designing simulations.
For further information see the chapter “Speed and Accuracy” on page 1243.
Transient Analysis Results
NOISE
NOISE TABLE
PATTERN
PULSE
PWL
SFFM
SIN
PBIT
EBIT
LFSR
The results of transient analysis runs are output using .EXTRACT, .PLOT, .PRINT, and
.PROBE commands.
Example transient analysis waveform output from a .PLOT statement is shown in Figure 6-2:
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Setting Up An Analysis
Saving and Restarting Transient Simulations
Figure 6-2. Transient Analysis Plot for a Butterworth Filter Circuit
Related Commands
• .TRAN in the Eldo Reference Manual
• .DATA in the Eldo Reference Manual
• Sources in the Eldo Reference Manual
Related Topics
Operating Point Analysis
DC Convergence Troubleshooting
Saving and Restarting Transient Simulations
Transient Noise Analysis
Saving and Restarting Transient Simulations
Simulation results can be saved and then used as a starting point for other simulations.
Performance advantages:
Eldo® User's Manual, 15.3 219

Setting Up An Analysis
Saving and Restarting Transient Simulations
• Skip DC operating calculation
• Skip a portion of transient simulation in subsequent run of the same design
Save/restart can also be used to backup data for long simulations, thus avoid re-simulating
design from the beginning if a power outage occurs.
There are two ways to save simulation information:
• .SAVE command saves analysis data to a file at DC, transient or end of transient
• .OPTION SAVETIME=val saves results every val CPU hours
There are three ways to read previously saved results:
• .USE command
This reads the saved DC result, and can be used as nodeset, ic, guess values.
Used to load DC or operating point information for one or more parts of the circuit to be
simulated; its application is thus in cases where a large or complex circuit is to be
simulated, and the DC or operating point data for parts of the circuit is already known.
Multiple .USE commands may be used in a simulation.
• .LOAD command
This reads the saved DC result, and can be used as nodeset, ic, guess values. Works in a
similar way to the .USE.
• .RESTART command
This reads transient and end of transient saved result. It only supports simple TRAN
simulation. .TRAN associated with .STEP, .MC, .WCASE, .NOISETRAN are not
supported. Modification of circuit topology is not allowed. Old and new waveforms are
concatenated.
The .RESTART command is different from the .USE command in several ways. Firstly,
whereas the .USE information may apply only to part of the circuit, .RESTART data
always applies to the whole circuit. In fact, the .RESTART command first checks that
the node names specified in the file used to restart the circuit, exactly correspond to
those specified in the circuit description file where the .RESTART command is placed.
The .RESTART command may be used to either load the operating (DC) point data and
thereafter perform a transient simulation, or it may be used to restart a transient
simulation from a specific point where the simulation had been interrupted in an earlier
run. To carry out a transient analysis from a specific point, the .TRAN command
parameters need to be changed to specify the new simulation times.
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.SAVE END in Combination with .RESTART
Setting Up An Analysis
Saving and Restarting Transient Simulations
It is possible to run a transient simulation and save the final state of the run. Thereafter, it is
possible to restart the transient simulation from the time the last simulation was ended. To
achieve this, use the .SAVE command in combination with the END parameter.
To restart the simulation, the circuit description file must be modified. The original .SAVE
command must be removed and the .TRAN command must be modified to reflect the new end
time. Furthermore, a .RESTART command must be included in the circuit description file:
.RESTART
Using the above procedure, the simulation will produce a new binary output file (.wdb file) that
contains data starting from the end of the last simulation. To concatenate old and new .wdb files,
the old .wdb file should be renamed to, for example, tmpfile and the previous .RESTART
command modified as follows:
.RESTART FILE=
The system then concatenates the old .wdb file data with the new .wdb data.
More Sophisticated .SAVE and .RESTART Procedures
The complete .SAVE syntax shown in the line below includes provision to save the simulation
state either periodically or at predefined times and/or temperature or sweep (STEP) parameter
conditions:
.SAVE [fname] {DC|END|TIME=value} [REPEAT] [TEMP=value] [STEP=value]
It is possible to save the result of the simulation periodically (with REPEAT), to save the run for
a particular temperature (with TEMP) or for a particular swept parameter (with STEP).
In each case, the rule to restart the simulation from a predefined state is the same; to restart the
simulation, the .RESTART command needs to be added to the circuit description file. The
.SAVE commands contained therein should be removed.
The transient simulation parameters in the .TRAN command may also need to be modified to
reflect the new desired simulation time stop.
Save and Restart Example
1. Run a simulation on the netlist file restart.cir containing the following command to save
simulation information at 400ns to file test.sav:
.SAVE test.sav time=400ns
2. Rename the generated simulation results file restart.wdb as test_previous.wdb.
3. Relaunch Eldo with the following command in the netlist:
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Setting Up An Analysis
Saving and Restarting Transient Simulations
.RESTART test.sav file=test_previous.wdb
A new wdb file is created, restart.wdb, which is the concatenation of the previous results
and the current simulation results file.
In this example, Eldo will create the file restart.wdb as usual, but will first copy
test_previous.wdb into restart.wdb before adding new points in the restart.wdb file. To permit
the concatenation of the previous binary output file with the new binary output file, you have to
rename it.
If the file=test_previous.wdb string is omitted from the .RESTART command, then the first
point in the restart.wdb file will correspond to the time at which simulation actually restarts.
Save and Use Example
1. Run a simulation containing the following command to save DC analysis results to file
test.ddt:
.SAVE test.ddt dc
2. Relaunch Eldo with the following command in the netlist
.USE test.ddt ic
This specifies DC operating point values in test.ddt should be read as .IC values
Aborting Simulation and Saving Current State
If a transient simulation run is interrupted by the user with a Control-C, Eldo prompts the user,
inquiring if the simulation status should be saved. If the user answers in the affirmative, the
simulation data is saved in a file named .sav where cirname is the name of the circuit
description file with no extension.
To restart the simulation from this interrupted point, the circuit description file should be
modified to include the command:
.RESTART
The simulation will then be restarted automatically from the time it was interrupted. The .TRAN
command needs to be updated. Options and/or stimuli might be changed as well.
Related Commands
• .SAVE in the Eldo Reference Manual
• .USE in the Eldo Reference Manual
• .LOAD in the Eldo Reference Manual
• .RESTART in the Eldo Reference Manual
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Setting Up An Analysis
Saving and Restarting Transient Simulations
Related Topics
Operating Point Analysis
Saving and Restarting DC Simulations
Transient Analysis
Eldo® User's Manual, 15.3 223

Setting Up An Analysis
AC Related Analyses
AC Related Analyses
The AC related analyses are:
• “AC Analysis” on page 224
• “Loop Stability Analysis” on page 229
• “Pole Zero Analysis” on page 230
• “Transfer Function” on page 237
See also “Noise Analysis” on page 239.
AC Analysis
A small-signal analysis that computes the magnitude and phase of output variables as a function
of frequency. Eldo first computes the circuit DC operating point (DCOP) with user-specifiable
initial conditions; thereafter the behavior of the linearized circuit is computed for a sine input of
user-specifiable amplitude, phase and frequency range.
Different types of AC analysis can be specified:
• Circuit frequency response analysis—.AC specified with the SWEEP parameter results
in a frequency response analysis within the frequency range fstart to fstop with a number
of points nb according to the sweep variation type.
• Parameter-driven analysis—The frequency response analysis can be performed while
sweeping a parameter or device.
• Data-driven analysis—.AC followed by the parameter DATA=dataname results in a
sweep of the values pre-defined in the .DATA command.
• List-driven analysis—A list of frequency points can be specified instead of a frequency
range.
• Adaptive analysis—An adaptive variant of AC analysis can be used when there are ports
in the design to generate an accurate touchstone file. Eldo will adjust the frequency
based on a tolerance value in order that sharp peaks in the AC response are not missed.
Whenever a .AC command, a .TRAN command, and a .OP command containing time
specifications are in the .cir file, then an AC analysis will be performed at each of these time
points. See Performing an AC Analysis During Transient Analysis for further details.
An adaptive variant of AC analysis can be used when there are ports in the design to generate an
accurate touchstone file. Eldo will then adjust the frequency in order that sharp peaks in the AC
response are not missed. See Adaptive AC Analysis Example for further details.
.MPRUN can be used to take advantage of multi-processor machines for data sweeps on the
.AC command.
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AC Analysis Results
Setting Up An Analysis
AC Analysis
The results of AC analysis runs are output using .EXTRACT, .PLOT, .PRINT, and .PROBE
commands.
The amount of information in the .chi file relating to operating point can be limited using the
option PRINT_ACOP.
Use option ACOUT to control how complex expressions VX(a,b) and IX(a,b) are computed in
AC analysis for their decibel magnitude, magnitude, phase, and group delay values.
Figure 6-3 shows an example AC analysis waveform output from a .PLOT statement:
Figure 6-3. AC Analysis Plot for an LCR Circuit
Related Commands
• .AC in the Eldo Reference Manual
• .MPRUN in the Eldo Reference Manual
• .OPTION ACOUT in the Eldo Reference Manual
• .OPTION PRINT_ACOP in the Eldo Reference Manual
Related Topics
Operating Point Analysis
Adaptive AC Analysis Example
Eldo® User's Manual, 15.3 225

Setting Up An Analysis
Adaptive AC Analysis Example
Performing an AC Analysis During Transient Analysis
Saving and Restarting AC Simulations
Adaptive AC Analysis Example
The following example shows the use of an adaptive AC analysis:
* S-par extraction
l1 1 1x 1e-7
r1 1x 2x 10
c1 2x 0 3e-12
T1 2x 0 3x 0 Z0=50 Td=1n
c2 3x 0 6e-12
l2 3x 4x 2e-7
r2 4x 2 8
T2 2x 0 5x 0 Z0=40 Td=1.5n
Vp 5x 0 0
c11 1 0 10p
c22 2 0 10p
L3 3x 6x 2e-7
R3 6x 5x 2
I1 0 1 iport=1 rport=50
I2 0 2 iport=2 rport=50
.extract ac yval(sdb(1,1),1.45e8)
.Ffile S sb1.s2p Hz RI
.plot ac sdb(1,1)
.ac adaptive 0.05 1e5 1e11
Specifies an adaptive AC analysis between 1.0×10 5 Hz to 1.0×10 11 Hz with a relatively small
tolerance. The magnitude of S11 is plotted in dB, and the extracted S parameters are stored in
the file sb1.s2p with the frequency in Hz. The data is stored in the form of the Real and
Imaginary parts.
Related Commands
• .AC in the Eldo Reference Manual
Related Topics
AC Analysis
Performing an AC Analysis During Transient
Analysis
Whenever a .AC command, a .TRAN command, and a .OP command containing time
specifications are in the .cir file, then an AC analysis will be performed at each of these time
points.
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Setting Up An Analysis
Saving and Restarting AC Simulations
In the following example Eldo will perform AC, NOISE and TRAN analyses at time 0, time 5n,
and time 7n:
.AC DEC 10 1 1e9
.NOISE v(5) vin 70
.TRAN 1n 20n
.OP 5n 7n
If some .EXTRACT commands related to AC analyses are specified, extract information will be
returned for each AC analysis.
When the output is cou format, an extra file, _tac.cou is created that holds the results
of those AC simulations which are performed from within a transient simulation.
When the output is JWDB, a folder TRAN is created with several AC folders inside, for
example AC_1, AC_2.
Limitations:
• AC results performed from within a transient simulation will not be dumped in GWL
and PSF output files.
• If there is a .TEMP or a .STEP command in the input file, the .ext file which normally
gets created will not be created in this instance.
• Information related to .EXTRACT SWEEP will not be available.
• Monte Carlo (.MC) enabled if .MC ALL is specified, Worst-Case (.WC), or transientnoise
(.NOISETRAN) simulations are disabled.
Related Commands
• .AC in the Eldo Reference Manual
• .TRAN in the Eldo Reference Manual
• .NOISE in the Eldo Reference Manual
• .OP in the Eldo Reference Manual
• .OPTION NOACT0 in the Eldo Reference Manual
Related Topics
AC Analysis
Saving and Restarting AC Simulations
To restart an AC simulation, you need to have both of the following commands in your input
netlist:
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Setting Up An Analysis
Saving and Restarting AC Simulations
• .RESTART file_name, where file_name comes from the results of a DC/TRAN
simulation.
• .AC ... UIC command.
then the .RESTART command will be interpreted as:
.USE file_name OVERWRITE_INPUT
A warning message will be displayed that no DC analysis has been performed if attempting to
run an AC simulation with UIC enabled without a restart file.
When initial conditions are used (UIC parameter) Eldo performs a logical initialization prior to
the AC run (that is, no DC analysis to be performed). Specify option NOINIT to disable this
logical initialization; Eldo still considers .NODESET and .IC statements, but all other node
voltages start at zero.
Usage of .RESTART and .TRAN with .NOISETRAN, .MC, .WCASE, .STEP
In the case of .TRAN and .RESTART associated with a .STEP, .MC, .WCASE or
.NOISETRAN, the same restart file will be used for all runs, for example:
.MC 5
.TRAN
.SAVE TIME = ...
.END
In this example you would assume that six restart files would be generated (five MC and one
nominal), and that in subsequent commands:
.MC 5
.TRAN
.RESTART
.END
each run would use its “restart file ancestor”. However, this is not how it works. Eldo will use
only the latest “restart file” which has been generated for all runs, and unless explicitly
specified, Eldo will create a restart file only for the first STEP run or the nominal MC run.
Related Commands
• .OPTION NOINIT in the Eldo Reference Manual
• .AC in the Eldo Reference Manual
• .RESTART in the Eldo Reference Manual
Related Topics
AC Analysis
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Loop Stability Analysis
Setting Up An Analysis
Loop Stability Analysis
Analyses the circuit stability. The classical method for stability analysis is to break the feedback
loop at an appropriate point on AC analysis, while maintaining correct DC conditions. This
means that the loop must be terminated with the appropriate impedance it ‘sees’ looking at the
loop input. Obtaining this impedance value is not always a simple task. Loop stability analysis
measures the loop gain by successive injection (Middlebrook Technique). A zero voltage source
is placed in series in the loop: the first pin of the voltage loop must be connected to the loop
input, the other pin to the loop output. The name of this voltage source is given in the .LSTB
statement, and the loop gain can be displayed.
Two loop stability analysis algorithms are available:
• The default Middlebrook technique with successive injection (default convention
T=AK, with an option to select the M. Tian convention T=−AK).
• The K. Kundert algorithm from “A Test Bench for Differential Circuits.”
Use the .IPROBE command with .LSTB to perform open loop simulations without editing the
device netlists (no need to add a voltage source and nets to create an open loop).
Related Commands
• .LSTB in the Eldo Reference Manual
• .IPROBE in the Eldo Reference Manual
Related Topics
Example 11—Loop Stability of an Opamp
AC Analysis
Eldo® User's Manual, 15.3 229

Setting Up An Analysis
Pole Zero Analysis
Pole Zero Analysis
This topic describes the usage of the pole-zero post-processor.
Eldo is able to obtain the locations of poles and zeros for analog circuits following a small
signal analysis. This data is useful for obtaining stability and phase margin information as well
as predicting closed loop performance from an open loop response. As a lot of closely spaced
poles or zeros are not easily discernible via a Bode plot, the interactive post processor and its
textual output clearly help to identify such singularities and evaluate the most important areas in
a circuit's behavior.
The pole-zero data is obtained by linearizing the circuit about an operating point and outputting
information about circuit matrix description and AC response. This data will be analyzed by the
Eigenvalue QZ algorithm, one of the most accurate techniques available.
The pole-zero post-processor enables the designer to detect all the roots of the analyzed circuit
and to simplify this information, extracting the most meaningful of these roots. Moreover, a
high-level model of the reduced circuit—equivalent for AC and small signal analysis—is
calculated and given in the form of an FNS device that can replace the original circuit when
used as part of a more complex design.
The pole-zero post-processor may be activated for circuits that have been simulated using the
.PZ and .AC commands. The .PZ command can take either the voltage at a node, the voltage
between two nodes, or the current through a voltage source as parameters. The pole-zero
analysis determines the transfer function relationship—expressed as complex poles and zeros—
between the input at which the AC voltage source is applied and the output specified as a
parameter in the .PZ command.
Pole-zero only works on quasi-static devices.
Tip
See “.AC” and “.PZ” in the Eldo Reference Manual.
Pole-Zero Analysis Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Running Pole-Zero Analysis in Batch Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Running Pole-Zero Analysis in Interactive Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
Pole-Zero Analysis Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
FNS Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Pole-Zero Numerical Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Pole-Zero Analysis Flow
To obtain the poles and zeros you must first run an analysis, then use the pole-zero postprocessor.
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Setting Up An Analysis
Pole Zero Analysis
Procedure
1. Run an AC analysis simulation using a netlist with both .AC and .PZ commands. If the
simulation is successful, a pole-zero data file with extension .pz will be generated.
2. Use the pole-zero post-processor to obtain the poles and zeros for the design under test.
The pz command specified with the .pz file as argument begins the dialog for pole-zero
analysis. Run the command:
pz circuit.pz
A list of poles and zeros will be generated and you will be prompted to refine the
solution by removing less important poles and zeros.
Related Topics
Tip
See “.AC” and “.PZ” in the Eldo Reference Manual.
Running Pole-Zero Analysis in Batch Mode
Running Pole-Zero Analysis in Interactive Mode
Pole-Zero Analysis Output
Running Pole-Zero Analysis in Batch Mode
In batch mode, the pole-zero analysis runs without user interaction. Where the interactive mode
would prompt for user input, the batch tool uses default responses.
Prerequisites
An AC analysis must have been run on the circuit of interest, and that analysis must have
included a .PZ command (to generate a .pz file in the output directory.
Procedure
1. Navigate to the directory containing the output .pz file from the AC analysis.
2. Run:
pz .pz -batch
The pole-zero post-processor runs until completion.
Related Topics
Tip
See “.PZ” in the Eldo Reference Manual.
Running Pole-Zero Analysis in Interactive Mode
Eldo® User's Manual, 15.3 231

Setting Up An Analysis
Pole Zero Analysis
Pole-Zero Analysis Output
FNS Model
Running Pole-Zero Analysis in Interactive Mode
In interactive mode, the pole-zero analysis prompts for user input as it runs, enabling the
accurate specification of its input parameters.
Prerequisites
An AC analysis must have been run on the circuit of interest, and that analysis must have
included a .PZ command (to generate a .pz file in the output directory.
Procedure
1. Navigate to the directory containing the output .pz file from the AC analysis.
2. Run:
pz .pz
3. The pole-zero post-processor runs. When prompted, enter arguments for the following:
• -th value
Threshold for pole/zero cancellation
• -cutoff value
Cutoff frequency
• -pindices indice_list -endpindices
List of indexes for pole selection; indices must be in increasing order
• -zindices indice_list -endzindices
List of indexes for zero selection; indices must be in increasing order
The pole-zero processor runs to completion.
Note
Any prompts for which an argument is not provided will take the default answer—
that is, the same as for the -batch mode.
Related Topics
Tip
See “.PZ” in the Eldo Reference Manual.
Running Pole-Zero Analysis in Batch Mode
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Setting Up An Analysis
Pole Zero Analysis
Pole-Zero Analysis Output
FNS Model
Pole-Zero Analysis Output
This topic details the results generated by a pole-zero analysis, and lists the steps that can be
taken—when running the analysis in interactive mode—to simplify the results.
Tip
You can view pole-zero analysis results with the AMS Results Browser.
The first result is the impression of all the roots found for the circuit, ordered by magnitude, but
with zeros divided in negative and positive real parts, as shown here for a typical example:
Poles Modulus Real Part Imaginary Part
1 6.264953E+00 -6.264953E+00 0.000000E+00
2 3.853866E+06 -3.824006E+06 -4.788095E+05
3 3.853866E+06 -3.824006E+06 4.788095E+05
4 4.396770E+06 -4.396770E+06 0.000000E+00
5 5.423444E+06 -5.423444E+06 0.000000E+00
6 6.554762E+06 -3.126871E+06 -5.760866E+06
7 6.554762E+06 -3.126871E+06 5.760866E+06
8 6.584083E+06 -5.150248E+06 -4.101840E+06
9 6.584083E+06 -5.150248E+06 4.101840E+06
10 1.343013E+07 -1.343013E+07 0.000000E+00
11 1.531050E+07 -1.531050E+07 0.000000E+00
12 2.217833E+07 -2.217833E+07 0.000000E+00
13 4.927351E+07 -4.927351E+07 0.000000E+00
14 6.564085E+07 -6.564085E+07 0.000000E+00
15 1.228260E+08 -1.228260E+08 0.000000E+00
Zeros Modulus Real Part Imaginary Part
1 3.853866E+06 -3.824006E+06 -4.788095E+05
2 3.853866E+06 -3.824006E+06 4.788095E+05
3 4.396770E+06 -4.396770E+06 0.000000E+00
4 5.423444E+06 -5.423444E+06 0.000000E+00
5 6.435558E+06 -5.867538E+06 -2.643560E+06
6 6.435558E+06 -5.867538E+06 2.643560E+06
7 6.554762E+06 -3.126871E+06 -5.760866E+06
8 6.554762E+06 -3.126871E+06 5.760866E+06
9 1.343013E+07 -1.343013E+07 0.000000E+00
10 1.531050E+07 -1.531050E+07 0.000000E+00
11 2.217833E+07 -2.217833E+07 0.000000E+00
12 6.564085E+07 -6.564085E+07 0.000000E+00
13 1.228260E+08 -1.228260E+08 0.000000E+00
14 3.857487E+06 3.857487E+06 0.000000E+00
15 2.908742E+09 2.908742E+09 0.000000E+00
At this point it is possible to simplify the results since, in practice, many poles and zeros will be
output, and some of them will be almost superimposed giving a negligible resultant effect.
Moreover, sometimes the circuit will work in a well-determined frequency range over which we
Eldo® User's Manual, 15.3 233

Setting Up An Analysis
Pole Zero Analysis
will focus our attention, while all the parasitic and less meaningful roots will also be detected.
For these reasons, the following reduction mechanisms are available:
• “Frequency Limit” on page 234
• “Pole-Zero Cancellation by Threshold” on page 234
• “Hand Selection” on page 235
• “Select Index” on page 235
Frequency Limit
Eldo offers the option to limit the analysis up to a certain frequency, as shown in the following
example:
Do you want to set an upper frequency limit for the selected poles and
zeros? [yes/no]:
y
So give the highest frequency to be considered:
5e7
Roots up to 0.5000E+08 Hz will be examined.
If the roots of the circuit are spanned up to a frequency significantly higher than the upper
frequency of the AC analysis, this limit can be very useful in simplifying textual output and
FNS models without meaningful loss of accuracy.
Pole-Zero Cancellation by Threshold
Very close poles and zeros can be deleted, as their influence on the circuit behavior
compensates. Big circuits with a lot of roots often have closely spaced poles and zeros, which
can be deleted to show the most meaningful remaining roots. A reminder about the threshold
mechanism shows the condition to delete a pole, P, and a zero, Z. The condition is that:
abs(RE[P]-RE[Z]) < abs(RE[P]) * TH + TH
and the same for the imaginary part.
Therefore, if a threshold of, for example, 0.1 is given, there are two possibilities:
• For very low frequency roots, for example, fractions of 1 Hz, TH has the meaning of
maximum difference between the real parts of the pole and the zero, and the same for the
imaginary part.
• In most cases, there are roots at quite high frequencies so the first term on the right side
of the relation dominates and TH takes the meaning of maximum ratio between the
distance amongst the roots and their value, so in this case a 10% tolerance.
At this point, a table of remaining poles and zeros (after the two elimination steps) is displayed.
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Hand Selection
Setting Up An Analysis
Pole Zero Analysis
After these steps, a further choice between the resulting roots is offered. A prompt asks:
Do you agree with the Selected POLES [Yes/No]?
If the selected poles and zeros are Ok, enter Y and the analysis continues. If only a certain
number of poles and zeros are required, enter N and the following prompt is displayed:
Poles selection by their index in INCREASING order
Enter a negative index to end the selection.
Select Index
A prompt asks for the specification of which poles are to be included in the final transfer
function. The selection is made via the index to the values—the index being the first number
that appears in the tables above. Once the values to use have been chosen, the selection is
terminated by entering a negative number. The process is then repeated for zeros.
Note
Ensure that the selections are made in increasing integer order including the negative
terminator, otherwise required values may be lost.
The remaining set of poles and zeros are printed, followed by another table showing the
difference between the actual and the now-approximated model, swept in frequency and giving
both the magnitude (dB) and the phase (degree) differences. For example:
Hz dB’s Error Degrees Error
1.000000E+01 6.525140E-04 1.020462E-02
1.000000E+02 6.201058E-04 1.096881E-02
1.000000E+03 5.805557E-04 1.102087E-02
1.000000E+04 5.806112E-04 1.107192E-02
1.000000E+05 5.791327E-04 3.599889E+02
1.000000E+06 5.815470E-04 1.444244E-02
1.000000E+07 1.179731E-03 4.588650E-02
1.000000E+08 5.953287E-02 3.609858E-01
1.000000E+09 4.490041E+00 2.134625E+00
FNS Model
The reduced circuit is now modeled as an S-domain transfer function (for example, an FNS
device in Eldo syntax) which can replace the original circuit with the introduced approximations
for AC and small-signal analysis—this can be very useful for developing complex designs,
enabling the replacement of even a complex block with its equivalent model and great
simplification of simulation of the higher-level system. The output format is as follows:
Eldo® User's Manual, 15.3 235

Setting Up An Analysis
Pole Zero Analysis
FNS1 IN OUT
+
+ 498057.650621
+ 0.0271151244556 ! * s^(-1)
+ 4.88425501019e-10 ! * s^(-2)
+ 2.65330374224e-18 ! * s^(-3)
+ -3.22583377778e-27 ! * s^(-4)
+ 8.84119411e-37 ! * s^(-5)
+ ,
+ 1
+ 0.0315272851854 ! * s^(-1)
+ 1.08957721435e-09 ! * s^(-2)
+ 1.85561098689e-17 ! * s^(-3)
+ 2.03791858143e-25 ! * s^(-4)
+ 1.03556420914e-33 ! * s^(-5)
If too many poles and zeros are left after the reduction steps, FNS evaluation could fail due to
too high coefficients (a message is displayed in such a case). However, the efficiency of the
reduction algorithm normally enables a reduction of, at most, 6-7 poles, which can give a very
good approximation of the original circuit.
The PZ program produces a .cpz output file for visualization with EZwave, which
shows the Bode diagrams of gain and phase for the original and the reduced circuit. Also, a file
.mpz is produced, showing a scatter map of the circuit’s roots in the complex plane.
Finally, a subcircuit containing FNS is stored in file .pzck, which can be included by
an upper level netlist.
After all these steps, a prompt asks whether to repeat the analysis, typically to alter some
parameters such as threshold, frequency limit, and so on, thereby modifying the accuracy/
simplicity ratio of the whole analysis.
If no is entered, the program exits, leaving an ASCII output file .pzr containing a trace
of all of the program outputs.
Related Topics
Running Pole-Zero Analysis in Batch Mode
Running Pole-Zero Analysis in Interactive Mode
Pole-Zero Analysis Output
Pole-Zero Numerical Issues
Pole-Zero Numerical Issues
There are possible numerical issues with poles and zeros. This topic explains why 500 variables
is a reasonable maximal system size, and suggests a workaround using a two-step S-parameter
block approach.
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Setting Up An Analysis
Transfer Function
Symptoms
The .PZ command generates G and C matrices. The pole-zero post-processor computes poles
and zeros, and generates approximated FNS to be used. It uses a QZ algorithm to solve the
generalized Eigenvalue system:
GX = λCX
The CPU cost of the QZ algorithm is approximately n 3 , where n is the size of the G and C
matrices. When n > 500, the CPU time is large, and numerical issues may arise. This is a
constraint of the QZ algorithm.
Solution
Use a two-step S-parameter block approach:
1. Extract the S-parameters of the circuit (using .FFILE and .AC commands).
This generates a .s2p file containing the S-parameters.
2. Use this S-parameter file in one of two ways:
o
o
Use this S-parameter file (.s2p) as a macromodel of the circuit (using an FBLOCK
model). This is more accurate than the FNS pole-zero approach.
Alternatively, specify the .PZ command with the S-parameter file (.s2p) (using an
FBLOCK model). The pole-zero post-processor can then be used to compute the
poles and zeros as before, avoiding any numerical issues.
Related Topics
Tip
See “.AC,” “.FFILE” and “.PZ” in the Eldo Reference Manual.
Pole-Zero Analysis Flow
Pole-Zero Analysis Output
FNS Model
Working with S, Y, Z Parameters
Transfer Function
The .TF command calculates the small signal transfer function by linearizing around a bias
point. The gain from the input voltage source to the output node or source is calculated and
output to the .chi file together with the input and output impedances.
Tip
See “.TF” in the Eldo Reference Manual.
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Setting Up An Analysis
Transfer Function
Example transfer function output:
0**** SMALL SIGNAL CHARACTERISTICS
0 V(OUT)/VIN 6.000000E-001
0 INPUT RESISTANCE AT VIN 5.000000E+004
0 OUTPUT RESISTANCE AT V(OUT) 1.200000E+004
The small signal transfer function is 0.6 for the voltage at node out with respect to the
independent voltage source VIN, for an output resistance of 12kΩ.
Related Topics
AC Analysis
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Setting Up An Analysis
Noise Analyses
Noise Analyses
The noise related analyses are:
• “Noise Analysis” on page 239.
• “Transient Noise Analysis” on page 241
• Eldo RF Steady-State Noise Analysis, see “RF Analyses” on page 283.
Noise Analysis
The .NOISE command specifies a noise analysis, which is performed in conjunction with the
small-signal analysis. The circuit is linearized around its DC operating point, and the
contribution of all noise sources is summed at a given output. All node voltages and currents are
assumed to be small sinusoidal signals, all at the same frequency.
The noise generated by devices is usually modeled as an equivalent noise spectral density,
which is a frequency-dependent function. Thermal noise, shot noise and flicker noise are all
noise sources due to different physical mechanisms, but they can be modeled as noise spectral
densities, enabling the computation of how much noise (as an RMS voltage) a device generates
in a given bandwidth.
Use the NONOISE parameter on a device model or instance to specify that no noise model will
be used for the device when performing noise analysis. The device presents no noise
contribution to the noise analysis.
Noise Analysis Results
Noise results can be sorted in different ways with the .OPTNOISE command.
Example noise results:
******** NOISE IN THE DOMAIN 1.000000E+002Hz 1.000000E+004Hz ********
OUTPUT NOISE PER DEVICE :
R8 : 2.45421E-011 V^2 ---> : 4.95400E-006 V
R12 : 2.09786E-011 V^2 ---> : 4.58024E-006 V
R11 : 1.86080E-011 V^2 ---> : 4.31370E-006 V
R9 : 9.84669E-012 V^2 ---> : 3.13794E-006 V
R10 : 4.74119E-012 V^2 ---> : 2.17743E-006 V
R2 : 2.03321E-012 V^2 ---> : 1.42591E-006 V
R6 : 1.69155E-012 V^2 ---> : 1.30060E-006 V
R5 : 6.59705E-013 V^2 ---> : 8.12222E-007 V
R4 : 5.86775E-013 V^2 ---> : 7.66012E-007 V
R3 : 3.27669E-013 V^2 ---> : 5.72424E-007 V
R1 : 2.04526E-013 V^2 ---> : 4.52246E-007 V
R7 : 2.02087E-013 V^2 ---> : 4.49541E-007 V
TOTAL OUTPUT NOISE 9.188156E-006 Volts
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Setting Up An Analysis
Noise Analysis
INPUT NOISE PER DEVICE :
R8 : 1.43229E-008 V^2 ---> : 1.19678E-004 V
R12 : 1.30353E-008 V^2 ---> : 1.14172E-004 V
R11 : 1.15623E-008 V^2 ---> : 1.07528E-004 V
R9 : 6.08587E-009 V^2 ---> : 7.80120E-005 V
R10 : 2.11063E-009 V^2 ---> : 4.59416E-005 V
R6 : 7.15178E-010 V^2 ---> : 2.67428E-005 V
R2 : 7.14807E-010 V^2 ---> : 2.67359E-005 V
R5 : 2.78919E-010 V^2 ---> : 1.67009E-005 V
R4 : 2.20371E-010 V^2 ---> : 1.48449E-005 V
R3 : 1.23060E-010 V^2 ---> : 1.10932E-005 V
R7 : 8.99627E-011 V^2 ---> : 9.48487E-006 V
R1 : 2.80800E-011 V^2 ---> : 5.29906E-006 V
TOTAL INPUT NOISE 2.220075E-004 Volts
See Also
• .NOISE in the Eldo Reference Manual
• .OPTNOISE in the Eldo Reference Manual
• Options THERMAL_NOISE and FLICKER_NOISE in the Eldo Reference Manual
• Noise in MOSFETs in the Eldo Reference Manual
Related Topics
Example 3—AC and Noise Analysis of a Band Pass Filter
AC Analysis
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Setting Up An Analysis
Transient Noise Analysis
Transient Noise Analysis
In most analog design applications, knowledge of noise levels generated by the circuit is of
great importance. In all traditional SPICE-like simulators, noise computation is only available
in AC analysis. In this case the circuit is assumed to have a fixed bias (DC operating point), and
noise simulation can only be applied to circuits working under small signal conditions. For this
reason, many applications cannot be simulated and their noise performance is unknown until
physical measurement is possible on the manufactured design. The only other method available
to obtain this important information is to perform tedious hand calculations (when possible).
The objective of a noise simulation is to see the effect of the physical noise generated by the
different devices on the characteristics of an electrical circuit. Three different noise analyses are
available inside Eldo: .NOISE, .SSTNOISE, and .NOISETRAN.
.NOISE and .SSTNOISE are similar in the sense that the effect of the noise sources is treated as
linear (meaning that doubling the noise amplitude will double the effect). To compute the
contribution from the different noise sources the circuit is linearized around its operation point
(can be DC OP for .NOISE analysis or large signal Steady-State OP for .SSTNOISE analysis).
The contributions from the individual noise sources are computed by multiplying the noise
Power Spectral Density (PSD) by the corresponding transfer functions (or harmonic transfer
functions) between the noise source and the specified circuit output.
• Noise and signal are handled separately.
• Noise is considered as small and noise effects are considered as linear.
• It is possible to see the individual contributions from all the different noise sources.
.NOISETRAN analysis is very different from .NOISE or .SSTNOISE analyses. It is a true noise
simulation, similar to what actually happens in reality when an electrical circuit is running.
There is no simplification, no linearization, and no assumption. Noise is handled as any other
electrical signal during a transient simulation. There is no separation between noise and other
signals, and no separation between the noise sources.
Transient noise simulation can be applied to all types of circuit without restriction. To perform
transient noise analysis, physical noise of electrical devices is emulated by time-dependent
current sources. The frequency characteristics of these sources are referred to the noise models
of the noisy components. The method used is simple, fast and does not disturb the simulated
behavior of the circuit because the noise signals introduced are continuous and fully
deterministic.
Tip
See “.NOISETRAN” in the Eldo Reference Manual.
Simulation results from transient noise analysis include:
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Setting Up An Analysis
Transient Noise Analysis
• Transient response of the circuit, as generated by a pure transient analysis (the nominal
run).
• Transient response(s) with the added noise generated by the circuit (plotted as an
oscillogram of experimental measurements).
• The RMS value of the noise versus time, which gives the accuracy of the ideal transient
response.
To compute the RMS value of the generated noise, Eldo performs a normal transient
analysis of the circuit, plus N transient simulations which include noise sources within
the noisy devices. The RMS value of noise is computed at each time-step as follows:
Where V ο (t) represents the nominal transient response of the circuit, and V ι (t) is the i th
transient response of the circuit including the noise sources; N is the number of noise
runs performed (specified by the NBRUN parameter of the .NOISETRAN command). If
NBRUN=1, no RMS waveforms are created.
To perform transient noise analysis, Eldo adds a noise contribution to the same components as
in AC noise analysis (R, M, B, J, D). An additional noise model, connected with the Switch
macromodel (S), is available to simulate noise in switched capacitor circuits.
Figure 6-4. Circuit Components with their Added Noise Sources
Refer to the noise models in the respective sections of the Eldo Reference Manual.
See also:
• “Transient Noise Analysis Principles” on page 243
• “Specifying .NOISETRAN Parameters” on page 244
• “Transient Noise Analysis Results” on page 259
• “Transient Noise Analysis Example 1—High-Rate Particle Detector” on page 1368
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Transient Noise Analysis Principles
Setting Up An Analysis
Transient Noise Analysis
A .NOISETRAN analysis is very similar to a normal .TRAN analysis except that the circuit
contains some additional time domain sources (current or voltage) that correspond to the
physical noise sources. Noise sources are generated as pseudo-random signals having gaussian
amplitude distribution and power spectral characteristics that correspond to the PSD model of
the noise source.
A .NOISETRAN can run an optional nominal run (normal transient run without noise sources)
and multiple runs including noise sources. The time steps and simulation tolerances are
automatically tuned to provide accurate results according to noise characteristics.
The results of the .NOISETRAN are multiple noisy runs or a RMS curve computed with
statistics from the difference between the noisy runs and the nominal run.
Applications for Transient Noise Analysis
A single noisy run may be used to compute:
• Noise PSD at the post-processing output of a circuit. This may be useful for Sigma-
Delta converters.
• A phase noise spectrum at the output of a circuit from post-processing. The targeted
circuits are free-running oscillators or PLLs. Forced circuits stimulated by periodic
signals can also be good candidates. In this particular application, multiple noisy runs
can be useful to average the phase noise results.
Multiple noisy runs are used to get the RMS value of the noisy signal function of time. This
functionality may be useful to characterize particle detectors, or CCD matrices for example.
About Simulating Multiple Noisy Runs
In some cases, you might want to run multiple noisy runs (by specifying the NBRUN parameter
of the .NOISETRAN command as > 1). Eldo can compute these noisy runs in different ways:
• Each individual run is performed sequentially, as independent transient simulations.
This mode is activated with the MRUN flag of the .NOISETRAN command. This mode
can also benefit from the distributed simulations with the .MPRUN command.
• Accelerated method (the default).
At each time step Eldo computes the nominal (noiseless) solution, and then computes
for each noisy run, a perturbation of the nominal run (in parallel). This is the default
method, and is used unless MRUN is set.
This method is much faster because it saves a lot of calculations. It considers that the
noise is a perturbation of the nominal transient simulation. This assumption is
sometimes not fully verified with some specific applications, when noise causes the
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Setting Up An Analysis
Transient Noise Analysis
signal to deviate from its nominal trajectory (phase shift). The consequence is that this
method can suffer from convergence problems or inaccuracy in some applications, such
as those having very non-linear circuits, where noise is not just a perturbation of the
nominal simulation. When convergence is affected a warning is reported, advising you
to use the alternative method by setting the MRUN flag. This method may not be
appropriate for PLLs or Sigma-Delta converter applications. By default, this method is
deactivated when NBRUN=1.
Related Topics
Tip
See “.NOISETRAN” in the Eldo Reference Manual.
Specifying .NOISETRAN Parameters
Transient Noise Analysis Results
Specifying .NOISETRAN Parameters
The .NOISETRAN command is used to control the transient noise analysis of a circuit and must
be used in conjunction with a transient analysis (.TRAN).
Tip
For full description of the .NOISETRAN command and its syntax, refer to “.NOISETRAN”
in the Eldo Reference Manual.
The most important parameters are:
• FMIN and FMAX define the range of the noise frequency band (same function as
FSTART and FSTOP in AC noise analysis). This frequency range may sometimes not
correspond to the noise frequency band at the output of the circuit. For instance, the
band (FMIN, FMAX) does not correspond to the output noise frequency band in the
case of filters, oscillators and mixers that exhibit frequency conversion.
• NBRUN defines the number of noise simulations to perform (those which include the
noise sources). This parameter defines the accuracy of the noise analysis. Care must be
taken when setting the NBRUN parameter as it strongly influences the CPU time used
by the simulation. This parameter is ignored when NONOM is specified to suppress the
nominal simulation; a single noisy run is performed and a warning generated.
• Other options are available for more advanced and more efficient use of the command.
Note
The .NOISETRAN command cannot be used in a netlist together with Monte Carlo
analysis (.MC), except for the specific case of a single run Monte Carlo analysis
specified with the IRUN parameter.
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Setting Up An Analysis
Transient Noise Analysis
Influence of .NOISETRAN Parameters on Simulation Performance and
Accuracy
The following guidelines describe the effect of the .NOISETRAN parameters FMIN, FMAX
and MRUN on simulation performance and accuracy, and provide guidance on how best to set
them.
• The FMAX parameter directly affects the time step size (through HMAX). Therefore,
this parameter has to be set large enough to accurately represent the noise sources but
not so large that simulation time is penalized. This parameter should correspond to the
circuit noise bandwidth. The appropriate value depends on the highest frequency in the
circuit.
• The FMIN parameter should be set to 0 (the algorithm to generate noise sources will be
faster and more accurate) unless you want to analyze the effect of the noise generated in
a specific narrow bandwidth.
• The MRUN flag should not be set except for some specific classes of circuits (PLLs,
Sigma-Delta converters) or when the simulator experiences a convergence problem and
reports that the MRUN flag should be used. With appropriate cases the .NOISETRAN
simulation runs much faster without the MRUN flag.
Related Topics
Tip
See “.NOISETRAN” and “.OPTION NOISETRAN_TUNING” in the Eldo
Reference Manual.
Generation of Time Domain Noise Sources
Speeding Up Transient Noise Analysis
Transient Noise Analysis Results
Transient Noise Analysis Algorithms
Two methods exist to generate transient noise signals, depending on the value of FMIN:
• When FMIN ≠ 0, the algorithm uses a sum of sine waves with random phases.
• When FMIN = 0, the algorithm uses gaussian random variables to generate noise
sources.
A noise source, with given frequency characteristics, will produce two different noise signals
depending on the method used to generate them. These signals will have different instantaneous
values but will have the same power and same frequency content.
During transient noise analysis, Eldo generates noise sources in the time domain for each noisy
component. These noise sources are generated as a sum of NBF sinusoids distributed between
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Setting Up An Analysis
Transient Noise Analysis
FMIN and FMAX. It means that the generated noise sources have a spectrum of discrete points
and the energy of the noise sources is localized in a limited number of frequency points. When a
frequency band is wide the corresponding generated noise source may have a poor frequency
resolution.
Consequently, an alternative algorithm was developed to generate the noise sources, leading to
a continuous spectrum in the frequency band zero to FMAX. This algorithm is approximately
twice as fast and with more accurate results. However, it cannot generate a noise source with a
frequency band beginning at a value of FMIN other than zero. This algorithm is automatically
activated by specifying FMIN as zero. When FMIN is not zero, the method using sinusoids is
then used. Both methods can work together, one for some components, the other method for
different noisy devices.
The alternative method (when FMIN=0) is used to generate flicker noise and white noise
sources (thermal and shot noise). It is not possible to have a flicker noise source with a
frequency band starting from zero, therefore the generated flicker noise source will have a white
spectrum from zero to f1 and a flicker noise spectrum from f1 to FMAX. The frequency f1 is
calculated from the transient simulation duration: f1=1/TSTOP.
Related Commands
• .NOISETRAN command in Eldo Reference Manual
• .TRAN command in Eldo Reference Manual
Related Topics
Generation of Time Domain Noise Sources
Generation of Time Domain Noise Sources
During noisy runs, each noise source is represented by a current or a voltage source. This source
is pseudo-random and its characteristic is computed from the PSD model of the noise source. As
the noise PSD models might depend on the device bias, and as the device bias is time varying
during a transient simulation, the characteristics of the sources are updated function of the
instantaneous device bias.
A time domain noise source n(t) is generated with the following form:
n(t) = m(t) . r(t)
Where m(t) is a deterministic modulation part, calculated from the instantaneous bias conditions
of the corresponding noisy device, and r(t) is a stationary random part that also contains the
frequency dependence of the noise source.
There exists two different ways to generate noise sources inside Eldo. The choice of the method
is triggered by the FMIN parameter of the .NOISETRAN command.
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Setting Up An Analysis
Transient Noise Analysis
• When FMIN=0:
Noise sources are generated from random pulses.
See “Noise Sources Generated From Random Pulses” on page 247.
• When FMIN≠0:
Noise sources are generated from a sum of sinusoids.
See “Noise Sources Generated From a Sum of Sinusoids” on page 253.
Noise sources from random pulses have a continuous spectrum, whereas noise sources from
sinusoids have a discrete spectrum. Noise sources from random pulses are much faster to
generate than noise sources from sinusoids.
It is recommended to use noise sources from random pulses rather than from sinusoids
(FMIN=0). But in some cases, noise sources from sinusoids are useful, for example, when
specifying noise in a specific narrow noise bandwidth.
Noise Sources Generated From Random Pulses
When FMIN=0, for white noise sources, r(t) is generated using random pulse with a specific
width. The pulse magnitudes correspond to a random variable, with a Gaussian distribution and
a variance equal to 1. The pulse width is computed from the .NOISETRAN command parameter
FMAX (Tp=0.5/FMAX).
The m(t) part of the noise source is computed from the PSD of the noise model:
m(t)=sqrt(PSD(t) × FMAX)
As PSD is bias dependent, m(t) is instantaneously updated function of bias changes.
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Setting Up An Analysis
Transient Noise Analysis
Figure 6-5. White Noise Signal From Random Pulses
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Setting Up An Analysis
Transient Noise Analysis
Figure 6-6. Random Pulses (Zoom)
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Setting Up An Analysis
Transient Noise Analysis
Figure 6-7. PSD of a White Noise Signal Generated with Random Pulses
Figure 6-7 shows that the Power Spectral Density of a noise source generated with random
pulses has an almost white spectrum (So) located between 0 and FMAX. In fact, it has a sinc
shape: So.sinc 2 (2 × FMAX).
The same kind of method is used to generate colored noise sources. A colored noise source is
obtained from a sum of “sinc-shape” sources. For instance a flicker noise source is a sum of
sinc-shape sources whose amplitudes and cut-off frequencies are determined such that the PSD
of the resulting source fits between FMIN_FLICKER and FMAX with the theoretical PSD, as
shown in Figure 6-8, Figure 6-9 and Figure 6-10.
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Setting Up An Analysis
Transient Noise Analysis
Figure 6-8. Flicker Noise Signal From a Sum of Random Pulses
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Setting Up An Analysis
Transient Noise Analysis
Figure 6-9. Flicker Noise Signal From a Sum of Random Pulses (Zoom)
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Figure 6-10. PSD of a Flicker Noise Signal
Setting Up An Analysis
Transient Noise Analysis
In the Power Spectral Density shown in Figure 6-10, FMIN_FLICKER is set to 1MHz and
FMAX to 100MHz. The signal has a white spectrum for frequencies below 1MHz, then a 1/f
shape (inversely proportional to the frequency) between 1MHz and 100MHz and then a sinc
shape.
Noise Sources Generated From a Sum of Sinusoids
When FMIN≠0, the r(t) part of the source is generated from a sum of sinusoids with random
phases. All the sinusoids have the same amplitude, and the frequencies are determined to
provide the source with the correct color (frequency dependency). The frequency distribution
can be seen on PSD plots.
For instance, white noise sources are obtained with evenly distributed frequencies between
FMIN and FMAX, as shown in Figure 6-13. Flicker noise sources are generated from a
logarithmic frequency distribution as shown in Figure 6-16.
The m(t) part of the noise source is computed from the PSD of the noise model. As PSD is bias
dependent, m(t) is instantaneously updated function of bias changes.
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Setting Up An Analysis
Transient Noise Analysis
Figure 6-11. White Noise Signal From a Sum of Sinusoids
Figure 6-12. White Noise Signal From a Sum of Sinusoids (Zoom)
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Transient Noise Analysis
Figure 6-13. PSD of a White Noise Signal Generated From Sinusoids
Eldo® User's Manual, 15.3 255

Setting Up An Analysis
Transient Noise Analysis
Figure 6-14. Flicker Noise Signal From a Sum of Sinusoids
Figure 6-15. Flicker Noise Signal From a Sum of Sinusoids (Zoom)
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Setting Up An Analysis
Transient Noise Analysis
Figure 6-16. PSD of a Flicker Noise Signal Generated From Sinusoids
Noise sources from random pulses have a continuous spectrum, whereas noise sources from
sinusoids have a discrete spectrum. Noise sources from random pulses are much faster to
generate than noise sources from sinusoids.
Related Topics
Transient Noise Analysis Principles
Speeding Up Transient Noise Analysis
Speeding Up Transient Noise Analysis
To reduce the CPU time, parallel noise runs are performed during a single transient analysis to
compute the RMS noise results, instead of several runs. This enables larger circuits to be
handled, a larger number of runs, and the ability to analyze a circuit with a CPU time close to a
normal (noiseless) transient analysis.
Eldo will use the multiple-run MRUN algorithm (perform several runs sequentially) by forcing
the MRUN parameter instead of the default single run algorithm if at least one of the conditions
below is met:
Eldo® User's Manual, 15.3 257

Setting Up An Analysis
Transient Noise Analysis
• .PART being used (for ADiT, and so on)
• .CHRSIM present
• Presence of DELAY operators, T elements, FNS elements
• Use of local truncation error algorithm (QTRUNC option active)
• Mixed-mode simulation (presence of .A2D/.D2A commands)
• Use of Verilog-A
The multiple-run MRUN scheme can also benefit from multi-processor machines to speed-up
simulations in the following ways:
• .NOISETRAN MRUN simulations can be distributed by the .MPRUN command
• .NOISETRAN can be accelerated by specifying multi-threading with eldo –use_proc N
As with many simulations, there is a compromise between accuracy and speed. The main
transient noise parameters controlling this are as follows:
• FMIN—setting to 0 uses a faster, more accurate algorithm.
• FMAX—main factor to increase accuracy, even much higher than circuit cutoff
frequency HMAX forced to 1/(2 × FMAX), thus CPU ~ FMAX. It is better to explicitly
set a lower value for HMAX than a high value for FMAX to achieve the best accuracy
possible.
• NBRUN—CPU time and accuracy increase with NBRUN.
• MRUN—single run algorithm is faster than multiple-run.
Transient noise analysis requires more accuracy by default, therefore the simulator accuracy
values (EPS, VNTOL, RELTOL) are overridden, see “Simulator Accuracy Considerations with
Transient Noise” on page 258.
Simulator Accuracy Considerations with Transient Noise
The default values of EPS, VNTOL, RELTOL, and HMAX are changed in transient noise
analysis from the values used in other analyses. For .NOISETRAN, the defaults are:
• EPS=1.0×10 −6
• VNTOL=1.0×10 −6
• RELTOL=1.0×10 −6
By default, Eldo is able to compute noise voltages down to approximately 1µV. As most of the
applications create higher levels of noise, this should be sufficient in most cases. In all other
cases, it is advisable to increase the simulator accuracy.
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Transient Noise Analysis
For .NOISETRAN, the default HMAX value is HMAX=1/(2×FMAX). It is better to explicitly
set a lower value for HMAX than a high value for FMAX to achieve the best accuracy possible.
Related Commands
• .NOISETRAN command in Eldo Reference Manual
• .OPTION NOISETRAN_TUNING in Eldo Reference Manual
Related Topics
Specifying .NOISETRAN Parameters
Transient Noise Analysis Results
Transient Noise Analysis Results
The results of transient noise analysis runs are output using .EXTRACT, .PLOT, .PRINT, and
.PROBE commands. Eldo prints in ASCII form the individual contributions of the noisy devices
in the .chi file.
If extracts have been specified, the results are provided inside the NOISETRAN EXTRACT
INFORMATION section of the .chi file.
Figure 6-14 shows example transient noise analysis results with and without noise:
Figure 6-17. Transient Noise Analysis Plot
Eldo® User's Manual, 15.3 259

Setting Up An Analysis
Transient Noise Analysis
When a .NOISETRAN simulation is requested with multiple run MRUN specified, transient
analysis extracts (or extracts without any analysis type) will by default return only nominal
values in the .chi file. Specify option DEFRMSNTR to dump both RMS values (computed by
the transient noise analysis) and nominal values (computed by the nominal transient analysis).
Use the analysis type NTR on the .EXTRACT command to select computation based on RMS.
If a single-run .NOISETRAN is performed, then the .EXTRACT command without any
analysis will be interpreted only for the transient run, not for the transient noise analysis.
Specify option DEFRMSNTR to report the nominal and the transient noise analysis (on RMS
waves). Use the keyword NTR on the extract to obtain the RMS extract value.
Spikes may appear in noisy runs of .NOISETRAN with the single-run algorithm. This is
because the circuit (a latch for example) has a very non-linear behavior with respect to noise.
Tip
See “.NOISETRAN” in the Eldo Reference Manual.
Related Topics
Transient Noise Analysis
Example: Extraction of the Phase Noise Spectrum at the
Output of a PLL Circuit
This example illustrates the use of a transient noise analysis to compute the phase noise
spectrum at the output of a PLL circuit.
The transient noise analysis is set in a single noisy run configuration without the nominal
(noiseless) simulation.
1. The following commands instruct the simulator to run a transient analysis up to the
steady-state and save the results:
.tran 0 5u
.save pll.sav end
.plot tran V(CP_VCNT)
.optwind vntol=(2.9u, 5u, 1e-6)
.optwind reltol=(2.9u, 5u, 1e-6)
The following actions are performed:
o
o
o
Run the transient simulation up to 5μs.
Save the state of the circuit at the end of the simulation, to the file pll.sav.
Plot the control node of the VCO. This is used to verify that the PLL is in the steadystate.
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o
Setting Up An Analysis
Transient Noise Analysis
Run the simulation with the default accuracy up to 2.9μ, then tighten the tolerance
(VNTOL and RELTOL set to 1e-6).
The plot of the VCO control node is shown in Figure 6-18 (blue curve). It shows the
steady-state being reached at about 4μs.
Figure 6-18. VCO Control Node - Steady State Reached
2. The following commands restart a transient noise analysis from the previously saved
steady-state, and plot the output of the PLL circuit.
.tran 0 100u
.noisetran fmin=0 fmax=2GigaHz tstart=6u nbrun=1 mrun nonom
.plot tran V(CP_VCNT)
.plot tran V(VCO_OUT)
.restart pll.sav
The following actions are performed:
o
o
o
Run a transient noise analysis on the PLL circuit up to 100μs, starting from the
steady-state store in the pll.sav file at 6μs. Noise sources are specified between 0 and
2GHz.
One noisy run is performed, without nominal simulation, in an MRUN
configuration.
Two simulation plots are requested: The VCO control node and the PLL output
node.
Eldo® User's Manual, 15.3 261

Setting Up An Analysis
Transient Noise Analysis
The plot of the VCO control node is shown in Figure 6-18 and Figure 6-19 (green
curves). The plot of the PLL output will be used to compute the phase noise spectrum.
Figure 6-19. VCO Control Node - Restarted Transient Noise Analysis
3. The Waveform Calculator in EZwave is used to compute the Phase Noise spectrum
from the transient noise analysis results. The post-processing function
noisetrantophasenoise() (located in the RF functions menu) is applied on the VCO
output waveform V(VCO_OUT) between 6μs and 100μs.
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Setting Up An Analysis
Transient Noise Analysis
Figure 6-20. EZwave Waveform Calculator - Phase Noise Computation
4. The phase noise results obtained from transient noise analysis are compared to those
obtained from partitioned steady-state noise analysis (use of .RFBLOCK, .SST PLL and
.SSTNOISE commands). Figure 6-21 shows that both results match well. Phase noise
results are plotted in green for transient noise analysis, and yellow for steady-state noise
analysis.
Eldo® User's Manual, 15.3 263

Setting Up An Analysis
Transient Noise Analysis
Figure 6-21. Phase Noise Plots Comparison
Summary
The upper frequency of the phase noise spectrum is Fout/2 (where Fout is the frequency of the
PLL output). The lower frequency is defined by the length of the transient noise analysis.
Therefore, increasing frequency resolution has a direct impact on simulation time.
In this example, this functionality is illustrated with an integer rank PLL but it can be used
exactly in the same way with a fractional PLL. The same methodology can be applied to get the
phase noise spectrum for other kind of circuits, for instance free running oscillators, frequency
dividers, clock trees.
Related Commands
• .NOISETRAN in the Eldo Reference Manual
• .SSTNOISE in the Eldo RF User’s Manual
• .SST PLL in the Eldo RF User’s Manual.
Related Topics
Transient Noise Analysis
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Setting Up An Analysis
Statistical and Sensitivity Related Analyses
Statistical and Sensitivity Related Analyses
The statistical and sensitivity related analyses are listed here.
Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Worst Case Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
DC Mismatch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
DC Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Transient Sensitivity Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
AC Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Sensitivity Analysis of Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Design of Experiments Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
Monte Carlo Analysis
Monte Carlo analysis (.MC command) determines the uncertainty in estimates for dependent
variables of interest. It focuses on data and how uncertainty in data propagates through
computations.
Eldo reads a netlist describing the circuit and translates it into mathematical equations. The
inputs are the various design parameters, the process parameters, and the environmental
conditions. The output space is characterized by the circuit performance of interest.
Monte Carlo-based uncertainty analysis is performed on multiple model evaluations with
randomly selected model input variables. The results of these evaluations (experiments) are
then used to determine the uncertainty in model predictions, and the input variables that gave
rise to this uncertainty.
In statistical models for transistor level simulation, there are two types of variability in device
properties:
• Inter-die (between chips) variations or global variations (LOT keyword).
Typical examples of statistical parameters with global tolerances are oxide thickness or
channel length reduction.
• Intra-die (within chip) variations are local variations that affect transistors individually
(DEV keyword).
A typical example of statistical parameters with local tolerances are the transistor
threshold voltages.
The overall Monte Carlo analysis run is made of several chunks of simulations. Using an
incremental approach provides an insight into the spread of distribution. You can also
extrapolate to obtain the general shape of the distribution. In Eldo, you control the sample size
Eldo® User's Manual, 15.3 265

Setting Up An Analysis
Monte Carlo Analysis
and optionally, how the sampling is generated. The SAVE/RESTART arguments are used to
save the random sampling and the simulated characteristics. These quantities can be used in
subsequent Monte Carlo experiments.
You can monitor the evolution of certain quantities. Eldo will flush out from the .wdb file the
average and standard deviation of extracts and measurements versus the Monte Carlo run index
to see how these entities evolve.
To control the run-length in the context of sequential Monte Carlo algorithms, use the
MCCONV extract function. In contrast to fixed run-length approaches, samples are generated
until some error criterion is satisfied.
Two algorithms are provided to control the convergence. It is possible to monitor the evolution
of the various moments to precisely quantify the notion of convergence. The Monte Carlo
process can be stopped early using .MC AUTOSTOP if these quantities do not vary more than a
user-specified limit.
Monte Carlo Analysis Results
The results of Monte Carlo analysis runs are output using the .EXTRACT, .PRINT and .PLOT
commands and provided in two ways:
• ASCII Output (.chi)
Examples of quantitative procedures are confidence intervals or bootstrap estimates for
the mean value. These analyses are provided within the .chi file. Eldo prints the
following basic statistics: the range, the mean (average), and the standard deviation.
Two standard deviation results are provided:
o
o
Standard Deviation
The RMS value of the deviation of output with respect to the average value.
Standard Deviation based on nominal run
The RMS value of the deviation of output with respect to the nominal run.
• Graphical Output
Eldo provides some tools such as scatter plots, histograms, or probability distribution
functions (PDF) which can be viewed using EZwave.
By default, without the ALL argument, only the nominal, minimum, and maximum results of
Monte Carlo simulations are saved. This includes both ASCII (.chi) and binary wave (.wdb)
results. When ALL is specified, the waveform results of every Monte Carlo simulation run are
stored in the output files.
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Setting Up An Analysis
Worst Case Analysis
The minimum and maximum waveforms correspond to the waveform envelope across all
Monte Carlo runs, not to a specific run. The minimum waveform is annotated _L in EZwave,
and the maximum waveform is annotated _H. For example:
.MC 10
.plot ac vdb(out)
This generates three waveforms:
• VDB(OUT): nominal run
• VDB(OUT)_L: minimum of v(out) across all 11 Monte Carlo runs (including nominal)
• VDB(OUT)_H: maximum of v(out) across all 11 Monte Carlo runs (including nominal)
See Also
• .MC in the Eldo Reference Manual
• Eldo Monte Carlo Quick Start
Related Topics
Monte Carlo Analysis
Worst Case Analysis
Worst Case analysis (.WCASE command) is a corner analysis that computes worst-case values
for waveform data extracted using the .EXTRACT command according to a set of Monte Carlo
parameters that have LOT and DEV variations.
Considering a design which contains P parameters that have a statistical variation, and T targets
(.EXTRACT commands), Eldo will perform several simulations:
1. The first simulation is the nominal simulation, using nominal values for the P
parameters.
2. Next P simulations are sensitivity analysis runs, where Eldo applies a small variation to
one of the P parameters, keeping all other parameters to their nominal value, and
computes the sensitivity of the T targets relative to the current parameter.
For each of the T targets, Eldo outputs a message like:
With respect to MODEL R LOT
Variation of MAX(V(1)) is negative: -1.000000e-02 (Unit/%) or
1.000000e+00 (%/%)
Negative variation means that when parameter is increased, target is decreasing.
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Setting Up An Analysis
Worst Case Analysis
3. With all the sensitivity data, Eldo computes the combination of min or max parameter
values that will generate the best and worst cases (MIN and MAX) for each of the T
targets.
There can be at most 2×T worst case simulations. During these simulations, Eldo does
not output anything.
4. Finally, Eldo computes the worst case information for all the targets, and outputs this
information.
Thus, there can be at most 1 + P + 2×T simulations. Worst Case analysis assumes the
influence of each parameter to be linear, and not correlated with other parameters.
Sorting parameters can be specified to quickly identify the most sensitive parameters.
Tip
See “.WCASE” in the Eldo Reference Manual.
Worst Case Analysis Results
The results of worst case analysis runs are output using .EXTRACT, .PLOT, .PRINT, and
.PROBE commands.
If extracts have been specified, the results are provided inside the WORST CASE
SENSITIVITY and WORST CASE INFORMATION sections of the .chi file, for example:
0**** WORST CASE SENSITIVITY TEMPERATURE = 27.000 DEG C
0************************************************************************
With respect to MODEL RMOD DEV: Object :R1
Variation of XYCOND(XAXIS,VDB(OUT)

Setting Up An Analysis
DC Mismatch
Related Topics
Monte Carlo Analysis
DC Mismatch
DC Sensitivity Analysis
AC Sensitivity Analysis
DC Mismatch
The .DCMISMATCH command runs a special form of sensitivity analysis based on statistical
deviation properties of device model parameters. It computes the sensitivity of node voltages
and of currents through voltage sources. All devices using a device model with statistical
deviations potentially contribute to the output deviation. The aim of the DC mismatch analysis
is to quantify these contributions and to identify the biggest contributors to the total output
deviation. It has some degree of similarity with the worst-case analysis (.WCASE). However, it
will usually provide (much) less pessimistic results than worst-case analysis.
Mismatch models try to model the inherent differences which exist between two identically
drawn transistors. Each transistor behavior departs (statistically) from the nominal behavior.
The deviation depends strongly on the geometry (W, L) of the transistor. Small transistors tend
to be more random than large ones.
DC mismatch considers the DEV or DEVX variations specified for device model parameters (in
.MODEL statements) and for global parameters in the .cir file (.PARAM statements specified at
the top-level, outside any subcircuit definition). Mismatch effects are ignored if DEV
specifications are associated to capacitance values (device or model parameters). The LOT
specifications are not taken into account.
Deviation is applied independently to the sensitive devices, and the resulting deviation of the
output is computed from the RMS sum of the resulting deviations.
Sorting parameters can be specified to quickly identify the most sensitive parameters.
Tip
See “.DCMISMATCH” in the Eldo Reference Manual.
DC Mismatch Results
Results of a DC mismatch analysis are provided inside the DC MISMATCH results section of
the .chi file.
Below is a typical DC mismatch analysis output showing N-sigma deviation of the outputs, and
a table of sorted contributors.
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Setting Up An Analysis
DC Sensitivity Analysis
In the report table, the first column is listed in descending order to easily identify the main
contributors. The second column is not listed in order; you need to manually examine the results
to identify the parameter which has the major effect.
In this example, XM2.M1 is the main contributor, and the deviation of the VTH0 mobility
parameter of its associated model—XM2.MOD2—is the main contributor to the XM2.M1
contribution.
0**** DC MISMATCH results TEMPERATURE = 27.000 DEG C
0************************************************************************
#.DCMISMATCH V(S) SORT_REL = 1.000000e-03 NSIGMA = 1.000000e+00
Analysis results:
Output DC value : 1.7892U Volt
Total output deviation : +/- 14.9166M Volt
Output deviation due to the
contributors in the report table : +/- 14.9166M Volt
Report table
----------------------------------------
Output deviation Contributor Parameter
7.9308M XM2.M1
5.1779M M(XM2.MOD2,U0)
6.0051M M(XM2.MOD2,VTH0)
163.0689U M(XM2.MOD2,TOX)
7.9294M XM1.M1
5.1769M M(XM1.MOD2,U0)
6.0040M M(XM1.MOD2,VTH0)
163.0386U M(XM1.MOD2,TOX)
6.1906M XM7.M1
2.5507M M(XM7.MOD1,U0)
5.6326M M(XM7.MOD1,VTH0)
302.4733U M(XM7.MOD1,TOX)
6.1906M XM6.M1
2.5507M M(XM6.MOD1,U0)
5.6326M M(XM6.MOD1,VTH0)
302.4703U M(XM6.MOD1,TOX)
...
Related Topics
Statistical and Sensitivity Related Analyses
DC Sensitivity Analysis
The .SENS [DC] command runs a DC sensitivity analysis. By linearizing the circuit around a
bias point, the sensitivities of each of the output variables in relation to all the device values and
the model parameters are calculated and output.
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Setting Up An Analysis
DC Sensitivity Analysis
Tip
See “.SENS” in the Eldo Reference Manual.
DC Sensitivity Analysis Results
Results of a DC sensitivity analysis are provided inside the DC SENSITIVITY ANALYSIS
section of the .chi file, for example:
0**** DC SENSITIVITY ANALYSIS TEMPERATURE = 27.000 DEG C
0************************************************************************
DC SENSITIVITIES OF OUTPUT V(OUT)
ELEMENT ELEMENT ELEMENT NORMALIZED
NAME VALUE SENSITIVITY SENSITIVITY
(VOLTS/UNIT) (VOLTS/PERCENT)
XM16.M1
XM17.M1
XM15.M1
XM13.M1
XM14.M1
XM12.M1
XM3.M1
...
VDD 1.650E+000 -3.50E-003 -5.78E-005
VSS -1.65E+000 -2.51E-004 4.145E-006
VINP -9.00E-001 1.000E+000 -9.00E-003
VB 9.500E-001 3.478E-003 3.304E-005
W 4.556E-006 -1.38E+002 -6.27E-006
L 1.075E-006 7.985E+002 8.588E-006
W 2.984E-006 1.941E+002 5.790E-006
L 9.934E-007 -7.57E+002 -7.52E-006
W 2.984E-006 -8.60E+001 -2.56E-006
L 9.934E-007 3.500E+002 3.477E-006
W 2.984E-006 -8.56E+002 -2.55E-005
L 9.934E-007 3.526E+003 3.502E-005
W 7.560E-007 3.625E+002 2.741E-006
L 1.075E-006 -2.64E+002 -2.84E-006
W 4.556E-006 6.052E+002 2.757E-005
L 1.075E-006 -2.80E+003 -3.01E-005
W 4.556E-006 -6.87E+004 -3.13E-003
L 1.075E-006 3.043E+005 3.272E-003
Related Topics
Statistical and Sensitivity Related Analyses
Transient Sensitivity Analysis
AC Sensitivity Analysis
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Setting Up An Analysis
Transient Sensitivity Analysis
Transient Sensitivity Analysis
The .SENS TRAN command runs a transient sensitivity analysis to estimate the relative impact
of design, process parameters or operating point conditions upon selected circuit responses.
Tip
See “.SENS TRAN” in the Eldo Reference Manual.
Transient Sensitivity Analysis Results
Results of a transient sensitivity analysis are provided inside the TRANSIENT SENSITIVITY
ANALYSIS section of the .chi file, for example:
0**** TRANSIENT SENSITIVITY ANALYSIS TEMPERATURE = 27.000 DEG C
0************************************************************************
TRANSIENT SENSITIVITIES OF OUTPUT V(2) AT TIME
5 s
ELEMENT ELEMENT ELEMENT NORMALIZED
NAME VALUE SENSITIVITY SENSITIVITY
(AMPS/UNIT) (AMPS/PERCENT)
0.000E+00 -6.61E-01 -0.000E+00
C1 1.000E+00 -6.61E-01 -6.61E-03
Related Topics
Statistical and Sensitivity Related Analyses
DC Sensitivity Analysis
AC Sensitivity Analysis
AC Sensitivity Analysis
The .SENS AC command runs an AC sensitivity analysis. By linearizing the circuit around a
bias point, the sensitivities of each of the output variables in relation to R, L, C devices present
in the design are calculated and output.
Tip
See “.SENS AC” in the Eldo Reference Manual.
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AC Sensitivity Analysis Results
Setting Up An Analysis
Sensitivity Analysis of Parameters
Results of an AC sensitivity analysis are provided inside the AC SENSITIVITY ANALYSIS
section of the .chi file, for example:
0**** AC SENSITIVITY ANALYSIS TEMPERATURE = 27.000 DEG C
0************************************************************************
.SENSAC V(OUT) SORT_REL = 1.000000e-003
Analysis results at 1.0000E+004 Hertz:
ELEMENT ELEMENT ELEMENT NORMALIZED
NAME VALUE SENSITIVITY SENSITIVITY
(VOLTS/UNIT) (VOLTS/PERCENT)
C on OUT 1.000E-012 2.998E+005 2.998E-009
CX 2.000E-007 -4.43E-001 -8.86E-010
Related Topics
Statistical and Sensitivity Related Analyses
DC Sensitivity Analysis
Transient Sensitivity Analysis
Sensitivity Analysis of Parameters
Designers need sensitivity information for design parameters (parameters they can act upon).
The .SENSPARAM command computes the sensitivity of voltages/currents and extracts to
these design parameters.
The first simulation is the nominal simulation, using nominal values for the parameters. The
following simulations are sensitivity analysis runs where Eldo applies a small variation to one
of the P parameters, keeping all others to their nominal value, and computes the sensitivity of
the targets relative to the current parameter. Therefore there are 1 + P simulations. The
sensitivity results represent the variation of the extracted value for a variation of 1% of the
parameter value.
Tip
See “.SENSPARAM” in the Eldo Reference Manual.
Sensitivity Analysis of Parameters Results
Results of a sensitivity analysis of parameters are provided inside the SENSPARAM
INFORMATION section of the .chi file, for example:
Eldo® User's Manual, 15.3 273

Setting Up An Analysis
Design of Experiments Analysis
0**** SENSPARAM INFORMATION TEMPERATURE = 27.000 DEG C
0************************************************************************
YVAL(I(R2),5N) NOM: 5.2297E-05
*| Absolute Relative Parameter Parameter Parameter
*| Sensitivity Sensitivity (%/%) Nominal Value Variation Name
*| -9.4162E-07 -1.0803E-01 6.00000e+00 3.000e+00% X2.C
*| -1.2688E-06 -7.2781E-02 3.00000e+00 1.000e-01% X2.D
*| -3.3851E-06 -6.4729E-02 1.00000e+00 1.000e-01% X3.X1.D
*| -3.3851E-06 -6.4729E-02 1.00000e+00 1.000e-01% X3.X2.D
*| -3.5221E-07 -4.0408E-02 6.00000e+00 1.000e-01% X1.D
Related Topics
Statistical and Sensitivity Related Analyses
Design of Experiments Analysis
Design of Experiments is concerned with the standard techniques of factor screening, location
and dispersion analysis, and response surface methodologies in circuit design. In this context, a
general situation is considered where an observable output (extracted measure in Eldo) depends
on a set of parameters and the effects (main effects and interactions) of parameters (factors) on
the output are explored using the techniques of Design of Experiments.
Eldo contains the basic tools to perform a factor screening experiment with the .DEX command.
Because the main issue in studying statistical design problems lies in a large number of circuit
parameters involved, the primary purpose of a variable screening experiment is to select or
screen out the few important main effects from the many less important ones. Once a small
number of important factors is identified, subsequent statistical design problems can be solved
more efficiently and require fewer runs.
In this context, a factor is a circuit parameter that is studied in the experiment. To study the
effect of a factor on one or several user-defined responses, two or more values of the factor are
used. These values are referred to as levels or settings. A combination of factor levels is called a
run and will be associated to a specific simulation run in Eldo.
In an experiment, one or more variables (or factors) are deliberately changed to observe the
effect the changes have on one or more response variables. The DEX techniques are efficient
procedures so that the data obtained can be analyzed to yield valid and objective conclusions.
This efficiency is founded on some key properties of orthogonal arrays, which offer a
systematic way of testing. The benefits include: a uniform distributed coverage of the test
domain, all pair-wise combinations of test set created, and arrive at complex combinations of all
the variables.
Tip
See “.DEX” in the Eldo Reference Manual.
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Design of Experiments Analysis
A screening experiment will be conducted on the performance response. The factors will be
taken from the list of circuit parameters specified by a .PARAMDEX statement. The results of
this experiment are generated in the .dex file. This output file contains an ordered data table for
each simulated response, a DEX mean table which provides the ranked list of factors (not
including the interactions), the ranking is from the most important factor to least important
factor, and a formal test of significance.
The .dex file is a structured text file that is organized with sections and subsections, and enables
you to skip one or more sections at different levels of detail. Run the utility named viewdex on
the .dex file to display the results.
Related Topics
Statistical Experimental Design and Analysis
Statistical and Sensitivity Related Analyses
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Other Miscellaneous Analyses
Other Miscellaneous Analyses
Other miscellaneous analyses are:
Optimization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
Aging and Reliability Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
Check Safe Operating Area Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
High Impedance Node Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Power Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
Viewing Power Analysis Results Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Electrothermal Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
Optimization
The Eldo optimizer is a general-purpose electrical circuit optimization program. The term Eldo
optimizer refers to the complete set of optimization tools available through the .OPTIMIZE
command. The optimizer will calculate the value of parameters (the optimization variables) in
the circuit such that the behavior or the characteristics of the circuit conform as close as possible
to the specifications. The optimizer can achieve a simultaneous improvement in AC, DC,
Transient domain, Steady-State and Modulated Steady-State analyses.
The designer specifies the design objectives and the optimizer will adjust the component
parameters of the circuit (such as resistor or capacitor values, the b value of a transistor, widths
and lengths of a MOSFET) to meet a specified electrical performance. Optimization can be
applied to:
• Circuit parameters.
• Model parameters.
• Element parameters.
• Device lengths, widths, areas, and peripheries.
The parameter values must conform to the manufacturing limits, process limits, or discrete
device values. To achieve this, restrictions can be specified on the design parameters. Various
constraints (or inter-relations) can be specified, for example, circuit parameters must be
non-negative, or must not violate upper boundaries. In addition, more complicated constraints
can be specified, for example, how components physically interact with each other to produce
non-linear relations.
The process of identifying the objective, variables, and constraints for a specific problem is
known as modeling. The construction of an appropriate model is the first step (sometimes the
most important) in the optimization process. If the model is too simplistic, it will not generate
useful insights into the practical problems. If too complex, it may become difficult to solve.
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Thus, the designer’s task is to discover what is the most appropriate model for their
requirements.
An objective is anything that can be extracted or measured from the output waveform. Regular
.EXTRACT statements can be specified with additional optimization parameters, or the
.OBJECTIVE command—specifically dedicated to optimization—can be used for more
complex objectives.
Tip
See “.OPTIMIZE” in the Eldo Reference Manual.
Optimization Results
The results of optimization must be analyzed to verify whether the optimization has succeeded
in its task of finding a solution. The results of optimization are output using the .EXTRACT and
.PLOT commands and provided in two ways:
• ASCII Output
o
o
The Eldo standard output (.chi) file provides simplified information about the
optimization process.
The results of optimization are generated in a .otm file. This is a structured text file
separated into three major sections: initialization (scaling of variables and
objectives), optimization phase, and the results of the process (final variables and
objectives). Run the utility named viewotm on the .otm file to display the results.
• Graphical Output
Extracted waveforms generated during an optimization process can be viewed using
EZwave. These are implicitly declared waves which have the same name as the extract
label they refer to.
Related Topics
Optimization
Aging and Reliability Analysis
Reliability models are implemented in the Eldo UDRM (User Defined Reliability Model)
interface.
The objective of aging and reliability simulation is to be able to model the gradual damage,
which occurs to the devices in a certain design causing degradation in the performance of that
design. It is required to evaluate the amount of degradation occurring in a certain period of
operation and examine the circuit performance after this period. The modeled damage could
follow one or more of several damage mechanisms, which show gradual degradation in device
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performance. Other mechanisms, which cause sudden and complete damage of the device, (like
the oxide breakdown for example) are not targeted in this scope.
Reliability changes can be analyzed for the following degradation effects:
• Hot-Carrier Injection (HCI).
• Negative Bias Temperature Instability (NBTI) degradation.
• Other stress effects can be modeled.
Aging and reliability analysis enables a comparison of the fresh and degraded (aged) waveforms
to see how much impact the degradation has on circuit performance. It is then possible to
determine which device parameter is primarily responsible for degradation and identify the
most sensitive part of the circuit.
Tip
You can view reliability analysis results with the AMS Results Browser.
See Also
• Eldo UDRM User’s Manual
• .AGE in the Eldo UDRM Manual
Check Safe Operating Area Analysis
The .CHECKSOA command checks for any violations of the circuit safe operating area (SOA)
limits. The safe operating area limits are set for device parameters, model parameters, and Eldo
expressions using the .SETSOA command.
Tip
You can view safe operating area violations with the AMS Results Browser.
Related Commands
• .CHECKSOA in the Eldo Reference Manual
• .SETSOA in the Eldo Reference Manual
Related Topics
Safe Operating Area (SOA) Checks
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Setting Up An Analysis
High Impedance Node Check
The .HIZ/.DCHIZ commands or option ADIT_CHECK checks for circuit nodes in high
impedance state (Hi-Z nodes). Eldo detects circuit Hi-Z states by checking the dynamic
behavior of all nodes. This detection method works on any circuit topology and applies to all
device types.
Specify the node impedance quantity, IMP(), inside SOA, .EXTRACT/.MEAS, or
.PLOT/.PRINT/.PROBE commands. The IMP quantity cannot be used to define the value of a
component (R1 … value = IMP(Z) is not allowed). Specifying this quantity might have an
impact on simulation time if lots of impedances are requested.
Tip
You can view high impedance detections with the AMS Results Browser.
See Also
• .DCHIZ in the Eldo Reference Manual
• .HIZ in the Eldo Reference Manual
• .OPTION ADIT_CHECK in the Eldo Reference Manual
Related Topics
High Impedance Node Checks
Tutorial—High Impedance Fault Detection of a PLL Circuit
Power Analysis
The .POWER_ANALYSIS command enables you to analyze power consumption of a circuit
and its components over time. You can optionally define a time range and thresholds to narrow
down problematic subcircuits or devices. The results are displayed in the EZwave Power
Analysis dialog box. For further post-processing, use the EZwave interface and TCL commands
to perform, for example, a batch analysis on multiple simulations or time range.
The power analysis is fully hierarchical, which means that you can display all the circuit
components, showing the hierarchy, and filter accordingly down through the hierarchy.
The main purpose of this analysis is to help designers understand where and when the power is
dissipated inside a large circuit, or which part of a circuit is consuming more than a specified
threshold, or which subcircuits are consuming what power. You can analyze the power without
having to resimulate, everything is manipulated in the Power Analysis dialog box and you
perform your debugging tasks accordingly there.
This analysis provides an effective way to report power and current consumption. For designs
operating on battery supplies, power consumption and leakage issues are important. Advanced
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Viewing Power Analysis Results Example
process nodes tend to make these problems worse. The power supply voltages tend to decrease,
and the leakage currents tend to increase exponentially at each new node. This means the
monitoring of current variables (that relate directly to power) is as important, if not more, than
the monitoring of voltages. Entire circuits are dedicated to the sole function of power
management, which means managing the complex sequences of powering up and powering
down multi-chip systems, or SOCs, that operate with 10 or 20 different power supply levels (to
save every microWatt possible).
Tip
See “.POWER_ANALYSIS” in the Eldo Reference Manual and “Analyzing Power
Consumption” in the EZwave User’s and Reference Manual.
Viewing Power Analysis Results Example
This example shows the power analysis of a simple circuit.
Prerequisites
• A netlist with a .POWER_ANALYSIS command specified, for example:
*Power Analysis example
.subckt bottom bottom_in
Rbottom1 bottom_in 0 100
Rbottom2 bottom_in 0 100
.ends bottom
.subckt top top_in
Xbottom top_in bottom
Xmiddle top_in bottom
Rmiddle top_in 0 100
.ends top
Vdd in 0 pwl ( 0 0 1u 0 2u 1 8u 1 10u 0)
Xtop in top
Rload in 0 100
.tran 15u 15u
.option eps=1e-4 nocatmx
.power_analysis
+ visible_columns=sum,type,max,avg
.probe tran v(in)
.end
• The power analysis results are stored in the waveform database folder named
POWER_TRAN.
Procedure
1. Run Eldo on a netlist with a .POWER_ANALYSIS command specified.
2. Open the waveform database containing the power analysis results.
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Viewing Power Analysis Results Example
3. Expand the set of power analysis results in the Waveform List Panel, right-click on the
POWER_TRAN folder and from the waveform pop-up choose Power Analysis to open
the Power Analysis dialog. (The dialog can also be opened from the main menu Tools >
Power Analysis.)
4. Click the Analyze button. The hierarchical tree view is populated with the power
waveform results from the design. As defined in the netlist in this case, the visible
columns are: sum, type, maximum, and average. You can also view the results in a list
view, with the full hierarchical name for each item.
5. If you change any of the settings in the dialog, for example the power thresholds or
analysis range, you need to click the Analyze button for the changes to take effect.
• Use the Filter Names field and click the Filter button to only list the results of names
matching the specified term. Clear the Filter Names field and click the Filter button
again to show all names. Some columns, for example Type and Mode, can be
filtered individually, by right-clicking on the column and choosing the items to
show.
• By default, Use Color Scaling is selected enhancing the results to easily show
problematic areas with a color scale.
6. Select the Save As to save the results as a CSV or text file.
Figure 6-22 shows the Power Analysis dialog in EZwave with color scaling enabled.
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Figure 6-22. Power Analysis Results
Example text file output:
Name Sum Type Max Avg
test01 6.448425e-1 - 6.000000e-2 1.572787e-2
test01.RLOAD 1.074737e-1 Passive 1.000000e-2 2.621311e-3
test01.VDD -6.448425e-1 Source 4.9E-324 -1.572787e-2
test01.XTOP 5.373687e-1 Subcircuit 5.000000e-2 1.310655e-2
test01.XTOP.RMIDDLE 1.074737e-1 Passive 1.000000e-2 2.621311e-3
test01.XTOP.XBOTTOM 2.149475e-1 Subcircuit 2.000000e-2 5.242622e-3
test01.XTOP.XBOTTOM.RBOTTOM1 1.074737e-1 Passive 1.000000e-2 2.621311e-3
test01.XTOP.XBOTTOM.RBOTTOM2 1.074737e-1 Passive 1.000000e-2 2.621311e-3
test01.XTOP.XMIDDLE 2.149475e-1 Subcircuit 2.000000e-2 5.242622e-3
test01.XTOP.XMIDDLE.RBOTTOM1 1.074737e-1 Passive 1.000000e-2 2.621311e-3
test01.XTOP.XMIDDLE.RBOTTOM2 1.074737e-1 Passive 1.000000e-2 2.621311e-3
Related Topics
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
Electrothermal Simulation
The .TEMPNODE command activates electrothermal simulation on a subcircuit to be
monitored. The voltage value on the specified node represents the temperature increase of the
corresponding subcircuit with respect to the global circuit temperature. Eldo computes the
power dissipated by the active devices present in the subcircuit containing .TEMPNODE
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RF Analyses
commands. This power, formally equivalent to a current source, is dissipated in the thermal
network attached to the thermal net, resulting in a new temperature value of the subcircuit.
The electrothermal simulation results can be sorted based on the thermal contributions. Specify
the .REPORT_HEATING command to generate a report listing the instances or subcircuits that
have seen their temperature change the most during an electrothermal simulation. The results
are generated in the default .chi output file or a dedicated .heat file, and can be filtered and
sorted.
Related Commands
• .TEMPNODE in the Eldo Reference Manual
• .REPORT_HEATING in the Eldo Reference Manual
• .OPTION ETMODE in the Eldo Reference Manual
Related Topics
Electrothermal Simulation
RF Analyses
Eldo RF extends the capabilities of the Eldo simulator with added extensions for RF simulation
to enable the fast large-signal Steady-State analysis (SST analysis) of high frequency electronic
circuits. Eldo RF provides a set of dedicated algorithms to accurately and efficiently handle the
multi-GHz signals in modern wireless communication applications.
Eldo RF capabilities include:
• Steady-State Analysis
Steady-State analysis of RF IC circuits excited with single-tone or multi-tone large
signal sources is easy with Eldo RF. Multi-tone steady-state analysis enables you to
quickly analyze amplifiers, filters, and mixers. Analysis features automate computation
of intermodulation products, compression points, intercept points, and extraction of
large-signal S parameters.
• Steady-State Small-Signal Analysis
A number of small-signal analyses such as the steady-state small signal (SSTAC)
analysis or the steady-state transfer function (SSTXF) analysis complement the steadystate
core algorithm. They are used to easily predict frequency responses when
frequency translation occurs due to a mixing operation for example, and regular small
signal analysis (AC) is not applicable.
• Steady-State Noise Analysis
Steady-state noise analysis determines the output noise spectrum and the noise figure,
with results sorted by the individual contribution of every noisy device. Eldo RF has the
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remarkable capability that nonlinear noise analysis can be performed under large signal
multi-tone conditions, which is mandatory for the accurate simulation of mixers.
• Oscillator and Phase Noise Analysis
Eldo RF computes the steady-state response of circuits containing multiple oscillators or
voltage-controlled oscillators in a fraction of the time needed by transient based
methods. Other fundamental frequencies are allowed, so large signal analysis of
combinations such as VCO and mixer are easy to analyze. You don’t need to worry
about the start-up conditions or the oscillator because everything is computed in the
frequency domain. Phase noise and amplitude noise are easily and accurately analyzed,
using proprietary algorithms, which yield accurate results both close to and far from the
carrier. Sorted contributions of each and every element is available in tabular formats.
Time domain period and long-term jitter information is also available, for both forced
and non-forced circuits.
• Frequency Dividers
Eldo RF supports the analysis of frequency dividers combined with voltage controlled
oscillators. Phase noise can also be predicted at the output of the dividers. Eldo RF is the
only tool to accurately predict the phase noise at intermediate division stages, due to its
unique handling of noise correlation. A very handy frequency divider macromodel is
available for architectural exploration.
• Modulated Steady-State Analysis
To accurately predict effects such as adjacent channel power ratio, Eldo RF supports a
dedicated algorithm that handles modulated signals. A time-varying spectrum is
computed by this algorithm, which basically merges the steady-state and the transient
algorithms, decoupling the resolution of the RF carriers from the slow-varying
modulation information. Eldo RF can also use the MODSST algorithm for some
partitions (typically, the RF blocks) and regular transient algorithm for the rest of the
circuit (typically, the baseband blocks). The speed up provided by this algorithm may
reach one or two orders of magnitude over brute force transient simulation, with no loss
of accuracy. A variety of standard outputs such as IQ trajectory diagram, constellation
diagram, or Eye diagram is available.
• Digitally Modulated Sources
To accommodate different wireless standards, Eldo RF supports all common digital
modulation formats, such as GMSK, QPSK, QAM, GFSK, EDGE, OFDM, etc. Built-in
sources deliver signals modulated according to these schemes, including the standard
baseband filters such as Root Cosine or Gaussian filters. The input signal can be either
explicit binary sequences, or CCITT compliant PRBS sequences. Arbitrary IQ
modulators can also be used, which read the IQ information from external user-defined
tables.
• Parametric Sweeping
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Take advantage of efficient parametric sweeping to vary signal power, fundamental
frequencies, temperature, power supply level, component values, or any parameterized
value for a complete verification of RF IC designs. Efficient parametric sweeping is
critical for many RF simulations such as compression points or intermodulation, and the
algorithms in Eldo RF are extremely well-suited for that purpose, thus maximizing
designers productivity.
• Phase-Locked-Loop Analysis
Eldo RF contains a dedicated algorithm for the analysis of the steady-state behavior of
PLLs. The analysis of PLLs is a difficult problem for classical transient simulation,
because the time constants at sake differ by several orders of magnitudes. The
bandwidth might be a few 100 kHz whereas the VCO oscillates at several GHz.
Unfortunately, transient simulation has to follow the fastest signal, and thus the number
of computed time points is prohibitive, leading to days or weeks of simulation, even on
the most powerful computers.
To overcome this difficulty, the Eldo RF steady-state PLL algorithm partitions the
design and uses a global convergence loop to directly compute the steady-state solution
(the locked state). The gain in CPU time is spectacular (typically 50X); and even better,
the results are more accurate than the solution provided by the transient simulation. This
is a rare case in which a clever algorithm provides both a spectacular speed up and
higher accuracy. Usually, you have to accept a tradeoff between speed and accuracy,
using either fast-spice or behavioral modeling techniques. The steady-state waveforms
enable analyzing the spurious in the output spectrum, directly in the frequency domain;
thus, the tedious post-processing FFTs of transient waveforms are completely avoided.
• Closed-Loop Phase Noise Analysis
See Also
The Steady-State PLL algorithm in Eldo RF can also compute the closed-loop phase
noise spectrum out of the PLL, using a partitioning strategy for accelerated convergence.
All noise sources are taken into account, without any simplifications, because the input
is a plain transistor-level netlist. All building blocks, such as phase-frequency detector,
charge pump, divider, and VCO, operate as non-linear elements. All transistor device
models are supported, and no behavioral modeling or linearization is necessary. A key
feature of the algorithm provides the individual contributions of the building blocks to
the global output phase noise.
• Eldo RF User’s Manual
Related Topics
Setting Up An Analysis
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Chapter 7
Running Parametric Analyses
Parametric analysis enables you to specify ranges of values for components, semiconductor
parameters, and other circuit parameters, and then analyze the circuit over these specified
values. This is called sweeping parameters.
Temperature Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
Assigning Parameter Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
Sweeping Parameters Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
.STEP Sweeping Parameters Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Nested Sweeps Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
.DATA Parameter Sweeps Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
Altering Netlist Data For Simulation Reruns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
Removing .EXTRACT Statements from a Simulation Rerun . . . . . . . . . . . . . . . . . . . . . . 299
Controlling Alter Blocks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
.ALTER Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
Using Output Results From a Previous Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302
Temperature Handling
Eldo enables temperature handling in a number of ways.
The order of priority of the following temperature related commands and parameters is, with
decreasing priority: T (TEMP or DTEMP), then TMOD (or TNOM), and then .TEMP. That is,
T has the highest priority.
• .TEMP command.
Specifies the circuit simulation temperature. You can specify this to execute several
successive simulations at various temperatures.
See “.TEMP” in the Eldo Reference Manual.
• Keyword TEMP in .DC analysis command.
.DC followed by the TEMP keyword results in a variation of temperature.
See “.DC” in the Eldo Reference Manual.
• TNOM option (.OPTION).
Sets the default model reference temperature for parameters provided in the .MODEL
statement (temperature at which the default model parameters were extracted). Default
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is 27°C. TNOM is the temperature at which the given model parameters are valid. If T
differs from TNOM, model parameters are internally recalculated to reflect the
temperature dependence of the simulated devices.
TNOM may appear in expressions. TNOM is a reserved keyword, however it may be
specified as a parameter in a .PARAM command when .OPTION DEFPTNOM is set.
The temperature value set with .OPTION TNOM=val is always used by the Eldo model
evaluator.
See options “DEFPTNOM” and “TNOM” in the Eldo Reference Manual.
• TMOD parameter in devices (diode, BJT, JFET, MOSFET).
Sets the model temperature in device model specifications. The value of this parameter
overrides the .TEMP command.
Note
.OPTION TMOD and TNOM in the .MODEL statement are synonymous, the last
one specified is used.
• DTEMP parameter in devices (resistor, capacitor, inductor, diode, BJT, JFET,
MOSFET, subcircuit).
The DTEMP parameter, in certain devices, sets the temperature difference between the
device and the rest of the circuit. You can also specify it on the subcircuit instance.
• T (or TEMP) parameter in certain devices.
The T parameter, in certain devices, sets the temperature of an individual instance of a
device or model. You can also specify it on the subcircuit instance. This parameter
overrides the TMOD parameter. If T differs from TNOM, the model parameters are
recalculated to reflect the temperature dependence of the simulated devices.
The T on the device overwrites the TMOD specified on the model statement, if any. If T
differs from the global TNOM, or from the TNOM specified on the model card attached
to that device, the model parameters are recalculated.
Note
TEMP and DTEMP are mutually exclusive. If both are specified, the last one is
used.
• Variable TEMPER (or TEMP) Eldo enables formulation of temperature-dependent
functions.
TEMPER (or TEMP) is a variable returned by Eldo supplying the value of the current
simulation temperature; it may be used in subsequent calculations. This variable is the
current simulation temperature resulting from a .TEMP command, a .DC TEMP sweep
or, if neither are specified, the value of .OPTION TNOM. The TEMPER variable may
be used in the formulation of temperature-dependent expressions. Any expressions
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containing the TEMPER variable will be automatically reevaluated in the case of a
change in this temperature.
Note
The TEMP variable is synonymous with the TEMPER variable. Both refer to the
temperature of the circuit.
If TNOM is not specified on a model, the global TNOM is used. If TEMP is not specified on a
model, the global .TEMP is used (or global TNOM if global .TEMP not specified).
To dynamically change temperature you can define a temperature source as a voltage source
and specify option VARTEMP to vary simulation temperature by following the source
variation. See option “VARTEMP” in the Eldo Reference Manual.
Temperature can be dynamic as well as static, and can be specified through a PWL source.
Examples
Differences between TNOM and TEMP
The difference between TNOM (model reference temperature) and TEMP (simulation
temperature) is shown in the examples below:
The following example assumes that devices using model foo1 will use model parameters
updated for a temperature of 30°C. Knowing that the parameters specified in the .MODEL
statement are given for a temperature of 25°C (through the TNOM option) the model
parameters will be updated accordingly. Devices using model foo2 will use model parameters
for the nominal temperature of 25°C. The rest of the circuit will be simulated at 10°C.
.model foo1 temp=30 vto=1
.model foo2 vto=1
.option tnom=25
.temp 10
The following example assumes that devices using model foo will use model parameters
updated for a temperature of 30°C. Knowing that the parameters specified in the .MODEL
statement are given for a temperature of 25°C (through the TNOM option) the model
parameters will be updated accordingly. The rest of the circuit will be simulated at 25°C
through the TNOM option.
.model foo temp=30 vto=1
.option tnom=25
In the following example, a nominal temperature of 20°C is used for model foo1, a nominal
temperature of 25°C is used for model foo2, and a nominal temperature of 30°C is used for
foo3.
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.model foo1 tnom=20 vto=1
.model foo2 vto=1
.model foo3 tmod=30 vto=1
.option tnom=25
DTEMP and TEMPER examples
In this example, the DTEMP parameter sets the temperature of the capacitor 10°C above the
circuit temperature.
c1 1 2 cmodel1 tc1=25e-3 m=2 dtemp=10
.model cmodel1 c cox=1e-12 capsw=1e-12 del=0.01 l=1 w=1
.TEMP 70
The TEMPER variable may be used in conjunction with VALUE={EXPR} in resistors,
capacitors and inductors to specify devices whose values vary with temperature.
The following example specifies a capacitor Cvariable connected between nodes 3 and 7 and its
value defined as the nominal capacitance C0 multiplied by (1+ 0.002 multiplied by the square of
the current simulation temperature TEMPER). The TEMPER variable may also be used in
expressions for model parameters.
Cvariable 3 7 VALUE={C0*(1+0.002*(TEMPER^2))}
The following example shows how the DTEMP parameter is used to specify a difference
between the circuit temperature and the subcircuit instance temperature. In this example Eldo
will assume that the temperature of devices inside X1 will be 40 + 10 = 50 °C:
.subckt r 1 2
r1 1 2 1 tc1=1
.ends
i1 1 0 1
x1 1 0 r dtemp = 10
.TEMP 40
.op
.end
See Also
• Resistor, Capacitor, and Inductor in the Eldo Reference Manual
• Diode Models, BJT Models, MOSFET Models in the Eldo Reference Manual
• Subcircuit Instance in the Eldo Reference Manual
Related Topics
Assigning Parameter Values
Electrothermal Simulation
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Assigning Parameter Values
Assigning Parameter Values
Use the .PARAM command to assign values to parameter variables used in model and device
instantiation statements.
The following types of parameter statements are supported:
• Simple description
• Algebraic description
• Character string assignment
• User-defined function
• Monte Carlo analysis
Parameter Scoping Rules
Option PARHIER controls the priorities for parameters. When PARHIER is GLOBAL or
LOCAL, then the parameter priorities adopted in subcircuit instances (X statements) are
performed as if the operations were executed inside the subcircuit. The following rules apply:
When PARHIER=GLOBAL, the priority is the following:
1. .PARAM statement at a higher level
2. Subcircuit instantiation (X instance)
3. .SUBCKT definition
When PARHIER=LOCAL, the priority is:
See Also
1. Subcircuit instantiation (X instance)
2. .SUBCKT definition
3. .PARAM statement
• .PARAM in the Eldo Reference Manual
• Options PARAM_BEFORE_USE and PARHIER in the Eldo Reference Manual
Related Topics
.STEP Sweeping Parameters Examples
Eldo® User's Manual, 15.3 291

Running Parametric Analyses
Sweeping Parameters Examples
Sweeping Parameters Examples
To perform several simulations while sweeping one or several circuit parameters (multiple
sweep) use the .STEP command.
The following types of sweeps are supported:
• Temperature sweep specified by TEMP keyword. Dipole (R, C, L) component whose
value is swept specified by the DIPOLE name.
.STEP TEMP | DIPOLE INCR_SPEC
• MOS—name of the MOS component whose W or L parameter is swept:
.STEP MOS W|L INCR_SPEC
• Parameter PARAM_NAME of model MNAME is swept:
.STEP MNAME PARAM_NAME INCR_SPEC
• PAR_NAME is a parameter name defined through the .PARAM command:
.STEP PARAM PARAM_NAME INCR_SPEC
• To sweep a device parameter:
.STEP E (device, parameter_name) INCR_SPEC
• To sweep a parameter defined through .PARAM:
.STEP P (global_parameter) INCR_SPEC
• To sweep a model parameter:
.STEP M (model_name, parameter_name) INCR_SPEC
• To sweep different variants of a library:
.STEP LIB (lib_name) INCR_SPEC
.STEP Sweeping Parameters Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Nested Sweeps Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
.DATA Parameter Sweeps Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
.STEP Sweeping Parameters Examples
Some examples of sweeping parameters with the .STEP command.
• This example specifies that the value of resistor r1 will be swept from 1kΩ to 2kΩ with
a step of 1kΩ, and then from 2kΩ to 4kΩ with a step of 500Ω:
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.STEP Sweeping Parameters Examples
.param r1 1k
*...
.step param r1 1k 2k 1k, 2k 4k 500
• This example shows how a non-primitive parameter p1 can be specified:
.param p2=100k
.param p1=sqrt(p2)
*...
.step param p1 1k 5k 1k
• Temperature sweep:
.step temp 25 40 2
• Parameter RB of model qmod sweep:
.step qmod rb 80 110 10
• Parameter sweep:
.param p2=100k
.param p1=sqrt(p2)
. . .
.step param p2 1k 5k 1k
Sweep cannot be done on p1 because p1 is not a primitive.
• Subcircuit component sweep:
.step x1.c1 1p 10p 1p
• Conditional parameter and parameter sweep:
.param p1 = 1 p2 = 2
.param p3 = valif ( p1 > p2 , p1 + 1.5 , p2 + 1.5 )
.param p4 = eval ( p1 > p2 ? P1 + 1.5 : p2 + 1.5 )
.step param p1 list 1 2 3
The following examples further show how the .STEP command can be used to sweep
Parameters, Elements, Models, or Models attached to specific Elements:
.PARAM P1=1u
.MODEL NMOS NMOS LEVEL=1 VTO=2
M1 p1 p2 p3 p4 NMOS w=p1 l=3u
M2 p1 p2 p3 p4 NMOS w=p1 l=3u
*...
.end
After the above specification, the following four .STEP commands are valid:
.STEP P(P1) 1u 10u 1u
Parameter P1 varies from 1μ to 10μ in steps of 1μ.
Eldo® User's Manual, 15.3 293

Running Parametric Analyses
.STEP Sweeping Parameters Examples
.STEP E(M1,l) 3u 4u 1u
Length of Element M1 varies from 3μm to 4μm in steps of 1μm.
.STEP M(NMOS,VT0) 1 3 1
Parameter VT0 of model NMOS varies from 1 to 3 in steps of 1.
.STEP EM(M2,VT0) 1 4 1
A private model will be assigned to M2. The VT0 of model attached to M2 will vary from 1 to 4
in steps of 1; the VTO of model attached to M1 will remain unchanged.
The following example shows a parameter vector sweep, with all parameters taking their values
from lists. Eldo will sweep parameters IG1 and LR1 over four simulations. The first simulation
with IG1 at 10u and LR1 at 1000u. The last simulation with IG1 at 100u and LR1 at 100u.
.param IG1=10u LR1=1000u
.step (p(IG1),p(LR1)) LIST (10u, 1000u) (20u, 500u) (50u, 200u)
+ (100u, 100u)
i1 1 0 ig1
r1 1 0 '10e6*lr1'
.plot dc v(1)
.dc
The following example shows how the .STEP command is used to make several Eldo runs, each
of them using a different variant of the libraries, using the keyword LIB(libname):
.LIB mylib TYP
*...
.STEP LIB(mylib) TYP MIN MAX
.END
Three simulations will be performed: one using the variant TYP of mylib, another one using the
variant MIN, and a last one using the variant MAX.
Note
The LIB specification can be used with any other specification.
TYP, MIN, and MAX are not keywords, but are the character strings that can appear as the
second arguments of the .LIB command (.LIB FNAME [LIBTYPE]). Usually, variant names
are TYP, MIN, and MAX, but they can be any string.
.STEP P(P1) 1 2 0.5 LIB(mylib) TYP MIN MAX
Here, Eldo will perform three simulations:
• One with both P1=1.0 and mylib using variant TYP.
• One with both P1=1.5 and mylib using variant MIN.
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Running Parametric Analyses
Nested Sweeps Examples
• One with both P1=2.0 and mylib using variant MAX.
Related Topics
Sweeping Parameters Examples
Nested Sweeps Examples
.DATA Parameter Sweeps Examples
Nested Sweeps Examples
You can define several .STEP commands with an unlimited number of nesting levels. Multiple
sweeps can change concurrently.
• This example specifies that the value of resistor R22 will be swept from 20k to 100k,
with an increment of 1k => 81 points, parameter COX will be swept from 0.4m to 0.3m
at the same time with 81 increment points. R22 and COX are varying together and 81
simulations are performed.
.STEP E(R22,R) 20k 100k 1k M(MOS1,COX) 0.4m 0.3m
• This examples specifies that 81 simulations for the first .step, 31 simulations for the
second .step, with a total of 81 x 31 simulations performed.
.STEP E(R22,R) 20k 100k 1k M(MOS1,COX) 0.4m 0.3m
.STEP P(p1) 1 1000 DEC 10
• In this example 3 simulations will be performed. The first one with p1=1 and mylib
using variant min, the second one with p1=1.5 and mylib using variant typ, and the third
one with p1=2 and mylib using variant max.
.STEP P(p1) 1 2 0.5 LIB(mylib) LIST min typ max
• In the following example, two simulations will be performed. The first with R1 value of
20k, TEMP is 27 and uses the LIB variant typ for file corna.lib. The second with R1
value set to 10k, a TEMP value of −40 and the LIB variant fast of the file corna.lib.
.STEP PARAM (E(R1,R) TEMP LIB(corna.lib)) LIST
+ (20k 27 typ)
+ (10k -40 fast)
Related Topics
Sweeping Parameters Examples
.DATA Parameter Sweeps Examples
Eldo® User's Manual, 15.3 295

Running Parametric Analyses
.DATA Parameter Sweeps Examples
.DATA Parameter Sweeps Examples
The .DATA command simultaneously defines a set of parameters. For example:
.TRAN 1n 10n SWEEP DATA=datatran
.DATA datatran p1 p2 p3
+ 1.0 3.0 4.0
+ 2.0 5.0 7.0
.ENDDATA
Here follow some examples of specifying multiple external files to be processed either
sequentially or in parallel:
.data example1 MERGE
+ file=data1.inc col1=3 col2=2
+ file=data2.inc colA=1 colB=3
+ out=example1.inc
.enddata
After the first file name, the names of the columns to be created and the index where the data
comes from are specified. The resulting .DATA is created using the merge of the two files:
1 2 3
4 5 6
7 8 9
10 20 30
40 50 60
70 80 90
The specification col1=3 col2=2 and colA=1 colB=3 literally means: the first column is named
col1 and its values come from the third column of merged files; the second column is named
col2 and its values come from the second column of merged files. The resulting .DATA will be:
.DATA example1
+ col1 col2 colA colB
+ 3 2 1 3
+ 6 5 4 6
+ 9 8 7 9
+ 30 20 10 30
+ 60 50 40 60
+ 90 80 70 90
.enddata
The following example shows the LAMINATED specification for processing in parallel:
.data example2 LAM
+ file=data1.inc col1=3 col2=2
+ file=data2.inc colA=1 colB=3
+ out=example2.inc
.enddata
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.DATA Parameter Sweeps Examples
As before, the names of the columns to be created and the index where the data comes from are
specified. However, unlike the merge form, values come from the original files so in this case
you will notice that the resulting .DATA will be different as follows:
.DATA example2
+ col1 col2 colA colB
+ 3 2 10 30
+ 6 5 40 60
+ 9 8 70 90
.enddata
See Also
• .PARAM in the Eldo Reference Manual
• .STEP in the Eldo Reference Manual
• .DATA in the Eldo Reference Manual
Related Topics
Sweeping Parameters Examples
Eldo® User's Manual, 15.3 297

Running Parametric Analyses
Altering Netlist Data For Simulation Reruns
Altering Netlist Data For Simulation Reruns
You can rerun simulations with a modified netlist using the .ALTER command. An alter block
consists of Eldo element, subcircuit, command, and comment statements. The alter block ends
with the next .ALTER or .END command. All Eldo statements in an alter block are backsubstituted
in the original netlist except for some commands which are always added to the
netlist with no substitution attempted. The circuit_name.chi ASCII log file contains a trace of
all modifications made.
The way Eldo processes a netlist with .ALTER blocks is as follows:
1. Eldo reads the netlist up to the first .ALTER statement and performs the analyses. This
is the first simulation run.
2. Eldo then reads the block of statements between the first .ALTER and .END (or another
.ALTER) statements.
3. Eldo modifies the netlist using these alter block statements.
4. Eldo reruns the simulation with the modified netlist.
For multiple .ALTER blocks, the initial netlist is always as the reference to be altered, not the
result of the previous .ALTER command. If there is an error in a .ALTER block, it will be
skipped and the next .ALTER block will be used.
To run a specific .ALTER block without first running the main netlist, invoke Eldo with the
-alter argument together with the corresponding name or index of the alter block required.
Specifying an index of 0 means the nominal run without any alters.
Multiple indexes can be specified without separators. When Eldo identifies -alter, it interprets
the following arguments as indexes until another argument is found (beginning with “-”). For
example:
eldo foo.cir -alter 2 5 10 11 12 13 20 21 22
Tip
See the “.ALTER” command and the “-alter” command-line argument in the Eldo
Reference Manual.
Removing .EXTRACT Statements from a Simulation Rerun. . . . . . . . . . . . . . . . . . . . . 299
Controlling Alter Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
.ALTER Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
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Running Parametric Analyses
Removing .EXTRACT Statements from a Simulation Rerun
Removing .EXTRACT Statements from a Simulation
Rerun
To remove .EXTRACT commands specified in the nominal netlist from the subsequent
simulation rerun (.ALTER) use the .FILTER command. For example, to remove the undesired
.EXTRACT labeled foo inside the .ALTER specify:
...
.extract label=foo
.alter
.filter extract label=foo pass(foo)
See Also
• .ALTER in the Eldo Reference Manual
• .FILTER in the Eldo Reference Manual
Related Topics
Controlling Alter Blocks
.ALTER Examples
Controlling Alter Blocks
Use option ALTER_NOMINAL_TEXT=label to attach a label to the nominal run. The label
used is the same as that specified in the command, for example: .ALTER label. This label is
printed in the .chi/.aex file or attached to the JWDB waveforms in the parameter table of
compound waveforms. The label string should be enclosed between double quotes if it contains
space characters.
Use option ALTER_SUFFIX to switch the naming convention for swept waves used in
.ALTER statements between: xxx and xxx_alter:XX.
For JWDB output, the alter index number can be viewed when highlighting waveforms in the
EZwave Waves window.
Error handling of multiple run netlists can be managed with option STOPONFIRSTERROR.
When set to 2, the first error stops the simulation even if the netlist file contains .ALTER
statements for multiple simulation runs. When set to 1, if the netlist file contains .ALTER
statements, Eldo will stop on the first .ALTER that has an error, but continue with the remaining
.ALTER statements.
To replace one file by another one when using the Eldo re-run facility, use the option ALTINC.
This forces Eldo to replace the first .INCLUDE statement found in an input netlist by the first
.INCLUDE statement found in the .ALTER section of the netlist.
Eldo® User's Manual, 15.3 299

Running Parametric Analyses
.ALTER Examples
By default, Eldo substitutes the .STEP commands in the main netlist by those found in .ALTER
statements. To append .STEP commands in .ALTER statements, instead of substituting, use
option ALTER_ADDSTEP.
.PARAM statements present in a .ALTER section are systematically added at the end of the
netlist being created for the current ALTER run. Eldo will not attempt to replace the parameter
name; it is recommended to avoid using .ALTER to replace parameters inside .SUBCKT
statements.
By default, .ALTER restarts from the original netlist, in compat mode .ALTER is cumulative,
see “Commands in Compat Mode” on page 168.
See Also
• .ALTER in the Eldo Reference Manual
Related Topics
Altering Netlist Data For Simulation Reruns
.ALTER Examples
.ALTER Examples
Examples of rerunning simulations with a modified netlist using the .ALTER command.
This example specifies two simulation runs. Both perform an AC analysis but certain
component values, the number of points and stop frequency of the AC analysis are changed
using the .alter command for the second run.
alter command example
r1 1 2 1k
r2 2 0 1k
c1 2 0 1n
.ac dec 10 200 1000meg
vin 1 0 ac 1
.plot ac vdb(2) (-90, 0)
.alter
r1 1 2 10k
c1 2 0 100p
.ac dec 15 200 1500meg
.end
This example shows how to replace one included file with another one when using the Eldo rerun
facility with the option ALTINC. The new_models file will be included in the re-run
simulation instead of models.
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Running Parametric Analyses
.ALTER Examples
.include models
.option altinc
r1 1 0 rval
v1 1 0 dc 1
.extract dc i(r1)
.dc
.alter
.include new_models
The example below demonstrates the use of the KEY parameter in conjunction with the
.ALTER command. This command sequence causes three simulations to be performed always
with library /work/bip/mymod typ.
In the first simulation, library /work/mos/mymod typ is used.
In the second simulation, library /work/mos/mymod best is used.
In the third simulation, library /work/private/mymod typ is used.
...
.lib key=K1 /work/bip/mymod typ
.lib key=K2 /work/mos/mymod typ
...
.alter
.lib key=K2 /work/mos/mymod best
.alter
.lib key=K2 /work/private/mymod typ
.end
This example shows how option ALTER_SUFFIX can be used to switch the naming convention
for swept waves used in .ALTER statements between: xxx and xxx_alter:XX. Run the circuit
with and without the option and look at the difference in results.
Eldo® User's Manual, 15.3 301

Running Parametric Analyses
Using Output Results From a Previous Simulation
*.option alter_suffix.param VTEST1=1
vdc 1 0 dc VTEST1
vin 2 0 dc 0
v2 4 0 dc 1
etest 3 0 value={mult*(2-v(1,2)*v(1,4))}
r1 3 0 rval
.dc vin 0 2 0.1
.step param VTEST1 0.5 1.5 0.1
.plot dc i(r1)
.extract label=imax max(i(r1))
.extract label=imin min(i(r1))
.defwave sweep TEST=meas(imax)
.param RVAL=1k
.param MULT=1
.alter first
.param RVAL=1.3k
.param MULT=1.3
.alter second
.param RVAL=0.7k
.param MULT=1.3
.alter
.param RVAL=0.7k
.param MULT=0.7
.alter fourth
.param RVAL=1.3k
.param MULT=0.7
.end
Tip
See “.ALTER” in the Eldo Reference Manual.
Related Topics
Altering Netlist Data For Simulation Reruns
Using Output Results From a Previous
Simulation
The .CHRSIM command enables you to use the output of previous simulations as input to the
current simulation. The previous simulation data must have been generated by a DC sweep or a
transient analysis. The simulator assigns to the node IN of the current simulation, the output
obtained at node OUT in the file FILE.wdb.
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Running Parametric Analyses
Using Output Results From a Previous Simulation
Tip
See “.CHRSIM” in the Eldo Reference Manual.
Eldo® User's Manual, 15.3 303

Running Parametric Analyses
Using Output Results From a Previous Simulation
304
Eldo® User's Manual, 15.3

Chapter 8
Specifying Simulation Output
This chapter describes how to use output commands and variables to display simulation results
in the time and frequency domains.
Output Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
Output Commands Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
Plotting, Printing and Probing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
Files Created . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
Types of Waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Monitoring of Hierarchical Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Using Wildcards for Plotting and Probing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
Plotting, Printing and Probing States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
Plotting Internal Pin Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Complex Modifiers and Initial Formatting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Compound Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
Plotting an Analog Signal as a Digital Bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
X-Axis of Waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
Tabular Listing Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Plotting Transmission Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Dynamically Adding Voltage/Current Plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318
Output Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
Extracting Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
.EXTRACT Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
Plot and Print Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Extract Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Extract Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Extraction Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Extract Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Defining Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
Examples of Defining Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
Safe Operating Area (SOA) Checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Plotting Safe Operating Area Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Safe Operating Area Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
High Impedance Node Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
How to Enable High Impedance Node Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
High Impedance Node Check Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Limiting Output Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
Limiting the Size of Transient Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
Eldo® User's Manual, 15.3 305

Specifying Simulation Output
Output Types
Incremental Saving of the JWDB Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
Output Types
Eldo can generate three types of output:
• Graphical output (.wdb) for the EZwave waveform viewer.
• Measurements from the results of simulation; either scalar or vector.
• Tables and reports in the ASCII output (.chi) file and additional files.
Related Topics
Output Commands Overview
Analyzing Simulation Results
Output Commands Overview
The output commands define which simulation results will be written to the output files for
display.
Output commands include:
• .EXTRACT
A fundamental and very powerful command in Eldo to extract information from the
various analyses and waveforms using a combination of arithmetic expressions or predefined
functions (.MEAS is also supported as an alternative).
• .PLOT
Specifies which simulation results have to be kept by the simulator for graphical
viewing and post-processing. Results are written to .wdb binary output files for postprocessing.
• .PRINT
Defines the contents of a tabular listing of any number of output variables. Results are
written to the .chi file in ASCII.
• .PROBE
Writes simulation results of specified objects to .wdb binary output files for postprocessing.
• .MEAS
Alternative to the more powerful .EXTRACT command.
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Specifying Simulation Output
Output Commands Overview
• .DEFWAVE
Defines a new waveform by relating previously defined waveforms and nodes. The
resulting waveform can be used in .EXTRACT commands with the results being listed
to the ASCII output (.chi) file, or may be plotted or printed using the .PLOT and .PRINT
commands.
Each output command specifies the output variables and type of result to be displayed, for
example DC, AC, TRAN, NOISE. Depending on the analysis, Eldo will generate different types
of output, for example some extract functions are specific to Monte Carlo analysis, see “Post-
Analysis of Monte Carlo Simulations” on page 463. The type of analysis specified with .PLOT
has an impact on what Eldo generates, for example specifying a NOISE plot will generate
different results to an AC plot.
Related Topics
Plotting, Printing and Probing
Output Variables
Extracting Information
Analyzing Simulation Results
Eldo® User's Manual, 15.3 307

Specifying Simulation Output
Plotting, Printing and Probing
Plotting, Printing and Probing
This section describes the types of output files generated by Eldo when plotting, printing and
probing. It refers to the main three commands .PLOT, .PRINT, and .PROBE, even when
generically referring to plotting.
Files Created. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
Types of Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Monitoring of Hierarchical Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
Using Wildcards for Plotting and Probing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
Plotting, Printing and Probing States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
Plotting Internal Pin Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Complex Modifiers and Initial Formatting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Compound Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
Plotting an Analog Signal as a Digital Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
X-Axis of Waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
Tabular Listing Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Plotting Transmission Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Files Created
The quantities listed in a .PLOT command are written to binary output files (.wdb) for viewing
with the EZwave waveform viewer. Saved windows files .swd are created with a .wdb database
and contain information on specific graph windows such as size or position. By default, the
quantities listed in a .PLOT command are not written to the ASCII .chi output file. This avoids
creating huge .chi output files in the case of large simulations.
Eldo generates .wdb by default, however other formats can be generated. See “Output Files
Generated” on page 358.
When using .PRINT, simulation results are written to the .chi log file in ASCII format. When
using .PROBE, the set of signals to be monitored is specified in the same way, but results are
written to binary output files (.wdb) meaning the simulated results are available for postprocessing.
Binary storage saves significant disk space and is faster to read/write than ASCII.
.PROBE and .PLOT both dump waves to a database but .PLOT also adds some information for
“plot combinations,” which means the ability to group waves into graphs, use Smith charts, and
change wave representation (scattered, histogram, and so on).
Related Topics
Plotting, Printing and Probing
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Specifying Simulation Output
Types of Waveforms
Types of Waveforms
This section describes the types of waveforms generated by Eldo.
Plotting Output Variables
Many different simulation results can be created by Eldo. The simulator can output simple node
voltages, but also currents through devices, currents through device or subcircuit pins, power
quantities, S parameters, internal variables from device models, and so on. All these results are
direct raw results from a simulation. For example:
.PLOT TRAN V(OUT)
.PLOT DC ISUB(XBIAS.VOUT)
Plotting Extractions
The .PLOT command may also be used to plot extraction results. A flexible language exists in
Eldo to extract characteristics from raw simulation results (for example the maximum value of a
waveform, or the time at which a given threshold is crossed by a waveform, and so on). See
“Extracting Information” on page 321 and “Plot and Print Quantities” on page 323.
Plotting Templates
The .PLOT command combined with the .DEFWAVE command can be used to generate socalled
template waveforms. Using .PLOT, these templates can be displayed together with the
simulation results. See “Defining Waveforms” on page 336.
Related Topics
Monitoring of Hierarchical Nodes
Plotting, Printing and Probing
Monitoring of Hierarchical Nodes
This output format is used to specify nodes that lie within subcircuits. The node itself cannot be
referenced directly from the ‘top-level’ of the circuit and so it must be addressed through the
levels of the subcircuit by separating elements with periods (.) in the output control statement.
The example below illustrates this output format.
.subckt sc1 n10 n12
r10 n10 n11 0.2
x2 n11 n12 sc2
.ends sc1
.subckt sc2 n20 n22
r20 n20 n21 0.1k
r22 n21 n22 0.1k
.ends sc2
x1 a b sc1
.print tran v(x1.x2.n21) v(a) v(b)
Eldo® User's Manual, 15.3 309

Specifying Simulation Output
Using Wildcards for Plotting and Probing
The above example specifies the output of three nodes. Node x1.x2.n21 is created as the second
pin of resistor r20, which is an element of the subcircuit sc2, instantiated using instance x2,
which is itself nested in the subcircuit sc1, instantiated using instance x1.
Related Topics
Using Wildcards for Plotting and Probing
Plotting, Printing and Probing
Using Wildcards for Plotting and Probing
To analyze simulation results for huge circuits, and to display only part of the circuit, you can
specify a .PLOT/.PROBE command with nodes defined via both hierarchy and wildcard
characters. The wildcard (*) may be used to select any list of items for plotting/probing
quantities such as voltage or current.
If the wildcard * is specified, then Eldo enables it to be used in conjunction with ? and [ ] for
matching characters (see “Special Characters” on page 312). If * is not in the specification, then
? and [] are not supported; a warning will be generated. If you want to keep the [ ] inside the
name specification and not have Eldo handle them as special characters, then specify .OPTION
NOCMPUNIX or use the backslash delimiter.
Note
Option LIMPROBE can be specified to set the maximum number of nodes that may be
monitored via the .PROBE command. By default, it is set to 10,000.
Wildcards in Subcircuit Instances
Subcircuit instances can be specified in the output command. A specific subcircuit node can be
referenced or wildcards (*) can be used to select any list of items for probing quantities such as
voltage or current. Subcircuit instances can be specified for keywords V, I, S, W, VX, IX, ISUB
and POW. The following syntax is used to specify wildcards in subcircuit instances:
V|I|S|W|VX|IX|ISUB|POW(.*)
V|I|S|W|VX|IX|ISUB|POW(->*)
When specifying parameters V, I, VX, IX, ISUB, POW with a subcircuit instance the -R
parameter can also be specified to enter levels of hierarchy.
V(Xnn.*) — Monitors the voltage on all of the nodes of subcircuit Xnn.
S(Xnn.*) — Monitors the states on all of the nodes of subcircuit Xnn.
S(Xnn.Ynn->*) — Monitors the states on all of the nodes of macromodel Xnn.Ynn.
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Eldo® User's Manual, 15.3

Examples of Wildcard Usage in Subcircuit Instances
• The below specifies that the node X1.1 will be probed:
.PROBE TRAN V(X1.1)
• To plot all nodes in subcircuit X1:
.PLOT TRAN V(X1.*)
• To store all currents in devices internal to the Xbias instance:
.PROBE TRAN I(Xbias.*)
Specifying Simulation Output
Using Wildcards for Plotting and Probing
• To plot all the nodes of subcircuit X1 but not probe internal nodes of the subcircuit
hierarchy:
.PLOT TRAN V(X1.*)
• Use the -R parameter to probe all internal and external nodes of subcircuits beginning
with the name X1:
.PROBE TRAN -R V(X1.*)
This can also be performed using the VX keyword.
• To probe all nodes of subcircuit X1 and enter inside the n level of hierarchy under X1
for plotting nodes:
.PROBE TRAN -Rn V(X1.*)
If n is 0 this specifies the top level.
• To plot all nodes of subcircuit X1 and enter inside the n level of hierarchy under X1 for
plotting nodes.
.PLOT TRAN -R LEVEL=n V(X1.*)
If n is 0 this specifies the top level. Equivalent to -Rn.
Note
.PLOT TRAN V(X1.*) is equivalent to: .PLOT TRAN -R0 V(X1.*)
• VX, IX and ISUB can be used to probe voltages and currents on all subcircuit input
nodes within the hierarchy. For example, to probe the current across all input nodes of
subcircuits beginning with the name X1:
.PROBE TRAN IX(X1.*)
• Waveform definitions (defwaves) and digital quantities can also be probed for subcircuit
instances using wildcards:
Eldo® User's Manual, 15.3 311

Specifying Simulation Output
Using Wildcards for Plotting and Probing
o
To probe all internal states (denoted by the syntax “->”) of macromodel y1 inside
subcircuit x1:
.PROBE TRAN S(x1.y1->*)
o
To probe all waveform definitions (defwaves) for subcircuits beginning with the
name x1:
Special Characters
.PROBE TRAN W(x1.*)
If the name used in a .PLOT/.PROBE command contains brackets, ( [ ] ), or the “?” character,
these are interpreted as special characters when the wildcard character “*” is used (see
Table 8-1). By default, according to UNIX convention, brackets are interpreted as special
characters defining a wildcard expression. These special characters may be overridden by using
the delimiter backslash character “\”, which removes the special function of the character that
immediately follows it, or by specifying .OPTION NOCMPUNIX to change the interpretation.
For example, the following only returns names that begin with X1.*, because, according to
UNIX convention, X[1].* means all names beginning with “X” followed by the character “1”:
.PROBE tran V(X[1].*)
Therefore, to display all nodes beginning with V(X[1].*) either of the following should be used:
or:
.option NOCMPUNIX
.PROBE tran V(X[1].*)
.PROBE tran V(X\[1\].*)
The following table contains a listing of the special characters that can be used with the .PLOT/
.PROBE command.
Table 8-1. Special Characters for Plotting and Probing
Character Description
* Matches any sequence of characters
? Matches any single character
[abcd]
Matches any character in the specified set
[-abcd]
Matches any character in the specified range, for example [A-Z]
matches all alphabetical characters
[!abcd] Matches any character not in the specified set, for example [!0-9]
matches all characters which are not digits
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Eldo® User's Manual, 15.3

See Also
• .PLOT command in the Eldo Reference Manual
Specifying Simulation Output
Plotting, Printing and Probing States
• Options LIMPROBE and NOCMPUNIX in the Eldo Reference Manual
Related Topics
Plotting, Printing and Probing States
Plotting, Printing and Probing
Output Variables
Limiting Output Information
Plotting, Printing and Probing States
To monitor or plot an internal state of a device, use the following syntax:
.PLOT analysis S(device->state)
For example, to monitor In for a given transistor Q1, specify the following in the netlist for DC,
AC or TRAN analyses respectively:
.PLOT DC S(Q1->In)
.PLOT AC S(Q1->In)
.PLOT TRAN S(Q1->In)
For example, to monitor the HICUM Level0 transistor device temperature change due to selfheating
in a transient simulation, specify:
.plot tran s(q1->vthermal)
For example, to monitor the TFT Amorphous-Si MOSFET device transconductance in a DC
simulation, specify:
.plot dc s(M1->Gm)
Internal states specific to each device model are documented in the Printing/Plotting States
tables in the Eldo Device Equations Manual.
Tip
See “.PLOT” in the Eldo Reference Manual.
Related Topics
Plotting Internal Pin Values
Plotting, Printing and Probing
Eldo® User's Manual, 15.3 313

Specifying Simulation Output
Plotting Internal Pin Values
Plotting Internal Pin Values
To measure the intrinsic value of a pin you use the same syntax as for measuring its extrinsic
value. However, you use an index number greater than the number of pins available that
corresponds to the pins position. For example, the source voltage pin is the third pin of a
MOSFET and there are four pins in total. Therefore, to obtain the intrinsic source voltage of this
MOSFET you would use:
.PLOT V(Mx.7)
To obtain the intrinsic value of the drain current pin of a JFET you would use:
.PLOT I(Jx.4)
Note
If the position number used is greater than the index available for the device it will return a
value of zero.
Related Topics
Complex Modifiers and Initial Formatting
Plotting, Printing and Probing
Complex Modifiers and Initial Formatting
Some results are real quantities, such as the currents and voltages from a transient analysis,
while others are complex. In this case, real or imaginary parts, magnitude or phase or group
delay, can be required by the user.
Use option ACOUT to control how complex expressions VX(a,b) and IX(a,b) are computed in
AC analysis for their decibel magnitude, magnitude, phase, and group delay values.
It is also possible to specify some initial basic formatting of the results. For example, spectral or
scattered display modes can be specified, instead of the default continuous-line mode. S, Y, Z
parameters can be automatically displayed in a Smith chart, and so on. These optional
specifications do not alter the raw data, they only tell the waveform viewer how to display the
data initially.
Tip
See “.OPTION ACOUT” in the Eldo Reference Manual.
Related Topics
Compound Waveforms
Plotting, Printing and Probing
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Compound Waveforms
Specifying Simulation Output
Compound Waveforms
Eldo can generate compound waveforms. This is a group of waveforms containing results of
several simulations for the same “node.” They can be generated from multiple-run sweep
analyses specified for example by .STEP or .ALTER commands.
For an example, the EZwave output in Figure 8-1 shows three waveforms, each corresponding
to a .ALTER:
Figure 8-1. Compound Waveform Example
Related Topics
Plotting an Analog Signal as a Digital Bus
Plotting, Printing and Probing
Plotting an Analog Signal as a Digital Bus
To enable the plotting of an analog signal as a digital bus, a setup command is required
(.DEFPLOTDIG) to be used in conjunction with the VDIG parameter of the .PLOT command.
.DEFPLOTDIG VTH1=2.2 VTH2=2.7
.PLOT TRAN VDIG(n2)
When .DEFPLOTDIG is used in conjunction with .PLOT VDIG, the signal node n2 is plotted
as a digital curve and will only have values of “1” or “0”.
• .DEFPLOTDIG [VTH[1]=VAL [VTH2=VAL]]
Eldo® User's Manual, 15.3 315

Specifying Simulation Output
X-Axis of Waveforms
This is used as a precursor to VDIG to plot an analog curve as digital with reference to
any stated threshold voltage(s).
• VTH[1]=VAL
If a voltage threshold is specified, the bus of an analog signal is plotted as a bus
(hexadecimal format), else all the different signals of the bus are plotted separately in
the waveform viewer as analog waves. (VTH and VTH1 are equivalent to ensure
backwards compatibility.)
• VTH2=VAL
This can be used to plot the indeterminate value as shown below:
o
o
When only VTH1 is given: If value < VTH then logic state 0. If value > VTH then
logic state 1.
When both VTH1 and VTH2 are given: If value < VTH1 then logic state 0. If VTH1
< value < VTH2 then state X. If value > VTH2 then logic state 1.
Related Topics
Tip
See “.DEFPLOTDIG” in the Eldo Reference Manual.
X-Axis of Waveforms
Plotting, Printing and Probing
X-Axis of Waveforms
In general, the created waveforms have their X-axis implicitly defined by the corresponding
analysis. For example, the X-axis of a transient waveform is time, the X-axis of an AC
waveform is frequency, and so on. The X-axis for a transient waveform is defined by the
.TRAN tstep tmax command, it ranges from t=0 to t=tmax. The X-axis for an AC waveform is
defined by the frequency points in the .AC command. DC and NOISE waveforms also inherit
their X-axis from the corresponding analysis command (.DC or .NOISE).
For all analyses but the transient analysis, the X-axis range and the spacing of points in the
X-axis are thus predictable. For example, the frequency points in a .AC command are either
listed explicitly or regularly spaced, in a predictable way. For transient analysis however, this is
different. Eldo always uses a variable timestep algorithm, and the spacing of the timepoints
where the circuit is solved is dictated by accuracy considerations only (see the Speed and
Accuracy chapter). Thus the total number of timepoints is generally not predictable. By default,
all computed timepoints are stored in the binary output files, so that any rapid change or glitch
can be inspected visually in the waveform processor.
However, when working with large circuits and/or long transient simulations and/or storing
many waveforms, this may generate huge output files. The loading and post-processing of these
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Specifying Simulation Output
Tabular Listing Output
huge output files by the waveform viewers may thus be slower. In extreme cases, this may also
impact the simulation time, as writing gigabytes to a disk, possibly through a busy network,
may take quite a while. To control this, see the discussion on the options available for Limiting
the Size of Transient Output Files.
In the case of .EXTRACT waveforms, the X-axis is defined in either of the following ways:
• sweep parameter (for example .STEP, .TEMP)
• .ALTER index or .MC run index
In the case of multiple .STEP statements, the X-axis is defined by the last .STEP command. For
example:
.step param W 2u 10u 2u
.step temp -25 75 25
The extract waveforms will have temperature as the X-axis.
.step temp -25 75 25
.step param W 2u 10u 2u
The extract waveforms will have width as the X-axis.
Related Topics
Tabular Listing Output
Plotting, Printing and Probing
Tabular Listing Output
Use the .PRINTFILE command to define the contents of a tabular listing of any number of
output variables, and dump them to the specified file in ASCII format or as a .DATA statement.
Tip
See “.PRINTFILE” in the Eldo Reference Manual.
Related Topics
Plotting Transmission Lines
Plotting, Printing and Probing
Plotting Transmission Lines
Use the I(Txx.) syntax to print the current out of transmission lines:
Eldo® User's Manual, 15.3 317

Specifying Simulation Output
Dynamically Adding Voltage/Current Plots
I(Txx.N1) I(Txx.N2) I(Txx.N3) I(Txx.N4)
Related Topics
Plotting, Printing and Probing
Dynamically Adding Voltage/Current Plots
It is possible to dynamically add .PLOT or .PROBE commands while a “batch” simulation is
running (not interactive mode). This could be useful if a simulation takes days to run, and you
realize when analyzing waveforms during the simulation that you need additional waveforms to
be plotted. It is also possible to send these commands to simulations running on remote
machines—simulations submitted to external dispatchers.
The steps required to use the simulation manager functionality are as follows:
Procedure
1. Run a simulation with Eldo.
By default, Eldo opens a communication port on the host it is running after a delay and
not before the elaboration of the design is finished. The default delay value is set to 30s.
This value can be modified with:
.option CONNECT_DELAY=
Once the port is opened the simulator creates an empty file in directory $HOME/.eldo/.
This file is named after the host IP address and port number, for example:
185.909.693.175:76. This file is removed once the simulator exits.
Note
To avoid the cost of port listening and file creation the simulation manager
mechanism can be completely disabled with the Eldo command line argument -
noconnect.
2. Run the simulation manager with eldo -connect.
To begin an interactive exchange, run the simulation session manager by entering on the
local machine:
eldo -connect
Eldo will browse the directory $HOME/.eldo/ in search of running simulations. The
active simulations are listed with their command line. A prompt is displayed enabling
you to interact with the remote simulations with the available commands.
3. Connect to a simulation.
Use the connect command to open a communication channel with a simulation. When
successful, the Simulation Connection Manager displays:
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Specifying Simulation Output
Dynamically Adding Voltage/Current Plots
connection established, remote simulator is waiting for commands.
When you connect to a simulation (Id1 for example), Active is displayed in the
Connection column. If you then connect to a different simulation (Id2 for example), the
Connection status of simulation Id1 changes to Opened and Id2 becomes Active. For
example:
+------------------------------------------------------------------------------------------
| Id | Connection | Host | Simulator | Registration date | Input arguments
+------------------------------------------------------------------------------------------
| 1 | Opened | shamba | eldo | 2011-03-09 17:17:35 | test -compnet -outpath work
| 2 | Active | shamba | eldo | 2011-03-09 17:17:37 | test
| 3 | | shamba | eldo | 2011-03-09 17:18:19 | test
| 4 | | shamba | eldo | 2011-03-09 17:24:06 | test -compnet -outpath work
| 5 | | shamba | eldo | 2011-03-09 17:27:05 | test -compnet -outpath work
| 6 | | shamba | eldo | 2011-03-09 17:42:30 | test -compnet -outpath work
| | | | | |
| | | | | |
Once a simulation is connected Eldo will display the following in the simulation
transcript:
Note 54: Remote connection established. Simulation is suspended
until connection is closed.
4. Enter required .PLOT/.PROBE commands.
For example:
> .plot v(1)
Each command entered is sent to the simulation and Eldo will verify the request. If the
command is valid, the Simulation Connection Manager displays:
Command successfully transmitted.
Eldo will display the following in the simulation transcript:
Note 57: Remote command received: .plot v(1)
If the command is not valid, Eldo transmits any .PLOT/.PROBE related warnings back
to the Simulation Connection Manager.
You can also create a file of .PLOT/.PROBE commands and, using the load command
of the Simulation Connection Manager, load the file content; each command is sent to
the active simulation.
5. Disconnect (or quit) to resume the simulation.
Once a simulation is disconnected Eldo will resume simulation and display the
following in the simulation transcript:
Note 55: Remote connection closed. Simulation is resumed.
Eldo® User's Manual, 15.3 319

Specifying Simulation Output
Output Variables
The waveform database will contain the dynamically added plots beginning at the time
they were added.
Related Topics
Simulation Connection Manager
Plotting, Printing and Probing
Output Variables
The output commands require output variables to plot analysis results for voltages, currents,
conductances, capacitances, charges, power, noise, or device instance parameters.
The output variables used by Eldo are divided into the following categories:
• MOSFET Plotting and Printing
• BJT Plotting and Printing
• JFET Plotting and Printing
• Diode Plotting and Printing
• Common Plotting and Printing
• Element Output
• Two-port Parameters
In most cases, the analysis type also needs to be specified, particularly when you have multiple
types of analysis in the netlist file.
Tip
See “Output Quantities for Plotting and Printing” in the Eldo Reference Manual.
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Specifying Simulation Output
Extracting Information
Extracting Information
The .EXTRACT command is a fundamental and very powerful command in Eldo used to
extract circuit information from the results of simulation (analyses and waveforms).
.EXTRACT Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
Plot and Print Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Extract Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Extract Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Extraction Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Extract Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Eldo® User's Manual, 15.3 321

Specifying Simulation Output
.EXTRACT Command
.EXTRACT Command
The most frequent usage is for simple extraction of a waveform value, with the following
general form:
Syntax
.EXTRACT function(wave, condition, [min, max])
Parameters
• function
User supplied function that can be any of the built-in functions, or a user-defined function.
Some built-in functions:
o
o
o
Yval returns the value of an abscissa (Y-coordinate) corresponding to a given
ordinate (X-value).
Xyvalue returns the ordinate (X-Value) for which the abscissa (Y-value) satisfies a
given condition.
Xup gives the value of X when Y crosses a threshold in the upward direction, and so
on for other functions.
• wave
Name of the waveform to which the function is applied. The wave can be any usual Eldo
output, or a user-defined quantity supplied as a function of Eldo outputs.
• condition
Specifies a condition to be satisfied for the application of the .EXTRACT command. It can
be expressed using any of the Eldo operators, including any legal mathematical expression.
• min, max
A pair of values defining the start and end of the range over which the .EXTRACT
command applies. Specifying a min point higher than the max point is allowed, the analysis
will proceed backwards from max to min. This can be useful in tracking the last occurrence
of a given event.
If MIN and MAX are not specified in a function call, information is returned when the
CONDITION is true for the first time.
The x-axis values MIN and MAX may be replaced by the keywords START and END to
specify the beginning and end of the simulation interval respectively. The x-axis value MIN
may be made greater than the MAX value. This causes Eldo to look backwards when
CONDITION is true for the first time. This is useful for extracting waveform settling time
data.
An alternative to the .EXTRACT command is the .MEAS command, which provides
compatibility with the HSPICE simulator.
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Specifying Simulation Output
Plot and Print Quantities
Tip
See “.EXTRACT” in the Eldo Reference Manual.
Plot and Print Quantities
Plotting and printing commands can be specified as extract commands. The plot and print
quantities are generic, so the same syntax applies when specifying these in .EXTRACT
statements. For example the following command plots the drain current of a MOSFET model:
.plot DC ID(XA2.M1)
This can also be specified as an extract as follows:
.extract DC ID(XA2.M1)
LVnn (Element) syntax is used to obtain user-input parameters, the following example returns
the effective channel width:
.extract DC LV2(M1)
LXnn (Element) is used to obtain computed values such as charges, capacitances and
derivatives, the following example returns the Drain-Source voltage (VDS):
.extract DC LX3(M1)
When extraction statements are combined with parameter sweeping statements (for example
.STEP) Eldo automatically creates waveforms showing the extraction results versus the swept
parameter. For example, you may extract the width of an output pulse from a transient
simulation and sweep the power supply level, in which case Eldo will automatically create a
waveform showing the width of the pulse versus the power supply level. Similarly, if
extractions and .ALTER statements are combined, Eldo will automatically create waveforms
showing the extraction results versus the index of the .ALTER runs. In this case, the X axis will
contain 1, 2, 3, and so on. The initial display in the viewer can also be prepared using .PLOT
commands (see the .PLOT EXTRACT... description). For example:
.EXTRACT TRAN label=VMAX MAX(V(out))
.PARAM powersupply=1.2
VDD VDD 0 'powersupply'
.STEP PARAM powersupply list 1.2V 1.3V 1.4V 1.6 2V
.PLOT EXTRACT meas(VMAX) ! this will create a waveform
* showing VMAX(powersupply)
By default, using the .wdb format, the .EXTRACT waveforms are saved inside the EXT folder
in the main .wdb file. Specify option EXTFILE to generate a .ext.wdb file with only the
extraction results. The .ext.wdb file will not always be created as it depends on the type of
simulation and the specification of the .EXTRACT command.
Eldo® User's Manual, 15.3 323

Specifying Simulation Output
Extract Outputs
If using the .cou format, these .EXTRACT waveforms are created in a separate file with the .ext
extension. The command line switch -couext (eldo -couext -i ) can be used to
merge the extract waveforms into the .cou file, when possible. In this case, a single .cou file will
contain the raw waveforms and also the extraction waveforms.
Tip
See “Output Quantities for Plotting and Printing” in the Eldo Reference Manual.
Related Topics
Types of Waveforms
Extracting Information
Extract Outputs
Extraction results are displayed in the standard output, and written to the ASCII output log file
(.chi). To write results to a separate file two methods are available:
• Specify option AEX.
All extraction data is written to the file circuit_name.aex. Useful for sweep analysis.
• Specify FILE=filename parameter of the .EXTRACT command.
Results of the extract extraction are written to the file filename.
Related Topics
Tip
You can view extraction results with the AMS Results Browser.
Extracting Information
Extract Functions
There are two types of extraction language: transient and general purpose.
• Transient Extraction Language:
Used in transient analysis, these functions are faster to execute, and consumes less
memory because they perform measurements instantaneously at each time step. They do
not require the signals they use to be stored in memory. The disadvantage is that their
parameters can not use results from other measurements because they can not go back in
time (for example if VH or TCROSS is known at the end).
Transient extraction language is based on the following functions (links open the Eldo
Reference Manual):
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Specifying Simulation Output
Extract Functions
Table 8-2. Transient Extraction Language Functions
D_WA
Distance between two waveforms
DELTA
Difference between the value for the current run and the first run
DTC
Duty cycle
SLEWRATE Slope of waveform at threshold
TCROSS
Crossing point of waveform
TFALL
Fall time of waveform
TINTEG
Integral of waveform
TPD
Propagation delay between two waveforms
TPDDD
Propagation delay between wave1 and wave2 both falling
TPDDU
Propagation delay between wave1 falling and wave2 rising
TPDUD
Propagation delay between wave1 rising and wave2 falling
TPDUU
Propagation delay between wave1 and wave2 both rising
TPERIOD
Period for crossing of a y-axis value
TRISE
Rise time of waveform
VALAT
Value of waveform at specified time
• General Purpose Extraction Language:
These functions are more expensive in terms of memory and CPU, but much more
general in the sense that arguments can be expressions. General purpose extraction
language is based on the following functions (links open the Eldo Reference Manual):
Table 8-3. General Extraction Language Functions
AVERAGE Average value of a waveform
COMPRESS Compression point value of a waveform
CROSSING Crossing point value of a waveform
DCM
DC mismatch information
DISTO
Total harmonic distortion of a waveform
EVAL
Element parameter value
FAIL
Fail information
FALLING Falling value of a waveform
INTEG
Integral value of a waveform
Eldo® User's Manual, 15.3 325

Specifying Simulation Output
Extract Functions
KFACTOR
LOCAL_MAX
LOCAL_MIN
MAXGMVT
MAX
MEAN
MIN
MODPAR
OPMODE
PASS
PVAL
RISING
RMS
SLOPE
VDSATC
VTC
WFREQ
WINTEG
XCOMPRESS
XDOWN
XMAX
XMIN
XTHRES
XUP
XYCOND
YVAL
Table 8-3. General Extraction Language Functions (cont.)
Stability factor information
Local maximum value of a waveform
Local minimum value of a waveform
Extracting Values During DC Analysis
Not all pre-defined extract functions can be used in the DC domain. None of the functions using
a waveform as an argument can be used in a .EXTRACT DC command. For example, the
following cannot be used:
.EXTRACT DC AVERAGE (WAVE,[MIN,MAX])
Maximum transconductance threshold voltage for a MOS device
Maximum value of a waveform
Mean value of a waveform
Minimum value of a waveform
Value of a model parameter
DC working mode of the device model
Pass information
Value of a parameter
Rising value of a waveform
Root mean square value of a waveform
Slope of a waveform
Threshold voltage for a MOS device
Gate-source voltage for a MOS device
Average frequency value of a waveform
Time integral value of a waveform
Compression point x-axis value of a waveform
Falling x-axis value of a waveform
Maximum x-axis value of a waveform
Minimum x-axis value of a waveform
X-axis crossing point of waveform
X-axis rising value of a waveform
Value of waveform for condition
Y-axis value of waveform at given x-axis
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Specifying Simulation Output
Extraction Mode
The functions listed below can be used in DC and are useful to check design settings:
• EVAL
• MAXGMVT
• MODPAR
• OPMODE
• POW and POWER
• PVAL
Related Topics
Tip
See “.EXTRACT” in the Eldo Reference Manual.
Extracting Information
Extract Examples
Extraction Mode
To activate extraction mode, to perform measurements using waves stored in .wdb files, run
Eldo with the -extract argument. Eldo only performs the .EXTRACT and .MEAS commands,
without performing the simulations. Eldo will decorrelate the simulation from the extraction.
The extractions in the netlist will be solved using the corresponding waves contained in the
specified file. This functionality can also be specified with the netlist command .EXTMOD.
Multiple levels of extraction (a combination of .STEP, .ALTER, .DC SWEEP, and so on) are
not supported with the extraction mode.
The extraction mode is driven by the input waveform file. This means:
• The SPICE input file can contain .EXTRACT/.MEAS commands only, to reduce the
parsing time for large designs.
• All multiple-run commands specified in the netlist are ignored: .STEP, .MC, .TEMP,
.ALTER, and so on.
• Eldo loads the data from the input file, one analysis after another.
• The main purpose of the extract mode is to calculate extracts as fast as possible,
therefore Eldo does not save them in a new .wdb file by default; specify option
EXTMOD_GENWAVE to enable the saving.
• Eldo loads varying parameters (if available) from the input file and recreates a .STEPlike
structure. SWEEP extracts are not replayed because Eldo does not know how the
.STEP commands were ordered.
Eldo® User's Manual, 15.3 327

Specifying Simulation Output
Extraction Mode
Examples
eldo -outpath my_out -extract my_file.wdb
Eldo uses file my_out/my_file.wdb.
eldo -outpath my_out -extract ./my_file.wdb
Eldo uses ./my_file.wdb, because the path is explicitly relative to the working directory.
eldo -outpath my_out -extract /tmp/my_file.wdb
Eldo uses /tmp/my_file.wdb, because the path is absolute.
See Also
• -extract in the Eldo Reference Manual
• .EXTMOD in the Eldo Reference Manual
• .OPTION EXTMOD_GENWAVE in the Eldo Reference Manual
Related Topics
Extracting Information
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Specifying Simulation Output
Extract Examples
Extract Examples
This section lists a number of examples using the .EXTRACT command:
Example Extracting OPMODE, POW, and POWER Values . . . . . . . . . . . . . . . . . . . . . 329
Example Extracting Parameter Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Example Extracting Model Parameter Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Example Extracting Element Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Example Extracting Transient Analysis Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
Example of Condition Function Reusing Extraction Results . . . . . . . . . . . . . . . . . . . . . 332
Example Combining Sweep Extract and .ALTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
Extracting Compression Point Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
Example Extracting OPMODE, POW, and POWER Values
This example focuses on the OPMODE, POW, and POWER extract functions in DC analysis
mode.
Prerequisites
• This example uses the extract_overshoot_opamp.cir netlist in $MGC_AMS_HOME/
examples/eldo/
Procedure
1. Open the extract_overshoot_opamp.cir netlist in your preferred text editor, then add
these extract commands to the netlist, then save it:
.extract POW(XA3)
.extract POWER
.extract OPMODE(XA2.M*)
2. Run the simulation:
eldo extract_overshoot_opamp.cir
3. View the extract results in the standard output or open the .chi file.
Results
• The first extract is a measure of the DC power absorbed by instance XA3.
• The second extract is a measure of the total DC power.
• The third extract measures the operating mode of all transistors inside XA2.
Output listing:
Eldo® User's Manual, 15.3 329

Specifying Simulation Output
Extract Examples
* POW(XA3) = 2.6784E-003 Watt
* POWER = 2.1469E-002 Watt
* OPMODE(XA2.M1) = subthreshold
* OPMODE(XA2.M2) = subthreshold
* OPMODE(XA2.M3) = subthreshold
* OPMODE(XA2.M4) = linear
* OPMODE(XA2.M5) = linear
* OPMODE(XA2.M6) = subthreshold
* OPMODE(XA2.M7) = subthreshold
* OPMODE(XA2.M8) = subthreshold
* OPMODE(XA2.M9) = subthreshold
* OPMODE(XA2.M10) = linear
* OPMODE(XA2.M11) = subthreshold
* OPMODE(XA2.M12) = subthreshold
* OPMODE(XA2.M13) = linear
* OPMODE(XA2.M14) = subthreshold
* OPMODE(XA2.M15) = saturation
* OPMODE(XA2.M16) = linear
* OPMODE(XA2.M17) = linear
* OPMODE(XA2.M18) = linear
* OPMODE(XA2.M19) = linear
* OPMODE(XA2.M20) = saturation
* OPMODE(XA2.M21) = saturation
Related Topics
Extracting Information
Extract Examples
Example Extracting Parameter Values
This example focuses on the PVAL (Parameter VALue) extract function in DC analysis mode.
PVAL is a predefined function returning the value of the parameter requested. The example
shows how to plot an extract versus a parameter when the parameter is swept with the .ALTER
command:
Procedure
1. Run Eldo on the netlist shown below. This example extracts both the original extract and
the parameter value.
R1 1 0 rval
V1 1 0 dc 1
.param rval=1
.dc
.extract dc label=ir i(r1)
.extract pval(rval)
.alter
.param rval=10
.alter
.param rval=100
2. Open the generated .wdb file in EZwave, and display both extracts in the same graph.
330
Eldo® User's Manual, 15.3

3. Right-click on the sweep parameter name, and select “Set as X axis.”
Related Topics
Extracting Information
Extract Examples
Specifying Simulation Output
Extract Examples
Example Extracting Model Parameter Values
This example focuses on the MODPAR (MODel PARameter) extract function in DC analysis
mode. MODPAR is a predefined function returning the value of a model parameter. This
function is useful to extract a parameter value of a model defined inside a subcircuit.
Run Eldo on the netlist shown below:
.subckt mysub d g s b p1=0.2
.model mymod NMOS
+VT0=1.2 PHI=0.6
M1 d g s b model=mymod w=1u l=1u
.ends
X1 d g 0 0 mysub p1=0.1
X2 d g 0 0 mysub p1=0.3
Vd d 0 dc 1
Vg g 0 dc 1
.op
.extract dc label=vto modpar(mysub.mymod,vt0)
.extract dc label=phi modpar(mysub.mymod,phi)
.end
View the extract results in the standard output or open the .chi file.
VT0 = 1.2000E+00
PHI = 6.0000E-01
Tip
See “MODPAR” function in the Eldo Reference Manual.
Related Topics
Extracting Information
Extract Examples
Example Extracting Element Values
This example focuses on the EVAL (Element VALue) extract function in DC analysis mode.
EVAL is a predefined function returning the value of the requested parameter for the circuit
element name.
Eldo® User's Manual, 15.3 331

Specifying Simulation Output
Extract Examples
.EXTRACT DC EVAL(X_A.M1,AD)
This extracts the drain area (AD) of MOSFET M1 in subcircuit instance X_A.
Additional parameters are available for MOSFET devices, for example:
.EXTRACT DC EVAL(X_B.M1,Weff)
This extracts the effective width (Weff) of MOSFET M1 in subcircuit instance X_B.
Related Topics
Extracting Information
Extract Examples
Example Extracting Transient Analysis Values
The transient start and stop times can be extracted as follows:
.extract tran label=tstart xmin(time)
.extract tran label=tstop xmax(time)
The combination of xmax/xmin functions with the time (or freq) keyword shows one way to use
the time (or freq) keyword in .EXTRACT statements.
If the transient analysis was specified as follows:
.tran 2ns 100ns 50ns uic
The extract results from the standard output or the .chi file would be:
TSTART = 5.0000E-08
TSTOP = 1.0000E-07
Related Topics
Extracting Information
Extract Examples
Example of Condition Function Reusing Extraction
Results
This example shows how the XYCOND() extract function conditions reusing extraction results.
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Specifying Simulation Output
Extract Examples
.step param p1 1 10 0.5
.extract tran label=idsm1 yval(ids(m1), 50n)
.extract sweep label=idsm1_min min(extract(idsm1))
.extract sweep label=p1_idsm1_min
+ xycond(xaxis, extract(idsm1)==extract(idsm1_min))
The first extract command finds the value idsm1 for each step. The second extract command
finds the minimum of idsm1 over the sweep. The third extract command finds the p1 value
corresponding to idsm1_min.
Related Topics
Extracting Information
Extract Examples
Example Combining Sweep Extract and .ALTER
This example shows how the sweep extract also works on waveforms generated from an
.EXTRACT combined with a .ALTER.
The example is based on the loop_stability_opamp.cir netlist in $MGC_AMS_HOME/
examples/eldo/, with some changes to the inputs, extracts, and with the addition of a .ALTER
block.
VINP INP 0 AC 1 0
VINN INN 0 AC 1 0
...
.ac dec 10 1 1e8
.plot ac v(out)
.extract ac label=G400M yval(vdb(out),1k)
.alter DM_GAIN
VINP INP 0 AC 0.5 90
VINN INN 0 AC 0.5 -90
.extract sweep label=CMRR yval(meas(G400M),1)-yval(meas(G400M),0)
The first extract command, labeled G400M, finds the y-axis value of the waveform vdb(out) at
1kHz. The .ALTER block, DM_GAIN, replaces the opamp input voltage sources with a
differential input where VINP is shifted in phase from VINN and extracts the G400M
information again. The .EXTRACT SWEEP command in the .ALTER block finds the
difference between the two extracted y-axis values to generate the CMRR result (ratio of the
differential mode gain and common mode gain).
Extract
Alter index0 G400M
Alter index1 G400M
CMRR
Value
-1.4292E+01
6.5083E+01
7.9375E+01
Eldo® User's Manual, 15.3 333

Specifying Simulation Output
Extract Examples
Related Topics
Extracting Information
Extract Examples
Extracting Compression Point Values
The COMPRESS/XCOMPRESS functions extract the co-ordinates of a compression point in
the curve specified in the first parameter of the function. XCOMPRESS provides the X-value
and COMPRESS the Y-value.
This compression point is the point where the curve is value below the straight line defined by
the slope of the curve at the origin. (value is the second parameter of the function.)
In the illustration above, the curve is meas(POUTDBm), and the compression (value) is 1.0
dBm.
Note
When these functions are used to extract compression points, the swept parameter (X-axis)
and the curve (Y-axis) must be in dB (or dBm).
Example
* 1dB compression point
.param fund=900Meg
.extract fsst label=POUTdBm YVAL(PdBm(RL), fund)
.extract sweep xcompress(meas(POUTdBm), 1.0)
.extract sweep compress(meas(POUTdBm), 1.0)
Related Topics
Extracting Information
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Specifying Simulation Output
Extract Examples
Extract Examples
Eldo® User's Manual, 15.3 335

Specifying Simulation Output
Defining Waveforms
Defining Waveforms
Use the .DEFWAVE command to define a new waveform by relating previously defined
waveforms and nodes. Some usage notes follow:
• Combining the .PLOT command with the .DEFWAVE command can be used to
generate so-called template waveforms, that is, piece-wise-linear waveforms defined by
a series of arbitrary (x,y) coordinates. Using .PLOT, these templates can be displayed
together with the simulation results (this is very useful when verifying whether a filter
response passes or not specifications such as cutoff frequencies, minimum attenuation,
and so on). For example:
.DEFWAVE FILTERSPEC=PWL(1e-3,0,100k,0,500k,-60,100G,-60)
.PLOT AC VDB(OUT) W(FILTERSPEC)
• Waveform definitions can be specified inside subcircuit definitions. Identical complex
calculations can be performed for each instance of the subcircuit. Typically the
subcircuit is declared once and instanced many times. This means there is no need to
have many instances of the same subcircuit with definitions of .DEFWAVE and .PLOT
for each. Eldo only calculates the .DEFWAVE statements that are called, not all
.DEFWAVE statements declared.
• Waveform names cannot contain arithmetic operators.
• Waveform names cannot contain the hierarchical separator: the period character “.”.
• Only one waveform may be defined per .DEFWAVE statement.
• It is not possible to use functions which expect at least one waveform as input.
• Built-in PPL functions that act on a waveform cannot be used in Tcl procs that are called
from .DEFWAVE statements. This is because .DEFWAVE expressions represent a
numerical value, and not a waveform.
• A wave is instantiated by preceding the wave name w, which can be followed by a
format suffix for complex waveforms, for example: wm, wdb, wp, wi, wr are enclosed
in parentheses ().
• A waveform expression cannot contain a division by zero. If this is the case, 1.0×10 -15 is
automatically assigned to a value.
• The .DEFWAVE command is order dependent in that all components of the waveform
expression must have already been defined earlier in the netlist. The following is illegal:
.defwave power_vdd=i(v1)*v(v1)
*...
v1 in out ...
However, the following is allowed:
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Specifying Simulation Output
Examples of Defining Waveforms
v1 in out ...
*...
.defwave power_vdd=i(v1)*v(v1)
• The waveform expression must consist of waves and functions which are related to the
type of analysis being performed as described in the .PLOT/PRINT commands. The
following is illegal and will produce false results:
.defwave amplification=v(2)/v(1)
*...
.plot ac w(amplification)
However, the following is allowed:
.defwave amplification=vm(2)/vm(1)
*...
.plot ac wdb(amplification)
• The waveform expression may use the result of some extracts from a sweep analysis
through direct reference to the label holding the result or use of the EXTRACT()
accessor function. The following is allowed:
.extract label=m1 yval(v(1),5n)
.defwave tran foo=v(1)+extract(m1) ! using the accessor function
.extract sweep label=m2 min(extract(m1))
.extract sweep label=m3 yval(extract(m1),2.5)
The following alternative is also allowed:
.extract label=m1 yval(v(1),5n)
.defwave tran foo=v(1)+m1 ! direct reference to the extract label
.extract sweep label=m2 min(m1)
.extract sweep label=m3 yval(m1,2.5)
• The PWL function in .DEFWAVE can not be used in complex expressions. An error
will be generated if the .DEFWAVE uses the function with other operators or
mathematical functions. The following is not accepted:
.defwave tran f1 = 1 + pwl(5n,0,7n,5,8n,5,9n,1)
However, the following is allowed:
.defwave tran f1 = pwl(5n,0,7n,5,8n,5,9n,1)
Examples of Defining Waveforms
Plot the AC power of the vxx voltage source:
.defwave powf = 0.5*(vdip(vxx) * CONJ(I(vxx)))
.plot ac wr(powf)
Example of applying a wave operator:
Eldo® User's Manual, 15.3 337

Specifying Simulation Output
Examples of Defining Waveforms
.EXTRACT LABEL = A MAX(V(1))
.EXTRACT LABEL = B MAX(V(2))
.STEP PARAM P1 1 3 1
.DEFWAVE SWEEP my_wave = MEAS(a) + MEAS(b)
.end
Example using the SIGMA function to sum various items (numbers, parameters or output
quantities); when items are output quantities, wildcards are accepted:
.EXTRACT dc SIGMA(v(*),1.0,'p1+2')
.DEFWAVE tran star3=SIGMA(ISUB(X2*.g),V(E*))
Example of using the PWL function:
v1 1 0 pwl ( 0 0 10n 10)
r1 1 0 1
.defwave tran foo = pwl(0,0,20n, meas(ex))
.extract label = ex yval(v(1),5n)
.tran 1n 10n
.plot tran w(foo)
.end
Example of using the PWL, PWL_CTE and PWL_LIN functions.
v1 1 0 pwl ( 0 0 10n 10)
r1 1 0 1
.defwave tran f1 = pwl(5n,0,7n,5,8n,5,9n,1)
.defwave tran f2 = pwl_cte(5n,0,7n,5,8n,5,9n,1)
.defwave tran f3 = pwl_lin(5n,0,7n,5,8n,5,9n,1)
.defwave tran f4 = pwl_lin(5n,0, 5n, 5)
.defwave tran f5 = pwl_lin(0n, 5)
.extract label = ex yval(v(1),5n)
.tran 1n 10n
.plot tran w(f1) w(f2) w(f3) w(f4) w(f5)
.end
The plot obtained from the netlist is shown in Figure 8-2. The wave f4 demonstrates how to plot
vertical waves with the .DEFWAVE command.
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Specifying Simulation Output
Examples of Defining Waveforms
Figure 8-2. Defining Waveforms: PWL, PWL_CTE and PWL_LIN Functions
The example below shows how waveform definitions can be specified inside subcircuit
definitions. In this example, the sat curves for both devices are plotted, even though they are
calculated differently.
Eldo® User's Manual, 15.3 339

Specifying Simulation Output
Examples of Defining Waveforms
.subckt nmos d g s b
m1 d g s b nmos w=10u l=1u
.defwave sat=vds(m1)-vdss(m1)
.defwave varI=(0.59*gm(m1)*gm(m1)+1.133*ids(m1)*ids(m1))*5u*1u
.ends
.subckt pmos d g s b
m1 d g s b pmos w=5u l=1u
.defwave sat=vdss(m1)-vds(m1)
.defwave varI=(0.79*gm(m1)*gm(m1)+1.589*ids(m1)*ids(m1))*5u*1u
.ends
x0 g g s b nmos
x1 d g s b nmos
x2 d g s b pmos
.plot dc w(x0.sat) w(x1.sat) w(x2.sat)
.defwave Ioffset=sqrt(w(x0.varI)+w(x1.varI)+w(x2.varI))
.plot dc w(Ioffset)
Tip
See “.DEFWAVE” in the Eldo Reference Manual.
Related Topics
Plotting, Printing and Probing
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Safe Operating Area (SOA) Checks
Specifying Simulation Output
Safe Operating Area (SOA) Checks
You can detect when a component is used outside safe operating area (SOA) limits. The SOA
can also be used to verify min-max measurements. A warning will be generated during the
simulation and displayed to the standard output and inside the .chi file. You can specify a
separate file to write SOA results to. They can also be plotted for display in EZwave.
Tip
You can view safe operating area violations with the AMS Results Browser.
Two commands are available for use with specifying and checking the safe operating area:
• .SETSOA
Specifies the safe operating area limits for devices, model parameters, or expressions.
This can be defined in the netlist or any device library.
See “.SETSOA” in the Eldo Reference Manual.
• .CHECKSOA
Checks the safe operating area limits previously set using .SETSOA.
See “.CHECKSOA” in the Eldo Reference Manual.
Plotting Safe Operating Area Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Safe Operating Area Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
Plotting Safe Operating Area Limits
Use the output quantity SOA(identifier) for .PLOT and .PROBE commands. This quantity only
applies to .wdb (EZwave) output because it creates an assertion bus type object. The following
syntaxes can be specified to create assertion buses:
• Generic command:
.probe [analysis] SOA
This will probe all .SETSOA commands in a design.
• SOA output quantity for subcircuit instance:
.probe|.plot SOA(xinst)
This will probe/plot all .SETSOA commands inside subcircuit instance named xinst.
• SOA output quantity for device:
.probe|.plot SOA(device)
Eldo® User's Manual, 15.3 341

Specifying Simulation Output
Plotting Safe Operating Area Limits
This will probe/plot all .SETSOA commands related to device name device.
• SOA output quantity for SOA identifier:
.probe|.plot SOA(full_name)
This will probe/plot a specific .SETSOA command as soon as full_name is a valid fully
qualified .SETSOA identifier. The default naming rule for a fully qualified identifier is:
where:
o
o
o
##
device is the device name when the SOA applies to a device.
FileName is the name of the netlist file containing the SOA.
Line is the line number of the SOA in the associated netlist file.
For example:
.probe tran SOA(XM7.M1#test.cir#13)
This will probe the .SETSOA command in line 13 of netlist file test.cir for device M1
inside instance XM7.
To change the format of the identifier, see “Modifying the SOA Identifier Format” on
page 344.
The PROBE keyword of the .CHECKSOA command can be used to save all output quantities
(waveforms) specified in .SETSOA commands, but it does not create SOA assertion buses.
EZwave displays SOA violations as an assertion bus that contains the simulated waveform(s),
related to the .SETSOA statements, upon which they rely.
Table 8-4 summarizes the graphic elements for SOA limits used in the EZwave graph window:
Table 8-4. Graphic Elements for SOA Limits
Graphic Element Cursor Label Meaning
Blue line inactive SOA is inactive
Green line active SOA is active
Red line fail SOA failed
Green triangle active_pass SOA passed
Red triangle with horizontal red
line below
Inverted red triangle with
horizontal red line above
fail_failDown
fail_failUp
SOA failed, crossed the lower
boundary
SOA failed, crossed the upper
boundary
342
Eldo® User's Manual, 15.3

Specifying Simulation Output
Plotting Safe Operating Area Limits
Example
*SOA check
.model n npn
r1 in out 10k
c1 out 0 1p
q1 c b 0 0 n
rl c vdd 1k
vin in 0 pwl 0 0 1n 10 20n 10 21n 100
vdd vdd 0 5
vb b 0 pwl 0 -1 40n 1
.setsoa label="DEVICE1" d r1 i=(*, 3m)
.setsoa label="MODEL1" m n ic=(-1u, 3m)
.checksoa file=test.soa
.option eps=1u
.tran 1n 50n
.probe tran SOA
.end
The first .SETSOA command specifies a current limit of 3mA for resistor device R1. The
second .SETSOA command specifies a collector current limit of between −1μA and 3mA for
any BJT model of name n. With the .PROBE TRAN SOA statement present, the EZwave output
displays when the SOA is exceeded, see Figure 8-3.
Figure 8-3. EZwave Display of SOA Limits Assertion Bus
Eldo® User's Manual, 15.3 343

Specifying Simulation Output
Plotting Safe Operating Area Limits
Note
There is a shift between the x values printed in the .chi file (or saved SOA file) and the .wdb
output because in the .chi file they are interpolated, but in the .wdb the events/data points are
synchronized with time steps.
Modifying the SOA Identifier Format
It may be difficult to identify the .SETSOA command in EZwave using the default naming
convention for SOA identifiers, option SOA_WAVE_FORMAT="value" can be used to control
the format of the identifier. The value of the option is a string, composed of several predefined
tokens identifying an element of a .SETSOA command:
• %label provides the LABEL specification of the .SETSOA.
• %code provides the SOACODE specification of the .SETSOA.
• %file provides the filename where the .SETSOA command is defined.
• %line provides the line in the file where the .SETSOA command is defined.
The complete waveform name is built using the instance/device name together with a VHDL
extended syntax suffix. For example, with the following:
.option SOA_WAVE_FORMAT="%code%file%line%label"
.setsoa tran SOACODE=1011 LABEL=foo ...
EZwave displays: SOA(XM7.M1\code:1011\\file:test.cir\\:line:12\\label:foo\)
A token may be specified more than once. For the following example:
.option SOA_WAVE_FORMAT="%code%code"
.setsoa tran SOACODE=1011 LABEL=foo ...
EZwave displays: SOA(XM7.M1\code:1011\\code:1011\)
TSMC SOA Support in Eldo
Eldo supports the TSMC Safe Operating Area check functionality. Parameters are provided in
the .MODEL statements for MOSFET, BJT, and Diode devices, and in both .MODEL
statements and instances for Resistor and Capacitor devices. The .CHECKSOA command
enables the TSMC SOA checks, unless option SWARN=0 is set. Alternatively, if there is no
.CHECKSOA option but option SWARN=1, then only the TSMC SOA are checked, not the
.SETSOA statements. (See option “SWARN” in the Eldo Reference Manual.)
Eldo supports TSMC SOA versions v0.4 and v0.5. TSMC SOA is different to the TMI SOA,
which is the SOA of the TSMC Modeling Interface (TMI). For further information, refer to the
TSMC SOA specification document.
344
Eldo® User's Manual, 15.3

See Also
• .CHECKSOA in the Eldo Reference Manual
• .SETSOA in the Eldo Reference Manual
• .OPTION SOA_WAVE_FORMAT in the Eldo Reference Manual
Related Topics
Safe Operating Area (SOA) Checks
Safe Operating Area Examples
Listing of examples to check safe operating area limits.
• The following examples check specific instantiations:
o
Check VDS(X1.M2) > 1.2V:
.SETSOA D X1.M2 VDS=(*,1.2)
.CHECKSOA
The following results will be generated in the .chi file:
*| X1.M2:
*| VDS(X1.M2)
*| X AXIS WINDOW: [ 0.00000 11.23011N ]
*| Value superior to 1.200000e+00
*| X AXIS WINDOW: [ 23.21157N 31.23011N ]
*| Value superior to 1.200000e+00
*| X AXIS WINDOW: [ 43.21157N 50.00000N ]
*| Value superior to 1.200000e+00
Total number of SOA instances : 1
Total number of violations : 3
Specifying Simulation Output
Safe Operating Area Examples
o
Check VTH(X2.M2) < 0.8V:
.SETSOA D X2.M2 VT=(0.8,*)
.CHECKSOA
The following results will be generated in the .chi file:
*| X2.M2:
*| VT(X2.M2)
*| X AXIS WINDOW: [ 5.14767N 10.04472N ]
*| Value inferior to 8.000000e-01
*| X AXIS WINDOW: [ 10.34305N 11.14998N ]
*| Value inferior to 8.000000e-01
*| X AXIS WINDOW: [ 12.45232N 24.34917N ]
Value inferior to 8.000000e-01
Total number of SOA instances : 1
Total number of violations : 3
Eldo® User's Manual, 15.3 345

Specifying Simulation Output
Safe Operating Area Examples
• The following example checks a model; it checks for all transistors abs(IDS) > 10μA for
more than 3ns, during the first 50 ns:
.SETSOA M NMOS ID(*)=(-10u,10u,3n)
.CHECKSOA TSTART=0 TSTOP=50n
The following results will be generated in the .chi file:
*| ID(X1.M2)
*| X AXIS WINDOW: [ 10.35049N 14.29079N ]
*| Both MIN (-1.000000e-05) and
*| MAX (1.00000e-05) values violated
*| for more than 3.00000N
*| X AXIS WINDOW: [ 30.35063N 34.29079N ]
*| Both MIN (-1.000000e-05) and
*| MAX (1.00000e-05) values violated
*| for more than 3.00000N
Total number of SOA instances : 1
Total number of violations : 2
• The following example checks an expression; it checks the absolute value of the sum of
2 Nmos drain currents < 100μA:
.SETSOA E ABS(ID(X1.M2)+ID(X2.M2)) = (*,100U)
.CHECKSOA
The following results will be generated in the .chi file:
*|ABS(ID(X1.M2)+ID(X2.M2))
*| X AXIS WINDOW: [ 10.44101N 46.03154N ]
*| Value superior to 1.000000e-04
Total number of SOA instances : 1
Total number of violations : 1
• The following is an example of SOA check syntax for device parameters (D), model
parameters (M) and Eldo expressions (E):
346
Eldo® User's Manual, 15.3

Specifying Simulation Output
Safe Operating Area Examples
SOA check
.width out=80
.model n npn
r1 in out 10k
c1 out 0 1p
q1 c b 0 0 n
rl c vdd 1k
vin in 0 pwl 0 0 1n 10 20n 10 21n 100
vdd vdd 0 5
vb b 0 pwl 0 -1 40n 1
.setsoa d r1 i=(*, 3m)
.setsoa m n ic=(-1u, 3m)
.setsoa e IC(q1)/IB(q1)=(*, 100)
.checksoa
.option eps=1u
.tran 1n 40n
.plot tran v(out)
.plot tran i(r1) ib(q1) ic(q1)
.end
This produces the following warning on screen (or in the .log file, if you are simulating
in background):
Warning 1897: SOA DETECTION: See output file soa.chi for details.
The following results will be obtained in the .chi file:
0*SOA check
0**** SOA INFORMATION (TRANSIENT ANALYSIS)TEMPERATURE = 27.000 DEG C
0******************************************************************
*| R1:
*| I(R1)
*| X AXIS WINDOW: [ 20.32351N 31.73644N ]
*| Value superior to 3.000000e-003 (up to 8.691883e-003 )
*| IC(Q1)/IB(Q1)
*| X AXIS WINDOW: [ 28.46930N 32.91922N ]
*| Value superior to 1.000000e+002 (up to 1.155804e+002 )
*| Q1: model=N
*| IC(Q1)
*| X AXIS WINDOW: [ 35.33005N 40.00000N ]
*| Value superior to 3.000000e-003 (up to 4.972460e-003 )
Total number of SOA instances : 3
Total number of violations : 3
• In the following example, two cards will be kept: the one in xsub corresponding to X1;
and the top level card .SETSOA D X1.R1.
Eldo® User's Manual, 15.3 347

Specifying Simulation Output
Safe Operating Area Examples
* Restrict SOA to list subckt instances
.model resis res r= 1k dev/gauss=10%
.subckt xsub a b
r1 a b resis 1k
.setsoa E I(R1)=(1.80u,1.90u) ! ((3 + D(M1,L)*2.0E+6) ) ) THEN V(G,S)=(*,0.3,2n) endif
• .SETSOA command in the Eldo Reference Manual
• .CHECKSOA command in the Eldo Reference Manual
Related Topics
Safe Operating Area (SOA) Checks
348
Eldo® User's Manual, 15.3

Specifying Simulation Output
High Impedance Node Checks
High Impedance Node Checks
A high impedance node (Hi-Z) refers to a circuit node in high impedance state. Eldo detects
circuit Hi-Z states by checking the dynamic behavior of all nodes. This detection method works
on any circuit topology and applies to all device types.
Tip
You can view high impedance detections with the AMS Results Browser.
How to Enable High Impedance Node Checks
To enable high impedance node checks use one of the commands: .DCHIZ, .HIZ,
.OPTION ADIT_CHECK.
Hi-Z detection is controlled by two parameters: GFLOAT_MAX and HIZ_TIME.
The Hi-Z detection algorithm evaluates nodes’ conductance as well as voltage and current
convergence criteria. This method allows more accurate and comprehensive Hi-Z detection
compared to just evaluating conductance or voltage. Instead of having to control three
parameters, namely voltage, current and conductance, a pseudo-conductance value
(GFLOAT_MAX) is provided as the controlling parameter for the algorithm. The guideline is
to set GFLOAT_MAX close to the conductance at Hi-Z; it does not set the exact conductance
limit in which nodes are reported as Hi-Z. You can use GFLOAT_MAX to increase or decrease
the number of nodes reported as Hi-Z. The default value is 1e-7. The smaller the
GFLOAT_MAX value, the less number of nodes to be reported as Hi-Z.
HIZ_TIME can be used to report only nodes that stay in Hi-Z state for longer than a specified
time. The default value is 0, which means a node in Hi-Z state is reported as soon as it is
detected at each transient time point. Reporting instantaneous Hi-Z states can generate massive
reports and raise false alarm. It is recommended to define HIZ_TIME appropriately to only
highlight significant Hi-Z states.
In the circuit check report, Hi-Z nodes are categorized into two groups:
• [HiZ_NULL_FANOUT] means the Hi-Z node does not drive any devices (has no
fanout).
• [HiZ] means the Hi-Z node drives some devices.
Example Hi-Z check report from .OPTION ADIT_CHECK:
[HiZ]:node(x1.n0) Hi-Z status from 1.58204e-05 to 5e-05
[HiZ_NULL_FANOUT]:node(x1.nms) Hi-Z status from 0 to 5e-05
[HiZ_NULL_FANOUT]:node(x1.nps) Hi-Z status from 0 to 5e-05
Example Hi-Z check report from .HIZ command:
Eldo® User's Manual, 15.3 349

Specifying Simulation Output
High Impedance Node Check Examples
INTCLK :
X AXIS WINDOW: [0.0 4.907E-06]Impedance min: 6.355E+07 | max: 1.858E+11 | average: 9.283E+09
N12OK :
X AXIS WINDOW: [0.0 6.544E-06]Impedance min: 2.924E+08 | max: 4.544E+11 | average: 9.459E+10
NET21 :
X AXIS WINDOW: [2.048E-08 5.876E-06]Impedance min: 1.420E+07 | max: 1.507E+11 | average:
9.603E+10
X AXIS WINDOW: [8.648E-06 9.292E-06]Impedance min: 1.045E+07 | max: 1.652E+11 | average:
1.593E+11
NET22 :
X AXIS WINDOW: [2.048E-08 5.876E-06]Impedance min: 1.268E+07 | max: 1.562E+11 | average:
1.034E+11
X AXIS WINDOW: [8.643E-06 9.294E-06]Impedance min: 1.736E+07 | max: 1.652E+11 | average:
1.518E+11
NET23 :
X AXIS WINDOW: [0.0 1.551E-06]Impedance min: 6.806E+07 | max: 2.368E+09 | average: 6.699E+08
X AXIS TIME: 3.588E-06 Impedance: 8.154E+07
X AXIS WINDOW: [3.714E-06 3.965E-06]Impedance min: 2.518E+07 | max: 8.157E+07 | average:
4.615E+07
X AXIS WINDOW: [6.503E-06 7.299E-06]Impedance min: 1.419E+07 | max: 2.977E+09 | average:
2.819E+09
X AXIS WINDOW: [9.298E-06 9.322E-06]Impedance min: 1.255E+07 | max: 3.656E+10 | average:
1.664E+10
X AXIS WINDOW: [9.480E-06 1.000E-05]Impedance min: 1.026E+07 | max: 1.186E+07 | average:
1.123E+07
See Also
• .HIZ in the Eldo Reference Manual
• .OPTION ADIT_CHECK in the Eldo Reference Manual
Related Topics
High Impedance Node Check Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
High Impedance Node Check Examples
In this example Eldo only checks the nodes connected to a gate through resistors or voltage
sources, that is, inside the subcircuit pass_gate the nodes input1, input2 and n2 are checked. All
nodes which have an equivalent impedance higher than 1e8 are displayed.
350
Eldo® User's Manual, 15.3

Specifying Simulation Output
High Impedance Node Check Examples
***** Pass Gate Example *******
.HIZ type=gate r=1e8
.subckt pass_gate input1 input2 output
mp1 vdd input1 n1 vdd pmos L=5e-7 W=2e-5
mn1 n1 input1 0 0 nmos L=8E-07 W=2E-06
mn3 n2 input2 n1 0 nmos L=8E-07 W=2E-06
mp2 vdd n2 output vdd pmos L=5e-7 W=2e-5
mn2 output n2 0 0 nmos L=8E-07 W=2E-06
.ends
vdd vdd 0 3.3
vin1 in1 0 pwl (0 0 9n 0 10n 3.3 15n 3.3 15.5n 0)
vin2 in2 0 pwl (0 5.3 2n 5.3 4n 5.3 10n 4.3 12n 0)
x1 in1 in2 out pass_gate
r1 out 0 1k
.probe tran V I
.plot tran vgs(*) vgd(*) vds(*)
.tran 20u 20u
.end
No report file is specified on the command, so the HiZ information is written to the .chi file, for
example:
***HIGH IMPEDANCE DETECTION
TRANSIENT ANALYSIS
TEMPERATURE = 2.7000E+01 Celsius
*> X1.N2 :
*> X AXIS WINDOW: [6.740E-09 9.819E-09]
Impedance min: 2.725E+08 | max: 9.999E+11 | average: 8.478E+11
*> X AXIS WINDOW: [1.172E-08 2.000E-05]
Impedance min: 8.150E+08 | max: 9.997E+11 | average: 9.859E+11
See Also
• .HIZ in the Eldo Reference Manual
• .OPTION ADIT_CHECK in the Eldo Reference Manual
Related Topics
High Impedance Node Checks
Tutorial—High Impedance Fault Detection of a PLL Circuit
Eldo® User's Manual, 15.3 351

Specifying Simulation Output
Limiting Output Information
Limiting Output Information
The following options can be specified to limit the quantity of output information written to the
.chi file.
• .OPTION LIMPROBE (in the Eldo Reference Manual)
Sets the maximum number of nodes that may be monitored via the .PROBE command.
• .OPTION NOASCII (in the Eldo Reference Manual)
Disables the printing of the output waveforms and print tables in the ASCII output .chi
file.
• .OPTION NOASCIIPLOT (in the Eldo Reference Manual)
Set by default. Disables the printing of the output waveforms in the ASCII output .chi
file. Print tables are still generated.
• .OPTION NODCINFOTAB (in the Eldo Reference Manual)
Disables the printout of the DC node information in the ASCII output .chi file.
• .OPTION NOMOD (in the Eldo Reference Manual)
Suppresses the printout of the model parameters in the ASCII output .chi file.
• .OPTION NOOP (in the Eldo Reference Manual)
Suppresses the printing of operating point (OP) table in the ASCII output .chi file.
• .OPTION NOTRC (in the Eldo Reference Manual)
Suppress the rewriting of the circuit description file in the ASCII output .chi file.
• .OPTION PREVENT_TRUNCATE_EXPRESSION_REPRESENTATION=0 (in the
Eldo Reference Manual)
Prevents the truncation of the string representation of long expressions in the simulation
outputs.
• .OPTION PRINT_ACCT=0 (in the Eldo Reference Manual)
Disables the printing of accounting information in the ASCII output .chi file.
• .OPTION PRINT_ACOP=0 (in the Eldo Reference Manual)
Disables the printing of the operating point information in the ASCII output .chi file
when a .AC analysis is specified.
• .OPTION PRINT_DC=0 (in the Eldo Reference Manual)
Disables the printing of the initial transient solution (or small signal bias) in the ASCII
output .chi file.
352
Eldo® User's Manual, 15.3

• .OPTION PRINT_OPTION=0 (in the Eldo Reference Manual)
Specifying Simulation Output
Limiting the Size of Transient Output Files
Disables the printing of the option summary in the ASCII output .chi file.
Limiting the Size of Transient Output Files
At least three options are available in Eldo to limit the size of the output files for transient
simulation: option OUT_STEP, option OUT_RESOL, and option INTERP.
Of course, the many options related to the accuracy settings do generally have an impact upon
the number of computed points and thus upon the size of the output files, but this is only
qualitative and indirect. There is no way to quantitatively relate, say the eps or the reltol
specification, to the final size of the output files—this all depends on the circuit. In contrast, the
options discussed in this section enable controlling the amount of data in a predictable way (the
OUT_RESOL option only sets a maximum size, whereas OUT_STEP and INTERP enable
exact predictions). These options may have a considerable impact on the overall simulation
speed, so it is important to define exactly what has to be achieved.
• .OPTION OUT_STEP=val (in the Eldo Reference Manual)
The .OPTION OUT_STEP=val command forces a timepoint at each multiple of val, and
only these timepoints are stored in the binary output files. These timepoints are forced,
that is, they come in addition to the normal timepoints picked by the simulator. When
using this option, the timepoints are forced, that is, they are computed even if they are
not required from an accuracy point of view. One of the applications of the OUT_STEP
option is for FFT computations. In this case, it is frequent that the user wants to have
exact, computed points, at regularly spaced timepoints, to minimize the interpolation
artifacts when computing an FFT. However the OUT_STEP option is also a way to
control the size of the output files, even if no FFT is scheduled. If not chosen properly, a
possible risk of the OUT_STEP option is to slowdown the simulation unnecessarily, by
forcing Eldo to compute more points than needed. This is particularly true if they are
long periods of time with little or no activity in the simulation. Forcing a short out_step
will force many useless timepoints during these periods, whereas Eldo would normally
accelerate and compute fewer timepoints. This option is however preferred by some
users because the output waveforms ultimately contain only computed points, without
interpolation.
• .OPTION OUT_RESOL=resolution (in the Eldo Reference Manual)
Another option used to reduce the size of the output file is the OUT_RESOL option.
With this option, the user can specify the smallest resolution of the output file.
Computed data is then dumped only if the current time is greater than the previously
written timepoint, augmented by the resolution. For example if OUT_RESOL is set to
1ns, and the simulator has written data at time t=24.65ns, all timepoints computed until
t=25.65ns will not be dumped. The first timepoint after t=25.65ns will be dumped. This
could be t=25.76ns for example, or t=27ns if the simulator can accelerate in this period
of time. No timepoints are forced other than those naturally picked by the simulator.
Eldo® User's Manual, 15.3 353

Specifying Simulation Output
Incremental Saving of the JWDB Database
Thus the spacing of timepoints in the output file is generally non-constant. The
maximum average density of timepoints in the output file is determined by the
resolution parameter of the option. The minimum density is not guaranteed, neither
locally, nor globally. This option is an interesting alternative, combining the certainty
that the points in the output are computed points only (no interpolation error), and the
ability to handle low activity periods efficiently. It is however, generally not well suited
for simulations where an FFT must be computed, because of the non-constant spacing of
the timepoints (this would result in interpolation errors when re-sampling for the FFT).
• .OPTION INTERP=1 (in the Eldo Reference Manual)
Both OUT_STEP and OUT_RESOL options dump only computed points to the output
file. Sometimes it may be desirable to obtain equally spaced time points, but forcing
timepoints (with OUT_STEP for example) would result in an unacceptable CPU
penalty. In these cases, interpolating may be useful. An interpolation option is available
to force Eldo to sample the output data along the parameter of the .TRAN
command. If using the option INTERP=1, the transient output waveforms are
interpolated, and the timepoints written to the file are aligned with multiples of
exactly. For example, if using both the following:
.tran 1ns 100ns
.option interp=1
the output waveforms will contain exactly 101 points (time 0 is always included),
spaced by 1ns. Glitches shorter than 1ns may not be caught in the resulting waveform.
This is a radical way to reduce the size of the binary output files (.wdb). However, the
written data is obtained by interpolation, thus including an unpredictable amount of
interpolation error. During low-activity periods, Eldo still picks the largest possible
timesteps which enable the accuracy requirements to be met, and fills the output data
with interpolated data (at no or little cost, as opposed to the OUT_STEP technique
discussed previously).
Related Topics
Error and Warning Message Classification
Error and Warning Messages
Plotting, Printing and Probing
Incremental Saving of the JWDB Database
By default, Eldo sends simulation results to the JWDB server, which stores them in memory and
then generates the .wdb file at the end of the simulation. To invoke incremental saving, forcing
Eldo to save JWDB format simulation results in to a .wdb file before the end of the simulation,
invoke Eldo with the -jwdb_threshold argument. Simulation results will be saved each time the
simulation result size has reached threshold value (default is 100 MB).
354
Eldo® User's Manual, 15.3

Specifying Simulation Output
Incremental Saving of the JWDB Database
This can be useful to avoid losing JWDB results from a very long Eldo simulation in case of a
JWDB server or machine problem.
Tip
See “Running Eldo” in the Eldo Reference Manual.
Related Topics
Invoking Eldo
Eldo® User's Manual, 15.3 355

Specifying Simulation Output
Incremental Saving of the JWDB Database
356
Eldo® User's Manual, 15.3

Chapter 9
Analyzing Simulation Results
This chapter describes how to analyze the results of your Eldo simulation. Simulation results
can be viewed as waveforms using the EZwave waveform viewer. A SPICE compatible output
log file containing ASCII data, including results and error messages, is generated.
Output Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
Output Files Generated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
Interpreting the Output Log (.chi) File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
Output Log (.chi) File Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
Simulation Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Locating Eldo Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368
Error and Warning Message Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369
EZwave Joint Waveform Database (JWDB). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370
EZwave Graph Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
Displaying Eldo Simulation Data in EZwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
Run Eldo With EZwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
Complete Eldo Simulation and View Simulation Data Later. . . . . . . . . . . . . . . . . . . . . . . 373
EZwave Reload Option. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Manual Status Update. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Marching Update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
Diagnosing Convergence and Performance Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Non-Convergence Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Time Step Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
Performance Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
Using the Statistics File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385
Statistics File Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
Output Types
Eldo can generate three types of output:
• Graphical output (.wdb) for the EZwave waveform viewer.
• Measurements from the results of simulation; either scalar or vector.
• Tables and reports in the ASCII output (.chi) file and additional files.
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Analyzing Simulation Results
Output Files Generated
Related Topics
Tip
You can view ASCII output files with the AMS Results Browser.
Output Files Generated
Interpreting the Output Log (.chi) File
EZwave Joint Waveform Database (JWDB)
Specifying Simulation Output
Output Files Generated
Eldo uses a number of different file types to accept control information and to provide results of
interest.
Table 9-1 contains a list of the file extensions Eldo uses, and where applicable provides a link to
the description of the file. is the name of the input netlist control file to be simulated
without the extension. For example, if the name of the input file is called test.cir, the associated
.wdb is test.wdb.
The files not generated by default are only produced by Eldo when the appropriate options have
been set in the input file or command line flags.
Table 9-1. Eldo Standard Output Files
File Extension
Description
Files Generated By Default
.chi
Main output log file containing ASCII data, including results and
error messages.
See “Interpreting the Output Log (.chi) File” on page 363.
You can view .chi files with the AMS Results Browser.
.wdb
Default when graphical output specified in netlist (option WDB
or -gwl wdb — default).
A binary output file generated by default for mixed-signal JWDB
format files. Viewed with the EZwave waveform viewer.
By default, using the .wdb format, the .EXTRACT and .MEAS
waveforms are also saved inside the EXT folder in the main .wdb
file. Waveforms defined by .DEFWAVE commands combined
with .PLOT are saved inside the appropriate analysis folder (for
example TRAN) in the main .wdb file.
See “EZwave Joint Waveform Database (JWDB)” on page 370.
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File Extension
Table 9-1. Eldo Standard Output Files (cont.)
Description
Analyzing Simulation Results
Output Files Generated
.swd
Default when graphical output specified in netlist with .PLOT
command (option WDB or -gwl wdb — default).
A saved windows JWDB output file used by the EZwave
waveform viewer. See “EZwave Graph Windows” on page 371.
.id
Contains the identifiers of the EZwave JWDB server used by
Eldo, to enable marching waveforms in EZwave. When you open
a wdb file in EZwave, it first tries to connect to the server in the
.id file. This is necessary because the file written on disk is
incomplete until the simulation ends.
.errm.log ASCII file containing warning/error messages. See “Locating
Eldo Messages” on page 368.
Additional Files Not Generated By Default
.ext.wdb 1 Contains extraction or waveform information. Created when
using a .EXTRACT command in the netlist with option
EXTFILE specified (using the default .wdb format). This file
will not always be output, it depends on the type of simulation
and the specification of the .EXTRACT command.
See “Extracting Information” on page 321.
.meas.wdb Contains extraction or waveform information. Created when the
commands .EXTRACT, .MEAS, or .PLOT W(XX) are present
in an input netlist with option MEASFILE specified (using the
default .wdb format). This file will not always be output, it
depends on the type of simulation and the specification of the
.EXTRACT, .MEAS, or .PLOT W(XX) command.
See .OPTION MEASFILE in the Eldo Reference Manual.
.aex
Contains extraction/measurement information. Created when
option AEX is used in conjunction with .EXTRACT or .MEAS
commands. See .OPTION AEX in the Eldo Reference Manual.
You can view .aex files with the AMS Results Browser.
.cml
Log of input commands in interactive mode.
See “Eldo Interactive Mode” on page 1457.
.hiz
Contains results of HiZ analysis for .DCHIZ, .HIZ and option
ADIT_CHECK commands.
See the .HIZ command in the Eldo Reference Manual.
You can view .hiz files with the AMS Results Browser.
.pls
S parameters file containing a list of poles and residues.
See “Working with S, Y, Z Parameters” on page 683.
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Output Files Generated
File Extension
.pz
.stat
.dex
.otm
.ops
.op
.opX
.probeop
.mapop
.files_dump
.iic
.sav
.sfo, .yfo, .hfo,
.nfo, .gfo, .tfo, .afo, .zfo
.nactivity
.activity
.trX
.acX
.swX
.mtX
.ftX
Table 9-1. Eldo Standard Output Files (cont.)
Description
Output file used by the Pole Zero post-processor. Created when a
.PZ command is specified in the netlist file.
See “Pole Zero Analysis” on page 230.
You can view .pzr files (generated from .pz files) with the AMS
Results Browser.
Created when Eldo is invoked with the -stat argument. This file
should be sent to a support engineer in the event of a problem.
See “Statistics File” on page 57.
Design of experiments output file. Created when a .DEX
command is specified in the netlist file.
See “Statistical Experimental Design and Analysis” on page 555.
Optimizer output file. Created when a .OPTIMIZE command is
specified in the netlist file.
See “Optimization” on page 587.
Operating point information output files. Created when a .OP
command is specified in the netlist file.
See the .OP command and .OPTION PROBEOP in the Eldo
Reference Manual.
File containing all the files opened by Eldo (except temporary
files) for a simulation. Useful for packaging an Eldo testcase.
See .OPTION DUMP_FILE_LIST in the Eldo Reference
Manual.
Saved simulation information to be reused for additional
simulations.
See the .SAVE command option in the Eldo Reference Manual.
S, Y, Z parameter output file specified with the .FFILE
command.
See “Working with S, Y, Z Parameters” on page 683.
Circuit activity check. List of inactive (or active) nodes inside a
design.
See the .ACTIVITY command option in the Eldo Reference
Manual.
Generated with option COMPAT or -compat.
HSPICE output files created during simulation in the netlist
control file directory.
See “HSPICE Compatibility” on page 162.
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File Extension
_csdf.trX
_csdf.acX
_csdf.swX
.fsdb
..fsdb
Multiple PSF output files
..wdf
.spi3
.cou
.ext
Table 9-1. Eldo Standard Output Files (cont.)
Description
Analyzing Simulation Results
Output Files Generated
Generated with option CSDF or -gwl csdf.
CSDF output file created during simulation in the netlist control
file directory.
See the -gwl argument in the Eldo Reference Manual.
Generated with option FSDB or -gwl fsdb, depending on the
setting of option FSDB_SINGLE_FILE.
Custom WaveView compatible output file.
If option FSDB_SINGLE_FILE is not set, is the
name of the corresponding JWDB folder.
See the -gwl argument in the Eldo Reference Manual.
Generated with option PSF or -gwl psf.
Format for Cadence viewer (used with Artist Link).
PSF output file created during simulation in the netlist control
file directory. One output file is created for each analysis. The
list of directories and files created by the PSF format is printed at
the end of the .chi file.
See the -gwl argument in the Eldo Reference Manual.
Generated with option WDF or -gwl wdf.
Custom WaveView compatible output file.
is the name of the corresponding JWDB folder.
See the -gwl argument in the Eldo Reference Manual.
Generated with option SPI3BIN or SPI3ASC.
SPICE3 compatible output file.
See Simulator Compatibility Options in the Eldo Reference
Manual.
(option COU or -gwl cou)
Legacy output format. A binary output file containing analog
simulation results data. A special interface is provided to access
this data from your own post-processor software if required.
See the Eldo cou Library User’s Manual for more details.
(option COU or -gwl cou)
Legacy output format. Contains extraction or waveform
information. Created when using a .EXTRACT command in the
netlist and the .cou format output is specified. This file will not
always be output, it depends on the type of simulation and the
specification of the .EXTRACT command.
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Analyzing Simulation Results
Output Files Generated
File Extension
.meas
.ali
.hmp
Table 9-1. Eldo Standard Output Files (cont.)
Description
(option COU or -gwl cou)
Legacy output format. Contains extraction or waveform
information. Created when the commands .EXTRACT, .MEAS,
or .PLOT W(XX) are present in an input netlist and the .cou
format output is specified. This file will not always be output, it
depends on the type of simulation and the specification of the
.EXTRACT, .MEAS, or .PLOT W(XX) command.
(option COU or -gwl cou)
Legacy output format. Cou output file to define waveform
aliases.
Legacy output format. Cou output file contains results for each
noise analysis. Created when option KEEP_HMPFILE is used in
conjunction with the .NOISETRAN command.
See the .NOISETRAN command in the Eldo Reference Manual.
1.The four extract/measurement types of file (.ext, .ext.wdb, .meas, .meas.wdb) are also generated when
functions are used in .DEFWAVE commands. In most cases, the result of such functions are known only
at the end of the simulation so the waves issued from a .DEFWAVE can not be plotted in the .cou output
file, but only in a specific file generated at the end of the simulation. These types of file are not generated
if you do not use .PLOT or .PRINT commands in the netlist or options EXTFILE or MEASFILE specified.
Related Topics
Interpreting the Output Log (.chi) File
Eldo Input and Output Files
Invoking Eldo
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Analyzing Simulation Results
Interpreting the Output Log (.chi) File
After a simulation is complete, Eldo writes simulator information to an output log (.chi) file
containing ASCII data. This file contains details of the simulation including any warning or
error messages, which may have been encountered during simulation.
Depending on the analysis defined, the structure will be different, for example with .ALTER
and .STEP commands there is usually a separate section for each analysis performed with
header information and so on. Each section corresponds to an analysis defined in netlist. See
“Setting Up An Analysis” on page 203 for example outputs for different types of analysis.
Tip
You can view .chi files with the AMS Results Browser.
Output Log (.chi) File Contents
A typical ASCII output log (.chi) file contains various information related to the netlist and the
simulation.
• System Information.
Information about the machine used for simulation including: clock frequency, the
number of cores, the number of threads used, and so on.
• Date, Eldo version number, simulation time.
• Circuit name (title).
• Input Listing.
Netlist with line numbers.
• Information about netlist analysis (errors and warnings).
• Generation.
Information about the database generation.
• Information about compilation.
o
Number of elements, nodes, input signals, and so on, for example:
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Analyzing Simulation Results
Output Log (.chi) File Contents
o
44 elements
29 nodes
11 input signals
Detail about objects and nodes found in the design...
Number of nodes 29
Number of intrinsic nodes 0
Number of input signals 11
Number of resistors 15
Number of short-circuited resistors 0
Number of floating capacitors 8
Number of grounded capacitors 4
Number of inductors 2
Number of voltage sources 7
Number of current sources 0
Number of dependent sources 2
Number of diodes 4
Number of BJT 0
Number of JFET 0
Number of MOS 0
Number of SWITCHES 0
Number of transmission lines 0
Total number of elements 48
Eldo version and compilation date.
• Simulation temperature.
• Option Summary.
Information about options.
• Information about DC analysis.
• Accounting information.
Information about simulation, for example:
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Simulation Counters
Number of nodes 29
Number of intrinsic nodes 2
Number of input signals 16
Number of resistors 1
Number of floating capacitors 2
Number of grounded capacitors 7
Number of inductors 5
Number of voltage sources 14
Number of current sources 0
Number of dependent sources 2
Number of diodes 0
Number of BJT 0
Number of JFET 0
Number of MOS 0
Number of SWITCHES 0
Number of transmission lines 2
CFAS devices 3
Total number of elements simulated 36
Number of equations 26
Number of non-zero terms 68
Percent Zeros 89.94
Number of Newton iterations 10718
Average number of Newton iterations 2.012
Number of accepted time steps 5328
Number of rejected time steps 15
due to LTE 0
due to Newton 0
Evaluation of active devices 0
Memory size (MB) 6.228
Number of time point rejection due
to 'CROSS evt' synchronization....15
• Total simulation time.
o
o
o
o
CPU time.
Related Topics
Global CPU time.
Global elapsed time.
Job start and end time.
Simulation Counters
Error and Warning Message Classification
Invoking Eldo
Simulation Counters
The information described in this topic is only generated with option OLDACCT specified. By
default, this option is disabled. Enable this option for backward compatibility with older postprocessing
scripts.
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Simulation Counters
Tip
See “.OPTION OLDACCT” in the Eldo Reference Manual.
After a simulation has been completed, Eldo writes simulation information, in tabular form, to
the ASCII output (.chi) file. The following information is output:
• Node and Element Information
• Node and Element Information
• Node and Element Information
• Node and Element Information
• Node and Element Information
Node and Element Information
Information concerning circuit nodes and elements is written to the .chi file in the following
format:
NUNODS NCNODS NUMNOD NUMEL DIODES BJT JFET MOSFET
16 16 16 22 0 0 0 19
where the parameters have the following definitions:
NUNODS Number of nodes before subcircuit expansion. Corresponds to the number of top
nodes, intrinsic nodes of devices not included.
NCNODS Number of nodes after subcircuit expansion.
NUMNOD Total number of nodes including those created by parasitic resistances.
NUMEL Total number of elements contained in the circuit.
DIODES Number of diode elements contained in the circuit.
BJT Number of BJT elements contained in the circuit.
JFET Number of JFET elements contained in the circuit.
MOSFET Number of MOSFET transistor elements contained in the circuit.
Grounded Capacitors Information
Information concerning grounded capacitors is written to the .chi file in the following format:
NUMGC
1
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Analyzing Simulation Results
Simulation Counters
where the parameters have the following definitions:
NUMGC Number of grounded capacitors not taken into account by NUMEL, see “Node and
Element Information” on page 366.
Matrix Information
When Eldo creates a matrix, the following information is written to the .chi file:
NSTOP NTERM PERSPA
13 122 7.219e+01
where the parameters have the following definitions:
NSTOP Number of lines in the matrix
NTERM Number of terms in the matrix
PERSPA Sparsity coefficient in percent (%)
Newton Block Information
When Eldo creates a number of Newton blocks, the following information is written to the .chi
file:
NBLOCKS NODEBLK MAXSIZE MINSIZE
where the parameters have the following definitions:
NBLOCKS Total number of Newton blocks created
NODEBLK Number of nodes contained in each Newton block
MAXSIZE Size of the biggest Newton block
MINSIZE Size of the smallest Newton block
Convergence Information
Information concerning circuit nodes and elements is written to the .chi file in the following
format:
NUMTTP NUMRTP LTERTP INWCALL ITERNW MEMSIZE
80 15 2 243 2.000e+00 581896
NDEVCALL NKIRCH NMAXCALL ITERM LATENCY
16038 0 9 1.00e+00 5.208e+00%
where the parameters have the following definitions:
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Analyzing Simulation Results
Locating Eldo Messages
NUMTTP Number of steps accepted by the simulator and sent to the binary output (.wdb) file
NUMRTP Number of steps rejected due to the truncation error being too large
LTERTP Number of time steps rejected due to LTE
INWCALL Total number of iterations or Newton calls needed to solve the Newton blocks
ITERNW Total number of Newton calls for .OP, .DC and .AC analyses; average number of
Newton calls needed to achieve convergence for a .TRAN analysis
MEMSIZE Memory size allocated to the circuit by Eldo
NDEVCALL Number of device calls
NKIRCH Number of calls or iterations needed to solve Kirchoff’s Law (OSR only)
NMAXCALL Maximum number of calls needed to solve a time or DC point
ITERM Average number of OSR loops
LATENCY Percentage of latency in the circuit
Related Topics
Interpreting the Output Log (.chi) File
Speed and Accuracy
Locating Eldo Messages
Error, warning, and information messages are not all grouped together in the same place inside
the output log file (.chi) so sometimes they can be difficult to locate.
Invoke Eldo with the -ovstatus command-line argument to generate in the standard output
(stdout) a summary message at the end of simulation informing of any warnings and errors, for
example:
Simulation finished.
There are 3 parsing warning(s).
There are 1 simulation error(s).
including %ld simulation non-convergence error(s).
The first line indicates the simulation has finished and the output file transcript is complete,
with or without errors and warnings. The second line indicates the number of parsing errors or
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Error and Warning Message Classification
warnings. The third line indicates the number of simulation errors or warnings. If there are nonconvergence
errors, then an additional line will be displayed detailing these.
This can be useful if using a browser to analyze the status of a run.
If errors or warnings have been generated, an error message log file, .errm.log,
is created. This file contains the error and warning messages used by the error message
manager. To disable the generation of this error message log file, specify option NOERRMLOG
or invoke Eldo with -noerrmlog.
Related Topics
Error and Warning Message Classification
Error and Warning Messages
Error and Warning Message Classification
When an error or warning message is detected during parsing of the simulation input file, a
message is printed out specifying the source line number and text containing the error.
Warnings
Warnings may be caused by improper use of commands or parameters which are then ignored
by the analyzer. A warning does not prevent the continuation of analysis and simulation. By
default, Eldo displays each type of node connection fault warnings (107, 108, 113 and 252) only
three times; to override this default use the MSGNODE option.
By default, all warnings are displayed by Eldo. Specify option NOWARN to suppress the
display of all warnings or specify it together with a message ID to only suppress that warning.
In order for this option to be taken into account, place it before the section of the netlist
generating the warnings, ideally place this option at the beginning of the netlist.
Syntax Errors
Error messages usually result from commands or parameters which are not recognized by the
analyzer. When a syntax error is detected the simulation does not continue. It is then necessary
to edit .cir and correct the syntax error. In the printout .chi, the error
location in the text is indicated by a “^” character, possibly accompanied by a message. The
source line number and the source line may not be indicated if the syntax error is detected on a
global basis without reference to a particular line.
Effects
In the event of a warning, execution continues. If a syntax error is detected on the first analysis
step (lexical and syntax analysis), circuit parsing continues until the end of this step, otherwise
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EZwave Joint Waveform Database (JWDB)
execution is aborted immediately. The numbers of errors and warnings found are displayed at
the end of the first and second step.
Note
After an error has been detected by the analyzer, subsequent error messages may be
unfounded. It is therefore recommended to modify the source file to eliminate the first error
before attempting to interpret the other messages.
See Also
• .OPTION MSGNODE in the Eldo Reference Manual
• .OPTION NOWARN in the Eldo Reference Manual
Related Topics
Locating Eldo Messages
Error and Warning Messages
EZwave Joint Waveform Database (JWDB)
The EZwave viewer obtains waveform data by loading a database. By default, the EZwave
viewer uses the Joint Waveform DataBase (JWDB) as its input format. Waveform data from the
simulation is stored in the JWDB, where it can be loaded into the EZwave viewer. In the
EZwave viewer, you can view a single database or multiple databases in a single session.
JWDB is a true mixed-signal waveform database. It can hold many different waveform types,
including analog (float, double or complex), histogram, spectral, scatter, Verilog, standard
logic, VHDL char, buses and records, bit, boolean, string, integer (16, 32, or 64 bits) and userdefined
enumerated types. X-values can either be 64-bit integers or double-precision floatingpoint
numbers. It can contain signals from the time and frequency domains, or any other domain
that is needed.
JWDB is also a multi-run database. Waveforms and buses are stored, managed, and analyzed as
compound waveforms. In addition to compound waveforms, JWDB has hierarchies which
enable waveforms to be placed in folders for further data management.
Tip
See the EZwave User’s and Reference Manual.
Related Topics
EZwave Graph Windows
Displaying Eldo Simulation Data in EZwave
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EZwave Graph Windows
EZwave Graph Windows
The EZwave viewer can store graph windows and waveform databases for future use through
.swd and .wdb files.
An .swd file can store:
• Waveforms associated with the graph window.
• Window size, position, axis and background settings.
• Complex waveform transformation settings.
• Waveform display and cursor settings.
Related Topics
Tip
See the EZwave User’s and Reference Manual.
Displaying Eldo Simulation Data in EZwave
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Displaying Eldo Simulation Data in EZwave
Displaying Eldo Simulation Data in EZwave
The Eldo simulator outputs waveform data that can be displayed by EZwave.
EZwave works with Eldo in the following scenarios:
Run Eldo With EZwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
Complete Eldo Simulation and View Simulation Data Later . . . . . . . . . . . . . . . . . . . . . 373
EZwave Reload Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Manual Status Update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Marching Update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
Run Eldo With EZwave
In this scenario, the Eldo simulator runs a complete simulation and outputs the data in JWDB
format to be directly viewed by EZwave.
Procedure
1. You can use one of the following methods:
• Invoke Eldo simulator from the command line as in the following example:
eldo test.cir -ezwave &
This command invokes the Eldo simulator and directs it to run a complete simulation
and output the data to a file.
The simulator regularly saves incremental data to the disk (by default, each 100Mbs
of data). This enables you to run very large simulations without consuming too much
memory.
• Use the -noisaving argument to disable incremental saves inside the Eldo simulator.
• Use a pre-defined configuration:
eldo test.cir -ezwave -wdb_config config.swd &
2. The simulator requests that EZwave display waveforms as defined in the config.swd file
(this is an EZwave Save Window file) instead of the .PLOT statements defined in the
netlist test.cir. If some post-processed waveforms were stored through config.swd, they
will be automatically re-computed with new simulation data.
3. When the simulation is completed, the simulator exits and EZwave remains until you
exit the program.
Tip
See the EZwave User’s and Reference Manual.
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Related Topics
EZwave Joint Waveform Database (JWDB)
Displaying Eldo Simulation Data in EZwave
Analyzing Simulation Results
Complete Eldo Simulation and View Simulation Data Later
Complete Eldo Simulation and View Simulation
Data Later
In this scenario, the Eldo simulator runs a complete simulation and outputs the data in JWDB
format to be read by EZwave. In EZwave, the data can be organized and the window contents
can then be saved for later viewing.
Procedure
1. Invoke Eldo simulator as in the following example:
eldo test.cir
This command invokes the Eldo simulator and directs it to run a complete simulation
and output the data to a file.
Alternatively, if you want to reuse the JWDB server launched by Eldo for other Eldo
simulations, use the -jwdb_servermode argument as in the following example:
eldo test.cir -jwdb_servermode
This setting can also be specified in the eldo.ini file. Refer to “Eldo Initialization File”
on page 51 for further details.
2. To display simulation results, invoke EZwave.
3. In EZwave, use the File > Open menu to open the JWDB file generated by the
simulator. The waveform data appears.
You can organize data in different graph rows and create some post processing
waveforms. You can save the window contents using the File > Save option and then
reuse the “saved window” .swd file later on.
Note
For this release, the following limitations apply for this scenario:
• The post-processed waveform is not automatically updated during the simulation.
• If EZwave still displays data at the end of the simulation, the data is “reloaded” from
the disk. This can be time-consuming.
• Having EZwave display multiple-run simulation results may lead to internal errors.
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EZwave Reload Option
EZwave Reload Option
The File > Reload option in EZwave is a shortcut to update waveform data in EZwave with
new simulated data with a single action. It also automatically updates all post-processed
waveform data.
Procedure
1. To use the reload functionality:
2. Invoke Eldo simulator as in the following example:
eldo test.cir
This command invokes the Eldo simulator and directs it to run a complete simulation
and output the data to a file.
3. To display simulation results, invoke EZwave.
4. In EZwave, use the File > Open option to open the JWDB file generated by the
simulator. The waveform data appears.
5. You can organize data in different graph rows and create some post processing
waveforms.
6. Modify simulation parameters in test.cir and run another simulation:
eldo test.cir
7. In EZwave, use the File > Reload option to update waveforms with new simulated data.
Related Topics
Tip
See the EZwave User’s and Reference Manual.
EZwave Joint Waveform Database (JWDB)
Displaying Eldo Simulation Data in EZwave
Manual Status Update
Waveform data can be manually collected from a running simulation at an interval of your own
choosing. This enables you to get a status update on a running simulation.
Procedure
1. Invoke Eldo simulator using one of the following methods:
Command line invocation: Invoke with EZwave using the following command:
eldo test.cir -ezwave &
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Analyzing Simulation Results
Marching Update
Output in JWDB format: Invoke the Eldo simulator and run a complete simulation as
in the following example:
eldo test.cir &
Then invoke EZwave and use the File > Open option to open the .wdb file generated by
the simulation.
2. To update the data in the EZwave viewer, click the Update Waveform Data button in the
EZwave toolbar. This updates displayed waveforms with new simulation data.
Note
For this release, the following limitation applies for this scenario:
If jwdb_servermode is set (from the command line or in the eldo.ini file) when an
Eldo simulation is invoked, the simulation output data cannot be accessed until after the
simulation completes.
Related Topics
Tip
See the EZwave User’s and Reference Manual.
EZwave Joint Waveform Database (JWDB)
Displaying Eldo Simulation Data in EZwave
Marching Update
Waveform data can be collected from a running simulation at a predefined set interval. This
interval is set in EZwave and is run simultaneously with the Eldo simulator. This automates the
process of updating waveform data viewed in EZwave.
Procedure
1. Invoke Eldo simulator using one of the following methods:
Command line invocation: Invoke with EZwave with the following command:
eldo test.cir -ezwave &
Output in JWDB format: Invoke the Eldo simulator and run a complete simulation as
in the following example:
eldo test.cir &
Then invoke EZwave and use the File > Open option to open the .wdb file generated by
the simulation.
2. In EZwave, select Edit > Options to invoke the EZwave Display Preferences dialog
box. Select General from the list in the dialog box to open the General options page.
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Marching Update
3. In the General options page, go to the Marching Waveforms area and set the update
interval by either of the following options:
Automatically Update Displayed Waveforms Every X time interval: The time
interval can be by second, minute, or hour.
Automatically Update Displayed Waveforms Every X% of Simulation: This updates
based on the percentage completion of the simulation.
Be careful not to set too small of an interval. Setting a short interval increase the number
of updates and then the amount of resources globally used to update the waveform data
viewed in EZwave.
Note
The following limitation applies for this scenario:
If jwdb_servermode is set (from command line or in the eldo.ini file) when an Eldo
simulation is invoked, the simulation output data cannot be accessed until after the
simulation completes.
Related Topics
Tip
See the EZwave User’s and Reference Manual.
EZwave Joint Waveform Database (JWDB)
Displaying Eldo Simulation Data in EZwave
376
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Analyzing Simulation Results
Diagnosing Convergence and Performance Issues
Diagnosing Convergence and Performance
Issues
A set of diagnostics are available through the -diagmode command line argument to help you
understand why a circuit does not behave as expected, or takes more time than expected to
simulate.
Diagnostics activated are:
Non-Convergence Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Time Step Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
Performance Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
Non-Convergence Analysis
The analysis of non-convergence issues is enabled with the -diagmode conv command line
argument. When Eldo stops because of a non-convergence a file is generated named
.noconv, used as an input for the convergence analysis (where filename is either the
netlist name or the name specified by the -out argument).
This functionality is only available with Eldo Classic.
Note
It is recommended to use the -outpath command line argument in
conjunction with this command as many new files might be generated during the new
simulation.
The non-convergence file generated, .noconv, contains:
• Time at which the non-convergence occurred.
• Cause of the non-convergence (Newton or LTE).
• List of nodes/devices for which the residual current is too high (Newton).
• List of nodes for which the bias is changing too much from one iteration to another
(Newton).
Based on this information Eldo automatically generates plots of the nodes, for Voltage (V) and
current contributions (IN), for the devices connected to the detected nodes. Doing so you can
monitor how the voltage evolves on those nodes and monitor the total current contributions of
each device connected on those nodes. All the automatic plots generated are referenced in a new
folder of the simulation database named DEBUG_.
For example:
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Analyzing Simulation Results
Non-Convergence Analysis
The -diagmode conv argument also activates two other analyses.
• The first returns the nodes that are either leading to a time step rejection because of
newton or because of the local truncation error.
• The other is the “stiff signal” detection returning the 20 nodes with the steepest voltage
variation.
During the new simulation Eldo triggers some automatic analyses when it detects convergence
difficulties. Eldo checks the characteristics of some of the devices (diodes, BJT, JFET, MOS
and Verilog-A instances) connected to the nodes that are suspected as problematic. Eldo creates
a new database, .diagmode.wdb (where filename is either the netlist name or the
name specified by the -out argument), containing all the sweeps it performed, assuming the
simulator detected at least one non-monotonous characteristic. Information is displayed in the
terminal, for example:
378
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Analyzing Simulation Results
Non-Convergence Analysis
Note 88: DIAGMODE(CONV) checking devices behavior at time 151.2517296711Us...
Note 90: Change sign detected while sweeping node XIOCDX.XR1.DX_RNWELL.N4
Note 91: On wave number 6, IX(XIOCDX.XR1.DX_RNWELL.6) at -185.0000MV
Note 90: Change sign detected while sweeping node XIOCDX.XR1.XI
Note 91: On wave number 6, IX(XIOCDX.XR1.DX_RNWELL.6) at -185.0000MV
Note 90: Change sign detected while sweeping node XIOCDX.LDMOS
Note 91: On wave number 4, ICB(XIOCDX.XMN4_1.M_NMOSMV) at -356.0000MV
Note 91: On wave number 5, QD(XIOCDX.XMN4_1.M_NMOSMV) at -365.0000MV
Note 91: On wave number 8, QB(XIOCDX.XMN4_1.M_NMOSMV) at -1.3280 V
Note 90: Change sign detected while sweeping node XIOCDX.GM12
Note 91: On wave number 4, ICB(XIOCDX.XMN4_1.M_NMOSMV) at 803.0000MV
Note 90: Change sign detected while sweeping node XIOCDX.GM12
Note 91: On wave number 4, ICB(XIOCDX.XI12.XI_1.XMMN1.M_DX_NMOS) at 2.0000M V
Note 91: On wave number 7, QS(XIOCDX.XI12.XI_1.XMMN1.M_DX_NMOS) at -184.0000MV
Because this stage can take some time, when Eldo starts checking it displays the Note 88 each
time. For each device connected to a problematic node Eldo does a voltage sweep of that node
and checks the derivatives of the characteristics of the devices with respect to that node. If the
sign of the derivative changes then it means that the characteristic is non-monotonous (Note 90)
and Eldo prints the name of the curves for which the sign of the derivative changed (Note 91).
Even if this is not always a problem for Newton, or if the convergence issue can come from
something else, this is usually an unsatisfactory characteristic and it could slow convergence or
even lead to non-convergence. If at least one characteristic was detected as non-monotonous
then all the sweeps done at that particular time point are saved in the new .wdb database. If
nothing is detected then nothing is saved.
Example of a generated database:
Eldo also generates a small netlist with the model card instantiated with the computed parameter
values. The device is instantiated with all its nodes (including the internal nodes), each of these
nodes connected to a voltage source so the bias condition is exactly the same as during the
simulation at that particular time point. Eldo also creates the required plot for all the simulation
characteristics of the device (current, charges, or internal states for the Verilog-A models). You
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Analyzing Simulation Results
Time Step Management
can then simulate a specific single device with the proposed DC sweep or you can try different
DC sweeps if you want to check the characteristics for some other dimensions (for example,
performing a sweep on some other nodes of the device). The generated filename is of the form:
.time=.sweep=.device=.cir
Tip
See “Running Eldo” in the Eldo Reference Manual.
Related Topics
Time Step Management
Performance Diagnostics
Time Step Management
The analysis of time step management is enabled with the -diagmode tstep command line
argument. Use this if Eldo performs too many average Newton iterations or if it rejects too
many time steps: if the ratio of accepted time steps compared to rejected time steps is lower than
six then specify this argument to try to understand what is limiting the simulator.
This flag behaves in a similar way to -diagmode conv, but does not use an extra file and can be
run directly.
Tip
See “Running Eldo” in the Eldo Reference Manual.
Related Topics
Non-Convergence Analysis
Performance Diagnostics
Performance Diagnostics
The analysis of performance diagnostics is enabled with the -diagmode perf command line
argument to help you understand why a circuit does not behave as expected, or takes more time
than expected to simulate.
The performance diagnostics generates the following information:
• “Nodes/Devices Impacting Time-Step Adjustment” on page 381
• “CPU Time Evaluating Device Types” on page 383
380
Eldo® User's Manual, 15.3

Nodes/Devices Impacting Time-Step Adjustment
Analyzing Simulation Results
Performance Diagnostics
The performance diagnostics records the nodes and/or devices which impact the Eldo time-step
adjustment. The .FORMAT_STEP_LIMITERS command formats the output of the
performance diagnostics report.
The performance diagnostics generates the following outputs:
• Statistics about time-step computation are returned in the ASCII .chi file output, for
example:
Rejection due to no-convergence
100% (11/11) due to Node 2
Rejection due to Local-Truncation-Error (fast variation of signal)
100% (48/48) due to Node 2
Step limitation due to Local-Truncation-Error (fast variation of
signal)
100% (147/147) due to Node 2
Step limitation due to time-synchronization
54.3% (19/35) due to Signal on node 1
Other items not dumped because 15% of total number reached
Summary of contribution per X instance
100% (241/241) due to Top circuit
The statistics generated are:
o
o
o
o
Rejection due to no-convergence.
Lists the nodes and/or devices which caused Eldo to not converge at a given time
step, and which force Eldo to take a smaller time-step.
Rejection due to Local-Truncation-Error (fast variation of signal).
Lists the nodes/devices for which Eldo has detected too steep a variation, which
caused a time step to be rejected.
Step limitation due to Local-Truncation-Error (fast variation of signal).
Lists the nodes and/or devices which caused Eldo to limit the increase of a time-step
due to variation on the nodes/devices because it anticipates that the variation on
these items will be large.
Step limitation due to time-synchronization.
Lists the nodes and/or devices on which an input signal is applied, and which cause
time-step adjustment. Typically, Eldo forces points on the time point of a PWL
statement.
In each of the above sections, the nodes/devices are listed by order of importance: Eldo
reports the first SORT_MAX items, or the list of items which would count for at least
Eldo® User's Manual, 15.3 381

Analyzing Simulation Results
Performance Diagnostics
SORT_REL. At the end of the report, Eldo reports the X instance names most frequently
seen in all sections.
These outputs are already present in the Questa ADMS statistics file when the tool is
invoked with the vasim -stat argument.
• A wave named dbg(tstep) is created, containing the information about the time-step:
which nodes had impact in the choice of that step. It shows the size of the time-step used
by Eldo as well as the node that was most limiting that time-step. For example:
Figure 9-1. EZwave Waveform Showing Nodes Impacting Time-Step
• The 20 nodes which have the steepest voltage variation are returned in the ASCII .chi
file output, along with values of the slope (and time at which the variation occurs). This
is a comparison between the maximum variation of the nodes. Example output showing
nodes with the largest slewrate:
382
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Analyzing Simulation Results
Performance Diagnostics
Node X1.Q1_C
Slope = 5.5538E+01V/ns
Time = 3.4168E+00ns
Node X1.3
Slope = 5.4934E+01V/ns
Time = 3.4168E+00ns
Node X1.2
Slope = 5.3028E+01V/ns
Time = 9.2519E-01ns
Node X1.Q1_B
Slope = 5.3025E+01V/ns
Time = 9.2519E-01ns
Node 1
Slope = 5.1499E+01V/ns
Time = 2.0100E+00ns
...
CPU Time Evaluating Device Types
The performance diagnostics records the percentage of CPU time spent evaluating the different
type of devices. This distribution is reported per Verilog-A model, and per type of MOS, BJT,
Diode, and JFET model. Example output of simulation time taken by the device model
evaluation:
Device Type/Model Name | nb of instances | Elapsed CPU Time | 1st %* | 2nd %**
-------------------------------------------------------------------------------------------
Linear Elements | 180269 | 11s | | 39.04%
-------------------------------------------------------------------------------------------
Diodes | 1458 | 2s | | 7.14%
BERKDIO | 1458 | 2s | 100.00% | 7.14%
-------------------------------------------------------------------------------------------
MOSFET | 18353 | 16s | | 53.65%
BSIM3V3 | 18353 | 16s | 100.00% | 53.65%
-------------------------------------------------------------------------------------------
• The “1st %” column is the percentage of time over the total load time for that type of
device (MOSFET for example).
• The “2nd %” column is the percentage of time over the total load time for all devices
included.
• All types taking less than 1s of elapsed CPU load time are ignored.
Performance Diagnostic Outputs
By default, for Questa ADMS and Eldo Classic/Premier, the reports are printed in the .chi file.
If the -stat flag has been set on the command line then the reports are printed in the statistics file
(.stat). Table 9-2 below summarizes the various ways to activate the performance diagnostics in
Eldo and Questa ADMS. In the table, steps is the step statistics, slope is the steepest variation
detection, and devcpu is the CPU time measurement in device evaluation.
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Analyzing Simulation Results
Performance Diagnostics
Table 9-2. Activating Performance Diagnostics
-diagmode perf -stat .format_step_limiters Eldo
-diagmode perf -stat .format_step_limiters Output: .stat file.
Default data: step statistics.
Data generated: steps, slope, device cpu.
Step statistics formatted by
.format_step_limiters options.
-diagmode perf -stat Output: .stat file.
Default data: step statistics.
Data generated: slope, device cpu.
Step statistics formatted by default options.
-diagmode perf .format_step_limiters Output: .chi file.
Default data: .chi default data.
Data generated: steps, slope, device cpu.
Step statistics formatted by
.format_step_limiters options.
-diagmode perf
Output: .chi file.
Default data: .chi default data.
Data generated: steps, slope, device cpu.
Step statistics formatted by default options.
-stat .fomat_step_limiters Output: .stat file.
Default data: step statistics.
Added data generated: none.
Step statistics formatted by
.format_step_limiters options.
-stat
Output: .stat file.
Default data: step statistics.
Added data generated: none.
Step statistics formatted by default options.
.format_step_limiters No data.
See Also
• .FORMAT_STEP_LIMITERS command in the Eldo Reference Manual
• Running Eldo in the Eldo Reference Manual
Related Topics
Diagnosing Convergence and Performance Issues
Using the Statistics File
384
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Analyzing Simulation Results
Using the Statistics File
Using the Statistics File
The statistics output file from Eldo can be useful to understand how a design behaves and to
monitor node/device activity. It can help to monitor the simulation performance, determine
circuit size impact on simulation, debug simulation slowdown, and determine which nodes and
blocks should be handled for minimizing rejections. The statistics file is generated by invoking
Eldo with the -stat argument.
Statistics File Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
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Analyzing Simulation Results
Statistics File Content
Statistics File Content
Output from: Eldo invoked with the -stat argument.
Statistics files are divided into sections highlighted by asterisks.
Tip
See “Running Eldo” in the Eldo Reference Manual.
Format
The content of the statistics file is divided into the following main parts:
• General Design Info
• Tool Versions
• High-level Design Information
• Analog Elaboration Information
• Simulation Information
Parameters
• General Design Info
o
Design name: Netlist Design Name
o
o
Machine: Machine and Platform information
Starting time: Starting simulation time and date record
• Tool Versions
o
Tool versions report
• High-level Design Information
o
Eldo kernel options: a list of Eldo kernel options used for the simulation
• Elaboration: Analog
o
Listing of number of Nodes in Eldo/Fast-SPICE/Both/Total
• Number of nodes
• Number of device internal nodes
• Number of stimulus nodes
o
Listing of number of Devices in Eldo/Fast-SPICE/Both/Total
• Number of resistors
• Number of capacitors
386
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Analyzing Simulation Results
Statistics File Content
• Number of grounded capacitors
• Number of inductors
• Number of voltage sources
• Number of current sources
• Number of controlled sources (E/F/G/H)
• Number of diodes
• Number of BJTs
• Number of JFETs
• Number of MOS
• Number of switches
• Number of transmissions lines
• Total number of the above listed devices
• Simulation: Rejection node list
• Rejection due to Local-Truncation-Error
Related Topics
Statistics File
• Step limitation due to Local-Truncation-Error
(limited to the first 10 items)
• Step limitation due to time-synchronization
• Summary of contribution per X instance
Contributions from subcircuit instances as a percentage of the total instances in
the design, to see how subcircuit instances impact the number of rejections.
Eldo® User's Manual, 15.3 387

Analyzing Simulation Results
Statistics File Content
388
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Chapter 10
Post-Layout Simulation
This chapter describes the DSPF (Detailed Standard Parasitic Format) backannotation and
network reduction capabilities for post-layout simulation in Eldo.
Post-Layout Simulation Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
DSPF Backannotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392
DSPF File Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
Parasitic Network Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Eldo Post-Layout Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Eldo Post-Layout Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395
DSPF Backannotation Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396
SPEF Backannotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398
SPEF File Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
SPEF File Example for Corners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
Eldo Reduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403
Basic Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403
Parameters Controlling the Reduction Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404
Reduction Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
Reduction Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
Reduction Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
Reduction Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
Post-Layout Simulation Overview
Eldo enables you to verify design functionality and timing including the effects of physical
layout. To include these effects of layout, you must generate a netlist that includes parasitics
extracted from layout using an extraction tool such as xCalibre. The extracted parasitic
information is included in the netlist in the form of large networks of passive resistors,
capacitors, and inductors connected to the transistors or other active objects of the circuit. Due
to the large number of elements that they contain, such parasitic networks strongly constrain
post-layout simulation both in terms of memory and CPU time.
A typical analog post-layout flow is shown in Figure 10-1:
Eldo® User's Manual, 15.3 389

Post-Layout Simulation
Post-Layout Simulation Overview
Figure 10-1. Post-Layout Flow
The areas to understand when dealing with post-layout simulation are as follows:
• “DSPF Backannotation” on page 392
When parasitics are contained inside a DSPF file.
• “SPEF Backannotation” on page 398
390
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Post-Layout Simulation
Post-Layout Simulation Overview
When parasitics are contained inside an SPEF file.
• “Eldo Reduction” on page 403
When parasitics are obtained either from a flat SPICE netlist or from a backannotated
DSPF file.
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Post-Layout Simulation
DSPF Backannotation
DSPF Backannotation
Parasitic information is extracted into a DSPF (Detailed Standard Parasitic Format) file. There
are typically two scenarios for parasitic extraction:
• Only parasitic elements (resistors and capacitors) are extracted.
• All devices, parasitics and internal nodes are extracted together.
Eldo enables the annotation of parasitic information onto the netlist by including the DSPF file.
To include the DSPF file after extracting your parasitics, specify the .DSPF_INCLUDE
command together with some parameters and options to your netlist.
The SPEF (Standard Parasitic Exchange Format) standard for backannotation is supported by
the .SPEF_INCLUDE command. See “SPEF Backannotation” on page 398.
DSPF File Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
Parasitic Network Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Eldo Post-Layout Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Eldo Post-Layout Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395
DSPF Backannotation Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396
392
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Post-Layout Simulation
DSPF File Structure
DSPF File Structure
Input for: .DSPF_INCLUDE command.
The DSPF file contains parasitic information extracted from layout.
Format
The file begins with a header including release number and tool used for extraction. It also
includes the hierarchical divider and the delimiter used in subnode names.
*|DSPF 1.0
*|DIVIDER /
*|DELIMITER :
The following section, net parasitics, contains the net names and their total net capacitance:
*|NET N1 5.324e-12
The following section contains port names, instances and nodes:
*|P (N1 X 0.0) --> A port in the net for external connection
*|I (M2:g M2 G I 0.0) --> Instance pin in the net for internal connection
*|S (N1:1) --> A subnode in the net
The native SPICE parasitic network follows (instance section), including the transistors:
Cin/01 N1 Vss 1.3pF
Rin/01 N1 N1:1 5
Rin/12 N1:10 M1:g 0.1k
M1 M1:d M1:g M1:s M1:b nmos w=2e-6 l=1e-6 ad=1.04e-12 as=6.2e-13
Note
Make sure all parasitics in the DSPF file are placed before the Instance Section. Differences
in DSPF files come from the different extraction tools.
Parameters
None.
Related Topics
Parasitic Network Types
Eldo Post-Layout Commands
Eldo Post-Layout Options
DSPF Backannotation Examples
SPEF File Structure
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Post-Layout Simulation
Parasitic Network Types
Parasitic Network Types
The types of Parasitic Networks handled by Eldo are:
• Capacitance (keyword C)
Coupling (capacitance between nets) and intrinsic (capacitance to ground) capacitors
represented as separate devices.
• Lumped capacitance (keyword CC)
Capacitors representing coupling + intrinsic capacitance.
• Resistance plus capacitance (keyword RC)
Resistors + capacitors representing coupling + intrinsic capacitance.
• Full RCC networks (keyword RCC)
Resistors and both types of capacitors.
Related Topics
Eldo Post-Layout Commands
Eldo Post-Layout Options
DSPF Backannotation Examples
Eldo Post-Layout Commands
The following post-layout backannotation simulation commands are available in Eldo:
• .DSPF_INCLUDE
Adds the parasitic elements described inside a specified DSPF file. Eldo loads the
specified DSPF file and backannotates the parasitic RCs in the specified DSPF file to the
pre-layout netlist. If the DSPF file contains the intentional devices, the geometric
parameters will also be backannotated to the corresponding devices in the pre-layout
netlist.
Three modes are available through the DEV=SCH[EMATIC]|DSPF|MIXED parameter:
o
o
SCH[EMATIC] specifies the DSPF file contains only the parasitics.
DSPF specifies the DSPF file contains both the parasitics and the intentional
devices. Sometimes it is more accurate to have the extractor generating a file
containing both. When this mode is specified, Eldo will take three actions:
i. Eldo will include the file specified in the command as if it was a .LIB command.
Eldo will therefore have two variants of the same subcircuit in its database, one
corresponding to the intentional devices which should be present in the circuit,
394
Eldo® User's Manual, 15.3

o
ii.
iii.
Post-Layout Simulation
Eldo Post-Layout Options
and another one included by the .DSPF_INCLUDE command, corresponding to
the version with its parasitics.
Eldo will emulate a .BIND command on the instances/subcircuits which are
specified on the .DSPF_INCLUDE command.
Eldo will apply filters, if any, to the DSPF devices.
MIXED specifies the DSPF file contains either only the parasitics or both the
parasitics and the intentional devices. It is the intended subcircuit which is
considered as being reference. This third mode is a mixture of the two other modes
available. Default mode for Eldo Classic and Eldo Premier.
MIXED is similar to mode SCH in that it is the intended SUBCKT which is taken as
the reference for building the simulation database, and is similar to mode DSPF
because the DSPF file may contains both parasitics and intended devices.
See the “.DSPF_INCLUDE” command in the Eldo Reference Manual.
• .MAP_DSPF_NODE_NAME
Maps node references to a new DSPF node name.
See the “.MAP_DSPF_NODE_NAME” command in the Eldo Reference Manual.
• .IGNORE_DSPF_ON_NODE
Ignores parasitic elements on a specified node when a DSPF file has been included.
See the “.IGNORE_DSPF_ON_NODE” command in the Eldo Reference Manual.
• .SELECT_DSPF_ON_NODE
Selects parasitic elements on a specified node when a DSPF file has been included.
See the “.SELECT_DSPF_ON_NODE” command in the Eldo Reference Manual.
Eldo Post-Layout Options
The following post-layout backannotation simulation options are available in Eldo:
• COLLAPSE_DSPF_OUTPUT
Regroup currents (I, Ix, Isub) and noise outputs according to the device or subckt
instance specified in arguments.
See “.OPTION COLLAPSE_DSPF_OUTPUT” in the Eldo Reference Manual.
• DSPF_LEVEL=C|CC|RC|RCC
Defines the level of parasitics to use from a specified DSPF file. The option will use part
of the information stored in the RC extracted DSPF file specified by C, CC, RC or RCC.
Eldo® User's Manual, 15.3 395

Post-Layout Simulation
DSPF Backannotation Examples
This can also be specified by the LEVEL parameter in the .DSPF_INCLUDE command.
If specified in the command it will overwrite this option.
See “.OPTION DSPF_LEVEL” in the Eldo Reference Manual.
• KEEP_DSPF_NODE
Keeps the reference to the original node names. Eldo keeps the original .PLOT/.PROBE
command if a node coming from the DSPF has the same name. It is not set by default,
because this node may be completely different to the original one.
See “.OPTION KEEP_DSPF_NODE” in the Eldo Reference Manual.
• KEEP_DANGLING
Keeps dangling objects in the Eldo database.
See “.OPTION KEEPDANGLING” in the Eldo Reference Manual.
• KEEP_SHORTED
Keeps shorted objects in the Eldo database.
See “.OPTION KEEPSHORTED” in the Eldo Reference Manual.
• MAX_DSPF_PLOT
Sets the maximum number of DSPF interface nodes plotted.
See “.OPTION MAX_DSPF_PLOT” in the Eldo Reference Manual.
Related Topics
DSPF File Structure
Eldo Post-Layout Commands
DSPF Backannotation Examples
DSPF Backannotation Examples
An example showing how to import a .dspf file containing layout parasitics is provided.
See “Example 21—Post-Layout Simulation using DSPF” on page 1324. Using .ALTER
statements, several simulations with different degrees of backannotation can be overlapped and
compared. The circuit is a 2-stage opamp, connected in follower mode.
Notice the generated notes relating to the replacement of nodes in the original netlist by DSPF
networks:
Note 70: Node X_OPAMP1.DIFFP has been replaced by a DSPF network.
Note 70: Node X_OPAMP1.DIFFN has been replaced by a DSPF network.
Note 70: Node X_OPAMP1.CURMIR has been replaced by a DSPF network.
396
Eldo® User's Manual, 15.3

Connecting a Source to a DSPF Backannotated Node
Post-Layout Simulation
DSPF Backannotation Examples
It is possible to connect a source to a node that is backannotated with DSPF. This might be
useful to insert a voltage or current source to a specific node to check a critical path. However,
after DSPF extension, the original node might be expanded in several nodes, and there might be
no path remaining between the extra source and the network, that is, the extra source no longer
has a connection to the network. This is because the extra source was not in the design when
DSPF information was created. The solution is that nodes connected to that extra source are not
expanded by DSPF. Eldo can detect such situations when the extra source is instantiated from
the top of the design and connected to a node at a lower level of hierarchy, using the full node
pathname. For example:
.SUBCKT INV in out
*...
R1 in internal 1k
*...
.ends
X1 in out INV
v1 X1.internal 0 5
!full pathname usage
Eldo will detect this configuration, and DSPF instructions will be ignored on node X1.internal.
This is similar to the command: .IGNORE_DSPF_ON_NODE X1.internal.
However if the extra source is added at the same level as the nodes (for example all at the top),
Eldo will only be able to issue a message that the node is connected to a single device only, and
will indicate that there is a possible DSPF connection problem. You must then manually add the
command .IGNORE_DSPF_ON_NODE on that node to deal with that specific situation.
Related Topics
SPEF Backannotation
DSPF File Structure
Eldo Post-Layout Commands
Eldo Post-Layout Options
Example 21—Post-Layout Simulation using DSPF
Eldo® User's Manual, 15.3 397

Post-Layout Simulation
SPEF Backannotation
SPEF Backannotation
The SPEF (Standard Parasitic Exchange Format) standard for backannotation, defined by IEEE
Std 1481-1999, is supported. The syntax is different from DSPF, but the processing is the same,
Eldo “translates” the SPEF format into DSPF and sends the parasitics to the DSPF-annotation
flow to achieve the SPEF-annotation.
Use the .SPEF_INCLUDE command to perform SPEF parasitic backannotation.
SPEF File Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
SPEF File Example for Corners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
398
Eldo® User's Manual, 15.3

SPEF File Structure
Post-Layout Simulation
SPEF File Structure
Input for: .SPEF_INCLUDE command.
The SPEF file is an alternative format for parasitic information extracted from layout.
Format
The file begins with a header. It includes various information on the tools used for extraction.
The important fields are the following:
*SPEF "IEEE 1481-1999"
*DESIGN "name"
*DIVIDER /
*DELIMITER :
If used, the DESIGN field is the name of the subcircuit on which the parasitics will be applied.
The DIVIDER field is the hierarchical divider, and the DELIMITER is used in subnode names.
The following section contains the units used in the body of the file:
*T_UNIT
*C_UNIT
*R_UNIT
*L_UNIT
1 NS
1 PF
1 OHM
1 HENRY
Time unit must be one of NS or PS; capacitance: PF or FF; resistor: OHM or KOHM; and
inductance: HENRY, MH or UH. They are all mandatory.
The next section contains the name mapping. You can map any net to a number. This is useful
when net names are very long.
*NAME_MAP
*1 N1
*2 N2
*3 NETWITHALONGNAME
*4 OTHER_NET
The next section contains the ground nets:
*GND_NETS VSS
The following section contains the nodes which are considered as ports, with their direction, and
an eventual load behind:
*PORTS
N0 O *L 10
N1 O
Top I
Eldo® User's Manual, 15.3 399

Post-Layout Simulation
SPEF File Structure
The following section contains the parasitics, grouped by net name. A net section begins by the
net name and the total net capacitance, and ends with a *END. This section contains subsections
about connections, capacitances, resistors, and inductions. They are defined as follows:
*D_NET N1 0.000153
*CONN
*P N1 I *L 0.1 --> port in the net for external connection
*I N2:P1 I *L 0.001308 --> instance pin in the net for internal connection
*CAP
1 N1:1 0.000084
2 N1 0.000032
3 N2:P1 0.000037
*RES
1 N1:1 N1 0.353405
2 N1:1 N2:P1 10.847200
*INDUC
1 N1 top 0.000001
*END
The following SPEF features are not supported:
• *DEFINE
• *PDEFINE
• *R_NET
• *D_PNET
• *R_PNET
• *PHYSICAL_PORTS
• *N statements
• *S and *D statements
Parameters
None.
Related Topics
DSPF File Structure
SPEF File Example for Corners
400
Eldo® User's Manual, 15.3

SPEF File Example for Corners
Post-Layout Simulation
SPEF File Example for Corners
This example shows how Eldo handles this SPEF file depending on the corner parameters
specified.
SPEF file:
*SPEF "IEEE 1481-1997"
*DESIGN "TEST"
*DATE "Wed Jun 18 11:28:40 2008"
*VENDOR "Mentor Graphics"
*DESIGN_FLOW ""
*DIVIDER /
*DELIMITER :
*BUS_DELIMITER [ ]
*T_UNIT 1 NS
*C_UNIT 1 PF
*R_UNIT 1 KOHM
*L_UNIT 1 HENRY
*PORTS
N0 O
top O
*D_NET N1 0.0000:0.01:0.2
*CAP
1 N1 N0 1.1:2.3:5.2
*RES
1 N1 top 1
*END
The Eldo handling of this SPEF file depends on the .SPEF_INCLUDE corner parameter
specified. If you have:
.SPEF_INCLUDE FILE=test.spef CORNER=1
In this example, with CORNER=1, Eldo takes *D_NET N1 0.0000 and 1 N1 N0 1.1.
.SPEF_INCLUDE FILE=test.spef CORNER=2
In this example, with CORNER=2, Eldo takes *D_NET N1 0.01 and 1 N1 2.3.
.SPEF_INCLUDE FILE=test.spef CORNER=3
In this example, with CORNER=3, Eldo takes *D_NET N1 0.2 and 1 N1 N0 5.2.
(min:typ:max) can be used as an alternative to select one of the three values. By default, Eldo
takes the second value if there are three values specified.
Eldo® User's Manual, 15.3 401

Post-Layout Simulation
SPEF File Example for Corners
Related Topics
DSPF Backannotation
SPEF Backannotation
Eldo Reduction
402
Eldo® User's Manual, 15.3

Post-Layout Simulation
Eldo Reduction
Eldo Reduction
The Eldo Reduction capabilities enable Eldo to cope with the parasitic networks constraint by
substituting such networks on the fly with approximately equivalent but smaller-sized networks
computed by the TICER reduction engine.
Note
See the TICER reduction engine references [1, 2, 3].
The quality of the approximation is controlled by setting a cut-off frequency and/or an accuracy
tuning parameter. Additionally a maximum delay error and/or a maximum noise error and/or a
cut-off frequency may be used as explained in this chapter.
Not only backannotated circuits can benefit from the savings in computer resources allowed by
the Eldo Reduction, but also some specific circuits. For instance, this is the case for power
distribution networks having large portions of purely resistive networks.
The reduction methods available in Eldo are also, primarily, available in the xCalibre extraction
tool, and it is strongly recommended to activate the reduction of parasitics while performing
extraction with Calibre ® xRC /xL.
Nevertheless, even when the reduction of parasitic networks is performed in the extraction tool
there may be some benefit in performing reduction in Eldo. This is clearly the case when the
parasitics were generated to be valid over a frequency range that far exceeds the signal
frequencies involved in the simulations to be performed. Using its reduction capabilities enables
Eldo to take full benefit of reduction for each simulation individually, while using parasitic
networks valid over a possibly larger range of frequencies. Although this provides a convenient
capability, it remains preferable (and it is recommended) to use different sets of extracted
parasitics corresponding to the various frequency ranges of the simulations to be performed.
The primary advantages of reduction are:
• Results in smaller circuits, thus faster simulations.
• Requires less memory resources (uses less RAM and reduces swap space allocations).
Basic Reduction
The easiest way of activating Eldo Reduction is by using the generic .REDUCE command:
.REDUCE [FREQUENCY=value] [TUNING=FAST|MODERATE|STANDARD|ACCURATE|VHIGH]
The TUNING=FAST setting is more targeted to digital-like circuits. These refer to circuits with
square signals and for which the accuracy on the signals’ amplitude and delay are less stringent
than for pure analog circuits. Other settings should be suitable for simulating circuits with
higher accuracy requirements. You may optionally specify a maximum delay error, noise error,
Eldo® User's Manual, 15.3 403

Post-Layout Simulation
Parameters Controlling the Reduction Process
or cut-off frequency for the reduction process. Default settings for these parameters usually
suitable for either analog or digital-like circuits may be selected using the optional
ANALOG=YES|NO parameter.
By default the Eldo generic .REDUCE command automatically activates a combination of
reduction methods expected to be well suited for the circuit being reduced according to its
topology. However, this automatic selection may induce some CPU and memory overhead, and
it is highly recommended that for large-sized backannotations, the type of (parasitic) network to
be reduced be specified using the REDUCE_NETWORK_TYPE option.
A third-party netlist reduction library, provided by EdXact SA (http://www.edxact.com), can be
selected with the optional ENGINE=JIVARO parameter. The integration of the netlist reduction
technology enables speeding up simulations with a large number of netlist parasitics, which are
mainly resistors and capacitors. The library is capable of reducing resistors, capacitors and
coupled capacitors. It has been derived from Jivaro , EdXact’s Model Order Reduction based
netlist reduction technology, using a subset of the available options and a dedicated direct
interface. The integration with Eldo is very tight, enabling a very easy integration for members
of CAD departments and a very simple usage for designers.
The Jivaro dynamic library and license to activate it is only provided by EdXact, and must be
purchased from EdXact; not from Mentor Graphics. If you are interested in using the Jivaro
reduction library with Eldo, please contact EdXact. Mentor Graphics does not ship the Jivaro
library, the license must be purchased solely from EdXact. There is no need for any additional
Mentor Graphics license to activate the library, only a license from EdXact is necessary.
Advanced Reduction
In addition to the .REDUCE [ANALOG=YES|NO] command, some specific reduction
commands for RLC or RC (.REDUCE TICER command), resistive-only reduction (.REDUCE
RONLY command) or coupling-capacitance reduction (.REDUCE CC command) are available.
Together with the available reduction options they provide full control of the reduction process.
See Also
• .REDUCE in the Eldo Reference Manual
• .REDUCE TICER in the Eldo Reference Manual
• .REDUCE RONLY in the Eldo Reference Manual
• .REDUCE CC in the Eldo Reference Manual
Parameters Controlling the Reduction Process
There are three main reduction parameters controlling the reduction methods activated by a
.REDUCE command, or more advanced specific reduction commands, described in the
dedicated sections of this chapter.
404
Eldo® User's Manual, 15.3

Post-Layout Simulation
Reduction Output
The NOISE_ERROR parameter is defined as the amount of change in noise amplitude relative
to a full-strength signal. The noise-error value is a ratio, a unitless floating number. The default
value is 0.01 (corresponding to 1%) for the .REDUCE ANALOG=YES command and 0.05
(5%) for the .REDUCE ANALOG=NO command. Default values for both .REDUCE
ANALOG=YES and .REDUCE ANALOG=NO commands are denoted analog default values
and digital-like default values respectively.
The DELAY_ERROR parameter refers to the timing delay threshold used for reduction. The
delay error units are seconds. The analog default is 0.5e-12 (a half picosecond); the digital-like
default is 1.0e-12 (one picosecond).
The FREQUENCY parameter (cut-off frequency) refers to the upper limit of the frequency
band ranging from DC upwards, over which the Eldo Reduction is requested to maintain
accuracy of the simulation results computed using the reduced circuit, within the effective noise
error and delay error margins, as compared to the simulation results that would be obtained with
the original unreduced circuit. Refer to the “.REDUCE” command in the Eldo Reference
Manual for a more detailed explanation of this cut-off frequency parameter.
Since the members of this parameter trio are interdependent, at most two of them can be
specified. Moreover, some of them—even if specified explicitly on the reduction command—
may be overridden according to parameters specified on some possibly conflicting reduction
commands, according to the minimum frequency required to resolve the circuit input signals
and possibly to the frequency range implied by the required simulation analyses as well. When
such a situation occurs, Eldo issues a warning indicating the effective value of the reduction
parameter being modified.
See Also
• .REDUCE in the Eldo Reference Manual
• Reduction Options in the Eldo Reference Manual
Reduction Output
Statistics are printed to enable you to assess the efficiency of the reduction process using the
default or specified parameter values (noise error, delay error, and/or cut-off frequency).
These statistics may change between two successive Eldo versions as a result of a permanent
development process toward increasing reduction efficiency. Nevertheless, the accuracy of the
simulation results, relative to those of the original unreduced circuit, is preserved as long as the
reduction cut-off frequency, noise error, and delay error are set adequately.
See Also
• Reduction Options in the Eldo Reference Manual.
Eldo® User's Manual, 15.3 405

Post-Layout Simulation
Reduction Commands
Related Topics
Parameters Controlling the Reduction Process
Reduction Commands
A number of reduction commands are available in Eldo:
• .REDUCE
Actives a combination of TICER, RONLY, and/or CC reduction methods expected to be
well suited for the circuit being reduced.
See “.REDUCE” in the Eldo Reference Manual.
• .REDUCE CC
Controls reduction of coupled capacitance between RLC or RC nets based on total
capacitance.
See “.REDUCE CC” in the Eldo Reference Manual.
• .REDUCE RONLY
Reduces resistive-only networks by eliminating all internal nodes.
See “.REDUCE RONLY” in the Eldo Reference Manual.
• .REDUCE TICER
Specifies to perform TICER reduction in a way that has little impact on circuit
characteristics, such as delay up to a specified frequency.
See “.REDUCE TICER” in the Eldo Reference Manual.
Related Topics
Reduction Options
Reduction Options
A number of options are provided with the aim of helping the reduction process to achieve
greater efficiency or controlling the topological impact of reduction on the circuit.
The following topics in the Eldo Reference Manual detail each option:
• .OPTION REDUCE_KEEP_INST
• .OPTION REDUCE_KEEP_NODE
• .OPTION REDUCE_KEEP_OUTPUTS
• .OPTION REDUCE_MAX_CAP
406
Eldo® User's Manual, 15.3

Post-Layout Simulation
Reduction Restrictions
• .OPTION REDUCE_MAX_IND
• .OPTION REDUCE_MAX_RES
• .OPTION REDUCE_NETWORK_TYPE
Note
For backward compatibility, the old (pre-2009.1 release) “RC_REDUCE_*” options
are still accepted for reduction. A warning message is displayed to inform you that
this syntax is deprecated, suggesting to use .REDUCE commands instead for greater
efficiency. If both syntax is found in a netlist then the newer .REDUCE syntax takes
precedence.
Related Topics
Parameters Controlling the Reduction Process
Reduction Restrictions
Reduction is disabled—even when a .REDUCE command has been explicitly used—when any
of the following analyses are requested:
• Monte Carlo (see the “.MC” command in the Eldo Reference Manual)
• DC Mismatch (see the “.DCMISMATCH” command in the Eldo Reference Manual)
• Worst-Case (see the “.WCASE” command in the Eldo Reference Manual)
• Sensitivity (see the “.SENSPARAM” command in the Eldo Reference Manual)
• Steady-State Mismatch (see the “.SSTMISMATCH” command in the Eldo RF User’s
Manual)
Related Topics
Eldo Reduction
References
Articles referenced in this chapter:
1. B. Sheehan, Branch Merge Reduction of RLCM networks, proceedings of the IEEE
International Conference on Computer-Aided Design, 9-13 Nov. 2003, pp. 658-664.
2. B. Sheehan, TICER: Realizable Reduction of Extracted RC Circuits, proceedings of the
IEEE International Conference on Computer-Aided Design, 7-11 Nov. 1999, pp. 200-
203.
3. B. Sheehan, Realizable Reduction of RC Networks, IEEE Trans. Computer-Aided
Design Integr. Circuits Syst., vol. 26, no. 8, pp. 1393-1407, Aug. 2007.
Eldo® User's Manual, 15.3 407

Post-Layout Simulation
References
408
Eldo® User's Manual, 15.3

Chapter 11
Monte Carlo Analysis
Monte Carlo analysis (.MC command) determines the uncertainty in circuit performance due to
simulated random variations.
Tip
For an overview of Monte Carlo analysis in Eldo, refer to the Eldo Monte Carlo Quick Start
manual.
Introduction to Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
Introduction to Uncertainty Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
The Monte Carlo Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Basic Statistical Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Monte Carlo Basic Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417
Specifying a Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421
Statistical Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Specifying Statistical Variations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Specifying Statistical Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427
Sharing Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429
How to Specify a Distribution Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431
Correlation Between Gaussian Input Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437
Local and Global Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
Specifying Statistical Variations for Individual Model Parameters . . . . . . . . . . . . . . . . . . 445
Statistical Variations on Binning Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446
Assigning Statistical Variations using the .MCMOD Command . . . . . . . . . . . . . . . . . . . . 446
Tolerance Setting Using DEV, DEVX or LOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447
Sampling Plan Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Standard Monte Carlo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Importance Sampling Monte Carlo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452
Quasi-Monte Carlo Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456
Latin Hypercube Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457
Model-Based Monte Carlo Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 459
Post-Analysis of Monte Carlo Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463
Output of Uncertainty Analysis (the .chi File) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465
Primary Statistics of Uncertainty Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
Additional Uncertainty Analyses (the .mcm File) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491
Input/Output Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
Graphical Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509
Run-Length Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514
Eldo® User's Manual, 15.3 409

Monte Carlo Analysis
CONFIDENCE Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514
SETTLING Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
MCCONV Extract Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518
Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
Global Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
Large Scale Variable Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
Monte Carlo Analysis Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526
A Simple Passive Low-Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526
Importance Sampling Monte Carlo Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528
Model-Based Approximations Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532
Further Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534
Parameter Naming Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536
Problems in Statistical Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544
Obsolete Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548
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Introduction to Monte Carlo Analysis
Monte Carlo Analysis
Introduction to Monte Carlo Analysis
The main goal of the Monte Carlo command is to analyze the uncertainty in circuit performance
due to simulated random variations. It focuses on how uncertainty in input data propagates
through computations.
The input data is the various design parameters, the process parameters, and the environmental
conditions. A circuit performance may be any measure that is extracted from the simulation, and
will be noted with the functional form , where we note the input parameters with the
generic symbol x.
Eldo reads a netlist describing the circuit and translates it into mathematical equations. The
Monte Carlo simulation is performed on multiple model evaluations with randomly selected
model input variables. The results of these evaluations are then used to determine the
uncertainty in model predictions, and the input variables that gave rise to this uncertainty.
To use the Monte Carlo analysis in Eldo, you must do the following:
• Provide a working netlist with one or more user-defined circuit performances (the output
measures) based on other analyses (DC, AC, TRAN, ...).
• Specify the .MC statement in the netlist. See “Specifying a Monte Carlo Analysis” on
page 421.
• Introduce some statistical variations on circuit parameters, model parameters and/or
environmental conditions (the input variables X). See “Statistical Variations” on
page 423.
The following topics are devoted to the definition of the concept of uncertainty and its relation
to the Monte Carlo simulation.
Introduction to Uncertainty Analysis
In our context, we may define the uncertainty u(H) of a circuit performance H, as a parameter
that characterizes the dispersion of the values that can be attributed to the random variations of
this performance. This parameter may be a standard deviation or the width of an interval having
a given level of coverage or yield. Conversely, one may be interested in estimating the
probability of being between user-defined specifications.
Standard Uncertainty
An estimate of the expectation of a random variable (the circuit performance of interest) for
which n independent observations Y i =H(X i ) are simulated, is the arithmetic mean:
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Introduction to Uncertainty Analysis
This is, in some sense, the best estimate possible of the expectation. The sample variance, which
estimates the variance of the probability distribution of Y, is given by:
This estimate of the variance and its square root (called the experimental standard deviation)
characterizes the variability of the observed values Y i , or their dispersion about their mean.
Figure 11-1. Central Tendency and Dispersion
A Monte Carlo experiment (with 1,000 runs, for example) provides one single realization of the
random variables (sample mean, variance, and so on). However, this realization is not useful if
the result does not come with a reliable confidence interval. Figure 11-1 shows an interval
that encloses the mean . This interval characterizes the precision obtained by
the Monte Carlo estimator of the mean.
In practice, the coefficient of variation and the relative standard error of mean
are often used to quantify the relative variability (or obtained precision) of one
given estimator . The Eldo Monte Carlo flow uses the following definition of the RSEM if the
mean is non-zero:
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Introduction to Uncertainty Analysis
If the mean is zero, the relative standard deviation scaled by
is used instead:
The coefficient of variation is defined as a multiple of the RSEM. Refer to “Mean and
Standard Deviation” on page 478 for more information.
Uncertainty as an Interval
Under the assumptions that the probability distribution of the output measure can be assumed to
be normal (Gaussian). The uncertainty is often defined as an interval about the measurement
result that may be expected to cover a given fraction of the distribution of values. This interval
can be associated to a number u(H) obtained by multiplying the standard deviation by a
coverage factor κ p :
The number p is the coverage probability or level of confidence of the interval. A measurement
is then conveniently expressed as:
Then for example, one may take κ p = 2 for having an interval with confidence interval of
approximately 95 percent. By taking κ p = 3, a confidence level of approximately 99 percent
would be obtained.
It is important to understand that the assumption of normality cannot be used in any cases, and
this motivates the introduction of Monte Carlo simulation methods as general and flexible tools
for addressing difficult estimation problems. The Monte Carlo method provides a numerical
approximation of the output distribution, which may be non-Gaussian. This distribution is in
general not symmetric, and a coverage interval is not necessarily centered on the average value.
Yield and Failure Probability Estimation
You may want to compute the probability values associated with lower and upper bounds
(y L , y U ) for a circuit performance Y. Conversely, you may want to compute the bound or
threshold that corresponds to a target probability value π L, U .
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Introduction to Uncertainty Analysis
Figure 11-2. Tail Probabilities and Yield Computation
These tasks typically enter in a manufacturing flow called “yield learning flow”. In such a flow,
yield is defined to be the proportion of the manufactured circuits that satisfy both the design
engineers’ and the process engineers’ specifications. The yield of a manufactured product
should increase from the initial design to the large-volume production. Yield is therefore related
to the cost of production. Process variations significantly impact circuit performance in nanoscale
technologies, and as process variations become relatively large beyond the 65nm
technologies, the task of yield estimation is increasingly important for circuit designers.
Yield is often interpreted as the probability of failure, rather than the probability of success. A
typical and important example is SRAM manufacturing yield, which is defined to be the
probability of a wrong operation (read, write, or retention) occurring in an SRAM circuit.
Yield may be quantitatively appreciated by considering an explicit value for the acceptable
quality limit (AQL). For example, an AQL for 1Megabit SRAM bit-cell circuits could be
100 ppm. If production of one million such circuits is targeted, the manufacturing process
cannot allow more than 100 defective bit-cells globally. This means that the probability of
failure must be at most:
A specific Monte Carlo algorithm must be used for such low probability values. Eldo provides a
a novel “rare events” Monte Carlo algorithm based on importance sampling techniques. Refer
to “Importance Sampling Monte Carlo” on page 452 for more information.
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The Monte Carlo Flow
Monte Carlo Analysis
The Monte Carlo Flow
To be more precise, the Monte Carlo is defined as a systematic sampling from the random
distribution f X (x)=PDF X (x) for the input variables X. A simple Monte Carlo estimate of the
distribution of Y=H(X) is obtained by generating X i for i = 1, 2, ..., n from the PDF X , and
simulating Y i =H(X i ). The observed values Y i are used as an estimate of the distribution of Y.
This is depicted in Figure 11-3.
Figure 11-3. Propagation of Distributions
In some sense, the Monte Carlo method provides an efficient way to propagate the input
distributions through the simulation engine, and to compute the distribution function:
Any property of the output distribution, such as the expectation (average value), variance and
coverage intervals can be obtained using CDF Y .
Basic Statistical Concepts
This short section formalizes some concepts in Probability Theory used in this chapter.
Some other materials can be found in Basic Concepts on Multivariate Distributions.
The basic ingredients of a statistical model are the following. First, a random variable Y, which
represents a quantity whose outcome is uncertain. The set of possible outcomes of Y, denoted Ω,
is the sample space. Second, a probability distribution, which assigns probabilities to events
associated with Y. The random variables we consider are continuous random variables: they
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Basic Statistical Concepts
have a sample space Ω, that is continuous. Probability distributions can be specified by their
probability distribution function, defined as:
for each y in Ω. From this identity we can calculate the probabilities of Y falling within intervals
as:
If the distribution function F Y is differentiable, it is also useful to define the probability density
function of Y as f Y (y) = dF Y /dy, in which case:
and:
It is often convenient to summarize a probability distribution by one or two statistics that
characterize its main features. The most common are expectation and variance. In the case of
continuous random variable with probability density function f Y , the expectation is
and the variance is:
Expectation provides a measure of location, or average value, of the distribution, while the
variance measures the dispersion or spread of the distribution. The standard deviation is defined
as the square root of the variance, providing a measure of variability in the same units as Y.
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Monte Carlo Basic Features
Monte Carlo Basic Features
Monte Carlo analysis can be understood as a form of integration algorithm, or as an incremental
approach providing a gradual insight into the spread of distribution.
Monte Carlo as an Integration Algorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417
Monte Carlo Incremental Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
Monte Carlo Analysis With a Varying Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
Monte Carlo as an Integration Algorithm
Monte Carlo analysis can be understood as a form of integration, where the expected value:
of a random variable Y = φ(H(X)) needs to be estimated. Depending on the chosen function φ,
several different quantities can be estimated:
• φ(h) = h
The mean of the output response Y = H(X) is estimated.
• φ(h) = h 2
The second order moment and the variance of the distribution are estimated.
• φ(h) = I {h ≥ y}
The probability of exceeding the threshold y is estimated.
The standard Monte Carlo approach (referred to as the “Monte Carlo method”, following
Metropolis and Ulam (1949)), is to use a sample X 1 , …, X n from the density f X to approximate
the expectation by the empirical average:
In a simple Monte Carlo analysis the values of the circuit characteristics are independent and
identically distributed (i.i.d.), therefore standard results apply (under some assumptions): the
Strong Law of Large Numbers and the Central Limit Theorem describe the convergence of the
sample mean. The average converges almost surely to the expectation E(H(X)) and the
speed of convergence can be assessed because the variance
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may be approximated with the summation:
This property implies that a convergence test can be constructed and that confidence bounds on
the computations can be provided. In Eldo it is possible to use the .MC AUTOSTOP parameter
to control the run length for estimating the average value E(H(X)) (this can save CPU time).
For example, a convergence test based on confidence interval techniques can be defined with
the extract function MCCONV as follows:
* EXTRACT SECTION
* THE PERFORMANCE CRITERIA OF INTEREST IS:
* THE OSCILLATION FREQUENCY: OFREQ
.EXTRACT TRAN LABEL=OFREQ 1/(XDOWN(V(1),2.5,END)-XDOWN(V(1),2.5,START))
* MONTECARLO ANALYSIS
.MC 1000 AUTOSTOP=’mc_conv_freq’
.EXTRACT MC LABEL=mc_conv_freq MCCONV(OFREQ, AVG, CONFIDENCE, 100, 0.95)
where the expression MCCONV(OFREQ, AVG, CONFIDENCE, 100, 0.95) is a Boolean
value, which is true if some specific criterion is satisfied for the sample mean value AVG.
Example with multiple MCCONV extracts:
* MONTE CARLO ANALYSIS
.MC 1000 AUTOSTOP='mc_conv_avg && mc_conv_std'
.EXTRACT MC LABEL=mc_conv_avg
+ MCCONV(V1,AVG,CONFIDENCE, 100, 0.99, 0.0004, 0)
.EXTRACT MC LABEL=mc_conv_std
+ MCCONV(V1,STD,CONFIDENCE, 100, 0.99, 0.0003, 0)
Note that the Central Limit Theorem says that the sample mean converges to the expected value
at the rate O(n −1/2 ) which means that in practice an extra digit of accuracy requires 100 times as
many simulations. The convergence is therefore slow compared to more efficient numerical
methods such as Riemann quadrature or Simpson method, but the convergence of the MC
method is completely independent of the dimension of the input space.
Related Topics
Specifying a Monte Carlo Analysis
CONFIDENCE Technique
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Monte Carlo Basic Features
Tips for Improving Simulation Performance
Monte Carlo Incremental Approach
The overall Monte Carlo analysis run is made of several batches of simulations. Using an
incremental approach provides gradually an insight into the spread of distribution.
In Eldo, you control the sample size n and optionally, how the sampling is generated. In this
example, 100 simulations are requested by including the following statement in the netlist
description:
* Monte Carlo Analysis
.MC 100 SAVE=mc_file RESTART=mc_file
The additional SAVE/RESTART arguments are used to save the random sampling and the
simulated characteristics (see “Tips for Improving Simulation Performance” on page 1259).
These quantities can be used in subsequent Monte Carlo experiments. SAMPLING=LHS is
disabled when RESTART is specified.
Tip
See “.MC” in the Eldo Reference Manual.
Monte Carlo Analysis With a Varying Circuit
When you specify Monte Carlo analysis, Eldo performs the complete Monte Carlo analysis
after each change of the circuit parameters or the circuit’s configuration.
The probability distribution of a random variable may depend on the values of some circuit
parameters. For instance, the temperature of a MOS device affects the device’s threshold
voltage. After each change of the circuit parameters, Eldo recomputes the probability
distributions of the random variables, then performs the specified Monte Carlo analysis using an
appropriate set of input samples.
The probability distribution of a random variable may also depend on the circuit’s
configuration, which you can alter using .ALTER statements. Eldo performs a separate Monte
Carlo analysis for each configuration specified in the netlist, starting with the unmodified
netlist.
The results of each Monte Carlo analysis follow the corresponding change of circuit parameters
or netlist modification in the .chi file. If you requested detailed statistical outputs, the results of
the ith Monte Carlo analysis are also contained in the file _.mcm. The optional
output files _.mci and _.mco contain tables of the input and output
samples for the ith Monte Carlo analysis.
For example, the following netlist specifies Monte Carlo analysis with a sweep of a circuit
parameter PVG through 7 values:
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* Example of Monte Carlo analysis with a swept parameter.
* Extract the leakage current of a BSIM4 device. The manufacturing
* process introduces statistical variation in the threshold voltage.
.MODEL N NMOS LEVEL=60 VTH0=250m DEV/GAUSS=5%
M1 D G 0 0 N W=1u L=65n
VD D 0 2
VG G 0 PVG
.DC
.EXTRACT DC LABEL=ID ID(M1)
* Specify Monte Carlo analysis and request statistical outputs.
.MC 1000 NBINS=60 DATAFLOW=1 PRINT_TEST_AP=1 PRINT_MOMENTS=1
* Sweep the voltage applied to the gate from 2V to 0V.
.PARAM PVG=2
.STEP PARAM PVG LIST 2 1 0.4 0.35 0.3 0.1 0
.END
In this example, Eldo will perform 7 separate Monte Carlo analyses and generate files
example_1.mcm, example_2.mcm, …, example_7.mcm containing statistical information about
the output measure ID (the leakage current of M1) for PVG=2, PVG=1, …, PVG=0
respectively. In particular, each .mcm file contains an estimate of the skewness of the
distribution of ID:
PVG Output File Skewness of ID
2 example_1.mcm 6.26×10 -2
1 example_2.mcm 5.86×10 -2
0.4 example_3.mcm 2.98×10 -2
0.35 example_4.mcm 3.31×10 -1
0.3 example_5.mcm 7.30×10 -1
0.1 example_6.mcm 1.40
0 example_7.mcm 1.42
The distribution of ID is almost normal for PVG=2 to PVG=0.4, but as PVG approaches 0 the
distribution of ID becomes log-normal.
In addition to affecting the input and output sample distributions, the values of circuit
parameters and the circuit’s configuration can affect the convergence rate of the Monte Carlo
algorithm. This means that the quality of the statistical results may vary as the circuit varies. In
the above example, the coefficient of variation for ID (at 95%) ranges from 0.408% to 2.756%
as PVG is swept from 2 to 0. By increasing the number of runs per Monte Carlo analysis to
10000, this range can be improved to 0.013%–0.888%. However, the disadvantage of uniformly
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Specifying a Monte Carlo Analysis
increasing the number of runs is that Eldo then performs unnecessarily long Monte Carlo
analysis for the larger values of PVG.
To ensure consistent quality of the statistical results across the full range of circuit parameters
and configurations, it is recommended to specify a large number of maximum runs and use a
convergence condition to automatically stop each Monte Carlo analysis. Refer to “Run-Length
Control” on page 514 for more information.
Related Topics
Specifying a Monte Carlo Analysis
Post-Analysis of Monte Carlo Simulations
Specifying a Monte Carlo Analysis
To specify a Monte Carlo analysis, include a .MC statement in your netlist. Optional parameters
for run-length (or convergence) control, the control of graphical output in EZwave, and the
sampling algorithm can be specified. The nrun_max argument is mandatory:
.MC NRUN_MAX [OV] [RUN CONTROL PARAMETERS] [OUTPUT CONTROL PARAMETERS]
[SAMPLING METHOD PARAMETERS]
Run Control Parameters
NRUN_MAX IRUN OUTER AUTOSTOP SAVE
RESTART NONOM DATAFLOW
Output Control Parameters
ALL OV SENS RESPONSE
NBBINS RULEBIN MEASCORR SIZECORR
PRINT_EXTRACT
PRINT_ALL_POST_ANALYSIS
PRINT_NO_ANALYSIS
PRINT_ASCII_HISTO
PRINT_ASCII_IN_SAMPLE
PRINT_ASCII_OUT_SAMPLE
PRINT_COV
PRINT_CONF
PRINT_ALT_STATS
PRINT_MINMAX
PRINT_MOMENTS
PRINT_TEST_AP
PRINT_CAPABILITY
PRINT_OUTPUT_CORREL
Sampling Method Parameters
SEED VARY SAMPLING SSD_COMPLEXITY
SSD_NRUN_TEST IS_MAXITER IS_RTOL
For a detailed description of all optional parameters, see .MC in the Eldo Command Reference.
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Other Parameters
MONITOR SIGBIN MAXABSBIN MAXRELBIN ORDMCS
MCLIMIT
The .MC command is used to control the Monte Carlo algorithm, and the setup of statistical
problem (input variables) is defined with some simple extensions of the basic statements:
.PARAM, .MODEL, and .MCMOD. More specific statements such as .CORREL, .DISTRIB,
and .LOTGROUP may also be used.
Tip
See “.MC” in the Eldo Reference Manual.
Related Topics
Statistical Variations
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Statistical Variations
Statistical Variations
How statistical models are specified depends in general on the foundries. They define to place
the most appropriate distributions on parameters within their PDK model files.
Statistical models are generally written as functions of both process parameters and geometrical
parameters.
• Process parameters
These parameters determine the behavior of the instantiated devices, such as junction
depths, sheet resistances, dielectric thickness and doping levels.
• Geometric layout parameters
Device length and width, and more specific parameters related to the layout.
Specifying Statistical Variations
In statistical modeling, the variations in parameter P are formulated as either relative or
absolute. Some physical quantities such as mobility, sheet resistances, dielectric thicknesses and
doping concentrations have their variations directly in a relative sense:
In this case, the models use the percentage value δP = ΔP/P typ in the definition of parameters,
and P = P typ (1 + δP).
There are parameters for which this model does not apply. Geometrical variations will have
their variations in the absolute sense:
For example, the following statements define a gaussian distribution on the TOX parameter in a
relative sense:
.PARAM A_MM_TOX=0.4543U B_MM_TOX=0.1435
+ DEV_MM_TOX = ’A_MM_TOX/SQRT(WDRAWN*LDRAWN)+B_MM_TOX’
.PARAM TOX = TOX_TYP DEV/GAUSS={DEV_MM_TOX}%
The standard deviation of the Gaussian distribution is specified with the percent % character.
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Statistical Configuration on Devices and Subcircuits
The device model argument, STATISTICAL=0|1, can be specified on X instances, device
declarations, or on .SUBCKT definitions, to specify whether any statistical variation due to .MC
can be applied to the specified entities.
If STATISTICAL is 0, the selected devices will keep their nominal values. If STATISTICAL is
1, the selected devices have statistical variation applied. The global default value can be
specified using the option STATISTICAL= 0|1. Default is 1. See the Statistical Configuration
Usage Example.
Note
When a Monte Carlo analysis is specified, merging devices or subcircuits in parallel (with
or without device multiplier M=val specified) is disabled.
Example of Process Variations on a Capacitor Model
The following example demonstrates the statements for a subcircuit to model a simple capacitor
device, and the effects of process variations upon this device. Typically, process experts create
libraries of subcircuits containing much more complex equations and interactions representing
the process effect. Here we have modeled the fact that large geometry devices tend to exhibit
better matching characteristics than small geometry devices.
In the subcircuit CAPA, a capacitor is connected across the two ports PLUS and MINUS. The
value of the capacitor is a function of the subcircuit parameters and the process parameters. The
subcircuit input parameters include the default values of the capacitor area CAREA and
perimeter CPERI (assuming a rectangular shape).
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.SUBCKT CAPA PLUS MINUS B
+ PARAM: CAREA=1.0 CPERI=2.0 C=-1 W=-1 MISMATCH=1 TOMETER=1E-6
.PARAM TOX_TYP = 1.9E-08
+ COX_TYP = ‘3.9 * 8.85418E-12 / TOX_TYP’
.PARAM D=’CPERI**2-4*CAREA’
.PARAM WDRAWN =
+‘VALIF((C>0)&&(W>0),W,
+ VALIF(D>0,SQRT(D)+CPERI,CPERI)/2)*TOMETER’
.PARAM LDRAWN =
+‘VALIF((C>0)&&(W>0),C/(COX_TYP*WDRAWN),
+ VALIF(D>0,CAREA/WDRAWN,WDRAWN))*TOMETER’
.PARAM A_MM_TOX=0.4543U B_MM_TOX=0.1435
+ DEV_MM_TOX = ’A_MM_TOX/SQRT(WDRAWN*LDRAWN)+B_MM_TOX’
.PARAM TOX = TOX_TYP DEV/GAUSS={DEV_MM_TOX}%
.PARAM COX = ‘3.9 * 8.85418E-12 / TOX’
.PARAM DL = 0.0 LOT/GAUSS={2.0E-09}
.PARAM DW = 0.0 LOT/GAUSS={5.0E-09}
.PARAM LEFF = ‘LDRAWN - DL’
.PARAM WEFF = ‘WDRAWN - DW’
.PARAM AEFF = ‘WEFF*LEFF’
*
CC PLUS MINUS VALUE=’COX * AEFF’
*
.ENDS CAPA
The subcircuit parameters also define intermediate values including the drawn length
LDRAWN and width WDRAWN of the device. These quantities are computed depending on
the values of capacitance C and width W, which are the input parameters of the subcircuit.
When the default value, -1, is used for these parameters the geometry is computed from
CAREA and CPERI. It may be more useful for a designer to specify the capacitance and width,
then calculate the drawn length at the layout stage.
The typical (or nominal) value of the COX parameter is used in the definition of the drawn
length:
You may use this value at layout time to determine the capacitor length that gives the desired
capacitance for a given width. Once a Monte Carlo analysis is started, the parameter COX will
be subject to statistical variations. This is why the typical value of the COX parameter is used,
because if the parameter COX were to be used in the previous expression instead of the nominal
value COX_TYP, different values for capacitor length would be calculated.
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The parameters LEFF, WEFF, and AEFF contain respectively the effective length, width, and
area of the capacitor. Indirectly, the expression of AEFF depends on the statistical variations of
the geometry. This will vary the effective area AEFF, and therefore will affect the effective
capacitance value.
Process Parameters and Geometrical Variations
The process parameters are given for the oxide thickness TOX and the geometrical variations
DL and DW. The nominal value for the oxide thickness is 19nm. The typical values for the
variations for DL and DW are fixed to 0.
The local variations of the oxide thickness have an area dependency:
In the netlist this matches the expression:
.PARAM DEV_MM_TOX = ’A_MM_TOX/SQRT(WDRAWN*LDRAWN)+B_MM_TOX’
where the two factors, A_MM_TOX and B_MM_TOX are defined for the statistical
distribution of oxide thickness. They are defined as constant terms:
• A_MM_TOX=0.4543U
• B_MM_TOX=0.1435
This equation relates the variance of the process parameter TOX to the inverse square root of the
area. The local variation decreases as the device size increases. Note that by contrast, the global
process variations are independent of the effective length L and width W.
This equation is based on the mismatch model proposed by Pelgrom: M.J.M. Pelgrom et. al.,
Matching Properties of MOS Transistors, IEEE Journal of Solid-State Circuits, Vol. 24, No. 5,
1989, pp. 1433-1439.
Local Mismatch Variations
The modeling of local mismatch variations can be done using a MOS device L, W, M by
accessing the EVAL() function: E(X1.M1,L) or EVAL(*,W).
Related Topics
Specifying Statistical Parameters
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Monte Carlo Analysis
Specifying Statistical Parameters
There are two different methods for the specification of statistical parameters using the
.PARAM statement.
First Syntax
.PARAM PARAMETER_NAME = UNIF|AUNIF|GAUSS|AGAUSS|LIMIT({OPTION_LIST})
where the distributions and their arguments are defined below:
• UNIF(NOM_VALUE, FRAC_VALUE)
Defines a uniform distribution with relative variation . The parameter
PARAM_NAME varies uniformly between and , where is the
NOM_VALUE argument and ρ is the positive value FRAC_VALUE.
• AUNIF(NOM_VALUE, ABS_VALUE)
Defines a uniform distribution with absolute variation . The parameter
PARAM_NAME varies uniformly between and , where is the
NOM_VALUE and h is the positive half-range ABS_VALUE.
• GAUSS(NOM_VALUE, FRAC_VALUE, SIGMA_COEF)
Defines a Gaussian distribution . The distribution is centered at NOM_VALUE,
and the standard deviation is given by σ = (NOM_VALUE × FRAC_VALUE) ÷
SIGMA_COEF.
• AGAUSS(NOM_VALUE, ABS_VALUE, SIGMA_COEF)
Defines a Gaussian distribution . The distribution is centered at NOM_VALUE,
and the standard deviation is given by σ = ABS_VALUE ÷ SIGMA_COEF.
• LIMIT(NOM_VALUE, ABS_VALUE)
Defines a discrete probability distribution on the finite set of values NOM_VALUE -
ABS_VALUE and NOM_VALUE + ABS_VALUE with equal probability.
There is an additional argument to the UNIF and GAUSS macro-definitions. This argument is
named MULT in the following syntax commands:
.PARAM PARAM_NAME = UNIF|AUNIF(NOM_VALUE, RANGE_VALUE, MULT)
.PARAM PARAM_NAME = GAUSS|AGAUSS(NOM_VALUE, STD_VALUE, SIGMA_COEF, MULT)
The role of the MULT argument, which is an integer value greater than 1, is to eliminate the
simulation of the sub-population that is “closed” to the median value of the parameter. The role
of this argument is explained in more detail in “Weighted Uniform and Gaussian Distributions”
on page 551.
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Eldo Native Syntax
The second approach uses a combination of the keywords DEV, DEVX, and LOT to specify the
individual statistical parameters. Sometimes it is more appropriate for modeling local (DEV)
and global (LOT) variations. This approach is also used within the .MODEL and .MCMOD
statements.
The syntax is defined as follows:
.PARAM PARAM_NAME=NOM_VALUE LOT/UNIF=HALF_RANGE_VALUE[%]
.PARAM PARAM_NAME=NOM_VALUE DEV/UNIF=HALF_RANGE_VALUE[%]
.PARAM PARAM_NAME=NOM_VALUE
+ LOT/UNIF=HALF_RANGE_VALUE[%]
+ DEV/UNIF=HALF_RANGE_VALUE[%]
.PARAM PARAM_NAME=NOM_VALUE
+ LOT=(UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%])
.PARAM PARAM_NAME=NOM_VALUE
+ DEV=(UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%])
.PARAM PARAM_NAME=NOM_VALUE
+ LOT=(UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%])
+ DEV=(UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%])
and for the Gaussian distributions:
.PARAM PARAM_NAME=NOM_VALUE LOT/GAUSS=SIGMA_VALUE[%]
.PARAM PARAM_NAME=NOM_VALUE DEV/GAUSS=SIGMA_VALUE[%]
.PARAM PARAM_NAME=NOM_VALUE
+ LOT/GAUSS=SIGMA_VALUE[%]
+ DEV/GAUSS=SIGMA_VALUE[%]
.PARAM PARAM_NAME=NOM_VALUE
+ LOT=(NOR,MINUS_3SIGMA_VALUE[%],PLUS_3SIGMA_VALUE[%])
.PARAM PARAM_NAME=NOM_VALUE
. DEV=(NOR,MINUS_3SIGMA_VALUE[%],PLUS_3SIGMA_VALUE[%])
.PARAM PARAM_NAME=NOM_VALUE
+ LOT=(UNI,MINUS_3SIGMA_VALUE[%],PLUS_3SIGMA_VALUE[%])
+ DEV=(UNI,MINUS_3SIGMA_VALUE[%],PLUS_3SIGMA_VALUE[%])
The argument [LOT|DEV]/UNIF=VALUE[%] specifies a range value for the uniform
distribution , and the additional percentage character % is used to specify the
distribution .
The DEVX keyword is used to indicate that the variations of a subcircuit parameter must have a
global scope within the .SUBCKT block. In other words, the DEVX parameters have LOT
variations within a .SUBCKT block. If a parameter is used at the top level (outside of a
subcircuit) and is defined with DEVX variation, the parameter keeps its nominal value during
statistical analysis.
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Controlling Statistical Parameter Value Types
Monte Carlo Analysis
Sharing Distributions
By default, the value used for statistical parameters in .EXTRACT and .DEFWAVE commands
is the nominal value. This allows easy interpretation of results mixing both LOT and DEV
variations.
To change the type of value returned by statistical parameters, specify .OPTION
OUT_MCPARAM=LOT.
Tip
See “.PARAM” in the Eldo Reference Manual.
Related Topics
Specifying Statistical Variations for Individual Model Parameters
Assigning Statistical Variations using the .MCMOD Command
Sharing Distributions
To enable different entities to share the same distribution specify the .LOTGROUP command.
Anywhere Eldo accepts LOT or DEV specification, LOTGROUP=GROUP_NAME can be
specified.
When used in Monte Carlo statistical variation, if the LOTGROUP variation is absolute, the
same random number is added to the nominal value for each parameter of the group. If the
LOTGROUP variation is relative, the same random number is multiplied by the nominal value.
The .LOTGROUP command enables a probability distribution function to be defined that will
be shared by different entities in the circuit. It may be thought of as a template where the
location value of the distribution (the mean for example) is not specified.
The .LOTGROUP only defines the family of the distribution (Uniform, Gaussian) and its range
or variance. For example, the statement:
.LOTGROUP MY_LOT_GROUP=UNIFORM/10%
defines a template of distribution UNIF(NOM_VALUE,0.1*NOM_VALUE) where
NOM_VALUE is unspecified. The NOM_VALUE parameter will be known when a statistical
parameter is associated to the LOTGROUP distribution. For example, you could have:
.PARAM P=1.0 LOTGROUP=MY_LOT_GROUP
and the statistical parameter P will be randomly chosen in the interval [0.9, 1.1].
Tip
See “.LOTGROUP” in the Eldo Reference Manual.
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Monte Carlo Analysis
Sharing Distributions
Related Topics
How to Specify a Distribution Function
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How to Specify a Distribution Function
Monte Carlo Analysis
How to Specify a Distribution Function
By definition, “simple” random variables refer to statistical distributions that can easily be
generated on a computer. The context usually dictates which random variables are meant. For
example, the uniform distribution U([0, 1]) is simple, and so are the normal or user-defined
cumulative distributions in most circumstances. In other terms, the simple distributions are
elementary building blocks, and “complex” distributions can be defined as the result of complex
transformations of the other distributions. The simple random variables are often associated to
independent variables such as some process parameters or environmental conditions. In some
cases, the PDK models are derived from Principal Components Analysis, and the principal
components are simple Gaussian distributions.
The available distributions are grouped into two classes. The first class is associated to
parametric models. These models aim to describe probability distributions of a random variable
with the aid of a limited number of parameters Θ. The probability density of X can be expressed
as f X (x, Θ). The list of these distributions is given here:
• Uniform Distribution
• Gaussian or Normal Distribution
• Weighted Uniform and Gaussian Distributions
The second class represents distributions that are specified by a non-parametric procedure. A
typical example is given by the so-called weighted uniform or gaussian that is defined implicitly
by an accept/reject algorithm. The list of these distributions is given here:
• User-defined Distribution
• NOR/UNI Distributions
• Weighted Uniform and Gaussian Distributions
Note
Some of these distributions, such as the “weighted” UNIF/GAUSS, may seem unusual or
non-standard for many users. They represent the legacy of past experimentations in Eldo
and other third part tools. The implementation of those distributions are described.
Uniform Distribution
The uniform distribution defines equal probability over a given range for a continuous
distribution. The parameters are Θ = (L, U), with the constraint L < U. The probability density
function is expressed as:
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How to Specify a Distribution Function
Figure 11-4 shows the common statistics for a uniform distribution ( ).
Figure 11-4. Common Statistics for UNIF Distribution
The common statistics for the uniform distribution are:
• mean:
• standard deviation:
The half-range of the distribution is the value h = (U − L)/2. Therefore, for the following
definition (using the Eldo native syntax, other syntaxes may also be valid):
.PARAM PARAMETER_NAME=NOMINAL_VALUE {LOT|DEV|DEVX}/UNIF=HALF_RANGE_VALUE
the value HALF_RANGE_VALUE, noted h in the formulae, represents the half range (see
Figure 11-4), giving:
or when this value h is specified as a percentage:
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Gaussian or Normal Distribution
Monte Carlo Analysis
How to Specify a Distribution Function
In this case the parameters are Θ = (μ, σ), with the constraint σ > 0. The probability density is
given as:
We note that a random variable which follows a Gaussian distribution as defined here takes real
values from (−∞, ∞). The simulated values are actually truncated to some user-defined interval.
This interval is defined with the SIGTAIL argument on the .MC statement. See the Remarks on
the Truncated Normal Distribution.
The parameter μ provides the most likely value (for which the probability density function is at
its highest), and the density function is symmetric around this value; μ is also the expected value
(mean) of this distribution. The parameter σ provides a measure of dispersion: the larger it is,
the flatter the probability density function is (that is, values far away from μ are still likely, or in
other words possible values are more spread out).
The plot in Figure 11-5 depicts the common statistics of the Gaussian distribution.
Figure 11-5. Percentage of Cases in Eight Portions of the Gaussian Distribution
This plot may help you define the SIGTAIL argument of the .MC analysis. For example, the
range [−σ, σ] represents 34.13% + 34.13% = 68.26% of cases obtained after running the sample
process in the Monte Carlo algorithm, and the range [−3σ, 3σ] covers 2(34.13% + 13.59% +
2.14%) = 99.72% of the cases.
Remarks on the Truncated Normal Distribution
For the truncated Normal distribution, the parameters are Θ = (μ, σ, a, b), with the constraints
that σ > 0, b > a.
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Monte Carlo Analysis
How to Specify a Distribution Function
The probability density function is expressed as:
where φ and Φ represent the probability density and the cumulative distribution function
respectively of the reduced centred Normal distribution (that is, the mean μ zero and standard
deviation σ equal to 1).
A random variable that follows a truncated Normal distribution takes values in the interval
[a, b]. The parameter μ describes the most likely value. Whilst σ provides a measure of
dispersion. Figure 11-6 shows an example with μ = 20, σ = 7, and [a, b] = [10, 35].
In Eldo, the centered and reduced Gaussian variables are generated with the truncated normal
distribution before transformation to the original scales of the input space.
Figure 11-6. Plot of the Truncated Normal
The bounds of the truncation interval are fixed by default to the SIGTAIL value. Note that this
interval is necessarily a symmetric interval.
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User-defined Distribution
Monte Carlo Analysis
How to Specify a Distribution Function
You can define an arbitrary model using the .DISTRIB command. Provided here is the example
of triangular distribution (which is actually a parametric distribution), where the .DISTRIB
command is used as a template for a slightly skewed triangular distribution.
This general triangular distribution is defined with three parameters (a, b, m), with the
constraints a≤m, m≤b, b>a. The probability density function is expressed as:
Note, a random variable that follows a triangular distribution as defined here takes in the
interval [a, b]. The parameter m describes the most likely value. Figure 11-7 shows the plot of
triangular distribution with m=15 and [a, b] = [5, 20].
Figure 11-7. Plot of the Triangular Distribution
The distribution given in Figure 11-7 can be obtained with the following statements:
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Monte Carlo Analysis
How to Specify a Distribution Function
.DISTRIB TRI (0, 0) (0.66666, 1) (1, 0)
.PARAM XVAL=5 LOT/TRI=15
V1 1 0 XVAL
.OP
.MC 1000 NBBINS=50
.EXTRACT DC LABEL=R1 E(V1,V)
.END
The distribution parameters a, b are defined implicitly by construction. The most frequent value
m is obtained by the formula: 5 × 0.66666 + 5 ≈ 15. Note also that the value XVAL=5 in the
PARAM statement cannot be considered as the nominal value of the resistor. It is used as a shift
in value of XVAL and LOT/TRI=15 is a scaling factor.
Other Common Distributions
You can generate additional distributions by using the basic building blocks of the previous
section.
• Half-Normal Distribution
The half-normal distribution is the probability of the absolute value of a normal
distribution with mean 0 and variance σ 2 . If X ~ N(0, σ 2 ), then Y = |X| is half-normally
distributed.
• Log-Normal Distribution
The log-normal distribution is the single-tailed probability distribution of any random
variable whose logarithm is normally distributed. If X is a random variable with a
normal distribution, then Y = e X has a log-normal distribution.
Related Topics
Tip
See “.DISTRIB” in the Eldo Reference Manual.
Correlation Between Gaussian Input Variables
Specifying a Monte Carlo Analysis
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Monte Carlo Analysis
Correlation Between Gaussian Input Variables
Correlation Between Gaussian Input Variables
You can specify linear correlations between random variables in Eldo under some conditions:
the variables must have Gaussian distribution and only LOT variations. We review some basic
notions on multivariate probabilities.
Basic Concepts on Multivariate Distributions
A multivariate random variable is a vector of random variables. Notation is made more compact
by writing X = (X 1 , …, X k ) T . Each of the components X i is a random variable in its own right,
but specification of the properties of X as a whole requires information about influence of every
variable on each of the others. Knowledge that one component is large therefore increases the
probability that the other components are large.
Generalizing the single variable case, the joint distribution function of X is defined by:
where x = (x 1 , …, x k ) T . When the X i are continuous random variables, and provided it exists, the
joint density function is given by:
In this case:
The probability density functions of each of the individual X i , termed marginal density
functions, are obtained by integrating out the other components. For example:
is the marginal probability density function of the component X 1 . Similarly:
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Monte Carlo Analysis
Correlation Between Gaussian Input Variables
is the joint marginal density function of (X 1 , X 2 ).
In the special situation where the outcome of one random variable has no effect on the
probability distribution of another, the variables are said to be independent. Formally, the
variables X 1 and X 2 are independent if their joint density function factorizes:
More generally, the influence of one random variable on the probability structure of another is
characterized by the conditional density function:
In the case of independent random variables:
but generally the conditional density function depends also on the value of x 2 .
The notions of expectation and variance apply to each margin in turn to give measures of the
location and dispersion of each marginal component. It is also useful, however, to summarize
the extent of dependence between components; that is the extent to which the components
increase or decrease in harmony. The usual summaries are pairwise. The covariance of the
variable X and Y, having joint density function f X, Y , is defined by:
The covariance coefficient is often re-scaled to obtain a measure on a fixed interval. This leads
to the correlation coefficient, defined by:
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Monte Carlo Analysis
Correlation Between Gaussian Input Variables
The correlation coefficient has a similar interpretation to the covariance, but is such that
-1≤ρ(X,Y)≤1. For independent random variables, the correlation is zero. The converse is false,
as the correlation is a measure only of the extent to which variables are linearly associated.
Consequently, variables may have zero correlation if their association is non-linear.
Figure 11-8. Scatter Plot of a Gaussian Sample and Contour Ellipses
For a general random vector X = (X 1 , …, X k ) T , it is usual to pack together all the information on
variances and covariances between each pair of variables into matrix, the variance-covariance
matrix, defined as:
where and for .
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Monte Carlo Analysis
Correlation Between Gaussian Input Variables
Like in the univariate case, there are standard families of probability distributions for random
vectors. In particular, the multivariate normal distribution with mean vector μ = (μ 1 , …, μ k ) T
and variance-covariance matrix C has the density:
This definition implies that each of the marginal distribution is normal and that the complete
joint distribution is determined once the marginal means and the variance-covariance matrix are
specified.
From its definition, we see also that the density of multinormal distribution is constant on
ellipsoids of the form:
Figure 11-8 shows the contour ellipses of a two-dimensional normal distribution. These contour
ellipses are the iso-distance curves from the mean of this normal distribution corresponding to
the metric C −1 .
Tip
As emphasized, the relationships between the input variables are described with the concept
of linear correlation. In fact “linearity” is strongly related to “gaussianity.” The two terms
could be consider as synonyms in this context. It is possible, however, to describe general
multivariate distributions and to represent dependence structure among the input variables.
Understanding these relationships can be done with the notion of a “copula” function. For an
introduction, see for example Bouye, E., Durrleman, V., Nikeghbali, A., Riboulet, G., Roncalli,
T., Copulas for Finance: A Reading Guide and Some Applications, 2000, Working Paper,
Groupe de Recherche Operationnelle, Credit Lyonnais.
Specifying Linear Correlation with .CORREL
You can define a correlation coefficient between Gaussian parameters using the .CORREL
command.
Refer to the .CORREL command in the Eldo Reference Manual.
The following netlist is a toy example which shows the effect of linear correlation between
input variables. We can indirectly visualize the joint distribution of the Gaussian input P1 and
P2.
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Monte Carlo Analysis
Correlation Between Gaussian Input Variables
R1 N1 0 P1
V1 N1 0 1
R2 N2 0 P2
V2 N2 0 1
.PARAM P1=10 LOT/GAUSS=10%
.PARAM P2=10 LOT/GAUSS=5%
.CORREL PARAM={P1,P2} CC=-0.5
.DC
.MC 500 ALL
.EXTRACT DC LABEL=IR1 1/I(R1)
.EXTRACT DC LABEL=IR2 1/I(R2)
After extraction of the simulated values one can plot the resulting scatter plot. Figure 11-9 also
shows the marginal densities of the joint distribution of (IR1,IR2).
Figure 11-9. Scatter Plot and Marginal Distributions
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Monte Carlo Analysis
Local and Global Variations
We also plot the regression line Y = aX + b which relates the dependent variable Y=IR2 to
X=IR1. It is a well known result that the slope of this line is given by the formula:
and the intercept is .
Local and Global Variations
In statistical models for transistor level simulation, there are two types of variability in device
properties:
• Inter-die (between chips) variations or global variations.
Typical examples of statistical parameters with global tolerances are oxide thickness or
channel length reduction.
• Intra-die (within chip) variations are local variations that affect transistors individually.
A typical example of statistical parameters with local tolerances are the transistor
threshold voltages.
Inter-die variability consists of the accumulated fluctuations of material characteristics between
lot-to-lot, wafer-to-wafer and die-to-die (chip-to-chip). However, once the wafers have been cut
into individual chips there is no longer a traceable correlation among them. Therefore, lot-to-lot,
wafer-to-wafer and die-to-die variations are pooled together into one term: the inter-die
variability. This variability equally affects all devices on a given chip. In simulation terms, this
means that all devices of a certain type use the same statistical model.
Local variations lead to an increase in the number of statistical parameters relative to the
number of transistors in a circuit. In a circuit with 100 transistors, there will be one global
threshold voltage V th, glob that affects all transistors equally and 100 local threshold voltages
V ith, loc for i = 1, ..., 100 that affect each transistor individually and independently from others.
Therefore, you can consider that the effective threshold voltage for the i-th device is the sum:
According to these definitions, global statistical parameters are not correlated with local
statistical parameters, and local statistical parameters are not correlated with each other.
Example
In this example, LOT and DEV variations are defined on the length and width of the resistor
model. By definition, there are two independent random variables associated to the inter-die
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Monte Carlo Analysis
Local and Global Variations
variations of the (W, L) parameters. The resistors R1 and R2 will receive the same random
values for DLR and DW during the Monte Carlo sampling. These variables are defined as the 2-
dimensional vector (DLR, DW R ).
.TITLE RCWIRE_EXAMPLE
* CIRCUIT PARAMETERS (WITH VARIATIONS)
.PARAM VARL=0 LOT/UNIF=0.05U DEV/UNIF=0.1U
.PARAM VARW=0 LOT/UNIF=0.05U DEV/UNIF=0.1U
* CIRCUIT
I1 0 1 1M
I2 0 2 1M
R1 1 0 RESISTOR
R2 2 0 RESISTOR
.MODEL RESISTOR R LEVEL=3 W=3U L=3U RSH=100 DW=VARW DLR=VARL
.DC
.MC 1000
* EXTRACT
.EXTRACT DC LABEL=V1 V(1)
.EXTRACT DC LABEL=V2 V(2)
.END
The resistor R1 (respectively R2) will be associated to two independent random variables. This
defines four independent uniform random variables (DL R1 , DW R1 , DL R2 , DW R2 ). The random
sampling will be run with a joint probability distribution that is the product of six uniform
distributions.
The vector of random variables associated to this circuit is a 6-dimensional vector noted as:
Note that, in the output file (the .chi file), these parameters will be named as follows:
• The global variables (DL R , DW R ) will be associated to P(VARW), P(VARL).
• The local variations of the width and the length of the R1 resistor will be:
PEM(VARW,R1,R), PEM(VARL,R1,R).
• The local variations of the width and the length of the R1 resistor will be:
PEM(VARW,R2,R), PEM(VARL,R2,R).
See “Parameter Naming Conventions” on page 536 for a detailed description of these macros.
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Monte Carlo Analysis
Local and Global Variations
Statistical Model
It is clear that X is a vector of independent variables, because there is no functional dependences
between these circuit parameters. From the designer’s view, the true physical model is actually
characterized by the correlations between the global and local variations. This can be made
explicit by rewriting the relations between the random variables. A new vector of random
variables is defined by:
such that:
The pair of variables
represents the effective length variations specified
in the circuit by the command expressions .PARAM VARL=0.0 LOT/UNIF=0.05U DEV/
UNIF=0.1U. In this example, the distribution of the variable L R1 is the sum distribution of DL R
+ DL R1 . This distribution can be obtained explicitly as the convolution product:
From these equations, it can also be deduced that the new variables are correlated. The
correlation structure is given by the following arguments: define the matrix A such that
. The variance of a linear transformation is known to equal:
Since the random variables X are independent, Var{X} = diag(σ), and
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Monte Carlo Analysis
Specifying Statistical Variations for Individual Model Parameters
This correlation structure is handled implicitly by the simulator. The transformation is
calculated during the simulation, and the sampling is generated in the space of the independent
variable X.
Related Topics
Specifying Statistical Variations for Individual Model Parameters
Input Sample
Specifying Statistical Variations for Individual
Model Parameters
Individual model parameters may have statistical variations. You can specify these using the
DEV and/or LOT parameters immediately following the model parameter in the .MODEL
statement.
For example, use the following syntax to define an NMOS model with VTO set to 0.6V and
TOX set to 1.5×10 −7 :
.MODEL N NMOS VTO=0.6 TOX=1.5e-7 DEV=1.0e-8
The model parameter TOX has a uniform distribution with σ = 1.0×10 -8 , but VTO has a
constant value. The following specification is equivalent:
.MODEL N NMOS VTO=0.6 TOX=1.5e-7 DEV=6.66%
To use a Gaussian distribution, change the DEV parameter to DEV/GAUSS. Using the same
example, changing the TOX distribution to Gaussian would modify the .MODEL card as
follows:
.MODEL N NMOS VTO=0.6 TOX=1.5e-7 DEV/GAUSS=1.0e-8
Tip
See “.MODEL” in the Eldo Reference Manual.
Related Topics
Statistical Variations on Binning Parameters
Assigning Statistical Variations using the .MCMOD Command
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Monte Carlo Analysis
Statistical Variations on Binning Parameters
Statistical Variations on Binning Parameters
Eldo takes into account changes in binning parameters (for example LMIN, LMAX) due to
Monte Carlo variations. Eldo will first make the variations on the .MODEL, and then select the
appropriate model at each Monte Carlo run. For example:
.PARAM P1=1 DEV=5%
.MODEL N.1 NMOS LMIN='1U*P1' LMAX = '2U*P1'
.MODEL N.2 NMOS LMIN='2U*P1' LMAX='3U*P1'
M1 D G S B N W=1U L=1U
Here Eldo will extract a new random value for P1. This value will be used to update parameters
of both N.1 and N.2. When all parameters of the .MODEL have been updated, Eldo will select
the appropriate model to be used for device M1.
If both the size of a device and the binning parameters of its model are altered by Monte Carlo
variations, Eldo will issue an error that it cannot handle this situation.
Use .OPTION MC_IGNORE_BINNING to disable this automatic selection of the binning
parameters at run time; the model selected at the nominal run will then be used for the whole
Monte Carlo process.
Tip
See .PARAM, .MODEL, and .OPTION MC_IGNORE_BINNING in the Eldo Reference
Manual.
Related Topics
Specifying Statistical Variations for Individual Model Parameters
Assigning Statistical Variations using the .MCMOD Command
Assigning Statistical Variations using the .MCMOD
Command
Modifying the .MODEL lines for the Monte Carlo analysis may not be convenient.
Alternatively, use the .MCMOD command to assign statistical variations for .MODEL
parameters without changing any part of the .MODEL statement.
.MCMOD MODEL_NAME [(LIST_OF_INSTANCES)]
+ PARAM1_NAME LOT|DEV=VALUE [PARAM2_NAME LOT|DEV=VALUE ...}]
The .MODEL name must be specified, followed by one or more pairs of parameters and LOT
and/or DEV values. Optionally, specifying a list of instances will apply the Monte Carlo
probabilities to only instances in that list.
Using the example above, the Monte Carlo parameter may be written as:
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Monte Carlo Analysis
Tolerance Setting Using DEV, DEVX or LOT
.MODEL N NMOS VTO=0.6 TOX=1.5e-7
.MCMOD N VTO DEV=0.1
DEV Variation
DEV variation specified with .MODEL statements (or .MCMOD) can refer to dimensions of the
current object directly, without any need to encapsulate models into subcircuits. The syntax for
accessing an instance parameter is for example:
E(*,)
The * character is used here to refer to the current instance.
Example
.MODEL M nmos VTH=1 DEV={sqrt(E(*,l)*(E(*,W))*1.0e-5}
M1 p1 p2 p3 p4 m w=10u l = 3u
The two lines above are equivalent to the five below:
.SUBCKT foo d g s b param: w=1u l=1u
.model m nmos VTH=1 DEV={sqrt(l*w)*1.0e-5}
M1 d g s b m w=w l=l
.ENDS
X1 p1 p2 p3 p4 foo w=10u l=3u
A full example to illustrate this:
* test DEVX
M1 D1 G1 0 B mos1 w=w l=l as=0 ad=0 ps=0 pd=0 m=1
M2 D2 G2 0 B mos1 w=w l=l as=0 ad=0 ps=0 pd=0 m=1
.MODEL mos1 nmos
+ level=53 version=3.24
+ u0=300 tox=5n
+ vth0=1 DEV={sqrt(E(*,l)*(E(*,w)))*1.0e-05}
.param l=5e-6 w=10e-6
.op
.MC 10
.option display_carlo EXTMKSA
Tolerance Setting Using DEV, DEVX or LOT
The size of the tolerance appears in a .MODEL command after the parameter keyword and
value. The tolerance may be specified either as a percentage or an absolute quantity. To denote
a percentage, the % sign must be used. Parametric expressions are allowed when specifying
DEV or LOT.
The DEV tolerance parameter causes devices which use the same .MODEL statement to vary
independently of each other, as illustrated in the following example:
c1 4 0 cmod 10p
c2 6 8 cmod 10p
.model cmod cap dev=10%
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Monte Carlo Analysis
Tolerance Setting Using DEV, DEVX or LOT
In the above example, both c1 and c2 use the model cmod. Their nominal values are both 10pF.
The dev declaration placed immediately after the cap keyword indicates that during a Monte
Carlo analysis, their values may vary independently of each other by at most ±10%. So, c1
could have a value of 9.9pF while c2 has the value of 10.1pF during a simulation run.
To use a Gaussian distribution, the DEV parameter is changed to DEV/GAUSS. Using the same
example, changing the distribution to Gaussian would alter the .MODEL card as follows:
c1 4 0 cmod 10p
c2 6 8 cmod 10p
.model cmod cap dev/gauss=10%
Both c1 and c2 may vary independently of each other with a Gaussian distribution, where the
standard deviation is 10 percent of the nominal value, 10pF.
The DEV tolerance is appropriate for situations where the variation of parameters is uncorrelated.
The devices on a printed circuit board are such an example.
The DEVX specification forces Eldo to use a new random value for each instance of a
subcircuit. The difference compared with DEV is that even if a parameter is used several times
in the same subcircuit, only one value will be used for that particular instance.
Note
DEVX can only be used in a .PARAM statement and not in a .MODEL statement. It is
impossible to have DEV and DEVX specified on the same parameter. If DEV and DEVX
are specified on the same parameter, the last specification will be retained.
The LOT tolerance setting causes devices which use the same .MODEL statement to vary
together with each other, as illustrated in the following example:
c1 4 0 cmod 10p
c2 6 8 cmod 10p
.model cmod cap lot=10%
This is the same as the previous example with the exception that the tolerance has been changed
from DEV to LOT. Now c1 and c2 will always have the same value. They may be both equal to
9.9pF during one run and 10.1pF during another run, but c1 will not have a value of 9.9pF
while c2 has the value of 10.1pF during the same run.
The LOT tolerance is appropriate for situations where there is a variation of the parameters
track. Devices in an integrated circuit are such examples.
When an instance parameter is used in the expression of a subcircuit parameter that varies with
LOT, one draw is made for all the parameter instantiations inside the subcircuit (LOT type) and
one draw is made for each instance of the subcircuit (DEVX type). In this particular case, the
LOT variation is equivalent to a DEVX variation. An example of this is provided below.
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Examples
Monte Carlo Analysis
Tolerance Setting Using DEV, DEVX or LOT
• This example specifies five Monte Carlo runs of the transient analysis at the output node
n5. All devices with the model name rmod have a dev tolerance attached to their
nominal value:
.model rmod res dev=2%
...
.mc 5 v(n5)
.tran 1n 100n
.plot tran v(n5)
• This example specifies five Monte Carlo runs of the transient analysis at the output node
n5. All devices with the model name cmod have a lot tolerance with a Gaussian
distribution, where the standard deviation is two percent of the nominal value:
.model cmod cap lot/gauss=2%
...
.mc 5 v(n5)
.tran 1n 50n
.plot tran v(n5)
Tip
An example of this type of analysis can also be found in “Example 7—Monte Carlo
Analysis Basic” on page 1290.
• This example illustrates a case of LOT/DEVX equivalence. Replacing LOT by DEVX
will generate the same Monte Carlo results.
* test LOT/DEVX equivalence
.subckt res2 a b param: rval=1k
.param rvalstat='2*rval' lot=10%
r1 a b rvalstat
r2 a b rvalstat
.ends
va a 0 dc 2
vb b 0 dc 0
x1 a b res2 rval=1k
x2 a b res2 rval=1k
.dc
.mc 100 seed=1
.extract dc label=i1_1 i(x1.r1)
.extract dc label=i1_2 i(x1.r2)
.extract dc label=i2_1 i(x2.r1)
.extract dc label=i2_2 i(x2.r2)
.option aex dump_mcinfo
.end
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Tolerance Setting Using DEV, DEVX or LOT
Related Topics
Specifying Statistical Parameters
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Monte Carlo Analysis
Sampling Plan Methods
Sampling Plan Methods
The goal of Monte Carlo analysis is usually to estimate the distribution of a measure of
performance defined over a circuit.
The sampling plan methods available in Eldo Monte Carlo analysis are specified with the
SAMPLING parameter of the .MC command, as follows:
• Standard Monte Carlo uses a pseudo-random number generator to draw the input
sample. This is the random input used by default in Eldo. It comes from a pseudorandom
generator that outputs numbers between 0 and 1, which are assumed to imitate a
sequence of uniform random variables between 0 and 1. These numbers are then
transformed to follow the probability distributions specified by the model.
• Importance Sampling Monte Carlo uses a dedicated method for computing tail
probabilities. This method is specified using the MCPROB and MCBOUND functions.
Importance sampling uses the same pseudorandom generator as standard Monte Carlo
sampling. The pilot runs are standard MC runs, and the standard post-analysis is
performed on these runs.
• Quasi-Monte Carlo Method is an empirical sampling method based on Monte Carlo, but
using low discrepancy point sets instead of pseudorandom numbers. This improved (and
deterministic) sampling scheme roughly ‘fill the space’ in a better way.
• Latin Hypercube Sampling may be considered as a particular case of stratified sampling.
The purpose of stratified sampling is to achieve a better coverage of the sample space of
the input factors.
• Model-Based Monte Carlo Simulation is a variability analysis where the sampling plan
is optimized with respect to the number of random input variables and a user-defined
budget of runs.
Standard Monte Carlo
There are two different random number generators in Eldo depending on the argument
DATAFLOW of the .MC command.
When DATAFLOW=0 Eldo uses the drand48 routine provided in the standard C library, and
when DATAFLOW=1 the RNARRY routine described in D.E. Knuth, The Art of Computer
Programming (3rd edition, Addison Wesley, vol 2, Seminumerical algorithms, Chap 3).
The pseudo-random generator proposed with DATAFLOW=1 belongs to the family of lagged
Fibonacci generators. It overcomes some well-known weaknesses of the linear congruential
generator used in the drand48 routine. Specifically, if we build d-dimensional vectors from
consecutive random numbers (X i , X i+1 , …, X i+d ), then the points will lie on a relatively small
number of hyperplanes. This is due to the fact that the low-order bits of the generated numbers
have very short periods. Using this routine attempts to satisfy three objectives:
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Importance Sampling Monte Carlo
• It should produce high-quality random numbers uniformly distributed in the interval
(0, 1).
• The computations should be fast. Separate threads of random numbers are allowed to be
generated in parallel.
• It should be portable (Unix and Windows platforms).
To start this generator, its initial state needs to be specified. Knuth introduced an algorithm that
uses a single integer, which can take on approximately 10 9 different values, in such a way that a
given seed is guaranteed to produce at least 10 21 different starts before colliding with those
produced by a different seed.
Importance Sampling Monte Carlo
The Importance Sampling Monte Carlo (ISMC) method is dedicated to the estimation of failure
probabilities (or the computation of parametric yield in circuit design terms) and, conversely, to
the estimation of the thresholds corresponding to user-defined yield.
Note
Estimation of low failure probabilities is often called a “high sigma” problem in the EDA
literature. The terms “low probability estimation” and “rare events simulation” are used in
this section to mean the same thing.
Rare events can be defined as the regions of the input parameter space that have a very small
volume with respect to the measure induced by the joint probability of the parameters. The
associated probabilities of interest are close to zero, and may range from 10 −4 to 10 −10 . In this
context, Monte Carlo analysis is used as a verification tool to check that the probability of
exceeding a performance specification is acceptably small.
The Monte Carlo algorithm is an iterative simulation method that may be described briefly as a
random exploration of the space of input parameters. The fundamental problem with this
technique is that the sample size has to be large when the probabilities to estimate are small. For
example, estimating a probability of around 10 −K (where K > 2) to a target accuracy of 10% will
involve more than 10 −(K + 2) simulations of the circuit performances.
The ISMC method is implemented using an adaptive procedure based on importance sampling,
and has the following properties:
• It is as insensitive as possible to the dimension of the problem.
• It requires no prior knowledge to function. Specifically, it functions if nothing is known
about the output distribution and its tails.
• It does not need to be manually tuned to work with a given cell or circuit.
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Importance Sampling Monte Carlo
• It includes a robust and reliable accuracy estimator.
Figure 11-10. The ISMC Method
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Importance Sampling Monte Carlo
Figure 11-10 illustrates the general principle underlying the ISMC method. The top plot
represents the probability distribution function of the output measure Y = H(X). The vertical
lines at y t are associated with the failure boundary curves C t = {x | H(x) = y t } shown in the
bottom plot. The difficult problem of estimating the very small probabilities is broken down
into a sequence of simpler intermediate problems of the form:
where the levels y t are a chosen monotone sequence that tend to the goal value y.
At each iteration t, an intermediate sample X t is generated in order to estimate the intermediate
probability π t . This intermediate sample is a standard Monte Carlo random sample of size at
least NRUN_PILOT. The number of steps needed to compute a single tail probability is
approximately NRUN_PILOT × IS_MAXITER. When both bounds are specified, the number
of steps needed is approximately double this value. Refer to “Probability and Quantile
Estimators” on page 480 and “Importance Sampling Monte Carlo Examples” on page 528 for
more information.
Yield and Failure Probability Computation using MCPROB
The yield value and probability of failure are complementary quantities used to measure how
well a given circuit conforms to a set of user-defined specifications. For practical reasons, the
ISMC method only considers failure probabilities.
The MCPROB function computes the probability π y that a given response is greater than or less
than a bound y:
• To calculate a left-tail probability:
use the following command:
.EXTRACT MC LABEL=LABEL MCPROB(OUTPUT, LE, BOUND)
where OUTPUT is the name of the output response H(X), and where BOUND is y.
• To calculate a right-tail probability:
use the following command:
.EXTRACT MC LABEL=LABEL MCPROB(OUTPUT, GE, BOUND)
where OUTPUT is the name of the output response H(X), and where BOUND is y.
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Importance Sampling Monte Carlo
The two forms of the MCPROB function can be combined to calculate yield, that is, the
probability π L, U that a given response is between bounds y L and y U (with y L ≤ y U ). To calculate
such a probability:
use the following commands:
.EXTRACT MC LABEL=PROB_L MCPROB(OUTPUT, LE, BOUND_L)
.EXTRACT MC LABEL=PROB_U MCPROB(OUTPUT, GE, BOUND_U)
.EXTRACT MC LABEL=PROB_LU '1-(PROB_L+PROB_U)'
where OUTPUT is the name of the output response H(X), and where BOUND_L and
BOUND_U are y L and y U respectively.
Quantile Computation using MCBOUND
The MCBOUND function computes the quantile y π associated with a given probability π.
Formally, the computed value is the solution to the following optimization problem. For 0 < π <
1, the quantity F Y −1 (π) = inf{y | F Y (y) ≥ π} is called the π-quantile of the random variable Y.
The MCBOUND function is inverse to the MCPROB(…, LE, …) function. To calculate a
quantile y π satisfying:
use the following command:
.EXTRACT MC LABEL=BOUND MCBOUND(OUTPUT, PROB)
where OUTPUT is the name of the output response H(X), and where PROB is π.
To determine a yield interval, defined as the interval (y L , y U ) such that the associated coverage
probability π L, U has a given value, use the following commands:
.EXTRACT MC LABEL=BOUND_L MCBOUND(OUTPUT, PROB_L)
.EXTRACT MC LABEL=BOUND_U MCBOUND(OUTPUT, PROB_U)
where OUTPUT is the name of the output response H(X), and where PROB_L and PROB_U
are probability values satisfying PROB_U - PROB_L = π L, U .
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Monte Carlo Analysis
Quasi-Monte Carlo Method
Quasi-Monte Carlo Method
Quasi-Monte Carlo is an empirical sampling method based on Monte Carlo, but using low
discrepancy point sets (such as the Faure, Sobol, or Niederreiter sequences) instead of
pseudorandom numbers.
This improved (and deterministic) sampling scheme roughly ‘fill the space’ in a better way as
shown in Figure 11-11. The left plot shows an example of LDS in (0,1) 2 compared to a
pseudorandom sequence calculated with a classical generator.
Figure 11-11. Comparison Between Low Discrepancy and Pseudorandom
Point Sets
The Monte Carlo integration error depends on the discrepancy of the sequence used:
where V Τ is the total variation function. The discrepancy is defined as the deviation to the
perfect uniformity as follows:
where λ(I) is the Lebesgue’s measure of the interval and n I the number of points in the interval.
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Latin Hypercube Sampling
The quasi-Monte Carlo efficiency relies on the empirical convergence rate of commonly used
sequences. This convergence rate is governed by the discrepancy that is asymptotically given
by:
Asymptotically this is smaller than the standard error of a pseudorandom estimate, the error
converges in O(n −1 ) instead of O(n −1/2 ) for traditional Monte Carlo. We then have a method
that can potentially compete with MC to run the simulations. Unfortunately the convergence
rate depends on the dimension d. For example, with d = 10, we have:
for n ≤ 10 34
We conclude that the current implementation of the QMC techniques should not be used as an
option to accelerate the Monte Carlo analysis when only a moderate number of simulations is
allowed and when the number of parameters is greater than 5.
The estimators of the mean, yield, variance, and so on, are the same as in the Monte Carlo
method. However, a disadvantage of this approach is that the use of a deterministic source
means that the unbiased and the usual error estimation methods are lost. Therefore it is difficult
to assess the final value of the integral (the mean value).
For a detailed overview of QMC methods, refer to: P. L’Ecuyer and C. Lemieux, Recent
Advances in Randomized Quasi-Monte Carlo Methods in Modeling Uncertainty: An
Examination of Stochastic Theory, Methods and Applications, Kluwer, 2001.
Related Topics
Sampling Plan Methods
Latin Hypercube Sampling
Latin hypercube sampling (LHS) may be considered as a particular case of stratified sampling.
The purpose of stratified sampling is to achieve a better coverage of the sample space of the
input factors. In the latin hypercube, sampling is undertaken as follows:
• The range of each input factor x j is divided into n intervals of equal marginal probability
1/n.
• One observation of each input factor is made in each interval using random sampling
within that interval.
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Latin Hypercube Sampling
• All the intervals having common state with the previous intervals are put apart from the
list of available intervals.
Thus, there are n non-overlapping realizations for each of the d input factors. The method has
the advantage of ensuring input factor has all portions of its distribution represented by input
values.
For further information on LHS, refer to the classical paper: M.D. McKay, R.J. Beckman and
W. J. Conover, A Comparison of Three Methods for Selecting Values of Input Variables in the
Analysis of Output from a Computer Code, Technometrics (Amer. Stat. Assoc.) Vol. 21, No. 2,
1979, pp. 239-245.
Two-dimensional Case
Suppose we can afford to sample 16 points in (0, 1) 2 . Sampling one point from each of 16
vertical strata would be a good strategy if the function f depended primarily on the horizontal
coordinate. Conversely if the vertical coordinate is the more important one, then it would be
better to take one point from each of 16 horizontal strata.
It is possible to stratify both ways with the same sample, in what is known as Latin hypercube
sampling (see “Latin Hypercube Sampling” on page 457). Figure 11-12 shows a set of 16 points
in the square, that are simultaneously stratified in each of 16 horizontal and vertical strata.
Figure 11-12. Latin Hypercube Sampling
The left plot shows 16 points, one in each of 16 vertical strata. The right plot shows the same 16
points. There is one in each of 16 horizontal strata. These points form what is called a Latin
Hypercube sample.
If the function f on (0, 1) 2 is dominated by either the horizontal coordinate or the vertical one,
then we will get an accurate answer, and we do not even need to know which is the dominant
variable. Better yet, suppose that neither variable is dominant but that
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Monte Carlo Analysis
Model-Based Monte Carlo Simulation
where f H depends only on the horizontal variable, f V depends only on the vertical one, and the
residual f RES is defined by subtraction.
Latin hypercube sampling will give an error that is largely unaffected by the additive part
f H (u) +f V (u). One can prove that the variance in Latin hypercube sampling is approximately
σ 2 RES /n where σ RES is the smallest variance of f RES for any decomposition of f.
LHS versus Random
The LHS method ensures that each of these components is represented in a fully stratified
manner, no matter which components might turn out to be important. It can be proved that LHS
is never worse than random sampling for estimating the mean and the population distribution
function. In particular the closer the output function is to being additive in its input variables,
the more reduction in variance (variance of the mean estimator).
When choosing the Monte Carlo sampling plan best suited for your analysis, follow these
guidelines:
• For uncertainty and sensitivity analyses, choose the standard Monte Carlo sampling plan
(RAND).
• For Large Scale Sensitivity (LSS) analysis, it makes sense to choose the Latin
Hypercube Sampling (LHS) method. It is related to the stratification method used in this
approach. The disadvantage of this method is the lack of a save/restart feature; the
current samples cannot be augmented with additional points. The LHS plans are in some
way very monolithic, unlike the standard Monte Carlo sampling plan which is very
flexible.
The LHS method is based on the classical approach, the stratification method used in LHS takes
into account the underlying distribution. The LHS sampling is uniform, (0, 1) N , but the resulting
sample is obtained by transforming this uniform sample into the scales (and shape) of the joint
probability distribution.
Related Topics
Sampling Plan Methods
Model-Based Monte Carlo Simulation
The basic idea of a model-based Monte Carlo simulation is to perform surrogate modeling to
drastically reduce the number of simulations from the response function of interest. The
surrogate model serves as a substitute for the high-fidelity SPICE simulations in the context of
Monte Carlo analysis.
The name that we used in Eldo to denote this feature is “Super Saturated Design” (SSD). It
refers to the early developments of the approach for constructing design plans satisfying optimal
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Model-Based Monte Carlo Simulation
requirements. SSD indicates a different approach compared to the standard Monte Carlo or
Latin Hypercube methods, where the specific sampling plan does not require too many
simulations. The SSD approach has to be understood now as an ensemble of modeling
techniques designed to accelerate the variability analysis.
In model-based Monte Carlo settings, the variability analysis is composed of three distinct
steps:
• The first one is the sampling phase where a space-filling design is used to collect
variations of the output responses of a circuit from the input variations.
• The modeling phase is formulated as a pure regression (or interpolation) problem.
• And the final variability analysis is directly performed on the surrogate function.
The key points of the SSD approach are as follows:
• You provide the number of runs that you want Eldo to perform, NRUN_MAX, based on
how much CPU-time you want to spend, and Eldo determines a sampling plan with
some space filling properties.
• You may also specify the number of test runs that you want Eldo to perform, using the
.MC parameter SSD_NRUN_TEST. The test runs are used to compute accuracy
metrics, contained in the .mcm file, which you can use to determine the quality of the
surrogate model. Refer to “Model Adequacy Checking for Model-Based MC” on
page 476 for more information.
Note
By default, Eldo does not perform any test runs. Prior to AMS release 15.3, Eldo
automatically determined how many test runs to perform based on the value of
NRUN_MAX.
• The complexity of the surrogate model for the SSD sampling method
(SAMPLING=SSD) is controlled with the .MC parameter SSD_COMPLEXITY,
defined as multiple choice from the simplest model (0) to the more complex (1) which is
the default.
We assume that each circuit response y i , i=1, …, N is simulated with d variables x 1 , …,
x d given the realizations {y i , x 1i , …, x di }. The goal is to estimate a function s that
satisfies a regression model:
over some domain: containing the input data. The additive stochastic term ε has
its expected value defined to be zero, and defines the dependence of the output variable
on quantities other than the selected input variables.
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Model-Based Monte Carlo Simulation
When SSD_COMPLEXITY=0, a model is optimized to capture the shape of the output
measures, and is defined as an affine combination of univariate random variables, as
follows:
In the chosen non-linear extension with SSD_COMPLEXITY=1, we assume that the
surrogate function s(.) is represented as a linear combination of basis functions ϕ k (x),
k=0, …, K:
Notes
and the coefficients α 0 , α 1 , …, α K are estimated with a dedicated optimization algorithm.
• After running the Monte Carlo analysis with the SSD method, statistical plots are
available in EZwave. The SSD method tries to provide the same post-analysis features
as standard Monte Carlo. View the outputs in the .mcm file and the additional .mch, .mci,
and .mco files.
The following notes aim at expressing some important facts you have to understand before
using this model-based approach. Some rules that may help you are provided.
• The SSD approach suffers from an issue that is common to many model-based Monte
Carlo Analyses. It is difficult to quantify the error committed on the Statistics obtained
from the variability analysis. The fundamental problem is that we cannot relate the error
estimated during the model-based Monte Carlo analysis to the true uncertainty that
could be obtained by running the Monte Carlo based on SPICE simulations. A specific
methodology has been implemented and tested.
If we translate the popular adage “There's no such thing as a free lunch” to our
variability settings, we want to express the idea that despite the potential CPU speedup
we may obtain, it is impossible to get something for nothing. Using the statistical
concepts of bias and variance, model-based approaches potentially reduce variance of
estimators to zero, but the bias may be large and not controllable. The reason is that the
cost of model evaluation becomes almost negligible with respect to true simulation.
Hence, a very large number of model evaluation is allowed and implies almost zero
variance estimators.
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Monte Carlo Analysis
Model-Based Monte Carlo Simulation
• The SSD approach is best suited to circuits where the CPU-time is a strong constraint for
the designer and specifically for applications with a very limited budget of simulations.
A typical sample size ranges from a few tens to hundreds of simulations. The linear
approximation used within the SSD algorithm assumes that the regression function is
linear in the inputs. Augmenting the number of runs does not automatically improve the
accuracy of the model. However, for prediction purposes, it can sometimes outperform
more complex non-linear models, especially in situations with small numbers of training
cases.
• You should first validate the SSD results against a standard Monte Carlo simulation
before applying the SSD method full-scale across a set of circuit variants.
• A non-linear model better takes into account the potential non-linearity of the circuit
responses. This compensates the rigid form of the linear models, and produce more
accurate models, leading to more accurate variability estimates. You should not expect
an accurate estimation of the output response in the tails. The SSD sampling plan is
designed to capture the so-called “normal events.”
• When the simulation budget ranges from a few hundreds or thousands of runs, the SSD
approach should not be considered as an alternative to the standard Monte Carlo.
Related Topics
Sampling Plan Methods
Model-Based Approximations Example
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Monte Carlo Analysis
Post-Analysis of Monte Carlo Simulations
Post-Analysis of Monte Carlo Simulations
Recall that the Monte Carlo analysis is mainly dedicated to uncertainty analysis. Monte Carlo
simulations provide a general (and efficient) approach for determining the distribution function:
for a circuit characteristic . This distribution function encodes all the information
known about Y, any property of Y such as expectation, variance and coverage intervals can be
approximated using CDF Y .
We consider this distribution function as the primary output of the Monte Carlo analysis. We
distinguish the parts in the output as follows:
• The primary output: the expectation of Y (the mean), taken as an estimate of the quantity
of interest, the standard deviation of Y, taken as the standard uncertainty associated with
y, and a coverage interval containing Y with a specified probability (the coverage
probability), approximation to the probability density function (via histograms) and the
discrete representation of the distribution function.
• The additional output contains: inter-quartile range (alternative measures of dispersion),
min/max values, confidence interval for the mean and prediction interval, distributional
measures (skewness, kurtosis), normal fit and normality test.
For backward compatibility constraints, some of these results will still be present in the .chi file.
Therefore, the post-analysis results of a Monte Carlo simulation are provided in two ways: the
.chi file and four files dedicated to the Monte Carlo analysis (see Figure 11-13).
• Output of Uncertainty Analysis (the .chi File)
The .chi file. This file contains the traditional output of the Monte Carlo analysis and
additional information extracted from the simulation. It is the file where users can find
the values of the extract after each run. The results are presented in raw manner.
• Primary Statistics of Uncertainty Analysis
The .mcm and the additional data files. The main file contains the primary output. This
file has extension .mcm and represents an evolution of the .chi file. Two optional files
are added for data mining features, with the extension .mci and .mco, containing the
complete input and output samples generated for the simulations.
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Monte Carlo Analysis
Post-Analysis of Monte Carlo Simulations
Figure 11-13. Output Files Organization
The idea which drives the multiple files option, is that the .chi should not mix
informations on how the circuit simulations are processed (the simulator job) and the
statistical analyses of the Monte Carlo simulations (the post-processing phase).
These outputs are available by specifying the argument DATAFLOW=1 on the .MC
command, which means that this feature is not activated by default. Due to backward
compatibility issues, this alternative Monte Carlo flow (and the resulting output) is
deactivated when some features of the Monte Carlo analysis are used. It is also
deactivated if no measurements (.EXTRACT statements) are specified in the netlist.
If the netlist contains swept parameters or .ALTER blocks, Eldo generates multiple
.mcm, .mci, and .mco files. Refer to “Monte Carlo Analysis With a Varying Circuit” on
page 419 for more information.
• Graphical Output
Eldo provides some tools such as scatter plots, histograms, or probability distribution
functions which you can view using EZwave.
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Output of Uncertainty Analysis (the .chi File)
Output of Uncertainty Analysis (the .chi File)
The .chi file contains the traditional output of the Monte Carlo analysis and additional
information extracted from the simulation.
Extract Functions Specific to Monte Carlo Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465
Extracting the Index and Total Number of Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 468
Basic Statistics and Histograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469
Bootstrap Estimates for Mean and Standard Deviation . . . . . . . . . . . . . . . . . . . . . . . . . 470
Global Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
Summary of Extracted Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
Extract Functions Specific to Monte Carlo Analysis
You can specify additional .EXTRACT commands in the netlist to obtain the minimum, the
maximum, the mean, and the standard deviation values, quantiles and probabilities, together
with higher order moments. The keyword MC is required on the .EXTRACT statements that
make use of these Monte Carlo extract functions.
In the following list, the string LABEL_EXT refers to the name of an existing .EXTRACT
command. Given a sequence of univariate data Y 1 , Y 2 , …, Y n extracted from a Monte Carlo
analysis, Eldo provides in the .chi file the values of the following MC extract functions:
• MCMIN(LABEL_EXT)
Returns the minimum value of the selected extract:
• MCIMIN(LABEL_EXT)
Returns the index of the run providing the minimum value of the selected extract.
• MCMAX(LABEL_EXT)
Returns the maximum value of the selected extract:
• MCIMAX(LABEL_EXT)
Returns the index of the run providing the maximum value of the selected extract.
• MCNBENCH(LABEL_EXT)
Returns the number of measured values for the selected extract.
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Output of Uncertainty Analysis (the .chi File)
• MCAVG(LABEL_EXT)
Returns the average value of the selected extract (see the section Mean and Standard
Deviation for more information):
• MCSTD(LABEL_EXT)
Returns the standard deviation of the selected extract (see the section Mean and
Standard Deviation for more information):
• MCVAR(LABEL_EXT)
Returns the sample variance
of the selected extract.
• MCSKEW(LABEL_EXT)
Returns the third standardized moment also known as sample skewness and denoted by
(see the section Parametric Fit and Normality Test for more information).
• MCSKEW_NB(LABEL_EXT)
Returns the Fisher G-statistics also known as the unbiased sample skewness and denoted
by G 1 (see the section Parametric Fit and Normality Test for more information). The
suffix _NB refers to no bias.
• MCKURT(LABEL_EXT)
Returns the fourth standardized moment also known as sample kurtosis and denoted by
β 2 (see the section Parametric Fit and Normality Test for more information).
• MCKURT_NB(LABEL_EXT)
Returns the Fisher g-statistics also known as the unbiased sample kurtosis and denoted
by G 2 (see the section Parametric Fit and Normality Test for more information). The
suffix _NB refers to no bias.
• MCMOM(LABEL_EXT,CENTER_VALUE,ORDER)
Returns the moment of order ORDER for the selected extract, centered at the value
CENTER_VALUE.
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• MCCORR(LABEL_EXT1,LABEL_EXT2)
Monte Carlo Analysis
Output of Uncertainty Analysis (the .chi File)
Returns the pairwise-linear correlation coefficient between each pair of output measures.
The sample correlation coefficient between two random variables (U, V) is given by the
formula:
(see the section Coorelation of Test Concordance for more information).
• MCCOVAR(LABEL_EXT1,LABEL_EXT2)
Returns the pairwise-linear covariance coefficient between each pair of output measures.
The sample covariance coefficient between two random variables (U, V) is given by the
formula:
When the value U i or V i is undefined, because the corresponding extract function cannot
be measured at the i-th run of the Monte Carlo simulation, then this data is removed
from the computation. When all the pairwise data are removed, Eldo will return the
value UNDEF (see the section Coorelation of Test Concordance for more information).
• MCPROB(LABEL_EXT,LE | GE, BOUND_VALUE)
Returns the probability π y that a given response is less or greater than a user-defined
bound y. We write this probability as follows:
when the second argument is LE, or
when the argument is GE. The probability can be recast into the evaluation of the
expectation
where I {A} is the indicator function of the event A, and
therefore computed through Monte Carlo simulations as follows:
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A similar expression can be obtained for the probability
“Less or Equal” with the operator “Greater or Equal.”
See section “Probability and Quantile Estimators” on page 480.
• MCBOUND(LABEL_EXT, PROB_VALUE)
by replacing the operator
Returns the quantile probability associated to a given probability π. This is the
inverse problem solved in the MCPROB(.) function. The argument PROB_VALUE is
the value π. Formally this function is computed with the following optimization
problem. For 0 < π < 1, the quantity:
is called the π-quantile of Y. The standard estimator of the π-quantile is
where
is the integer ceiling function and Y (k) is the k-th order statistics with
.
See section “Probability and Quantile Estimators” on page 480.
• MCMED(LABEL_EXT)
Returns the median value of the output sample of a given response Y. The median value
is the 0.5-quantile of the distribution (see the section Robust Measures of Location for
more information).
• MCQ1(LABEL_EXT) and MCQ3(LABEL_EXT)
Returns the first quartile and the third quartile of the distribution of a given response Y.
We have the 0.25 quantile and the 0.75 quantile (see
the section Alternative Measures of Dispersion for more information).
Extracting the Index and Total Number of Runs
Use the ICARLO and NBCARLO keywords to extract the index of the current run and the total
number of runs:
• ICARLO
Extracts the index of the current Monte Carlo run (first index is 0). See the ICARLO
Usage Example.
• NBCARLO
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Extracts the total number of Monte Carlo runs.
Monte Carlo Analysis
Output of Uncertainty Analysis (the .chi File)
Note
These keywords are not functions like those listed in Extract Functions Specific to Monte
Carlo Analysis.
Basic Statistics and Histograms
At the end of Monte Carlo simulations, Eldo prints the following basic statistics in the .chi file:
the range, the mean, the standard deviation, and a basic histogram for each .EXTRACT
command. Eldo also provides bootstrap estimates for the mean and the standard deviation.
For example, the following syntax:
.EXTRACT TRAN LABEL=OPFREQ (1/MAX(EXTRACT(DELAY6), EXTRACT(DELAY7)))
+ LBOUND=280Meg
generates the following output in the .chi file:
Distribution of OPFREQ
Range [ 2.6909E+08 3.7686E+08]
Nominal value: 3.2011E+08
Average value: 3.1768E+08
Standard Deviation: 1.9211E+07
Standard Deviation based on nominal run: 1.9364E+07
Passed : 191 ( 96.46465 %)
[ 250.000MEG 265.000MEG] NB = 0 FREQ = 0.00e+00% |
[ 265.000MEG 280.000MEG] NB = 7 FREQ = 3.54e+00% |*
[ 280.000MEG 295.000MEG] NB = 14 FREQ = 7.07e+00% |***
[ 295.000MEG 310.000MEG] NB = 48 FREQ = 2.42e+01% |************
[ 310.000MEG 325.000MEG] NB = 68 FREQ = 3.43e+01% |*****************
[ 325.000MEG 340.000MEG] NB = 36 FREQ = 1.82e+01% |*********
[ 340.000MEG 355.000MEG] NB = 15 FREQ = 7.58e+00% |***
[ 355.000MEG 370.000MEG] NB = 8 FREQ = 4.04e+00% |**
[ 370.000MEG 385.000MEG] NB = 2 FREQ = 1.01e+00% |
[ 385.000MEG 400.000MEG] NB = 0 FREQ = 0.00e+00% |
In this output provided in the .chi file we can extract the following information:
• The range is the interval given by the largest and smallest values in a data set. Note that
this measure is based only on the minimum and maximum values in the sample. The
spread near the center of the data is not captured at all.
• The nominal and average values.
• The standard deviation (or the square root of the sample variance). Note that the
standard deviation restores the units of the spread to the original data units (the variance
squares the units). Although the variance is intended to be an overall measure of spread,
it can be greatly affected by the tail behavior.
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• Standard Deviation based on nominal run is also computed:
• The histogram. You can specify the number of bins for the histogram in the .MC
command using the NBBINS parameter (the default is 10). The histogram is output in
the binary output file and displayed with EZwave.
• Approximation of the Yield. It is defined as the percentage of circuits that satisfy a userdefined
set of performance specifications. The LBOUND and UBOUND arguments of
the .EXTRACT command are used to control the lower and upper specifications
imposed on the extracted value. In our example this specification is given by a single
lower bound on the frequency: LBOUND=280Meg.
*** MC runs which passed all extract: 191 ( 96.46465 %)
MC run 46 Failed
MC run 53 Failed
MC run 77 Failed
MC run 94 Failed
MC run 144 Failed
MC run 147 Failed
MC run 148 Failed
A Monte Carlo analysis can use this information to divide the acceptability region in the
parameter space into two parts: the “pass” circuits with acceptable performance and the
“fail” circuits with unacceptable performance.
Bootstrap Estimates for Mean and Standard Deviation
The bootstrap is a general method for doing statistical analysis without making strong
parametric assumptions. It was originally designed to estimate bias and standard errors for
statistical estimates. In Eldo, the bootstrap technique is used to estimate the uncertainty of a
statistic such as the mean and the standard deviation.
These computations are given after the histogram. In our example, the following bootstrap
confidence intervals for AVG are obtained:
[------ Average value ------------]
Level LeftLimit Estimate RightLimit
95.0000% 3.1487E+08 3.1766E+08 3.1994E+08
99.0000% 3.1438E+08 3.1766E+08 3.2103E+08
99.9000% 3.1401E+08 3.1766E+08 3.2142E+08
99.9900% 3.1465E+08 3.1766E+08 3.2123E+08
99.9990% 3.1290E+08 3.1766E+08 3.2162E+08
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This tabular output estimates the left and right limits θ L and θ U , respectively, in the definition of
the confidence interval:
for some values of the confidence level α.
You can generate a summary of the Monte Carlo bootstrap estimates and sensitivity analysis
results in a specific file, the .aex file, and the file specified in the .EXTRACT command using
the options .OPTION DUMP_MCINFO_CONF (bootstrap estimates) and .OPTION
DUMP_MCINFO_SENS (sensitivity analysis).
Global Sensitivity Analysis
The ASCII output for the sensitivity analysis is provided here. This result is composed of:
• The name of the measure, the number of Monte Carlo runs, and the dimension of the
random vector.
• A list of important factors and their sensitivity index.
See “Global Sensitivity Analysis” on page 520.
This example is extracted from the output file of the “Model-Based Approximations Example”
on page 532.
Estimation of Sensitivity Indices for Output Measure : OPFREQ
Number of metamodel-based Simulations : 10000 (Effective Number of Runs)
List of Important Parameters :
Index(I) Histo S(I) (percent / cumulative) Variable
Value
Name
35 |-------------------- 30.7% 30.7% P(TP)
8 |------- 11.9% 42.7% M(SBSIMN,U1)
6 |--- 6.1% 48.8% M(SBSIMN,MUZ)
11 |- 2.5% 51.2% M(SBSIMN,X3E)
7 |- 2.4% 53.7% M(SBSIMN,U0)
14 |- 1.9% 55.6% M(SBSIMN,MUS)
Summary of Extracted Results
You can generate a summary of the extracted Monte Carlo distribution results in the .aex file,
and the file specified in the .EXTRACT command using the option DUMP_MCINFO.
Tip
See “.OPTION DUMP_MCINFO” and “.EXTRACT” in the Eldo Reference Manual.
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Related Topics
Graphical Output
MCCONV Extract Function
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Primary Statistics of Uncertainty Analysis
The .mcm file is composed as a sequence of sections that give numerical summaries of the
Monte Carlo simulations and statistical tests. The Primary Statistics section provides: the
average value and the standard deviation of each output measure, and an estimation of the
coverage interval (at different level of coverage probability). When the model-based approach
is used a specific section is added for model adequacy checking.
Some sections in the post-analysis files are not printed by default:
• Summary Statistics: Robust measures of location, Alternative measure of location, Min/
Max values, Confidence Intervals.
• Parametric Fit: scale and shape, normal fit, test of normality.
• Capability Indices.
• Correlation between the output responses.
• Sensitivity analysis.
When some the these analyses are disabled, for instance when the correlation analysis is not
performed on the whole set of output responses, it is still possible to request a specific value of
correlation between two chosen responses. For further details see “Control of the Monte Carlo
Post-Analysis” on page 473.
Control of the Monte Carlo Post-Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
General Information and Status of Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474
Model Adequacy Checking for Model-Based MC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476
Mean and Standard Deviation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478
Confidence Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 479
Probability and Quantile Estimators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480
Approximations of the CDF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 485
Coverage Intervals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 487
Approximation of the Density Function (Histogram File .mch) . . . . . . . . . . . . . . . . . . . 489
Control of the Monte Carlo Post-Analysis
Use optional arguments to control the post-analysis. You can enable or disable the generation of
the ASCII output data files and specific subsections of the main primary output (.mcm) file.
• Generation of ASCII output data files (.mcm, .mch, .mci, and .mco):
PRINT_NO_ANALYSIS
PRINT_ASCII_HISTO
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PRINT_ASCII_IN_SAMPLE
• Generation of subsections of the primary .mcm file:
PRINT_ASCII_OUT_SAMPLE
PRINT_ALL_POST_ANALYSIS
PRINT_CONF
PRINT_MINMAX
PRINT_TEST_AP
PRINT_OUTPUT_CORREL
PRINT_COV
PRINT_ALT_STATS
PRINT_MOMENTS
PRINT_CAPABILITY
General Information and Status of Simulations
The following sections utilize a slight modification of the example monte_carlo_sensitivity.cir.
Some arbitrary lower and upper specifications are added to the output measures.
.EXTRACT AC LABEL=MAX MAX(VDB(OUT)) LBOUND=0.765 UBOUND=0.885
.EXTRACT AC LABEL=BW 'CROSSING(VDB(OUT), -3) / 10E6' UBOUND=2.2
.EXTRACT DC LABEL=IVDD I(VDD) LBOUND=-0.540
.MC 1000 DATAFLOW=1
The first part of the .mcm file contains some general informations such as the dimension of the
problem and the type of algorithm used to run the Monte Carlo simulations.
The most important is a table of counters associated to each output measures. These counters
give the number of undefined values in the Monte Carlo simulations. This information is also
available in the .mco file for each run.
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**********************************************************
*** ***
*** Monte Carlo Analysis ***
*** ***
**********************************************************
...
==> Main File for Monte Carlo Analysis (test31.mcm)
==> Version 1.0
==> Additional Files :
Input Sample test.mci (no)
Output Sample test.mco (no)
Histograms test.mch (no)
==> Optional Sections in Post-Analysis :
Print Coverage Intervals (yes)
Print Confidence Intervals (yes)
Alternative Statistics (no)
Min/Max Values
(no)
Scale and Shape Values (no)
Normality Test
(no)
Capability Indices
(no)
Output Correlation Analysis (no)
Sensitivity Analysis
(no)
==> Dimensions:
Random Variables : 51
Output Measures : 3
==> Parameters:
Design : Standard Monte Carlo (pseudo-random generator)
==> Simulations : 1000 (Number of Runs)
List of Output Measures:
Undef. Filtered %Relative
Simulations Out Std Dev Name
--------------------------------------------------------------------
Meas 1 0 ( 0.00 %) No 4.6215 MAX
Meas 2 0 ( 0.00 %) No 0.9024 BW
Meas 3 0 ( 0.00 %) No 1.4823 IVDD
Here “Undefined” means that for some reason Eldo failed to extract the value from an
individual simulation. It has nothing to do with yield approximation. This latter is given in the
.mco file, see Output Sample.
It is important to note that we automatically remove undefined data from the computations.
The column Filtered Out indicates whether or not the corresponding extract has been removed
from the list of analyzed measures. This typically occurs when the measure is constant or almost
constant. In this case the Relative Standard Deviation would be less than 10 −6 ( = 0.0001%).
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If the netlist contains swept parameters or .ALTER blocks, Eldo generates multiple .mcm files.
In this case, each .mcm file corresponds to the Monte Carlo analysis that Eldo performed for
particular values of the circuit parameters and a particular configuration of the circuit. Refer to
“Monte Carlo Analysis With a Varying Circuit” on page 419 for more information. The first
part of each .mcm file contains the following section:
Where:
==> Analysis Included in Outer Loop : yes
Index in Loop : 3
Number of Outer Parameters : 1
List of Outer Parameters:
-------------------------
Param 1 PVG : 4.0000000e-01
• Index in Loop identifies the Monte Carlo analysis that the .mcm file corresponds to. For
example, if a circuit parameter is swept through 7 values, Index in Loop will range from
1 to 7 in the .mcm files.
• Number of Outer Parameters is the total number of swept parameters and .ALTER
blocks in the netlist.
• List of Outer Parameters lists the values that any swept parameters were set to before
Eldo performed the Monte Carlo analysis. List of Outer Parameters also indicates which
.ALTER block was in force, if any, with 0 representing the unmodified netlist.
Model Adequacy Checking for Model-Based MC
In practice, no surrogate model will represent its simulator with perfect validity. What is
searched are “good enough” surrogate models to capture the central tendency.
The problem of assessing a modeling method for prediction is classically solved by evaluating
the test-error. The method consists in dividing the dataset into two parts: a training set for
regression R, and a test set T. The regression set is used to fit the models and the test set is used
for assessment of the test-error of the optimal model. It is the prediction error over an
independent test sample T of finite size. This gives the sample approximation:
The regression set R is fixed, and the test error refers to the error for this specified regression
set. Classical estimators associated to the prediction error are the following:
• RMSE — Root Mean Squared Error
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• RRMSE — Relative Root Mean Square Error
• MAE — Maximum Absolute Error
• RMAE — Relative Maximum Absolute Error
• Rsqr — Coefficient of determination
with:
The R 2 coefficient may be understood as a measure of the unexplained variance, since the
second term compares the unexplained variance (Mean Square Error Test) with the total
variance of the test data. The values of these estimators are given in the Modeling Accuracy part
of the .mcm file:
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******************************
*** Modeling Accuracy ***
******************************
==> Measures of prediction error:
RMSE ... Root Mean Square Error
RRMSE ... Relative Root Mean Square Error
MAE ... Maximum Absolute Error RMAE ... Relative Maximum Absolute Error
Rsqr ... Coefficient of determination
Index
Name
of Meas RMSE RRMSE MAE RMAE Rsqr of Meas
-------------------------------------------------------------------------------------------
1 2.82286e-01 2.95719e-01 7.44927e-01 7.80375e-01 0.910766 DELAY6
2 2.51033e-01 2.63053e-01 5.68490e-01 5.95709e-01 0.929391 DELAY7
3 2.67857e-01 2.78019e-01 6.00334e-01 6.23111e-01 0.921128 OPFREQ
Mean and Standard Deviation
The first table in the .mcm file provides basic summaries.
==> Mean and Standard Deviation:
Mean ... Arithmetic Mean %RSEM ... Relative Standard Error of Mean
Std ... Standard Error StdNom ... Standard Error w.r.t Nominal
Index Nominal Name
of Meas Value Mean %RSEM Std StdNom of Meas
--------------------------------------------------------------------------------
1 8.38073e-01 8.37262e-01 0.304762% 4.02154e-02 4.02236e-02 MAX
2 2.19652e+00 2.19539e+00 6.355605% 2.00982e-02 2.01302e-02 BW
3 -5.44334e-02 -5.44318e-02 2.380805% 7.52874e-04 7.52876e-04 IVDD
What is called Std here is defined as the “corrected for bias” sample standard deviation:
It is actually a biased estimator for the population standard deviation, but less biased than the
uncorrected sample standard deviation.
The bias is of the order n −1 , and decreases as the sample size increases.
What we called CV here is defined as the relative half-range of the confidence interval on the
mean at a 95% level of confidence. The standard definition of the confidence interval is defined
as follows for n:
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where α = 0.05 = 5%. The relative half-range of this interval is therefore given by:
The approximation comes from the fact that we have
. The last term is two times
the coefficient of variation of the mean estimator. The RSEM value gives a relative estimate of
the committed error in the empirical estimator of .
We also give standard deviation based on nominal run StdNom.
Confidence Intervals
Confidence limits for the mean are an interval estimate for the mean. Interval estimates are
often desirable because the estimate of the mean varies from sample to sample. Instead of a
single estimate for the mean, a confidence interval generates a lower and upper limit for the
mean. The interval estimate gives an indication of how much uncertainty there is in our estimate
of the true mean. The narrower the interval, the more precise is our estimate.
Confidence limits are expressed in terms of a confidence coefficient. Although the choice of
confidence coefficient is somewhat arbitrary, in practice 90%, 95%, and 99% intervals are often
used, with 95% being the most commonly used.
Confidence limits are defined as:
where is the sample mean, s is the sample standard deviation, n is the sample size, α is the
desired significance level, and t (α/2, ν−1) is the upper critical value of the t distribution with n -1
degrees of freedom. Note that the confidence coefficient is 1 −α.
From the formula, it is clear that the width of the interval is controlled by two factors:
• As n increases, the interval gets narrower from the term. That is, one way to obtain
more precise estimates for the mean is to increase the sample size.
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• The larger the sample standard deviation, the larger the confidence interval. This simply
means that with a large standard deviation, are going to generate wider intervals than
data with a smaller standard deviation.
Note
A 95% confidence interval does not mean that there is a 95% probability that the
interval contains the true mean. The interval computed from a given sample either
contains the true mean or it does not. Instead, the level of confidence is associated with
the method of calculating the interval. The confidence coefficient is simply the
proportion of samples of a given size that may be expected to contain the true mean.
That is, for a 95% confidence interval, if many samples are collected and the confidence
interval computed, in the long run about 95% of these intervals would contain the true
mean.
We provide confidence intervals on the mean and the standard deviation. An expression of the
confidence interval for the standard deviation is given in section Stopping Test for STD.
The confidence intervals are given in the following manner. We also give the value of the Mean
and the Standard Deviation (Sigma).
==> Confidence Intervals:
Mean CI ... 95 percent Confidence Interval for the Sample Mean
Sigma CI ... 95 percent Confidence Interval for the Sample Std. Dev.
Index Mean CI Sigma CI Name
of Meas [ Lower, Upper ] [ Lower, Upper ] of Meas
------------------------------------------------------------------------------
1 8.64645e-01 4.88203e-02 MAX
8.29721e-01 8.99569e-01 3.35803e-02 8.91269e-02
2 2.20836e+00 2.34238e-02 BW
2.19161e+00 2.22512e+00 1.61117e-02 4.27628e-02
3 -5.42017e-05 4.93124e-07 IVDD
-5.45544e-05 -5.38489e-05 3.39188e-07 9.00253e-07
Probability and Quantile Estimators
The MCPROB and MCBOUND functions compute probabilities and quantiles (respectively)
associated with circuit performances. The output examples may be obtained using a modified
copy of the netlist $MGC_AMS_HOME/examples/eldo/monte_carlo_vco_lc_tank.cir.
Probability Estimator using Standard Monte Carlo
The first MCPROB extract is modified as follows:
.EXTRACT MC LABEL=proba_fosc_left_1_75 MCPROB(fosc, LE, 1.82G)
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The lower bound on the frequency FOSC is raised to increase the probability of simulating “tail
events”. The second probability estimator is kept at its original value. Running Eldo with
SAMPLING=RAND and 5000 runs produces a .mcm file containing the following data:
==> Table of Estimators and Confidence Intervals:
[...]
Tail Boundary/ Lower Pr. Value Upper CV(%) Name
Dist. Sigma Tail / Complementary of Meas
--------------------------------------------------------------------------------
Left 1.82000e+09 2.030e-01 2.144e-01/7.856e-01 2.258e-01 5.31% FOSC
-0.780 NQ = -0.831 -0.791 -0.753
WCI = 2.032e-01 2.146e-01/7.854e-01 2.260e-01 5.30%
Right -1.10000e+02 0.000e+00/1.000e+00 0.00% PHASE_N
19.736 ECI = 0.000e+00 5.991e-04
Note that the results differ for the two MCPROB functions:
• The results of the FOSC extract indicate that the left-tail probability is approximately
2.144×10 −1 , with confidence interval [2.030×10 −1 , 2.258×10 −1 ]. The precision or the
coefficient of variation is 5.3% at a 95% confidence level. This confidence interval is
known in the statistical literature as the Wald interval or the Normal approximation. The
formula is:
The line below the Wald interval contains the following information:
o
The value of q σ , which represents a normalized distance of the user specification
y = y l or y u . It is given by the following ratio:
In the case of perfect normality of the output Y, this value is the normal quantile of
the bound y. The value of q σ is -0.780 in the above example. Compare this value
with the NQ values contained in the same line.
o
The NQ values of the corresponding quantiles of the normal N(0, 1). If π y is a
probability given by the normal interval then the associated normal quantile is
y NQ = Φ −1 (π y ), where Φ is the distribution function of normal distribution N(0, 1).
The second NQ value in the above example is -0.791 ≈ Φ −1 (2.144×10 −1 ).
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The third line contains another confidence interval, known as the Wilson score interval
(WCI). This interval has better properties, even for a small number of runs. The formula
is:
• The results of the phase noise extract indicate that no fail simulation was found, because
the reported failure probability is zero. Only the value of q σ (which represents a
normalized distance of the user specification) and the extract confidence interval (ECI)
are reported for this case. The ECI gives an upper bound on the “true” failure
probability. Refer to “Zero Failure Probability and True Failure Probability” on
page 482 for more information.
Zero Failure Probability and True Failure Probability
If a certain event related to a user specification does not occur in a sample of size n, the reported
failure probability is zero. The standard Monte Carlo method provides a conservative estimator
of the true failure probability, which might actually be non-zero. However, use of this estimator
will result in “overdesign” of the circuit characteristics by taking large margins.
Given a random variable Y and a threshold y, the probability π y = Pr{Y ≤ y} has estimator:
where:
The expectation and the variance of this empirical estimator are:
Since S n follows a binomial law with parameters n and π y , an exact confidence upper bound
b n, α on π y is available such that Pr(π y ≤ b n, α ) ≥ 1 - α. When S n = 0, which happens with
probability (1 - π y ) n , the (1 - α)-confidence interval is [0, 1 - α 1/n ]. For a 95% confidence level (α
= 0.05), the upper bound is approximately given by:
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The value of this upper bound in the above example is:
Importance Sampling Monte Carlo efficiently handles these cases of low failure probabilities.
Quantile Estimators using Standard Monte Carlo
The first MCBOUND extracts are modified as follows:
.EXTRACT MC LABEL=quantile_fosc_left_1em4 MCBOUND(fosc, 1e-1)
.EXTRACT MC LABEL=quantile_phn_right_1em4 MCBOUND(phase_noise_1meg,1.0 -
1e-1)
The target probabilities in the left tail of the frequency FOSC and the right tail of the phase
noise are shifted to the “normal events” domain. These specifications can be simulated more
easily using the standard Monte Carlo method. Running Eldo with SAMPLING=RAND and
5000 runs produces a .mcm file containing the following data:
Tail Probability Lower Quantile Upper Prec(%) Name
(Goal Value) Value of Meas
--------------------------------------------------------------------------------
Left 1.000e-01 1.80857e+09 1.80963e+09 1.81042e+09 0.10% FOSC
Right 9.000e-01 -1.17933e+02 -1.17911e+02 -1.17887e+02 0.04% PHASE_N
The lower and upper bounds are obtained by inverting the confidence interval:
where π is the target probability, and where h is the half-range of the confidence interval:
A theoretical result ensures that a central limit theorem exists for quantiles.
Probability and Quantiles using Importance Sampling Monte Carlo
Running Eldo with SAMPLING=ISMC and 500 runs for each batch produces a .mcm file
containing the following data:
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Tail Bndry/ Lower Pr. Value Upper CV(%) #Runs Speedup Name
Dist. Sigma Tail / Comp of Meas
--------------------------------------------------------------------------------
Left 1.75e+09 7.69e-05 8.45e-05/1.0e+00 9.22e-05 9.05 3530 1.6e+03 FOSC
-4.631 NQ=(-3.785 -3.761 -3.739)
Right -1.10e+02 3.53e-06 3.88e-06/1.0e+00 4.23e-06 9.05 5560 2.2e+04
21.303 NQ=( 4.492 4.472 4.453)
PHASE_N
These values may be compared with the results obtained using the standard Monte Carlo
method (refer to “Probability Estimator using Standard Monte Carlo” on page 480).
Using the standard Monte Carlo method, the upped bound for the phase noise response was
5.99×10 −4 . The ISMC method returns 3.88×10 −6 as an estimation of the probability, with 9%
precision. The confidence interval (3.53×10 −6 , 4.23×10 −6 ) for this estimator is given on the
same line. Notice the major gap (almost two orders of magnitude) between the upper bound
based on the binomial law and the value obtained using ISMC. This implies that the probability
of the phase noise exceeding -110dBC/Hz is much less than the conservative estimation
computed using the standard Monte Carlo method.
An estimation of the speedup over the standard Monte Carlo method is given in the .mcm file. In
the case of the phase noise response, approximately 5560 × 2.2 × 10 4 ≈ 120 million standard
Monte Carlo runs would need to be carried out to obtain equivalent results (in terms of value
and precision).
The .mcm file contains the normal quantiles (NQ) corresponding to the probability estimator
and its confidence interval. The normalized distance of the user specification to the mean of the
distribution (q σ ) is also given. In the above example, the first response is slightly non Gaussian
(compare NQ = -3.761 with q σ = -4.631), while the phase noise has a very right-skewed
distribution which is clearly non-Gaussian (compare NQ = 4.472 with q σ = 21.303). In this
second case, making the assumption that the output distribution is Gaussian can lead to severe
underestimation of the true risk.
The ISMC method produces an .mcm file containing the following data about quantile
estimators:
Tail Probability Lower Quantile Upper Prec(%) #Runs Speedup Name
(Goal Value) Value of Meas
--------------------------------------------------------------------------------
Left 1.00e-04 1.750e+09 1.751e+09 1.752e+09 0.06% 3010 2.0e+02 FOSC
Right 1.00e+00 -1.124e+02 -1.121e+02 -1.119e+02 0.27% 2510 1.1e+02 PHASE_N
Two columns are added to the standard Monte Carlo results: the number of runs associated with
the estimator and the speedup over the standard Monte Carlo method. The precision is obtained
by inverting the confidence interval on the underlying probability estimator.
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Recall that the Monte Carlo method enables the computation of the full empirical CDF function
of the random output Y=H(X).
We will first explain how the distribution function is built for the standard Monte Carlo
method and secondly for the model-based approach. The second section is devoted to the
presentation of these results and how to use it.
CDF Function and Confidence Bounds
The computation of the empirical CDF uses the simulated sample Y 1 , …, Y n and is given by a
staircase function whose usual definition resembles the Monte Carlo estimator in:
This function approximates the probability
follows:
. Its estimated variance is defined as
This variance in turns enables an approximation of the 100(1−α)% confidence interval bounds
on the empirical CDF thanks to the Central Limit Theorem (provided the number of runs n is
sufficiently large). These two bounds read as follows:
where
is an appropriate percentage point from the normal distribution.
In the case of model-based approach, one proposes to consider estimating
substitution:
by simple
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This should result in a good estimate if the model m(x) is a good approximation of H(x), but the
main issue lies in quantifying the uncertainty in the estimate. One consider estimates of the
distribution function based on extreme estimates of H(x)
where c(Xi) is a measure of variance at the point Xi coming from a 100(1−α)% prediction
interval for an unknown observation. It is important to note that there is no theoretical
justification for this expression. These “pseudo-bounds” are only related to the quantities that
we are interested in. The previous expression is based on the distribution function for
100(1-α)% pointwise bounds on H(X), when the real interest is in pointwise bounds of the
distribution function of H(X).
How to Interpolate the CDF function
We provide the order statistics in the .mco file and the associated uniformly spaced cumulative
probabilities: (Y (i) , p i ). These values can be useful to work with a piecewise linear
approximation of the cumulative distribution. We describe how you can build a continuous
approximation of the CDF and how the confidence intervals are defined point-wise on this
function.
If Y (1) , Y (2) , …, Y (n) is the sample sorted from smallest value to largest value. The order statistics
Y (i) can be found in the column labelled with “Value(order)” and the cumulative probabilities in
the column “CDF(Cum.Prob)”:
.
. ==> Main sample (runs 1..1000)
.
.
.
. Index Output Measure 1 : MAX
. of Run/ Index
. Order of Meas ... Value(order) CDF(Cum.Prob) +/- T*STD
. -------------------------------------------------------------------------------
1 1 ... 7.1261259e-01 1.0000000e-03 6.1992631e-05
2 1 ... 7.1281508e-01 2.0000000e-03 1.2386115e-04
3 1 ... 7.2847591e-01 3.0000000e-03 1.8560556e-04
4 1 ... 7.3749211e-01 4.0000000e-03 2.4722587e-04
5 1 ... 7.3848200e-01 5.0000000e-03 3.0872206e-04
6 1 ... 7.3881086e-01 6.0000000e-03 3.7009415e-04
7 1 ... 7.3981639e-01 7.0000000e-03 4.3134212e-04
...
To build the function
we define:
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• The uniformly spaced probabilities p i =(i-1/2)/n where i=1, ..., n, the p i are the midpoints
of n contiguous probability intervals of width 1/n.
• The continuous strictly increasing piecewise-linear function joining the n points
(Y (i) ,p ι ):
where:
To avoid undefined denominators one must remove interior points in an interval of
constant output values.
Because is piecewise-linear, so is its inverse, and for a rank i such that , the
expression of inverse CDF is:
Coverage Intervals
A coverage interval for an output measure is an interval containing a known proportion of the
probability content of the distribution of that measure. That is a 100p% coverage interval for a
quantity Y with probability density function f Y is an interval [y low , y high ] for which:
We give in the .mcm file two different coverage intervals computed with the approximation
of the cumulative density function:
• The symmetric coverage interval defined as follows. Let α denote a value between 0 and
1 − p. The bounds of a 100p% coverage interval are obtained by linear inverse
interpolation.
To identify the lower endpoint such that
, we determine the rank r for
which the points and satisfy . Then by
interpolation:
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The upper endpoint defined as
, is given by the formula:
where the rank s satisfies
. The choice α =(1− p)/2 gives the
coverage interval defined by (1 − p)/2- and (1 − p)/2-quantiles. The symmetry is
defined with respect to the median value of the distribution.
• The shortest coverage interval is obtained from the CDF approximation by computing α
that:
is minimum. There is no analytical formula for the solution. This interval has the
property that, for unimodal distributions, it contains the mode which is the most
probable value of the output. Moreover, it is a more practical information for nonsymmetric
distributions.
==> Coverage Intervals:
Required Coverage Probabilities: p = 0.68, 0.90, 0.95, 0.99
Symmetric Cov. Inter. ... Cov. Int. (1-p)/2- and (1+p)/2-quantiles
Shortest Cov. Inter. ... Shortest Coverage Interval
Index Coverage Symmetric Cov. Inter. Shortest Cov. Inter. Name
of Meas Prob. [ Lower Upper ] [ Lower Upper ] of Meas
-------------------------------------------------------------------------------
1 0.68 7.98633e-01 8.77034e-01 7.99932e-01 8.78198e-01 MAX
0.90 7.70098e-01 9.03279e-01 7.75404e-01 9.06395e-01
0.95 7.58738e-01 9.12106e-01 7.59759e-01 9.12617e-01
0.99 7.38646e-01 9.39293e-01 7.37492e-01 9.34906e-01
2 0.68 2.17662e+00 2.21513e+00 2.17724e+00 2.21546e+00 BW
0.90 2.16188e+00 2.22854e+00 2.16432e+00 2.23077e+00
0.95 2.15420e+00 2.23476e+00 2.15689e+00 2.23655e+00
0.99 2.14510e+00 2.25731e+00 2.14460e+00 2.24787e+00
3 0.68 -5.51864e-02 -5.36483e-02 -5.51178e-02 -5.36134e-02 IVDD
0.90 -5.56705e-02 -5.32053e-02 -5.56753e-02 -5.32140e-02
0.95 -5.59181e-02 -5.29856e-02 -5.59735e-02 -5.30732e-02
0.99 -5.62951e-02 -5.26181e-02 -5.62996e-02 -5.26464e-02
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Approximation of the Density Function (Histogram File
.mch)
The histogram is an effective graphical technique for assessing the variability of a data sample
showing. It can help to analyze both of the components of the variability:
• How spread out are the data values near the center?
• How spread out are the tails?
The histogram is provided in a specific file with the extension .mch.
Histogram for measure : MAX
Size of sample : 1000
Frequency 2 10 75 164 269 264 157 51 6 2
Frequency% 0.2 1.0 7.5 16.4 26.9 26.4 15.7 5.1 0.6 0.2
-----------------------------------------------------------------
Each * equals 9 points
270 *
261 * *
252 * *
243 * *
234 * *
225 * *
216 * *
207 * *
198 * *
189 * *
180 * *
171 * *
162 * * *
153 * * * *
144 * * * *
135 * * * *
126 * * * *
117 * * * *
108 * * * *
99 * * * *
90 * * * *
81 * * * *
72 * * * * *
63 * * * * *
54 * * * * * *
45 * * * * * *
36 * * * * * *
27 * * * * * *
18 * * * * * *
9 * * * * * * * *
-----------------------------------------------------------------
Interval : 0.705 0.765 0.825 0.885 0.945
Mid-points: 0.735 0.795 0.855 0.915 0.975
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In addition to this ASCII plot we provide an automatic rule for the computation of the number
of bins. You can control this rule with the RULEBIN argument of the .MC command. The
number of bins K is controlled with following rules:
• RULEBIN=0. The default rule. The number of bins is user-defined and specified with
the NBBINS argument.
• RULEBIN=1. The Sturge’s rule takes where n is the number of
Monte Carlo runs.
• RULEBIN=2. The Scott’s rule takes:
where
is Gaussian.
is the bin width. This rule is “optimal” when the distribution
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Additional Uncertainty Analyses (the .mcm File)
The .mcm file contains additional numerical summaries of the statistical tests.
Basic Concepts on Quantitative Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491
Robust Measures of Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 492
Alternative Measures of Dispersion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494
Min/Max Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495
Parametric Fit and Normality Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495
Capability Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499
Coorelation of Test Concordance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500
Monte Carlo Sensitivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501
Basic Concepts on Quantitative Statistics
In statistics, it is very common to use in a complementary way, graphical techniques and
quantitative techniques. For example, if the quantitative methods yield different conclusions
than the graphical analysis, then some effort should be invested to understand why. Often this is
an indication that some of the assumptions of the classical techniques are not satisfied. Many of
the quantitative techniques given in the .mcm file fall into two general categories:
• Interval estimates
• Hypothesis tests
Interval Estimates
A classical task in statistics is to estimate a parameter from a sample of data. The value of the
parameter using all of the possible data, not just the sample data, is called the population
parameter or true value of the parameter. An estimate of the true parameter value is made using
the sample data. This is called a point estimate or a sample estimate.
For example, the most commonly used measure of centrality or location is the mean. The
population mean (or the “true” mean) is the sum of all the members of the given population
divided by the number of members in the population. In our simulation context, random
variables have continuous distributions, it is therefore impossible to simulate every member of
the population. A random sample is drawn from the population with the Monte Carlo method.
The sample mean is calculated by summing the values in the sample and dividing by the number
of values in the sample. This sample mean is then used as the point estimate of the population
mean.
Interval estimates incorporate the uncertainty of the point estimate. In the example for the mean
above, different samples from the same population will generate different values for the sample
mean (for example by varying the seed value in the .MC command setup). An interval estimate
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quantifies this uncertainty in the sample estimate by computing lower and upper values of an
interval which will contain the population parameter (with a given level of confidence.)
Hypothesis Tests
Hypothesis tests also address the uncertainty of the sample estimate. However, instead of
providing an interval, a hypothesis test attempts to refute a specific claim about a population
parameter based on the sample data.
To reject a hypothesis is to conclude that it is false. However, to accept a hypothesis does not
mean that it is true, only that we do not have evidence to believe otherwise. Thus hypothesis
tests are usually stated in terms of both a condition that is doubted (null hypothesis) and a
condition that is believed (alternative hypothesis).
A common format for a hypothesis test is:
• H0 — A statement of the null hypothesis, for example, a population is normal.
• Ha — A statement of the alternative hypothesis, for example, a population is not
normal.
• Test Statistic — The test statistic is based on the specific hypothesis test.
• Significance Level — The significance level, alpha, defines the sensitivity of the test. A
value of α = 0.05 means that we inadvertently reject the null hypothesis 5% of the time
when it is in fact true. This is also called the type I error. The choice of α is somewhat
arbitrary. In practice values of 0.1, 0.05, and 0.01 are commonly used.
Note
There is an important distinction between statistical significance and practical significance.
Statistical significance simply means that we reject the null hypothesis. The ability of the
test to detect differences that lead to rejection of the null hypothesis depends on the sample size.
For example, for a particularly large sample, the test may reject the null hypothesis that a output
measure is normal. However, in practice the non-normality may be relatively small and has no
real engineering significance. Moreover, if the sample size is small, a difference that is large in
engineering terms may not lead to rejection of the null hypothesis. The designer should not trust
blindly the results of a test, but should combine engineering judgment with statistical analysis
(this is why graphical analysis is important).
Robust Measures of Location
A basic task is to estimate a location or central value that best describes the data. There are
various alternatives to the mean for measuring location. These alternatives were developed to
address non-normal data since the mean is an optimal estimator if the data are normal. The
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mean lacks robustness, that is confidence intervals based on the mean tend to be not precise if
the underlying distribution is in fact not normal.
The subsection “Robust Measures of Location” provides three of the classical robust measures
of location: the median, the mid-mean, and the trimmed-mean.
==> Robust Measures of Location:
Median ... Median Value (50th percentile)
Mid-Mean ... Mean between 25th and 75th percentiles
Trimmed Mean ... Mean with 5% of trimmed points in lower/upper tails
Index Nominal Mid Trimmed Name
of Meas Value Median Mean Mean of Meas
-----------------------------------------------------------------------------
1 8.38073e-01 8.37607e-01 8.37391e-01 8.37282e-01 MAX
2 2.19652e+00 2.19540e+00 2.19524e+00 2.19535e+00 BW
3 -5.44334e-02 -5.44314e-02 -5.44231e-02 -5.44296e-02 IVDD
What Robustness Means
There are two properties that we expect for robust measures of location, where robustness
means independence to the effects of non-normality:
• Robustness of type I: the confidence intervals for the population location have a large
probability of covering the population location regardless of what the underlying
distribution is.
• Robustness of type II: the confidence intervals for the population location tend to be
almost as narrow as the best that could be done if we knew the true shape of the
distribution.
The median is an example of an estimator that tends to have robustness of type I, but not of type
II. The median is the value of the point which has half the data smaller than that point and half
the data larger than that point. That is, if Y (1) , Y (2) , …, Y (n) is a sample sorted from smallest
value to largest value, then the median is defined as:
The alternative measures of location try to balance these two concepts of robustness. That is, the
confidence intervals for the case when the data are normal should be almost as narrow as the
confidence intervals based on the mean. However, they should maintain their validity even if
the underlying data are not normal.
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Alternative Measures of Location
These alternatives can solve the problem of heavy-tailed distributions:
• Mid-mean: computes a mean using the data between the 25th and 75th percentiles.
• Trimmed mean: similar to the mid-mean except different percentile values are used. A
common choice is to trim 5% of the points in both the lower and upper tails, that is,
calculate the mean for data between the 5th and 95th percentiles.
The first three alternative location estimators defined above have the advantage of the median in
the sense that they are not affected by extremes in the tails. However, they generate estimates
that are closer to the mean for data that are normal (or nearly so).
Alternative Measures of Dispersion
When analyzing the variability of a simulated sample, the designer may face two key questions:
• How spread out are the simulated values near the central value?
• How spread out are the tails?
In the normal case, the variance (and its square-root the standard deviation) fully answers to
these two points. But it is known that it lacks what we defined robustness of type I.
In the subsection “Alternative Measures of Dispersion” of the .mcm file, we provide the range
and the inter-quartile range. These two numerical summaries are different answers to these two
points. The choice of the dispersion estimator is often driven by which of these points you want
to summarize.
==> Alternative Measures of Dispersion:
IQR ... Inter-Quartile Range
Q1, Q3 ... Lower and Upper Quartile
Index Range IQR Name
of Meas [ Min , Max ] [ Q1 , Q3 ] of Meas
-------------------------------------------------------------------------
1 2.72468e-01 5.55356e-02 MAX
7.12613e-01 9.85080e-01 8.09695e-01 8.65231e-01
2 1.31492e-01 2.57794e-02 BW
2.13597e+00 2.26746e+00 2.18230e+00 2.20808e+00
3 4.67989e-03 1.02707e-03 IVDD
-5.68030e-02 -5.21231e-02 -5.49313e-02 -5.39042e-02
We define these summaries as follows:
• The range is the largest value minus the smallest value in a data set. This measure is
based only on the lowest and highest extreme values in the sample. The spread near the
center of the distribution is not captured at all.
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• The inter-quartile range is the value of the 75th percentile minus the value of the 25th
percentile. This measure of dispersion attempts to measure the variability of points near
the center.
The inter-quartile range is an estimates of dispersion that have robustness of type I (but not of
type II).
Note
If the histogram of an output measure indicates that the data are in fact reasonably
approximated by a normal distribution, then it makes sense to use the standard deviation as
the estimate of dispersion. However, if the data are not normal, and in particular if there are long
tails, then using an alternative measure such as inter-quartile range makes sense. Moreover,
comparing the range to the standard deviation gives an indication of the spread of the data in the
tails.
Min/Max Values
Minimum and maximum values in data sample are given for each output measures in the
following table.
==> Min and Max Values:
Min ... Minimum Value Max ... Maximum Value
I-min ... Index of Minimum I-max ... Index of Maximum
Index
Name
of Meas I-min Min I-max Max Range of Meas
--------------------------------------------------------------------------------
1 231 7.12613e-01 367 9.85080e-01 2.72468e-01 MAX
2 551 2.13597e+00 247 2.26746e+00 1.31492e-01 BW
3 109 -5.68030e-02 711 -5.21231e-02 4.67989e-03 IVDD
We also provide the index of the corresponding run. These numbers may be used with the IRUN
argument on the .MC command for extracting more informations of these “extreme”
simulations.
Parametric Fit and Normality Test
The section “Parametric Fit and Normality Test” in the .mcm file is important when the designer
wants to check the normality assumption of the sample data.
Scale and Shape
We provide the sample estimates of the third and fourth standardized moments as an indication
of non-normality.
These two standardized moments of interest are given by:
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and:
These values measure the skewness and the kurtosis. The skewness for a normal distribution is
zero , and any symmetric data should have a skewness near zero. Negative values for
the skewness indicate data that are skewed left and positive values for the skewness indicate
data that are skewed right. Skewed left means the left tail is long relative to the right tail.
Similarly, skewed right means the right tail is long relative to the left tail. Some measurements
have a lower bound and are skewed right. We plot two examples of skewed distributions in
Figure 11-14.
Figure 11-14. Illustration of Kurtosis and Skewness with μ=0 and σ=1
The kurtosis refers to the curvature of the distribution. The kurtosis for a standard normal
distribution is three. When β 2 > 3 then unimodal distributions tend to have heavier or thicker
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tails than the normal distribution. They also have higher modes in the central area. When β 2 3(n−1)/(n+1)
indicates thick tails in the distribution.
In the .mcm file we provide Fisher G-statistics to remove the bias in b 2 . The quantities are
analogous to
and b 2 , but involve ratios of unbiased cumulant. We give the formulae here:
These values are presented in the following table:
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==> Scale and Shape:
Mu ... Maximum Likelihood (ML) Estimation to the Mean
Sigma ... ML Estimation to the Standard Deviation
Skewness ... Third Central Moment Divided by the Cube of Sigma
Kurtosis ... Fourth Central Moment Divided by Fourth Power of Sigma
(Sample Skewness and Kurtosis are Corrected for Bias)
Index
Name
of Meas Mu Sigma Skewness Kurtosis of Meas
----------------------------------------------------------------------------
1 8.38289e-01 9.93480e-03 -5.07100e-02 2.90190e+00 MAX
2 2.19635e+00 5.09067e-03 -3.76104e-02 2.90041e+00 BW
3 -5.44169e-02 1.96232e-04 -3.38857e-02 3.17208e+00 IVDD
D’Agostino-Pearson Test of Normality
We provide the test of normality of D’Agostino-Pearson K 2 (K-squared test) based on the
skewness and kurtosis coefficients. When these two numbers are different from the reference
value, one may conclude that the empirical distribution is not compatible with the normal law.
As the number of samples increase this test becomes particularly efficient when n ≥ 20, and is
better than the Kolmogorov-Smirnov test. The idea is relatively simple. One tries to center and
reduce the skewness and kurtosis indicators to obtain two statistics z 1 and z 2 . And one can prove
that the statistics z 1 and z 2 are asymptotically normal. The D’Agostino-Pearson statistic is the
combination:
If the null hypothesis of normality is true, then K 2 is approximately distributed as the χ 2
distribution with two degrees of freedom. Given a significance level α, the hypothesis regarding
the normality is rejected if the test statistic satisfies:
Tip
For an instructive introduction to this test see: R. B. D’Agostino, A. Belanger and R. B.
D’Agostino Jr, A suggestion for Using Powerful and Informative tests of Normality. The
American Statistician, Vol 44, No 4. (1990), pp. 316-321.
The results of this test are organized as classical hypothesis tests, see Hypothesis Tests section
for more information.
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==> D’Agostino-Pearson Hypothesis Test of Normality:
Null Hypothesis H0 : Distribution is Normal
Alternate Hypothesis HA: Distribution is not Normal
Number of Observations : 1000
*** Output Measure : MAX
Test Statistic K2 : 3.62537e-02
P-value : 9.82036e-01
Alpha Level
Conclusion
90.00 % Accept H0
95.00 % Accept H0
99.00 % Accept H0
*** Output Measure : BW
Test Statistic K2 : 5.43884e+00
P-value : 6.59130e-02
Alpha Level
Conclusion
90.00 % Reject H0
95.00 % Accept H0
99.00 % Accept H0
*** Output Measure : IVDD
Test Statistic K2 : 2.37019e+00
P-value : 3.05716e-01
Alpha Level
Conclusion
90.00 % Accept H0
95.00 % Accept H0
99.00 % Accept H0
Capability Indices
Capability indices or process capability ratios are statistical indicators of the ability of a process
to produce output within specification limits.
Under the assumption of normality we provide the probability of being within an interval of
specifications [L, U]:
The function represents the cumulative distribution function of the normal distribution
with parameters (μ, σ).
The capability indices are given in the last columns of the table.
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==> Warning: The indices are computed under the assumption of normality
P ... Estimated Probability of Being Within Limits
Pl ... Prob. of Being Below L (lower spec)
Pu ... Prob. of Being Above U (upper spec)
Cp ... (UBound-LBound)/(6*Sigma)
Cpl ... (Mu-LBound)/(3*Sigma)
Cpu ... (UBound-Mu)/(3*Sigma)
Cpk ... min(Cpl, Cpu)
Index P Cp Name
of Meas [ Pl , Pu ] [ Cpl, Cpu ] Cpk of Meas
---------------------------------------------------------------------------------
1 8.46218e-01 4.97321e-01 MAX
3.61774e-02 1.17604e-01 5.98960e-01 3.95683e-01 3.95683e-01
2 5.90732e-01 Infinity BW
0.00000e+00 4.09268e-01 -Infinity 7.64764e-02 -Infinity
3 1.00000e+00 Infinity IVDD
0.00000e+00 0.00000e+00 2.14984e+02 Infinity 2.14984e+02
Coorelation of Test Concordance
This feature computes the pairwise-linear correlation coefficient between each pair of output
measures. The sample correlation coefficient between two random variables (U, V) is given by
the formula:
There are some practical conventions used for computation:
• By default, when one of two random variables has no variation, Eldo set the correlation
coefficient to zero (0/0=0).
• When the value U i or V i is undefined, because the corresponding extract function cannot
be measured at the i-th run of the Monte Carlo simulation, then this data is removed
from the computation. When all the pairwise data are removed, Eldo will return the
value UNDEF.
We also computes the p-value for testing the hypothesis of no correlation against the alternative
that there is a non-zero correlation. If P-Val is small, say less than 5%, then the correlation r U, V
is significantly different from zero.
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Additional Uncertainty Analyses (the .mcm File)
Number of Computed Correlations : 3
Number of Simulations : 1000
Size of Sample for Test : 200
==> Test of no correlation:
Null Hypothesis H0: no correlation between measures I and J
Alternate Hypothesis HA: there is a non-zero correlation
==> Type of Correlation: Pearson (linear correlation)
Coef ... Correlation with -1

Monte Carlo Analysis
Additional Uncertainty Analyses (the .mcm File)
Method : Functional ANOVA (global sensitivity indices)
Number of Simulations : 1000 (Number of Runs)
Number of Random Variables : 51
==> List of Random Variables:
Avg.Sens ... Arithmetic Mean of the Sensitivities
Index
of Var Distrib Mean Std. Dev. Name
---------- ... -----------------------------------------------------------
1 Gaussian 1.90000e-08 2.92115e-11 EM(XM16.M1,TOX)
2 Gaussian -3.73283e-01 -1.01878e-03 EM(XM16.M1,VTH0)
3 Gaussian 1.38761e+02 8.35592e-01 EM(XM16.M1,U0)
...
50 Gaussian 3.32200e-01 7.29079e-04 EM(XM10.M1,VTH0)
51 Gaussian 3.88320e+02 1.58357e+00 EM(XM10.M1,U0)
The left part summarizes the average sensitivities for each output measure. The column
Avg.Sens. is an indicator of importance. This number is not necessarily the most representative
value of sensitivity since all measures are considered identically.
==> List of Random Variables:
Avg.Sens ... Arithmetic Mean of the Sensitivities
Index
of Var Meas 1 Meas 2 Meas 3 Avg.Sens ... Name
------------------------------------------------------------
1 0.31% 0.55% 0.86% 0.57% ... EM(XM16.M1,TOX)
2 0.48% 6.32% 11.01% 5.94% ... EM(XM16.M1,VTH0)
3 0.64% 6.66% 11.29% 6.20% ... EM(XM16.M1,U0)
4 0.93% 2.94% 2.38% 2.08% ... EM(XM17.M1,TOX)
...
Ordered Sensitivity Indices
This result is organized as a Pareto chart and it is composed as follows:
• The name of the measure, the effective number of Monte Carlo runs used for the
calculations.
• A list of important factors and their sensitivity index.
See “Global Sensitivity Analysis” on page 520 for more details on the methodology.
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Additional Uncertainty Analyses (the .mcm File)
Estimation of Sensitivity Indices for Output Measure : MAX
Number of Simulations : 1000 (Effective Number of Runs)
List of Important Parameters :
Index(I) Histo S(I) (percent / cumulative) Variable
Value
Name
11 |-------------------- 16.1% 16.1% EM(XM13.M1,VTH0)
17 |------------ 10.1% 26.3% EM(XM12.M1,VTH0)
18 |------------ 10.1% 36.4% EM(XM12.M1,U0)
35 |----------- 9.4% 45.8% EM(XM9.M1,VTH0)
12 |----------- 9.0% 54.7% EM(XM13.M1,U0)
48 |------- 6.1% 60.8% EM(XM8.M1,U0)
45 |------ 5.5% 66.4% EM(XM7.M1,U0)
30 |------ 4.9% 71.2% EM(XM1.M1,U0)
27 |----- 4.8% 76.0% EM(XM11.M1,U0)
36 |----- 4.6% 80.6% EM(XM9.M1,U0)
33 |---- 3.9% 84.5% EM(XM2.M1,U0)
28 |---- 3.3% 87.9% EM(XM1.M1,TOX)
51 |--- 2.9% 90.7% EM(XM10.M1,U0)
47 |--- 2.8% 93.6% EM(XM8.M1,VTH0)
10 |--- 2.7% 96.3% EM(XM13.M1,TOX)
26 |-- 2.1% 98.4% EM(XM11.M1,VTH0)
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Monte Carlo Analysis
Input/Output Samples
Input/Output Samples
Two files are provided for use in “Data Mining” applications, which exploit the input and
output data set generated during the Monte Carlo analysis. The file with extension .mci contains
the sample from the input space, and the file .mco contains the output results.
Depending on the size of the problem, these files may be quite large in size. To disable the
generation of the .mci and .mco files specify PRINT_ASCII_IN_SAMPLE=0 and
PRINT_ASCII_OUT_SAMPLE=0 on the .MC command.
File Organization (the .mci and .mco Files)
The .mci and .mco files are organized in a similar fashion. The data sets are available in a raw
form and separated from a formatted table containing respectively some informations on the
input variables and simulated results. This additional information is printed in the file with a dot
‘.’ character in the first place. These lines can therefore be skipped during data extraction.
Input Sample
The .mci starts with basic informations about the size of the problem and the algorithm used to
draw the random input variables.
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Monte Carlo Analysis
Input/Output Samples
.
. **********************************************************
. *** ***
. *** Monte Carlo Analysis ***
. *** ***
. **********************************************************
.
.
. ...
.
. ==> Input Sample File (test.mci)
.
. ==> Dimensions:
. Simulations : 1000
. Random Variables : 51
. Output Measures : 3
.
. ==> Parameters:
. Design : standard Monte Carlo (pseudo-random generator)
.
.
. ==> List of Random Variables:
. Index Mean Std. Index Name
. of Var Distrib Value Deviation of Ref Var / Ref
. ------------------------------------------------------------------------------
. 1 Gaussian 1.90000e-08 2.92115e-11 0 EM(XM16.M1,TOX)
. 2 Gaussian -3.73283e-01 -1.01878e-03 0 EM(XM16.M1,VTH0)
. 3 Gaussian 1.38761e+02 8.35592e-01 0 EM(XM16.M1,U0)
. 4 Gaussian 1.90000e-08 7.13135e-11 0 EM(XM17.M1,TOX)
...
. 49 Gaussian 1.90000e-08 4.91192e-11 0 EM(XM10.M1,TOX)
. 50 Gaussian 3.32200e-01 7.29079e-04 0 EM(XM10.M1,VTH0)
. 51 Gaussian 3.88320e+02 1.58357e+00 0 EM(XM10.M1,U0)
.
A list of random variables is also printed and contains the following informations:
• The type of the distribution and the parameters of this distribution are provided for each
X i , the i-th input variable (mean value, standard deviation, half-range, ...).
• The column “Index of Ref” contains integer values that refer to the “Index of Var”
column. A positive integer k > 0 in this column, indicates that this variable is associated
to local variations of a device and that the effective value is composed by summing the
value of the k-th variable with global variations and the value of the i-th variable with
independent and local variations.
A zero value k = 0 in this column indicates the i-th variable has no local variations.
For instance, with the example given in section Local and Global Variations, there is one
global threshold voltage V th, glob that affects all transistors equally and 100 local
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Monte Carlo Analysis
Input/Output Samples
threshold voltages V th, loc for i= 1, ..., 100 that affect each transistor individually and
independently from others. The effective threshold voltage for the i-th device is the sum:
This configuration is represented in Figure 11-15.
Figure 11-15. Global/Local Hierarchy
The second part of the .mci file contains the data set. It is organized as a sequence of tables: one
table for each variable. In table associated to a variable we give the index of the Monte Carlo
run, the index of this variable, the status of the simulation and the value of the variable.
.
. ==> Main sample (runs 1..1000)
.
.
. Random Variable 1 : EM(XM16.M1,TOX)
.
. Index Index Sim
. of Run of Var Status Value(indep) Value(effect)
. -----------------------------------------------------------------
1 1 1 1.8949413e-08 1.8949413e-08
2 1 1 1.8969849e-08 1.8969849e-08
3 1 1 1.9051539e-08 1.9051539e-08
4 1 1 1.9009045e-08 1.9009045e-08
5 1 1 1.8968941e-08 1.8968941e-08
6 1 1 1.8973925e-08 1.8973925e-08
7 1 1 1.8990268e-08 1.8990268e-08
The column “Sim Status” indicates that for the corresponding MC run, one or more output
measures cannot be extracted (Undefined value).
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Input/Output Samples
The column labelled “Value(indep)” represents the independent variations associated to a
random variables. In the previous example it is the random variable V i th, loc . The effective value
V i th is given in the column “Value(effect)”. When the variable is not associated to local
variations, the values in the columns are the same (there is no correlation).
If the netlist contains swept parameters or .ALTER blocks, Eldo generates multiple .mci files. In
this case, the table for each random variable contains an additional column, Index in Loop,
which identifies the Monte Carlo analysis that the .mci file corresponds to. Refer to “Monte
Carlo Analysis With a Varying Circuit” on page 419 for more information.
Output Sample
The list of output measures is printed in the first part of the file. Users will also find a short
summary of the Monte Carlo simulations. We give the nominal value, the average value and the
empirical estimation of the Yield. This estimation is given in the column “Pass (percent)”. The
column “Number of Undef” counts the number of runs with Undefined value.
. ==> List of Output Measures:
.
.
. Index Number Nominal Lower Mean Upper Pass Name
.of Meas of Undef Value Bound Value Bound (percent) of Meas
. -------------------------------------------------------------------------------
. 1 0 8.380e-01 7.650e-01 8.372e-01 8.850e-01 84.70 % MAX
. 2 0 2.196e+00 -Infinity 2.195e+00 2.200e+00 60.30 % BW
. 3 0 -5.443e-02 -5.400e-01 -5.443e-02 Infinity 100.00 % IVDD
.
The second part is a sequence of tables containing the detail results of the Monte Carlo runs.
Each table has n rows where n is the number of MC runs. The first column gives the run index
which corresponds to the column “Value”, and the order of the run that corresponds to the order
statistics. In other words, the column “Value” gives the sequence Y 1 , Y 2 , ..., Y n , and the column
“Value (order)” gives the sequence Y [1] , Y [2] , ..., Y [n] of order statistics.
.
. ==> Main sample (runs 1..1000)
.
.
.
. Index Output Measure 1 : MAX
. of Run/ Index
. Order of Meas Value P/F Value(order) CDF(Cum.Prob) +/- T*STD
. ------------------------------------------------------------------------------
1 1 8.7112e-01 1 7.1261e-01 1.0000e-03 6.1992e-05
2 1 8.9774e-01 0 7.1281e-01 2.0000e-03 1.2385e-04
3 1 7.8203e-01 1 7.2847e-01 3.0000e-03 1.8560e-04
4 1 8.1764e-01 1 7.3749e-01 4.0000e-03 2.4722e-04
5 1 8.6639e-01 1 7.3848e-01 5.0000e-03 3.0872e-04
6 1 7.8002e-01 1 7.3881e-01 6.0000e-03 3.7009e-04
...
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Input/Output Samples
The column “P/F” corresponds to Pass/Fail condition. If it is 1 the value satisfies the optional
specifications LBOUND/UBOUND, otherwise it is 0.
Finally, the three last columns return an approximation of the CDF and the half-range of 1-
sigma confidence interval for the CDF.
If the netlist contains swept parameters or .ALTER blocks, Eldo generates multiple .mco files.
In this case, the table for each output measure contains an additional column, Index in Loop,
which identifies the Monte Carlo analysis that the .mco file corresponds to. Refer to “Monte
Carlo Analysis With a Varying Circuit” on page 419 for more information.
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Monte Carlo Analysis
Graphical Output
Graphical Output
During the post-analysis and, Eldo provides, through EZwave, some basic tools for statistical
analysis and/or exploratory data analysis.
• Statistical Analysis Plots
o
The histogram. The purpose of this plot is to graphically summarize the distribution
of a response variable. It shows the following: the typical value, the spread of the
data, the skewness of the data, and the presence of multiple modes in the data.
In Eldo, the most common form of the histogram is used. It is obtained by splitting
the range of the data into equal-sized bins. Then for each bin, the number of points
from the data set falling into that bin are counted.
A Kernel Density Estimation of the PDF can be added to the histogram plot. It can
be thought of as a “smooth” histogram that may help to extrapolate the data to the
whole range of values.
A Gaussian PDF can also be added to the Histogram Plot.
o
The empirical CDF. The empirical distribution function is a step function defined
by:
This value is therefore a probability estimator, and confidence bounds are provided.
• Exploratory Data Plots
o
o
o
The Response-sequence plot summarizes a univariate data set. It provides a plot of
an output response with respect to the index of the Monte Carlo run.
The AVG-sequence plot shows the evolution of the mean value estimator versus the
index of the Monte Carlo run. This plot is available by adding the argument
MONITOR to the .MC statement.
The STD-sequence plot shows the evolution of the standard deviation estimator
versus the index of the Monte Carlo run. This plot is available by adding the
argument MONITOR to the .MC statement.
In this section:
Histogram Annotations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510
Cumulative Distribution Function (CDF) Annotations . . . . . . . . . . . . . . . . . . . . . . . . . . 511
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Monte Carlo Analysis
Graphical Output
Histogram Annotations
Specify the .HISTOGRAM command to control the measurement annotations displayed by
EZwave.
• SPEC_BOUNDS: controls the plot of lower bound (LBOUND) and upper bound
(UBOUND) cursors and the corresponding yield value. These specification values are
not necessarily entered by users for each extract. It is also possible that only one value is
given. In this case, the other bound must be considered as +/-infinity.
• GAUSS_PDF: controls the plot of the Gaussian PDF that best approximates the data.
This waveform is named Gaussian PDF.
• GAUSS_FIT: controls the plot of 1-sigma, 2-sigma and 3-sigma cursors and their
associated yield values. All three cursors are plotted.
• STAT_LEGEND: controls the presence of the statistical measures legend displayed on
the histogram, which contains for example:
o
o
o
o
o
Size Sample (Samples). The number of MC runs. The nominal run is never used in
computations.
Empirical Mean (Mean)
Standard Deviation (Std. Dev.)
Coefficient of Variation (Coef. of Var.). Note that we actually provide the Relative
Standard Deviation.
Min/Max values (Min/Max)
When the .HISTOGRAM statement is not specified within the netlist, the default annotations
are controlled by EZwave.
Figure 11-16 shows a histogram plotted with the following annotations: Kernel PDF curve,
Coverage intervals (yield percentage) at 1σ, 2σ, 3σ specifications, based on empirical CDF.
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Monte Carlo Analysis
Graphical Output
Figure 11-16. Histogram Annotations 1
See Also
• .HISTOGRAM command in the Eldo Reference Manual
• Plotting Histograms in the EZwave User’s and Reference Manual
Related Topics
Graphical Output
Cumulative Distribution Function (CDF) Annotations
Cumulative Distribution Function (CDF) Annotations
Specify the .CDF command to control the measurement annotations displayed by EZwave.
• CONF_BOUNDS: controls the plot of Lower and Upper Confidence Bounds (LCB and
UCB).
• LEFT_TAIL and RIGHT_TAIL: controls the plot of the left- and right-tail parts of the
Empirical CDF.
• GAUSS_FIT: controls the plot of the Gaussian CDF that best fits the empirical data.
• INTERPOLATE: controls how the CDF curve is plotted. The usual method is to use the
staircase representation that strictly follows the mathematical notion of this function.
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Monte Carlo Analysis
Graphical Output
Note
The CDF plot in EZwave also plots the empirical CDF without interpolation, as a
staircase function. The interpolated representation is accessible by setting the
Interpolate option in the dialog box.
• STAT_LEGEND: controls the presence of the Statistical Summary legend displayed on
the CDF plot, which contains for example:
o
o
o
o
o
o
size sample
empirical mean
standard deviation
coefficient of variation (percentage)
min/max values
number of UNDEF values
When the .CDF statement is not specified within the netlist, the default annotations are
controlled by EZwave.
Figure 11-17 shows a CDF plotted with confidence bounds on the central tendency plot of the
CDF. The Lower Confidence Bounds (LCB) curve in blue and the Upper Confidence Bounds
(UCB) in yellow are computed with the formulae given in “CDF Function and Confidence
Bounds” on page 485.
Figure 11-17. CDF Plot (with Confidence Bounds)
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Graphical Output
Figure 11-18 shows a CDF plot dedicated to the analysis of the “tail-behavior.” The right-tail
matches the values greater than the empirical mean to the cumulative probabilities. This is
similar to the left-tail plot but instead we use the complementary function:
They are represented with a semi-log plot (the y-axis is log-scaled) to ensure that lower
probabilities are clearly visible. For example, the cursor indicates a quantile value of y=54.0
and gives the empirical estimation of Pr(Y≥y) jointly with the 95% confidence bounds.
Figure 11-18. CDF Plot Right-Tail Part of the Empirical CDF
See Also
• .CDF command in the Eldo Reference Manual
• Plotting CDFs in the EZwave User’s and Reference Manual
Related Topics
Graphical Output
Histogram Annotations
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Monte Carlo Analysis
Run-Length Control
Run-Length Control
You can use the MCCONV extract function to control the run-length in the context of
sequential Monte Carlo algorithms for estimating E(Y). In contrast to fixed run-length
approaches, samples are generated until some error criterion is satisfied.
Two algorithms CONFIDENCE Technique and SETTLING Technique are provided to control
the convergence. You can monitor the evolution of the various moments to precisely quantify
the notion of convergence. The moments are: AVG and STD for the CONFIDENCE method
and AVG, STD, KURT and SKEW for the SETTLING method to precisely quantify the notion
of convergence. You can stop the Monte Carlo process early by using .MC AUTOSTOP if these
quantities do not vary more than a user-specified limit. This can save CPU time.
The simulation framework used to estimate μ = E[Y]:
• First simulate θ 1 , θ 2 , ..., θ n and set:
• The strong Law of Large Numbers says as .
At this point it is not known how large n should be to obtain a confidence in μ n as an estimator
of μ. In other words, for a fixed value of n, what can be said about the quality of μ n ? There are
two methods to answer this: CONFIDENCE Technique and SETTLING Technique.
Note
Using the Monte Carlo analysis convergence test may interfere with the sensitivity analysis,
and the combination of these features should be avoided as much as possible. The global
sensitivity analysis in the Monte Carlo analysis needs a minimum number of simulations to
provide good results (for example, ~1000 simulations). Users must be careful when interpreting
global sensitivity analysis when the number of simulations is small.
CONFIDENCE Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514
SETTLING Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
MCCONV Extract Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518
CONFIDENCE Technique
Convergence test based on confidence interval techniques.
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Stopping Test for AVG
Monte Carlo Analysis
CONFIDENCE Technique
Suppose it is required to estimate μ with a random sequence θ 1 , θ 2 , ..., θ n whose distribution
depends on μ. Then L(Y) and U(Y) are searched for such that:
where 0 ≤ α ≤ 1 is a pre-specified number. We then say that [L(θ), U(θ)] is a 100(1 − α)%
confidence interval for μ.
There are two types of error to consider:
• The absolute error, given by:
• The relative error, given by:
It is known that as so that the errors both tend to 0. If μ = 0 then the relative
error E r is not defined. The following error criterion is specified:
Error Criterion: Given 0 ≤ α ≤ 1 and ε > 0, the condition required is:
E is the error type specified (relative or absolute).
To satisfy the condition
, then samples continue to be generated until:
where z 1 −α/2 is the (1 −α/2) percentile point of the N(0, 1) distribution and σ p is the estimate of
σ based upon the first p samples. It is important that p be sufficiently large, so that μ n and σ n are
sufficiently good estimates of μ and σ respectively. As a result, it is typically insisted that p = 20
before stopping. The parameter p may be redefined by setting the NRUN_PILOT within the
MCCONV function.
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Monte Carlo Analysis
CONFIDENCE Technique
To control the relative error and have
, then samples are simulated until:
This statistical test is implemented as follows:
where ε ABS and ε REL are respectively the absolute tolerance and the relative tolerances for
convergence, with default values ε ABS = 10 −2 and ε REL = 10 −2 . By default the confidence level
is chosen such that a 95% confidence interval is computed for μ, and you can adjust this
parameter.
Stopping Test for STD
A similar criterion exists for the standard deviation. It is possible to give a confidence interval
for the variance under some assumptions. With a random sequence θ 1 , θ 2 , ..., θ n which follows a
normal distribution N(μ, σ 2 ) where the mean value μ is unknown, we can prove that:
With a confidence interval:
with confidence level 1 − α. The numbers a and b are automatically computed and satisfy the
relation where . This statistical test is implemented as
follows:
The value σ p is obtained after p pilot simulations.
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Monte Carlo Analysis
SETTLING Technique
Related Topics
MCCONV Extract Function
SETTLING Technique
The SETTLING method controls the absolute and relative errors with a simple moving average
of the estimator μ. In other words, the unweighted mean of the previous w data points is
computed:
and we test for all
the inequality:
where ε ABS and ε REL are respectively the absolute tolerance and the relative tolerances for
convergence, with default values ε ABS = 10 −2 and ε REL = 10 −2 .
Figure 11-19. Principle of the SETTLING Procedure
The parameter w is the size of the ‘window’ used within the test.
Related Topics
MCCONV Extract Function
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Monte Carlo Analysis
MCCONV Extract Function
MCCONV Extract Function
The test of convergence is associated to a specific ‘pseudo-extract’ in Eldo’s language for
extraction. The MCCONV extract returns 0 or 1 to indicate convergence of the Monte Carlo
process for the specified quantity. This extract function, used in conjunction with .MC
AUTOSTOP, controls the run-length of the Monte Carlo process, and can save CPU time.
Syntax
.EXTRACT MCCONV(meas_name, AVG|STD|KURT|SKEW,
+ SETTLING[,WINDOW[,ABSTOL[,RELTOL]]])
.EXTRACT MCCONV(meas_name, AVG|STD,
+ CONFIDENCE[,NRUN_PILOT[,CONFIDENCE_LEVEL[,ABSTOL[,RELTOL]]]])
Parameters
• SETTLING
The Monte Carlo process is stopped if adding new samples no longer changes the output by
more than a certain threshold. When the SETTLING algorithm is specified, the default
values are WINDOW=20, ABSTOL=0.01, and RELTOL=0.01. In the description of the
SETTLING Technique algorithm, the WINDOW argument is referred to as parameter w,
and the arguments ABSTOL and RELTOL are referred to as ε ABS and ε REL .
• CONFIDENCE
The Monte Carlo analysis is stopped when the confidence interval is small. This algorithm
is defined for AVG and STD; not for SKEW, or KURT. When the CONFIDENCE
algorithm is specified, the default values are NRUN_PILOT=20,
CONFIDENCE_LEVEL=0.95, ABSTOL=0.01, and RELTOL=0.01. In the description of
the CONFIDENCE Technique algorithm, the NRUN_PILOT argument is referred to as
parameter p, and the arguments ABSTOL and RELTOL are referred to as ε ABS and ε REL .
The CONFIDENCE_LEVEL argument is the value 1 − α within the error criterion, it must
satisfy the bounds 0 < 1 − α < 1. For example, a 99% confidence interval will correspond to
CONFIDENCE_LEVEL=0.99. If a value is specified out of the bounds it will default to
0.95 (or 95%).
Note
The arguments WINDOW and NRUN_PILOT have a different meaning. The
window size represents the number of times the convergence test has to be satisfied
before stopping the Monte Carlo procedure. On the other hand, the number of pilot runs
represents the minimum number of runs that Eldo must perform before controlling the
run-length. This number must be considered as the minimal number of runs to perform
to obtain a first approximation of the AVG or STD estimator.
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MCCONV Extract Function
Examples
• In this example, the second extract returns a boolean value (1 or 0). It returns 1 when the
standard deviation of quantity GAIN_DB has converged to within ± (0.01 + 0.05 ),
where
is the average value of the STD taken from the last w=20 Monte Carlo runs.
.EXTRACT AC LABEL=GAIN_DB YVAL(VDB(OUT), 1MEG)
.EXTRACT MC LABEL=STDDEV_GAIN_DB_CONV
+ MCCONV(GAIN_DB, STD,SETTLING, 20, 0.01, 0.05)
• Similarly, a test on the standard deviation can be specified with the confidence
techniques:
.EXTRACT MC LABEL=STDDEV_GAIN_DB_CONV
+ MCCONV(GAIN_DB, STD, CONFIDENCE, 40, 0.95, 0.00, 0.01)
• In the next example, the first three .EXTRACT statements are taken into account, and all
three of them must have converged before the MCCONV() function returns 1.
.EXTRACT AC LABEL=GAIN_DB YVAL(VDB(OUT), 1MEG)
.EXTRACT AC LABEL=PHASE_DB YVAL(VP(OUT), 1MEG)
.EXTRACT DC LABEL=CC I(VDD)
.EXTRACT MC LABEL=STD_CONV MCCONV(ALL, STD, SETTLING, 20, 0.01,0.05)
Tolerance tuning is inefficient in this situation; instead, use the default values as much
as possible, for instance, the following syntax should give a first estimate of the
uncertainty:
.EXTRACT MC LABEL=MC_AVG_CONV MCCONV(ALL, AVG, CONFIDENCE)
Then, use the SAVE/RESTART feature to obtain more accurate estimates.
Related Topics
CONFIDENCE Technique
SETTLING Technique
Post-Analysis of Monte Carlo Simulations
Monte Carlo Analysis Examples
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Monte Carlo Analysis
Sensitivity Analysis
Sensitivity Analysis
There are two different methods that can post-process the Monte Carlo simulations for
computing the sensitivities. The first method, the Global Approach, is a variance-based method
that does not rely on model assumptions. The second method, Large Scale Variable Screening,
specifically builds a regression function which attempts to capture the main variations of the
response variables of interest.
As a rule of thumb, the global approach should be used when the context enables a large number
of Monte Carlo simulations, say a few thousand. This sensitivity analysis is independent of the
problem dimension (the number of circuit parameters with statistical variations). On the other
hand, when you can afford only a few tens of simulations and the number of variables is much
larger, the approach must be based on the assumption that the problem dimension (or the
effective dimension) is very small, say ten variables are really important. This assumption is
important for efficiency and the interpretability of the approach.
Global Sensitivity Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
Large Scale Variable Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
Global Sensitivity Analysis
Use global sensitivity analysis to identify the parameters in the circuit that, left free to vary over
their range of uncertainty, make no significant contribution to the variability of the output. The
identified factors can then be fixed at any given value without affecting the output variance.
A variance-based method is used with the capacity to capture the influence of the full range of
variation of each input factor. The method is based on the decomposition of the response:
into a set of functions of increasing dimensionality:
This expansion, also named ANOVA decomposition, is not unique. In Eldo, an approximation
is made of the first terms that form a sum of univariate functions in the representation:
The univariate terms are called the first-order ‘main effects’, and the bivariate terms f ij (X i ,X j )
the interactions of second-order.
In particular, it can be proved that under some assumptions:
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Monte Carlo Analysis
Global Sensitivity Analysis
where
is the conditional expectation.
This conditional expectation is approximated. In this way, if the scatter plot (X i , Y) has a pattern,
the conditional expectation has a large variation across X i values, and parameter X i is
revealed to be important. In fact, the variance of the terms in the decomposition above is the
measure of importance being sought. We then compute
and when this is divided
by the unconditional variance Var(Y), the first-order sensitivity index is obtained:
Tip
For further reading on Global Sensitivity methods, see: Saltelli, A. et. al., Global Sensitivity
Analysis. The Primer, John Wiley & Sons, 2008.
Different sensitivity computation modes are available in Eldo, specified by the SENS parameter
of the .MC command.
Interpreting a Global Sensitivity Analysis
Global sensitivity analysis results are written to the .chi and .mcm files.
Some properties used in the interpretation of sensitivity indices are:
• The index S i is a number always between 0 and 1. A large value indicates an important
parameter X i .
• The sum of the sensitivity indices is less than 1 (in theory). In other words, the sum of
the conditional variances
cannot be greater than the total variance.
• The sum of all S i is equal to 1 for additive output Y, such that:
and less than 1 for non-additive models. The difference:
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Global Sensitivity Analysis
is an indicator of the presence of interactions in the model.
• It is possible for the sum of all S i to be close to 0 (therefore a number of S i indices are
also very small). It indicates that the variability of the output cannot be analyzed without
taking into account the interactions. This output is truly non-additive.
In practice, the sum of all S i can be greater than 1. These are some artifacts due to the
approximation procedure of the conditional expectation. Small variations of the order 1% or
less, when cumulated, may give , and some truly non-important parameters would be
classified as important. This is particularly true when the number of statistical parameters is
large. Eldo uses some statistical tests to overcome this situation, refer to the example “Example
17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier” on page 1309.
Example
A simple example is analyzed here for the purpose of familiarization with sensitivity indices.
The input distributions are X i ~ N(0, 1). The scatter plots of the output Y = X 1 + X 2 2 + X 1 X 2 are
given in Figure 11-20.
Figure 11-20. Scatter Plots of Output
This function has an immediate representation:
• The mean value: .
• The first-order terms: and .
• The interaction term: .
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Large Scale Variable Screening
Except for the relative inaccuracy at the border, the non-parametric model, which fits the
conditional expectation, is a good approximation of the first-order terms.
The numerical procedure for computing the sensitivity indices gives S 1 = 0.2096 and
S 2 = 0.3990 with sample size N = 1024. The non-zero difference 1 − S 1 − S 2 < 1 is a clear
indication that the interaction term f 12 (X 1 , X 2 ) cannot be neglected in the output.
Related Topics
Post-Analysis of Monte Carlo Simulations
Sensitivity Analysis
Monte Carlo Analysis Examples
Large Scale Variable Screening
As already mentioned, this second approach to sensitivity analysis is a model-based method. It
means that a (meta-) model is specified for the regression function f(x) = E[Y|X=x], with the
assumption that this function f(x) is approximately linear in its arguments:
At this step, it is clear that each individual component of the vector β gives a certain amount of
information about the relative importance of the parameters (the main effects).
Classically, the parameters β are found by Ordinary Least Squares regression based on the set of
training data (x i ,y i ) from the Monte Carlo simulation. This estimation method finds the β by
minimizing the residual sum of squares:
In the context of large scale screening the dimension of the vector of variables x is much larger
than the number of simulations, and it is assumed that there is only a small set of important
variables. This means we are willing to determine a small subset of variables that give the main
effects and neglect the small effects. We perform this task by using the well known method
LASSO which is stable and exhibits good properties for subset selection. The LASSO method
find a continuous path of solutions by minimizing the residual sum of squares and a L 1
penalization of the vector β:
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Large Scale Variable Screening
and by varying the penalty parameter λ. Typically, only a small subset of the β j will be non-zero
for a fixed value of λ.
Tip
For an introduction to Subset Selection and Shrinkage methods, see Hastie, Tibshirani and
Friedman, The Elements of Statistical Learning: Data Mining, Inference, and Prediction,
2009, 2nd Edition, New York: Springer Verlag.
Using the Large Scale Variable Screening Method
The Large Scale Variable Screening method should be used when the number of variables is
much larger than the number of simulations that can be afforded. However, the method can only
perform well if the number of simulations is around five times greater than the number
significant variables. In most cases, only a few dozens of variables are important. Thus, one
hundred simulations should be sufficient. For computational efficiency, the Large Scale
Variable Screening method only uses the first 500 Monte Carlo simulations. The sensitivity
indices computed by the Large Scale Variable Screening method have the same meaning as
those of the “Global Sensitivity Analysis” on page 520.
The Large Scale Variable Screening method is applied to a simple circuit composed of 500
serial resistors whose nominal value is 10kΩ. Ten resistors have their standard deviation equal
to 1kΩ while the standard deviation of the others is set to 1Ω. A Monte Carlo analysis with 100
runs is performed. The results of the sensitivity analysis are shown below:
Estimation of Sensitivity Indices for Output Measure : V(1,0)
List of Important Parameters :
Index(I) Histo S(I) (percent / cumulative) Variable
Value
Name
494 |-------------------- 8.6% 8.6% PE(DEV_1000,R7,R)
498 |------------------- 8.3% 16.9% PE(DEV_1000,R3,R)
491 |------------------- 8.2% 25.2% PE(DEV_1000,R10,R)
495 |------------------- 8.2% 33.4% PE(DEV_1000,R6,R)
497 |------------------ 8.0% 41.4% PE(DEV_1000,R4,R)
492 |------------------ 8.0% 49.4% PE(DEV_1000,R9,R)
493 |------------------ 8.0% 57.4% PE(DEV_1000,R8,R)
499 |------------------ 7.8% 65.2% PE(DEV_1000,R2,R)
496 |------------------ 7.8% 73.0% PE(DEV_1000,R5,R)
500 |----------------- 7.6% 80.6% PE(DEV_1000,R1,R)
174 | 0.0% 80.6% PE(DEV_1,R327,R)
133 | 0.0% 80.6% PE(DEV_1,R368,R)
337 | 0.0% 80.6% PE(DEV_1,R164,R)
190 | 0.0% 80.6% PE(DEV_1,R311,R)
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Large Scale Variable Screening
The ten resistors whose standard deviation is set to 1kΩ are correctly identified as important
parameters by the Large Scale Variable Screening method. This example is provided in the
netlist file large_scale.cir in the $MGC_AMS_HOME/examples/optimizer directory.
Related Topics
Sensitivity Analysis
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Monte Carlo Analysis
Monte Carlo Analysis Examples
Monte Carlo Analysis Examples
This section contains the following examples of Monte Carlo Analysis:
A Simple Passive Low-Pass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526
Importance Sampling Monte Carlo Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528
Model-Based Approximations Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532
Further Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534
A Simple Passive Low-Pass Filter
You can easily see the effects of Monte Carlo analysis in a simple passive low-pass filter.
.MODEL C CAP DEV=20%
.MODEL R RES LOT=20% DEV=5%
.MC 1000 ALL
V1 VIN 0 AC=1 DC=1
R1 VIN A R 1k
C1 A 0 C 10P
.AC DEC 10 100 1e8
.PROBE V
.END
The capacitor model has uniform LOT variations with a half-range of 20%, so all capacitors
using this model are uncorrelated and vary up to 20% from the nominal value specified in the
element instantiation. Capacitor C1 varies uniformly between 8 pF and 12 pF. The resistor
model produces resistors such that the resistance values are correlated. After Eldo applies the
20% LOT variations, each resistor has a 5% non-correlated variations.
The .MC ... ALL argument requests Eldo to save the result from every Monte Carlo iteration.
Running this simulation and viewing the voltage at node A produces the graph in Figure 11-21.
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Figure 11-21. Monte Carlo Analysis Example
Monte Carlo Analysis
A Simple Passive Low-Pass Filter
Related Topics
Model-Based Approximations Example
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier
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Monte Carlo Analysis
Importance Sampling Monte Carlo Examples
Importance Sampling Monte Carlo Examples
The sample netlists monte_carlo_sram_bitcell.cir and monte_carlo_vco_lc_tank.cir can be
used to demonstrate the advantages of the IMSC method over the standard Monte Carlo
method.
SRAM Bit Cell Circuit
Netlist file: monte_carlo_sram_bitcell.cir
The sample circuit is a classic six-transistor SRAM bit cell designed in CMOS 45nm. A subset
of the device model parameters has variability information, in the form of a DEV/GAUSS
specification. The total number of statistical parameters is 36 (6 per device). Although the
IMSC method is insensitive to the number of statistical parameters, it is always preferable to
keep this number “reasonable”.
The cell is configured for measuring the write delay, and the purpose of the Monte Carlo
simulation is to estimate the probability of the write delay exceeding a certain threshold. This
threshold could be used to define a “fail” behavior for yield estimation. Formally, the problem is
to estimate π = Pr{Y > y} and the associated confidence interval on (the empirical estimator
of π), where y is the threshold.
The following .EXTRACT MC … MCROB() statement is given in the netlist:
.EXTRACT MC LABEL=prob_plus_6 MCPROB(write_delay_qx, GE, 53.12)
This statement illustrates how to use the .EXTRACT and MCPROB commands to specify this
kind of probability estimation problem: refer to (usually) another .EXTRACT or .MEAS
statement, specify a right tail (upper threshold) or a left tail (lower threshold), then specify the
threshold. The following results are obtained:
Lower Pr. Value Upper CV(%) #Runs Speedup
Tail / Complementary
-----------------------------------------------------------------------------
8.89e-06 9.65e-06/1.00e+00 1.04e-05 7.87 8060 8.0e+03
This kind of low probability estimation is very difficult (if not impossible) using the standard
Monte Carlo method because a very large number of runs is required to obtain a decent
accuracy (in terms of the confidence interval on the probability). In this example, the ISMC
method estimates a probability of 9.6×10 −6 to within +/-7.8% (with a 95% confidence level) in
roughly 8,000 runs, whereas the standard Monte Carlo method would require roughly
64,000,000 runs (see Table 11-1).
The estimation of the speedup of the ISMC method over the standard Monte Carlo method
comes from the binomial law. The random variable:
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Monte Carlo Analysis
Importance Sampling Monte Carlo Examples
follows a binomial law with parameters (n, π y ). Since S n is the sum of independent Bernouilli
random variables with parameter π y (such that
), the central limit theorem
gives:
where
At a confidence level α, the precision ε can be related to the sample size via 2Φ(-t) ≤ α. The
number of Monte Carlo simulations is:
In terms of the relative precision (the IS_RTOL parameter in the .MC statement) τ > 0, the
number of Monte Carlo simulations is:
because ε = τπ y .
The reported speedup can be calculated by replacing τ by the effective relative precision
obtained for the estimator. This value is given in the CV(%) column of the results. The ratio
n MC / n ISMC then gives the speedup, where n ISMC is the effective number of runs.
Table 11-1 displays the results of an experiment that can be carried out using this example. The
value of IS_MAXITER is 50 to limit the total number of Monte Carlo runs. The ISMC method
only failed to reach the desired precision within 50 iterations in the last experiment (1% RTOL).
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Importance Sampling Monte Carlo Examples
RTOL
Table 11-1. Speedup of ISMC Over Standard Monte Carlo
Effective Relative
Precision
Probability
Estimator
Number of
Runs
Speedup
20% 10.80% 9.6×10 −6 7040 4.9×10 3
10% 7.87% 9.65×10 −6 8060 8.0×10 3
5% 4.88% 9.11×10 −6 11120 1.6×10 4
1% 1.83% 9.051×10 −6 53960 2.3×10 4
In general, the number of runs does not significantly decrease as the precision increases
(compare 10% and 20% RTOL in Table 11-1). This is because the ISMC method uses batches
of runs, and a whole batch must be completed before the accuracy can be determined. However,
decreasing the batch size would have a negative impact on the rate of convergence and the
robustness of the results.
Now compare 10% and 1% RTOL in Table 11-1. It is known that to achieve a single extra digit
of precision, the number of standard Monte Carlo runs must increase by a factor of 100. For
effective precision, the results in Table 11-1 (7.9% precision with 8060 runs and 1.8% precision
with 53960 runs) give the following reduction in variance:
This speedup remains moderate with respect to one obtained using the standard Monte Carlo
method. It also indicates that sampling for a high precision is (still) difficult. The default value
of 10% was chosen from this practical point of view.
The following .EXTRACT MC … MCROB() statement specifies a rare events simulation:
.EXTRACT MC LABEL=prob_rare MCPROB(write_delay_qx, GE, 63.40)
The following results are obtained using the ISMC method:
Lower Pr. Value Upper CV(%) #Runs Speedup
Tail / Complementary
--------------------------------------------------------------------------
3.30e-09 3.65e-09/1.00e+00 4.00e-09 9.66 24340 4.6e+06
The failure probability is obtained with a precision of 9.66% using 24340 Monte Carlo runs,
yielding a variance reduction factor of over 4 million. The standard Monte Carlo method would
require over 12 billion runs to obtain comparable results.
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Monte Carlo Analysis
Importance Sampling Monte Carlo Examples
VCO Circuit
Netlist file: monte_carlo_vco_lc_tank.cir
The sample circuit is configured for .SST analysis and transient simulation (much slower than
.SST). The circuit is a simple LC-tank VCO oscillating at 1.8GHz (adapted from Craninckx &
Steyaert, IEEE JSSC, May 1997). The oscillation frequency is obtained using the .SST analysis
of Eldo RF (requires an Eldo RF licence).
The phase noise at 1meg offset from the carrier is also extracted using the steady-state noise
analysis of Eldo RF. Both the oscillation frequency and the phase noise are strongly non-
Gaussian. The distributions are heavily skewed (left and right respectively). This means that
Gaussian extrapolations using the estimated standard deviation with a few hundred runs are
completely wrong.
With this analog IP block, the ISMC method can easily capture extreme events. In contrast, the
standard Monte Carlo method is useless as soon as the probabilities are in the range of 10 −3
because the number of runs needed to obtain a decent confidence interval becomes prohibitively
large.
This example sets up four simultaneous measurements: two probabilities and two quantiles.
With importance sampling, the total number of runs grows roughly linearly with the number of
measurements, so simulations are shorter if only one probability or quantile is measured at a
time. For this reason, when preparing and checking simulations, it is better to proceed one
.EXTRACT command at a time.
Even with moderately small probabilities and quantiles, the speedup of the ISMC method over
the standard Monte Carlo method ranges from 200 to 26,000. This can be observed in the .mcm
output file. Refer to “Probability and Quantiles using Importance Sampling Monte Carlo” on
page 483 for more information.
The results of the transient simulation are obtained using Monte Carlo extracts. First, the
following statement sets up a Monte Carlo simulation using the ISMC method:
.MC 500 DATAFLOW=1 SAMPLING=ISMC
The 10 −4 -quantile for the oscillation frequency is close to 1.75Ghz (see below). The following
statement extracts this quantile:
.EXTRACT MC LABEL=quantile_fosc_left_1em4 MCBOUND(fosc_tran, 1e-4)
The following statement extracts the probability that the oscillation frequency is lower than
1.75GHz:
.EXTRACT MC LABEL=proba_fosc_left_1_75 MCPROB(fosc_tran, LE, 1.75G)
The following results are obtained for the probability estimator:
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Monte Carlo Analysis
Model-Based Approximations Example
Lower Pr. Value Upper CV(%) #Runs Speedup
Tail / Complementary
------------------------------------------------------------------------------
8.86e-05 9.60e-05/1.00e+00 1.03e-04 7.69 3530 1.9e+03
Additionally, the quantile estimator returns a value of 1.74980×10 9 , which is very close to the
value specified in the MCPROB extract statement. The speedup of the ISMC method over the
standard Monte Carlo method is modest, but still very interesting. The standard Monte Carlo
method would require 6.7 million runs to reach the same precision.
Model-Based Approximations Example
Netlist file: monte_carlo_ssd.cir
This example centers around an 8-bit CMOS ripple carry adder, which is able to add to 7-bit
binary numbers in parallel. The adder is constructed from a chain of 7 cascaded one-bit adder
stages, with each stage connected to the next via a carry-link.
The maximum operating frequency of such an adder is limited by the time it takes for the carry
signal to propagate (ripple) through the chain, from the far-right stage to the sum6 and sum7
outputs on the left. Given the circuit topology, this propagation delay depends on:
• The design parameters (geometries of transistors in the carry path).
• The statistical variations in transistor parameters due to manufacturing tolerances.
• Environmental temperature.
You, the designer, can choose the values of the design parameters. Temperature and some
manufacturing process parameters may be controllable, but more often are not “designable.”
The objectives for the 8-bit adder in this example are:
• To simulate the fluctuation of the maximum operation speed due to manufacturing
variations and as a function of temperature.
• To predict the likely manufacturing yield with respect to a user-specified lower limit on
the operating speed.
• To compare the standard Monte Carlo method and the supersaturated design (SSD)
approach.
Approximation of the Parametric Yield
Here, we calculate an approximation of the probability that a given circuit fails to satisfy a set
performance specification. In the example, this value is obtained using the LBOUND and
UBOUND arguments on the .EXTRACT command:
.EXTRACT TRAN LABEL=OPFREQ (1/MAX(EXTRACT(DELAY6), EXTRACT(DELAY7)))
+ LBOUND=280Meg
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Monte Carlo Analysis
Model-Based Approximations Example
For 10,000 runs, 9765 circuits are obtained that pass the specification. The approximate yield is
therefore 97.65%.
Comparison of Standard Monte Carlo and SSD Methods
The Monte Carlo simulations of reference involves 1000 runs, and the SSD sampling is defined
with a simulation budget of 100 runs. The results provide in Table 11-2 are extracted from the
.mcm file. A comparison is generated only for the extract OPFREQ (in Hz).
Table 11-2. Comparison of Standard Monte Carlo and SSD Methods
This simple example shows the SSD algorithm correctly captured the central location and the
range of the distribution. The relative error on the range is about 5% with respect to the golden
Monte Carlo simulation. The worst error is given by the approximation of the third moment.
The skewness of the distribution is clearly underestimated. This fact comes from the linear
model used to approximate the output response. This model cannot identify asymmetric
distributions.
The choice of simulation budget here is based on preliminary experiments. NRUN=100 was
used here, but sometimes it is necessary to increase this budget. A use model, could be to first
run a golden Monte Carlo simulation on typical circuits that represent a large class of other
circuits and then find a sufficient number of runs for the SSD algorithm.
Related Topics
Data MC Reference
(command .MC 1000
SAMPLING=RAND)
Fitted Distribution
(command .MC 100
SAMPLING=SSD) with
relative error Err%
Mean Value 3.18873×10 8 3.20965×10 8 (Err% = 0.6 %)
Standard Deviation 2.66935×10 7 3.16319×10 7 (Err% = 18%)
Skewness 2.23588×10 −1 1.26011×10 −2 (Err% = 94%)
Kurtosis 3.02094 2.84756 (Err% = 5.7%)
Shortest Coverage Interval
(L,U) with α = 0.95
(2.70380×10 8 , 3.72227×10 8 ) (2.55207×10 8 , 3.78589×10 8 )
(Err% = (5.6%,1.7%))
Model-Based Monte Carlo Simulation
Further Examples
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier
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Monte Carlo Analysis
Further Examples
Further Examples
This section provides a selection of further examples:
• Device sizes can be subject to a probabilistic distribution, simulating process variation,
through the use of .PARAM statements. In this example, the NMOS transistor’s width
follows a Gaussian distribution, centered around 20e-6 with σ = 0.2×20e-6 = 4e-6 as
defined by the parameter nwidth. This parameter will also be subject to DEV variation.
A .EXTRACT measures the propagation time through the inverter. The .chi file contains
statistical information about the outcome of the .EXTRACT:
.MODEL N NMOS LEVEL=1 VTO=1.2 KP=2.5e-5 GAMMA=1.5
.MODEL P PMOS LEVEL=1 VTO=-1.5 KP=1.2e-5 GAMMA=1.2
.PARAM NWIDTH=GAUSS(20U,0.2,1)
M1 OUT IN VSS VSS N W=NWIDTH L=15U
M2 OUT IN VDD VDD p W=30U L=15U
COUT OUT 0 0.1P
VDD VDD 0 5
VSS VSS 0 0
VIN IN 0 PWL (0 0 50N 0 51N 5)
.MC 1000 ALL
.TRAN 1N 100N
.PROBE TRAN V(OUT)
.EXTRACT TRAN LABEL=TPD TPDUD(V(IN), V(OUT))
.END
The .PARAM usage may be applied to model parameters as well. The VTO of the
NMOS transistor can be replaced with a Gaussian random parameter. In this case, the
standard deviation σ is 0.24. This technique may be more useful if the parameter needs
to be a mathematical function of several variables.
.PARAM NVTO=GAUSS(1.2,0.2,1)
.MODEL N NMOS LEVEL=1 VTO=NVTO KP=2.5E-5 GAMMA=1.5
.MODEL P PMOS LEVEL=1 VTO=-1.5 KP=1.2E-5 GAMMA=1.2
M1 OUT IN VSS VSS N W=20U L=15U
M2 OUT IN VDD VDD P W=30U L=15U
COUT OUT 0 0.1P
VDD VDD 0 5
VSS VSS 0 0
VIN IN 0 PWL (0 0 50N 0 51N 5)
.MC 1000 ALL
.TRAN 1n 100n
.PROBE TRAN V(OUT)
.EXTRACT TRAN LABEL=TPD TPDUD(V(IN), V(OUT))
.END
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Further Examples
Each instance of a transistor using the NMOS model will have the same value of VTO
because NVTO affects a model parameter, and therefore LOT variation is used.
• The following is an example of statistical configuration usage:
.MODEL R RES TC1=2 LOT=5% DEV=10%
.SUBCKT R A B
R1 A B 1K
.ENDS
I1 1 0 PWL (0 1 10N 10)
X1 1 2 R STATISTICAL=0
X2 2 3 R
X2 3 0 R
.TRAN 1N 10N
.EXTRACT DC V(1)
.TEMP 10
.MC 1000
.END
Here, X1.R1 will remain at its nominal value during Monte Carlo analysis. This is
because STATISTICAL is set to 0 for X1.
.MODEL R RES TC1=2 LOT=5% DEV=10%
.SUBCKT R A B
R1 A B R 1K
.ENDS
I1 1 0 PWL (0 1 10N 10)
X1 1 2 R
X2 2 3 R STATISTICAL=1
X3 3 0 R
.TRAN 1N 10N
.EXTRACT DC V(1)
.TEMP 10
.MC 1000
.OPTION STATISTICAL=0 !Consider all the devices non-statistical by
default
.END
Here, only X2.R1 will vary during Monte Carlo analysis. This is because the global
STATISTICAL option is set to 0, meaning that devices are considered non-statistical by
default, but this is overridden by the STATISTICAL keyword, which is set to 1 for X2.
• The following is an example of using ICARLO in an extract:
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Parameter Naming Conventions
* ICARLO example
.MODEL C CAP DEV=20%
.MODEL R RES LOT=20% DEV=5%
.MC 5 ALL
V1 VIN 0 AC=1 DC=1
R1 VIN A R 1k
C1 A 0 C 10P
.TRAN 20ns 20ns
.PROBE V
.EXTRACT tran file=test_out label=maxA max(v(A))
.EXTRACT tran file=icarlo_out {1+ICARLO}
.end
This will generate the following results in the icarlo_out file:
TITLE * ICARLO example
EXTRACT for TRANSIENT ANALYSIS
TEMPERATURE = 2.7000E+01 Celsius
ICARLO = 0
*{1+ICARLO} = 1.0000E+00
TITLE * ICARLO example
EXTRACT for TRANSIENT ANALYSIS
TEMPERATURE = 2.7000E+01 Celsius
ICARLO = 1
*{1+ICARLO} = 2.0000E+00
...
Related Topics
Monte Carlo Analysis Examples
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier
Parameter Naming Conventions
This topic describes the naming conventions for the identification of statistical parameters. It is
necessary to use these conventions in a sensitivity analysis to identify the significant circuit
parameters.
As an example, if X is a uniform random variable defined on the interval [−1, 1] then the
variable Y = function(X) is a dependent variable obtained by simulating the uniform variable
and applying a given transformation. The following example models a voltage dependent
resistor, with a linear dependence with respect to the uniform random variable RSH,
.PARAM W=1U L=1U
.PARAM RSH=AUNIF(1K,100,1)
.PARAM B1=-0.4 B2=8U
R1 A B ’RSH*L/W*(1+B1*(TANH(B2*ABS(V(A,B)/L))))’
In this section, the RC Wire model is used to demonstrate the effect of various formulations that
combine local and global variations. The LEVEL parameter is set to LEVEL=3 for the RC wire
model. The expression of the wire resistance is given by:
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Parameter Naming Conventions
where and .
The model parameters DW and DLR are the differences between drawn and actual width and
length respectively. The sheet resistance is fixed to RSH = 100.
Note
This is a simplification of the effective expression where the scaling factors have been
removed. Refer to RC Wire in the Eldo Reference Manual for the full formula.
Implicit Rule
An implicit rule exists to determine whether a parameter has global or local variations. If the
parameter P is defined as a simple random variable such as:
.PARAM P=AUNIF(...)
then this variable has implicit DEV variations. It means that each reference of P in the circuit
netlist will lead to the creation of an independent random variable.
Macro PE(.)
The following example illustrates the use of the macro PE(.). There are two references to the
VAR parameter:
.PARAM VAR=AUNIF(3U,0.1U)
.PARAM BIAS=1M
I1 0 1 BIAS
I2 0 2 BIAS
R1 1 0 RESISTOR W=3U L=VAR
R2 2 0 RESISTOR W=3U L=VAR
.MODEL RESISTOR R LEVEL=3 W=3U L=3U RSH=100
Two random variables will be associated to the resistors R1 and R2. These variables will be
named PE(VAR,R1,L) and PE(VAR,R2,L).The macro PE has three arguments. The syntax is
defined as follows:
PE(parameter_name, device_name, instance_parameter)
The random variable that affects the instance parameter instance_parameter associated to the
device device_name is such that its distribution is specified in the definition of the parameter
parameter_name.
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Macro PP(.)
In the following netlist, a new parameter GLOBVAR is introduced, and the instance parameter,
W, of each resistor is associated to the GLOBVAR variable:
.PARAM VAR=AUNIF(3U,0.1U)
.PARAM GLOBVAR=VAR
.PARAM BIAS=1M
I1 0 1 BIAS
I2 0 2 BIAS
R1 1 0 RESISTOR W=GLOBVAR L=VAR
R2 2 0 RESISTOR W=GLOBVAR L=VAR
.MODEL RESISTOR R LEVEL=3 W=3U L=3U RSH=100
The GLOBVAR parameter will have implicit LOT variations. Multiple references to
GLOBVAR do not create multiple random variables. The parameter variations are defined
globally; this is an artifact of the syntax that enables circuit parameters to be specified with
global variations.
For Eldo, the GLOBVAR parameter does not inherit the DEV variations of the VAR parameter,
and only one random variable will be created in the Monte Carlo sampling. This should be
avoided as much as possible in the netlist, and instead explicit specifications with the DEV/LOT
keywords should be used.
The random variable associated to this parameter GLOBVAR is named with the macro PP(.)
according to this syntax:
PP(parameter1_name, parameter2_name)
The random variable that affects the parameter parameter2_name such that its distribution is
specified in the definition of the parameter parameter1_name.
Example of Macro PP(.) and PE(.) Usage
Consider the statements:
.PARAM VAR=AUNIF(3U,0.1U)
.PARAM GLOBVAR=VAR
.PARAM LOCVAR=AUNIF(0U,0.02U)
.PARAM BIAS=1M
I1 0 1 BIAS
I2 0 2 BIAS
R1 1 0 RESISTOR W=’GLOBVAR+LOCVAR’ L=VAR
R2 2 0 RESISTOR W=’GLOBVAR+LOCVAR’ L=VAR
.MODEL RESISTOR R LEVEL=3 W=3U L=3U RSH=100
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Five independent random variables will be created in the sampling:
• The variable PP(VAR,GLOBVAR) with global variations.
Monte Carlo Analysis
Parameter Naming Conventions
• The two variables PE(LOCVAR,R1,W) and PE(LOCVAR,R2,W) which come from the
statement LOCVAR=AUNIF(0U,0.02U).
• The two variables PE(VAR,R1,L) and PE(VAR,R2,L).
Macro PM(.)
Consider the following statements:
.PARAM VAR=AUNIF(0U,0.05U)
.PARAM BIAS=1M
I1 0 1 BIAS
I2 0 2 BIAS
R1 1 0 RESISTOR
R2 2 0 RESISTOR
.MODEL RESISTOR R LEVEL=3 W=3U L=3U RSH=100 DW=VAR DLR=VAR
This example is another application of the previous implicit rule on variations. The parameter
VAR has DEV variations, and it is used two times in the .MODEL definition. Two random
variables are associated to this model, but these variables are global for the circuit, because the
model has a global scope. The resistors R1 and R2 will share the same random variables.
The macro PM(.) was introduced for referencing these random variables. In this example, we
have two independent variables: PM(VAR,RESISTOR,DW) and PM(VAR,RESISTOR,DL).
The syntax is defined as follows:
PM(parameter_name, model_name, model_parameter)
The random variable that affects the model parameter model_parameter associated to the model
model_name is such that its distribution is specified in the definition of the parameter
parameter_name.
It is important to note that the variables PM(VAR,RESISTOR,DW) and
PM(VAR,RESISTOR,DL) have the same distribution. The previous lines are strictly equivalent
to the following (from the mathematical view):
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.PARAM VARW=AUNIF(0U,0.05U)
.PARAM VARL=AUNIF(0U,0.05U)
.PARAM BIAS=1M
I1 0 1 BIAS
I2 0 2 BIAS
R1 1 0 RESISTOR
R2 2 0 RESISTOR
.MODEL RESISTOR R LEVEL=3 W=3U L=3U RSH=100 DW=VARW DLR=VARL
In this case, Eldo will create the variables PM(VARW,RESISTOR,DW) and
PM(VARL,RESISTOR,DL).
Implicit Rules of Inheritance
It is possible to define global and local variations by using implicit rules of inheritance.
Consider the following netlist:
.PARAM VAR=AUNIF(3U,0.05U)
.PARAM VARW=AUNIF(VAR,0.01U)
.PARAM BIAS=1M
I1 0 1 BIAS
I2 0 2 BIAS
R1 1 0 RESISTOR W=VARW L=3U
R2 2 0 RESISTOR W=VARW L=3U
.MODEL RESISTOR R LEVEL=3 W=3U L=3U RSH=100
Where we have VARW=AUNIF(VAR,0.05U), a reference to the statistical parameter VAR is
used in the definition of the distribution associated to VARW. In other words, VARW is the
sum VAR + AUNIF(0,0.01U); the distribution of VARW is the sum of two random variables.
In this example, there are three random variables:
• PP(VAR,VARW) the random variable with global variations.
• PE(VARW,R1,W) and PE(VARW,R2,W) the local random variables.
The VARW parameter does not inherit the DEV variations of VAR. During the Monte Carlo
sampling, a value for PP(VAR,VARW) is drawn from the uniform distribution
AUNIF(3U,0.05U) and two independent values PE(VARW,R1,W) and PE(VARW,R2,W) are
obtained from the uniform distribution AUNIF(0,0.01U). The final values of the width W in R1
and R2 are therefore computed by summing these random values to PP(VAR,VARW).
Note that this behavior cannot be obtained with following statements:
.PARAM VAR1=AUNIF(0,0.05U)
.PARAM VAR2=AUNIF(0,0.01U)
.PARAM VARW=’3U + VAR1 + VAR2’
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In this case two random variables are obtained PP(VAR1,VARW) and PP(VAR2,VARW) with
global variations.
This use of the implicit rules should be avoided as much as possible. It is encouraged for users
to specify explicit DEV/LOT variations.
Macro P(.)
The macro P(.) has only one argument:
P(parameter_name)
and the associated random variable has global variations. Consider the following netlist
.PARAM VARL=0 LOT/UNIF=0.05U
.PARAM VARW=0 LOT/UNIF=0.05U
.PARAM BIAS=1M
I1 0 1 BIAS
I2 0 2 BIAS
R1 1 0 RESISTOR
R2 2 0 RESISTOR
.MODEL RESISTOR R LEVEL=3 W=3U L=3U RSH=100 DW=VARW DLR=VARL
The parameters VARL and VARW now have explicit LOT variations, and there are two
independent random variables P(VARL) and P(VARW).
Macro PEM(.)
If a DEV argument is added to the previous .PARAM definitions,
.PARAM VARL=0 LOT/UNIF=0.05U DEV/UNIF=0.02U
.PARAM VARW=0 LOT/UNIF=0.05U DEV/UNIF=0.02U
we will have six random variables in the Monte Carlo sampling:
• P(VARL) and P(VARW) the global components of the variations on the width and
length of resistors.
• PEM(VARW,R1,R) and PEM(VARL,R1,R) the local components of the variations on
the width and length of the resistor R1.
• PEM(VARW,R2,R) and PEM(VARL,R2,R) the local components of the variations on
the width and length of the resistor R2.
The syntax of the PEM(.) macro is defined as follows:
PEM(parameter_name, device_name, instance_parameter)
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As above, one may read this macro as follows: the random variable that affects the instance
parameter instance_parameter associated to the device device_name and such that its
distribution is specified in the definition of the parameter parameter_name.
Note that it may happen that on some devices there is no instance_parameter, there are only two
arguments in the macro. An example follows.
Macros EM(.) and M(.)
Here, consider a more elaborate netlist which uses a combination of local and global variations
on some model parameters of a bipolar junction transistor NPN. It represents a notable situation
where no implicit rule conflicts with the common sense.
The circuit is a Low Noise Amplifier. DEV and LOT variations are defined on the model
parameter ISS (saturated current for substrate junction), and the parasitic resistances parameters
RE, RB, and RC. 16 random variables are obtained:
• The global or LOT component for each model parameters: M(BIPNPN.NPNBIP,RB),
M(BIPNPN.NPNBIP,RC), M(BIPNPN.NPNBIP,RE), M(BIPNPN.NPNBIP,ISS). In
these macros there is no reference to local instances of subcircuits or devices. The model
cards are placed at the top level of a circuit.
• The local or DEV component for each instance of the subcircuit BIPNPN:
EM(XDUT.XDUT.XQ0.Q0,RB), EM(XDUT.XDUT.XQ0.Q0,RC),
EM(XDUT.XDUT.XQ0.Q0,RE), EM(XDUT.XDUT.XQ0.Q0,ISS),
EM(XDUT.XDUT.XQ1.Q0,RB), etc. The letter E means Element. The name of the
model is given, but is clearly associated to the given instance.
Syntax
The syntax of the M(.) macro is defined as follows:
M(model_name, model_parameter)
which may be interpreted as the random variable that affects the model parameter
model_parameter of the model model_name and such that its distribution is specified in the
definition of the parameter.
The syntax of the EM(.) macro is defined as follows:
EM(device_name, model_parameter)
You may read this macro as follows: the random variable that affects the model parameter
model_parameter of the device device_name and such that its distribution is specified in the
definition of the parameter.
Example
The complete netlist is provided below:
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LNA demo
.GLOBAL GND!
.CONNECT GND! 0
* BIPOLAR
.SUBCKT BIPNPN 1 2 3 4
Q0 1 2 3 4 NPNBIP
.MODEL NPNBIP NPN IS=24.5E-18 BF=121 NF=1 VAF=35 IKF=32E-3 ISE=847E-18
+ NE=1.9 BR=3.81 NR=1 VAR=3.2 IKR=2E-3 ISC=847E-18 NC=1.9
+ IRB=80E-6 RBM=5 XTB=0.5 EG=1.2 XTI=3 CJE=59.6E-15 VJE=0.895
+ MJE=0.41 TF=11E-12 XTF=15 VTF=1.5 ITF=40E-3 PTF=0 CJC=45.8E-15
+ VJC=0.642 MJC=0.33 XCJC=0.3 TR=5E-9 CJS=75.5E-15 VJS=0.65
+ MJS=0.33 FC=0.875
+ TRB1=1.05E-3 TRB2=4.4E-6 TRC1=1E-3 TRC2=3.1E-6 TRE1=0 TRE2=0
+ KF=1.32E-10 AF=1.8
+ RE=3.5 LOT=5% DEV=2.5%
+ RC=25 LOT=5% DEV=2.5%
+ RB=100 LOT=5% DEV=2.5%
+ ISS=1E-16 LOT=5% DEV=2.5%
.ENDS
* ANALYSIS
.PARAM FEND=3.8E9 FSTART=1.4E9 IBIAS=5M VCC=1.5
.TEMP 27
.AC LIN 100 FSTART FEND
* MEASURES
.DEFWAVE AC GAIN=V(OUT)/V(IN)
.EXTRACT AC LABEL=MAX_GAIN MAX(WM(GAIN))
.EXTRACT AC LABEL=GMAX MAX(W(GAIN))
.EXTRACT AC LABEL=FRES CROSSING(W(GAIN), MAX(W(GAIN))-0.001)
** CIRCUIT
XDUT GND! IN OUT VPLUS LNA_DEMO
RROUT OUT GND! 50
VVIN IN GND! DC 0 AC 1 RPORT=50
VVCC VPLUS GND! DC VCC
.SUBCKT LNA_TEST GNDA IN IREF OUT SUB VPLUS
LL1 NET8 GNDA L=1.2N
CC0 NET16 OUT C=500F
RR1 NET14 IN R=2K
RR0 NET19 NET14 R=2K
XQ2 IREF NET19 GNDA SUB BIPNPN
XQ1 VPLUS IREF NET14 SUB BIPNPN
XQ0 NET16 IN NET8 SUB BIPNPN
LL0 VPLUS NET16 L=8N
.ENDS LNA_TEST
.SUBCKT LNA_DEMO VMINUS IN OUT VPLUS
XDUT VMINUS NET020 NET022 OUT VMINUS VPLUS LNA_TEST
LL0 IN VMINUS 3.9N
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Problems in Statistical Modeling
CC0 NET020 IN 4P
II6 VMINUS NET022 IBIAS
.ENDS LNA_DEMO
.MC 1000
Suppose now that the subcircuit BIPNPN is defined as follows:
.SUBCKT BIPNPN 1 2 3 4
Q0 1 2 3 4 NPNBIP
.PARAM RE_VAR=3.5 LOT=5% DEV=2.5%
.PARAM RB_VAR=100 LOT=5% DEV=2.5%
.PARAM RC_VAR=25 LOT=5% DEV=2.5%
.PARAM ISS_VAR=1E-16 LOT=5% DEV=2.5%
.MODEL NPNBIP NPN IS=24.5E-18 BF=121 NF=1 VAF=35 IKF=32E-3 ISE=847E-18
+ NE=1.9 BR=3.81 NR=1 VAR=3.2 IKR=2E-3 ISC=847E-18 NC=1.9
+ IRB=80E-6 RBM=5 XTB=0.5 EG=1.2 XTI=3 CJE=59.6E-15 VJE=0.895
+ MJE=0.41 TF=11E-12 XTF=15 VTF=1.5 ITF=40E-3 PTF=0 CJC=45.8E-15
+ VJC=0.642 MJC=0.33 XCJC=0.3 TR=5E-9 CJS=75.5E-15 VJS=0.65
+ MJS=0.33 FC=0.875
+ TRB1=1.05E-3 TRB2=4.4E-6 TRC1=1E-3 TRC2=3.1E-6 TRE1=0 TRE2=0
+ KF=1.32E-10 AF=1.8
* PARAMETERS WITH VARIATIONS
+ RE=RE_VAR RC=RC_VAR RB=RB_VAR
+ ISS=ISS_VAR
.ENDS
The statistical variations are defined outside the .MODEL statement. In this case, we still have
16 random variables with different names. The following table gives the equivalence between
these two different syntaxes.
First syntax
Second syntax
LOT variations M(BIPNPN.NPNBIP,RB) P(BIPNPN.RB_VAR)
M(BIPNPN.NPNBIP,RC) P(BIPNPN.RC_VAR)
... ...
DEV variations EM(XDUT.XDUT.XQ0.Q0,RB) ...
EM(XDUT.XDUT.XQ0.Q0,RC) PEM(BIPNPN.RC_VAR,XDUT.X
DUT.XQ0.Q0)
... ...
There is no clear difference between these approaches; it depends on the context.
Problems in Statistical Modeling
This section is devoted to some issues that you may encounter in statistical modeling.
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Problems in Statistical Modeling
Using the final example in “Macros EM(.) and M(.)” on page 542, modifying the subcircuit
definition to replace the .PARAM statements with .MCMOD commands:
.SUBCKT BIPNPN 1 2 3 4
Q0 1 2 3 4 NPNBIP
.MODEL NPNBIP NPN IS=24.5E-18 BF=121 NF=1 VAF=35 IKF=32E-3 ISE=847E-18
+ NE=1.9 BR=3.81 NR=1 VAR=3.2 IKR=2E-3 ISC=847E-18 NC=1.9
+ IRB=80E-6 RBM=5 XTB=0.5 EG=1.2 XTI=3 CJE=59.6E-15 VJE=0.895
+ MJE=0.41 TF=11E-12 XTF=15 VTF=1.5 ITF=40E-3 PTF=0 CJC=45.8E-15
+ VJC=0.642 MJC=0.33 XCJC=0.3 TR=5E-9 CJS=75.5E-15 VJS=0.65
+ MJS=0.33 FC=0.875
+ TRB1=1.05E-3 TRB2=4.4E-6 TRC1=1E-3 TRC2=3.1E-6 TRE1=0 TRE2=0
+ KF=1.32E-10 AF=1.8
+ RE=3.5 RC=25 RB=100
+ ISS=1E-16
.MCMOD NPNBIP RB LOT=5% DEV=2.5%
.MCMOD NPNBIP RE LOT=5% DEV=2.5%
.MCMOD NPNBIP RC LOT=5% DEV=2.5%
.MCMOD NPNBIP ISS LOT=5% DEV=2.5%
.ENDS
then Eldo will generate several warning messages during the first phase of simulation:
Warning 921: In file “./test71_2.cir” line 22:
+ MC variation on BIPNPN.NPNBIP: new MC LOT (5.000000e-02 ) on
parameter RB specified.
+ Previous specification is ignored.
Warning 921: In file “./test71_2.cir” line 22:
+ MC variation on BIPNPN.NPNBIP: new MC DEV (2.500000e-02 ) on
parameter RB specified.
+ Previous specification is ignored.
...
The reason for these warnings is that the .MCMOD introduces local modifications of the
NPNBIP model while the .MODEL card has global scope in the netlist (it is placed at the top
level). The .MCMOD commands therefore redefine and overwrite the previous definitions. This
situation should be avoided.
Here is another example. The example of the 2-stage operational amplifier given in the previous
section is used.
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.SUBCKT N D G S B PARAM: W=1U L=1U
M1 D G S B MODN W=W L=L
.PARAM TOX=19E-09 A_MM_TOX=0.4543U B_MM_TOX=0.1435
+ DEV_MM_TOX =’A_MM_TOX/SQRT(W*L)+B_MM_TOX’
.PARAM VTH0=.3322 A_MM_VTH0=0.40654U B_MM_VTH0=0.11654
+ DEV_MM_VTH0 =’A_MM_VTH0/SQRT(W*L)+B_MM_VTH0’
.PARAM U0=388.3203 A_MM_U0=0.565745U B_MM_U0=0.264563
+ DEV_MM_U0 =’A_MM_U0/SQRT(W*L)+B_MM_U0’
.MODEL MODN NMOS
+LEVEL=53
+TOX = TOX DEV/GAUSS={DEV_MM_TOX}%
+VTH0 = VTH0 DEV/GAUSS={DEV_MM_VTH0}%
+U0 = U0 DEV/GAUSS={DEV_MM_U0}%
+KF=1E-27 AF=2
+TNOM=27.0
...
.ENDS
We will have 51 random variables (17 transistors and 3 three statistical parameters with DEV
variations) in the Monte Carlo sampling: EM(XM1.M1, TOX), EM(XM1.M1,VTH0),
EM(XM1.M1,U0), etc. See the definition above of the macro EM(.).
In this case, it is important to note that Eldo will create one model entry for each instance of the
subcircuit N. This is due to the definition of the model parameters TOX, VTH0, U0 which are
functions of the instance parameter W and L (the geometry). The .MODEL MODN definition
has a local scope. This implicit rule may have some unexpected side effects. Consider this
simple modification of the previous netlist:
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.SUBCKT P D G S B PARAM: W=1U L=1U
M1 D G S B MODP W=W L=L
.PARAM TOX=19E-09 A_MM_TOX=0.365543U B_MM_TOX=0.001435
+ DEV_MM_TOX =’A_MM_TOX/SQRT(W*L)+B_MM_TOX’
.PARAM VTH0=-.3732829 A_MM_VTH0=0.30654U B_MM_VTH0=0.1452
+ DEV_MM_VTH0 =’A_MM_VTH0/SQRT(W*L)+B_MM_VTH0’
.PARAM U0=138.7609 A_MM_U0=0.565745U B_MM_U0=0.366454
+ DEV_MM_U0 =’A_MM_U0/SQRT(W*L)+B_MM_U0’
.MODEL MODP PMOS
+LEVEL=53
+TOX = TOX LOT/GAUSS=2% DEV/GAUSS={DEV_MM_TOX}%
+VTH0 = VTH0
DEV/GAUSS={DEV_MM_VTH0}%
+U0 = U0 DEV/GAUSS={DEV_MM_U0}%
+KF=1E-27 AF=2
+TNOM=27.0
...
.ENDS
A global variation is added on the oxide thickness and we will have nine random variables for
the LOT component of the TOX parameter: M(XM1.MODN,TOX), M(XM2.MODN,TOX),
M(XM7.MODN,TOX), M(XM8.MODN,TOX), M(XM9.MODN,TOX),
M(XM10.MODN,TOX), M(XM13.MODN,TOX), M(XM15.MODN,TOX),
M(XM17.MODN,TOX). We obtained nine independent random variables instead of only one
random for the global variations of the TOX parameter. It is very unlikely that this list of
parameters is what you want to model in this case.
The global variations can be obtained by rewriting the netlist as follows:
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Obsolete Features
.PARAM TOX=19E-09
.PARAM TOX_GLOB =TOX
LOT/GAUSS=2%
.SUBCKT N D G S B PARAM: W=1U L=1U
M1 D G S B MODN W=W L=L
.PARAM A_MM_TOX=0.4543U B_MM_TOX=0.1435
+ DEV_MM_TOX =’A_MM_TOX/SQRT(W*L)+B_MM_TOX’
.PARAM VTH0=.3322 A_MM_VTH0=0.40654U B_MM_VTH0=0.11654
+ DEV_MM_VTH0 =’A_MM_VTH0/SQRT(W*L)+B_MM_VTH0’
.PARAM U0=388.3203 A_MM_U0=0.565745U B_MM_U0=0.264563
+ DEV_MM_U0 =’A_MM_U0/SQRT(W*L)+B_MM_U0’
.MODEL MODN NMOS
+LEVEL=53
+TOX = TOX_GLOB DEV/GAUSS={DEV_MM_TOX}%
+VTH0 = VTH0 DEV/GAUSS={DEV_MM_VTH0}%
+U0 = U0 DEV/GAUSS={DEV_MM_U0}%
+KF=1E-27 AF=2
+TNOM=27.0
...
.ENDS
Outside the .SUBCKT block we created the parameter TOX_GLOB with explicit LOT
variations. This results in the generation of a random variable named P(TOX_GLOB). Finally
we will have 52 independent variables.
Related Topics
Statistical Variations
Obsolete Features
The features described here are related to sampling methods, not statistical models, and should
not be used.
LIMIT Distribution
The LIMIT distribution is a discrete probability distribution on finite set {L, U} which can be
characterized by saying that the values L and U are equally probable.
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Figure 11-22. LIMIT Distribution with L=-1 and U=+1
Monte Carlo Analysis
Obsolete Features
This distribution is implicitly used when the argument MCLIMIT is specified on the .MC
command. This option forces Eldo to draw random variations of uniform and Gaussian
distributions from the extreme limits of their support. For example, for a uniform variable we
will get:
NOR/UNI Distributions
As described in the topic “Specifying Statistical Parameters” on page 427, use the following
syntax to assign a statistical distribution to the parameter.
.PARAM PARAM_NAME=NOM_VALUE
+ LOT=(UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%])
.PARAM PARAM_NAME=NOM_VALUE
+ DEV=(UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%])
.PARAM PARAM_NAME=NOM_VALUE
+ LOT=(UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%])
+ DEV=(UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%])
.PARAM PARAM_NAME=NOM_VALUE
+ LOT=(NOR,MINUS_3SIGMA_VALUE[%],PLUS_3SIGMA_VALUE[%])
.PARAM PARAM_NAME=NOM_VALUE
. DEV=(NOR,MINUS_3SIGMA_VALUE[%],PLUS_3SIGMA_VALUE[%])
.PARAM PARAM_NAME=NOM_VALUE
+ LOT=(UNI,MINUS_3SIGMA_VALUE[%],PLUS_3SIGMA_VALUE[%])
+ DEV=(UNI,MINUS_3SIGMA_VALUE[%],PLUS_3SIGMA_VALUE[%])
For UNI distributions, only the absolute values of
MINUS_HALF_RANGE,PLUS_HALF_RANGE are considered, and they represent the
negative and positive half-ranges (respectively) of the distribution from its nominal value. A
negative value for MINUS_HALF_RANGE can be used if considered more readable, but it
does not matter. In all cases, the parameter will take its values between NOM_VALUE-
ABS(MINUS_HALF_RANGE) and NOM_VALUE-ABS(PLUS_HALF_RANGE).
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Obsolete Features
If the specified values MINUS_HALF_RANGE,PLUS_HALF_RANGE are different (in
absolute value), the resulting distribution will no longer be uniform. An example is given
Figure 11-23 in top-left plot, where the support of the distribution is the union of two
contiguous intervals of different length: [2, 5] and [5, 10]. The points are uniformly sampled in
each intervals.
For NOR distributions, if MINUS_3SIGMA_VALUE,PLUS_3SIGMA_VALUE have the same
absolute value, then the distribution is a Gaussian distribution with mean value NOM_VALUE,
and a standard deviation of ABS(MINUS_3SIGMA_VALUE)/3 or
ABS(PLUS_3SIGMA_VALUE)/3. The samples from this distribution are generated from a
centered and reduced truncated normal distribution where the interval of truncation is [−3, 3].
Note
When using this notation, it is key to understand that what is given is the 3-sigma value, not
the 1-sigma value.
It is also possible to specify different values for the 3-sigma bounds of the NOR distribution. An
example is given Figure 11-23 in top-right plot.
Note
When the nominal value is not zero, it is possible to specify percentages instead of absolute
values for the bounds. In this case the percentages must be understood as percentages of the
nominal value.
Examples
• The following syntax gives a Gaussian distribution with mean value 0, and standard
deviation (1-sigma) equal to 4 (12/3). The values taken by P1 will vary between -12 and
12.
.PARAM P1=(0) LOT=(NOR, -12, 12)
• The following syntax specifies a distribution with a longer right tail compared to the left
tail:
.PARAM P2=(5) LOT=(NOR, -3, 5)
See Figure 11-23 in top-right plot.
• Using the following syntax, the parameter will take values between 180 and 220. Its
mean value will be 200, and its standard deviation will be 20/3.
.PARAM P3=(200) LOT=(NOR, -10%, 10%)
550
Eldo® User's Manual, 15.3

Figure 11-23. Four Random Samples from NOR/UNI Distributions
Monte Carlo Analysis
Obsolete Features
It is possible to specify an interval of rejection for the NOR/UNI distributions. This means that
Eldo will never draw random values within this interval. The bounds of this interval are
specified with two additional arguments after the keyword bi. For example, one statement for a
LOT or DEV variations will satisfy the following syntax:
.PARAM PARAM_NAME=NOM_VALUE
+ [LOT | DEV]=(
+ UNI,MINUS_HALF_RANGE[%],PLUS_HALF_RANGE[%],
+ bi, MINUS_DEAD_ZONE[%],PLUS_DEAD_ZONE[%])
Two examples were simulated in Figure 11-23 in bottom plots.
Weighted Uniform and Gaussian Distributions
There is an additional argument to the UNIF and GAUSS macro-definitions. This argument is
named MULT in the following syntax commands:
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Monte Carlo Analysis
Obsolete Features
.PARAM PARAM_NAME = UNIF|AUNIF(NOM_VALUE, RANGE_VALUE, MULT)
.PARAM PARAM_NAME = GAUSS|AGAUSS(NOM_VALUE, STD_VALUE, SIGMA_COEF, MULT)
The role of the MULT argument, which is an integer value greater than 1, is to eliminate the
simulation of the sub-population that is “closed” to the median value of the parameter. The
LIMIT distribution (also known as the Rademacher distribution) may be considered as the
extreme case, where only the limits of the interval [-1, 1] are effectively simulated. By
augmenting the multiplier argument, continuous approximations of the LIMIT distribution are
generated.
In Figure 11-24, four realizations are plotted of the random sample obtained by varying the
multiplier of the AUNIF macro. For example, one can see that the median value 0 will not be
simulated (or with a very small probability) when MULT=5.
Figure 11-24. Four Random Samples when AUNIF(0,1,MULT) is Specified
This kind of distributions is often described as bimodal distributions. The distributions have two
modes (the most frequent values) which are closed to the extreme values of the original
distribution. The phenomenon is much more visible in Figure 11-25.
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Monte Carlo Analysis
Obsolete Features
Figure 11-25. Four Random Samples when AGAUSS (0,1,1,MULT) is Specified
If we are interested in the extreme values of a dependent random variable Y = F(X), where X is a
given random variable, then it is possible to simulate only the extreme cases of the input
distribution. Be aware that the effectiveness of this approach is related to a strong assumption of
monotonicity about the function F. For example, if this function F is monotonically increasing,
it preserves the order of the real set, for all x and y such that x ≤ y one has F(x) ≤ F(y). Therefore
the extreme realizations of X are mapped directly to the extreme realizations of F.
Related Topics
Specifying Statistical Parameters
Eldo® User's Manual, 15.3 553

Monte Carlo Analysis
Obsolete Features
554
Eldo® User's Manual, 15.3

Chapter 12
Statistical Experimental Design and
Analysis
Statistical Experimental Design and Analysis focuses on the standard techniques of factor
screening, location and dispersion analysis, and response surface methodologies in circuit
design. An observable output (extracted measure in Eldo) depends on a set of parameters and
you can then explore the effects (main effects and interactions) of parameters (factors) on the
output using the design of experiment techniques.
Introduction to Statistical Experimental Design and Analysis . . . . . . . . . . . . . . . . . . . . 555
Factor Screening Experiments in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557
DEX Example Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558
Factorial Design Comparison with Worse Case Analysis . . . . . . . . . . . . . . . . . . . . . . . . . 559
Statistical Modeling for Discrete Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560
Designing a Screening Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562
Reference Factors for the DEX Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562
Defining the Levels of Factors for the DEX Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565
Determining the List of Noise Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570
Conducting a Screening Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573
Choosing the Type of Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573
Selecting the Number of Factors and the Design Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . 574
Viewing the Experiment Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 576
Examples of Factor Screening Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
Example of Experiment Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
Example of Conducting an Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579
Example of Analysis Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586
Introduction to Statistical Experimental Design
and Analysis
The primary purpose of a factor screening experiment is to select or screen out the few
important main effects from the many less important ones. By reducing the large number of
circuit parameters involved, subsequent statistical design problems can be solved more
efficiently and will require fewer runs. A screening experiment is often referred to as phase zero
of a response surface study.
Eldo® User's Manual, 15.3 555

Statistical Experimental Design and Analysis
Introduction to Statistical Experimental Design and Analysis
A factor is a circuit parameter that is studied in the experiment. To study the effect of a factor on
one or several user-defined responses, two or more values of the factor are required. These
values are referred to as levels or settings. A combination of factor levels is called a run and will
be associated to a specific simulation run in Eldo. In an experiment, one or more variables (or
factors) are deliberately changed so that the effect the changes have on one or more response
variables can be observed.
Factor screening experiments require two different types of circuit parameter:
• Deterministic or designable parameters x, also referred to as control parameters.
• Statistical or hard to control parameters s, also referred to as noise parameters.
Integrated circuit designs feature both types of parameter. The transistor geometries, such as
widths and lengths, are deterministic design parameters. They are in a different space to the
transistor model parameters which are statistical parameters that reflect manufacturing
fluctuations.
This is different from discrete RLC circuits where the designable parameters and the statistical
parameters are in the same space. For discrete RLC circuits, to screen out the important main
effects you can safely investigate only the main effects associated with noise factors. See
“Statistical Modeling for Discrete Circuits” on page 560 for more detail.
Related Topics
Factor Screening Experiments in Eldo
Designing a Screening Experiment
Conducting a Screening Experiment
Viewing the Experiment Results
Examples of Factor Screening Experiments
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Statistical Experimental Design and Analysis
Factor Screening Experiments in Eldo
Factor Screening Experiments in Eldo
Eldo contains the basic tools for performing a factor screening experiment. Use the Eldo .DEX
command to perform the factor screening.
The DEX techniques incorporated in the Eldo command .DEX are efficient procedures ensuring
the data obtained can be analyzed to yield valid and objective conclusions. This efficiency is
founded on some key properties of orthogonal arrays, which offer a systematic way of testing.
The benefits include: a uniform distributed coverage of the test domain; all pair-wise
combinations of the test set are created; and you can arrive at complex combinations of all the
variables.
The procedures implemented in the DEX analysis should be qualified. The quantitative
techniques used for factor screening are incomplete since they are numeric summaries. By
reducing the data to a few numbers (filtering the data) you are omitting and screening out other,
sometimes crucial, information.
The .DEX command enables for two-level designs that have just “High” and “Low” settings for
each factor. The most popular experimental designs are two-level designs. These are ideal for
screening designs, because they are simple and economical and also give most of the
information required to go to a multilevel response surface experiment if one is needed.
Note
In two-level experiments, only the linear effects can be studied. To detect a curvature effect
three-level factors should be considered. For example, the factor “temperature” may affect
the responses in a non-monotone way. Using only two temperature levels (“High” and “Low”)
makes a strong assumption about the relationship between the responses and the temperature.
Use the following Eldo commands for experimental design:
• .PARAMDEX — Assigns values to parameters (factors) used in the design of
experiments.
• .DEX — Conducts a screening experiment. Factors are taken from the list of circuit
parameters appearing on a .PARAMDEX statement.
• viewdex — A service routine that is run on the .dex file to display the results.
Tip
For the syntax and detailed descriptions, see “.PARAMDEX” and “.DEX” in the
Eldo Reference Manual.
DEX Example Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558
Factorial Design Comparison with Worse Case Analysis . . . . . . . . . . . . . . . . . . . . . . . . 559
Statistical Modeling for Discrete Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560
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Statistical Experimental Design and Analysis
DEX Example Files
DEX Example Files
Example circuit files are provided to illustrate using design of experiments with Eldo.
Table 12-1 lists the example files that are available in your installed directory:
$MGC_AMS_HOME/examples/dex/.
Table 12-1. Example Files
Example Filename Description
Passive band pass filter bpass.cir Basic discrete RLC circuit
Active band pass filter filter.cir Another discrete circuit
CMOS delay circuit cmos_delay.cir Basic example with BSIM1 models
CMOS ring oscillator cmos_ring.cir Another example with BSIM1 models
8-bit CMOS ripple
carry adder
adder.cir Another example with BSIM1 models
The following example is extracted from the sample netlist bpass.cir (available in the directory:
$MGC_AMS_HOME/examples/dex/):
* DETERMINISTIC PARAMETERS.PARAM
+ LL1=1.824 CC1=78.7N LL2=427.2M CC2=988N
* CIRCUIT
LL1 N2 N1 'LL1 + D_LL1'
CC1 N2 N3 'CC1 + D_CC1'
LL2 N6 N5 'LL2 + D_LL2'
CC2 N6 N7 'CC2 + D_CC2'
* DEFINE PERFORMANCE TARGETS (EXTRACT SECTION)
.EXTRACT AC LABEL=V210 YVAL(VDB(OUT),210)
UBOUND=-45.36
.EXTRACT AC LABEL=V240 YVAL(VDB(OUT),240)
UBOUND=-45.36
.EXTRACT AC LABEL=V360 YVAL(VDB(OUT),360) LBOUND=-10.96 UBOUND=-8.36
.EXTRACT AC LABEL=V490 YVAL(VDB(OUT),490) LBOUND=-10.96 UBOUND=-8.36
* DETERMINISTIC PARAMETERS
* LEVELS FOR SCREENING EXPERIMENTS.PARAMDEX
+ LL1 CTRL/REL=20% NOM=1.824
+ CC1 CTRL/REL=20% NOM=78.7N
+ LL2 CTRL/REL=20% NOM=427.2M
+ CC2 CTRL/REL=20% NOM=988N
* SCREENING EXPERIMENT: USING ORTHOGONAL ARRAYS BASED
* ON HADAMARD MATRIX.DEX+ EXPERIMENT=SCREENING+ DESIGN=ORTHA_2_2N
+ RESPONSE=V210,V240,V360,V490
Related Topics
Factorial Design Comparison with Worse Case Analysis
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Statistical Modeling for Discrete Circuits
Examples of Factor Screening Experiments
Statistical Experimental Design and Analysis
Factorial Design Comparison with Worse Case Analysis
Factorial Design Comparison with Worse Case
Analysis
The traditional “one-factor-at-a-time” design method based on a single or double-sided
sensitivity analysis does not conduct a systematic or comprehensive search over the
experimental region.
By comparison with the factorial design method implemented in the DEX procedures,
traditional design methods have the following disadvantages:
• Some interactions cannot be estimated.
• Conclusions from the analysis are not general.
• Optimal settings of factors can be missed.
When investigating main effects, the following main effect model around the nominal point x 0
is assumed:
This model can be applied to the following cases:
• Where interactions can be tentatively assumed to be zero.
• For screening a large set of factors where some factors have large main effects on the
output y.
The traditional “one-factor-at-a-time” design method to estimate the coefficients α i is used in
the sensitivity computations of the .WCASE command. Here, each of the variables x i are
perturbed by ±Δx i about the nominal point x 0 , keeping all the others at their nominal values.
The .WCASE command also provides the so-called worst case values of the response y(x)
where x is replaced by the following ‘worst case points’:
where the coordinates are all set to their extreme values: a low level of x low = (1− Δ) · x i and a
high level of x high = (1+ Δ) · x i .
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Statistical Experimental Design and Analysis
Statistical Modeling for Discrete Circuits
These points, which are not necessarily the true worst case points, are systematically tested
when the selected screening design uses about 2N runs (this is the default argument of the
DESIGN argument of the .DEX command).
Related Topics
Factor Screening Experiments in Eldo
Statistical Modeling for Discrete Circuits
Statistical Modeling for Discrete Circuits
When screening out the important main effects for discrete RLC circuits you can safely
investigate only the main effects associated with the noise factors.
Consider the following netlist (extracted from the example filter.cir available in the directory
$MGC_AMS_HOME/examples/dex/):
V1 1 0 DC 0 AC 1
R1 1 2 ’R1 + D_R1’
R3 2 0 ’R3 + D_R3’
C2 2 INN ’C + D_C’
C3 2 OUT ’C + D_C’
R2 OUT INN ’R2 + D_R2’
Y1 OPAMP1 0 INN OUT 0 PARAM: GAIN=’GAIN + D_GAIN’ P1=’P1 + D_P1’
where the circuit parameters are defined as follows:
* DETERMINISTIC PARAMETERS
.PARAM R1 = 159K R2 = 3.18MEG R3 = 79.5
+ C = 1U
+ P1 = 10 GAIN = 10E6
* NOISE PARAMETERS
.PARAM D_R1 = AGAUSS( 0, 10.6K, 1)
.PARAM D_R2 = AGAUSS( 0, 0.212MEG, 1)
.PARAM D_R3 = AGAUSS( 0, 5.30, 1)
.PARAM D_C = AGAUSS( 0, 0.067U, 1)
.PARAM D_P1 = AGAUSS( 0, 0.667U, 1)
.PARAM D_GAIN = AGAUSS( 0, 0.667E6, 1)
For the resistors, the statistical model is expressed by transformations of the form R + D_R
where R represents the nominal value and D_R is the element tolerance or the random
variations associated with the control parameter R. These random variables have zero mean.
This reflects an important property of discrete RLC circuits—that the controllable parameters x
and the statistical variables s are in the same space. In other words, any circuit performance is a
function of random expressions E(x i , s i ) = x i + s i .
This property implies that a circuit performance y(x, s) = y(x + s) satisfies the following
relation:
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Statistical Experimental Design and Analysis
Statistical Modeling for Discrete Circuits
The computation of the sensitivity with respect to the designable variables x will be equivalent
to the computation of the sensitivity with respect to the tolerances s. Hence, to screen out the
important effects you can safely investigate only the main effects associated to noise factors.
Related Topics
Factor Screening Experiments in Eldo
Factorial Design Comparison with Worse Case Analysis
Eldo® User's Manual, 15.3 561

Statistical Experimental Design and Analysis
Designing a Screening Experiment
Designing a Screening Experiment
These sections describe how to specify the parameters (factors) that will be considered by the
.DEX command when conducting the experiment by adding .PARAMDEX command
statements to added to the netlist.
The .PARAMDEX statements can either be prepared by manually editing the working netlist or,
for noise parameters, the .DEX command has a FIND_FACTOR option which can be used to
determine the list of noise parameters prior to the DEX analysis. This list is generated in an
include file _paramdex.inc which contains the related .PARAMDEX statements.
Preparation of the .PARAMDEX statements involves:
• “Reference Factors for the DEX Analysis” on page 562
• “Defining the Levels of Factors for the DEX Analysis” on page 565
See also “Determining the List of Noise Parameters” on page 570 for more information about
the FIND_FACTOR option.
Note
The .PARAMDEX statement also contains an optional argument [NOISE/ | CTRL/] which
specifies the category of the factor (noise or control). Although Eldo automatically
determines this category, for clarity in the netlist we recommend including this argument within
all .PARAMDEX statements.
Tip
For more detail on .PARAMDEX statements see “.PARAMDEX” in the Eldo Reference
Manual.
See also “Example of Experiment Design” on page 577.
Reference Factors for the DEX Analysis
Selectors are used to identify circuit parameters (noise and control factors) within
.PARAMDEX statements as reference factors.
Tip
See “.PARAMDEX” in the Eldo Reference Manual.
Global Parameter Selector Specification
The P() selector enables global parameters to be referenced.
The syntax of the P() selector is:
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Reference Factors for the DEX Analysis
P(parameter_name)
This is equivalent to:
parameter_name
Consider the situation:
.PARAM param4_global=value
The global parameter param4_global has no random variations. It is therefore a deterministic
(control) parameter and can only be referenced with these equivalent statements:
.PARAMDEX param4_global [CTRL/] ...
.PARAMDEX P(param4_global) [CTRL/] ...
Model Parameter Selector Specification
The EM(.,.) and M(.,.) selectors enable random variables that are associated with model
parameters to be referenced.
The syntax of the M(.,.) selector is:
M(model_name, model_parameter)
This references the random variable that is associated with the model parameter
model_parameter of the model model_name. Its distribution is specified in the definition of the
parameter. It will always be associated with a parameter with LOT variations, since it refers
globally to a model parameter.
The syntax of the EM(.,.) selector is:
EM(device_name, model_parameter)
This references a random variable that is associated with the model parameter model_parameter
of the device device_name. Its distribution is specified in the definition of the parameter. It will
always be associated with a model parameter that is associated with a specific instance, hence it
means that this parameter must have DEV or DEVX variations.
Consider a model MOD1 with two parameters:
* MODEL DEFINITION
.MODEL MOD1 ...
+ param1_model=value DEV=value param2_model=value LOT=value ...
and a device named MA:
MA ... MOD1 param1_inst=value ... param1_model=value param2_model=value
...
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Statistical Experimental Design and Analysis
Reference Factors for the DEX Analysis
Assume that the model MOD1 has some instance parameters, named param1_inst, and so on.
The .PARAMDEX statements for the model parameters param1_model and param2_model
would take the form:
.PARAMDEX
+ EM(MA,param1_model) [NOISE/] ...
+ M(MOD1,param2_model) [NOISE/] ...
Tip
For further details see “.PARAMDEX” in the Eldo Reference Manual.
Related Topics
Defining the Levels of Factors for the DEX Analysis
Determining the List of Noise Parameters
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Statistical Experimental Design and Analysis
Defining the Levels of Factors for the DEX Analysis
Defining the Levels of Factors for the DEX Analysis
The Eldo .PARAMDEX command statement is used to specify the levels of factors, including
the normal and uniform distributions. The .PARAMDEX command is also used to specify
levels of factors with respect to the standard deviation and half ranges of these distributions, and
with respect to the nominal value for both noise and control factors.
Note
When writing levels for factors within .PARAMDEX statements, extreme values may give
runs that are not feasible. These runs are simply ignored during post-analysis of the
experiment.
Tip
See “.PARAMDEX” in the Eldo Reference Manual.
This topic is divided into:
Defining Levels for Noise Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565
Defining Levels With Respect to the Nominal Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570
Defining Levels for Noise Factors
For noise factors, the .PARAMDEX command statement is directly related to the statistical data
defined in the .PARAM statement.
The levels information is extracted from the arguments of the .PARAM statement:
.PARAM PARAMETER_NAME=EXPRESSION
+ {LOT|DEV|DEVX}[/GAUSS|/UNIFORM] = RVALUE|RVALUE%
The value EXPRESSION defines the nominal value x nom , or the mean value, for the normal and
uniform distributions. The value RVALUE represents the standard deviation σ for the normal
distribution and the half-range for the uniform distribution.
Note
In Eldo, the definition of the standard deviation σ for the uniform distribution is not correct
from a statistical point of view. There is confusion between the standard deviation and the
range of the distribution.
For coherency, the DEX analysis uses the proper definition of this statistical value, with
arguments SIG and RNG available for factors associated with uniform distributions.
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Statistical Experimental Design and Analysis
Defining the Levels of Factors for the DEX Analysis
Normal Distribution
The normal (or Gaussian) distribution, is a bell shaped continuous distribution. The general
formula for the probability density function of a normal distribution is:
where the parameters , the mean μ, and the standard deviation σ > 0 are known.
Note
The macro GAUSS(NOM_VALUE, REL_VALUE, SIG_COEF) enables negative values
for the standard deviation SIGMA which is computed as NOM_VALUE*REL_VALUE/
SIG_COEF. The .DEX command will only consider the absolute values of these parameters,
even if the nominal value NOM_VALUE is negative.
Figure 12-1 depicts the common statistics relating to the Gaussian distribution.
Figure 12-1. Percentage of Cases in Eight Portions of the Gaussian Distribution
The range [−σ, σ] represents 34.13% + 34.13% = 68.26% of cases obtained after running the
sample process in the Monte Carlo algorithm. The range [−3σ, 3σ] covers 2×(34.13% + 13.59%
+ 2.14%) = 99.72% of cases.
The high and low levels, defined as ±n·σ, are the worst case points of these ranges.
Uniform Distributions
For a continuous distribution, the uniform distribution defines equal probability over a given
range. The general formula for the probability density function of the uniform distribution is:
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Statistical Experimental Design and Analysis
Defining the Levels of Factors for the DEX Analysis
for
The common statistics for the mean μ uniform distribution are:
The common statistics for the standard deviation σ uniform distribution are:
The range of the distribution is the value U − L.
For the definition:
.PARAM PARAMETER_NAME=EXPRESSION {LOT|DEV|DEVX} /UNIFORM=RVALUE|RVALUE%
.PARAM PARAMETER_NAME={AUNIF|UNIF}(EXPRESSION,RVALUE)
the value RVALUE, shown as h in our formulas, represents half of the range (see Figure 12-2).
Figure 12-2. Common Statistics for UNIF(x,h)
The standard deviation σ in terms of the half range h is given by:
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Statistical Experimental Design and Analysis
Defining the Levels of Factors for the DEX Analysis
When h is specified as a percentage:
Defining Levels as a Fraction of the Standard Deviation
You can specify the levels as a fraction of the standard deviation σ defined on noise parameters
that are associated with the normal or uniform distribution. The values of the low level xlow and
high level x high are defined as ±n·σ.
This situation is depicted in Figure 12-3, with factor levels x low and x high for parameter x.
Figure 12-3. Factor Levels for a Circuit Parameter x
The syntax for this is defined as:
.PARAMDEX FACTOR_NAME [NOISE/] SIG=NSIGMA
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Statistical Experimental Design and Analysis
Defining the Levels of Factors for the DEX Analysis
Note
This syntax assumes that a uniform or gaussian distribution has been defined on the circuit
parameter.
For example:
.PARAM TP = AGAUSS( 35.0, 11.667, 1.0)
.PARAMDEX TP NOISE/SIG=1.2
Note
It is possible to define levels outside of the range of a uniform distribution.
If the NSIGMA value is greater than √3, we have x high ≥ U and x low ≤ L.
Defining Levels as a Fraction of the Half Range of Uniform Distribution
This option enables you to specify the levels as a fraction of the half range h that is defined on
noise parameters which are associated with the uniform distribution. The values of the low level
x low and high level x high are defined as ±n·h where h is the half range of the uniform distribution
on the factor.
The command syntax is:
.PARAMDEX FACTOR_NAME [NOISE/] RNG=NRANGE
For example:
.PARAM VARL=0 LOT/UNIF=0.05U DEV/UNIF=0.1U
.PARAMDEX VARL NOISE/RNG=0.5
Note
It is possible to define levels outside of the range of a uniform distribution.
If the NSIGMA value is greater than 1.0, we have x high ≥ U and x low ≤ L.
Tip
See “.PARAMDEX” in the Eldo Reference Manual.
Related Topics
Defining the Levels of Factors for the DEX Analysis
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Statistical Experimental Design and Analysis
Determining the List of Noise Parameters
Defining Levels With Respect to the Nominal Value
This option enables you to specify the levels for noise or control parameters with respect to the
nominal value x nom . The low levels x low and high levels x high can be defined using the following
syntax:
* NOISE FACTORS
.PARAMDEX FACTOR_NAME [NOISE/] ABS=DELTA
.PARAMDEX FACTOR_NAME [NOISE/] REL=DELTA%
* CONTROL FACTORS
.PARAMDEX FACTOR_NAME [CTRL/] ABS=DELTA [NOM=RVALUE]
.PARAMDEX FACTOR_NAME [CTRL/] REL=DELTA% [NOM=RVALUE]
The ABS=DELTA argument is used to specify an absolute perturbation of the nominal value
x nom giving a low level of x low = x nom − Δ and a high level of x high = x nom − Δ for each factor.
The REL=DELTA% argument is used to specify a relative perturbation of the nominal value
x nom giving a low level of x low = (1− Δ)·x nom and a high level of x high = (1+ Δ)·x nom for each
factor.
With control factors, you can also specify the nominal value x nom using the argument
NOM=RVALUE. For example:
.PARAMDEX
+ WIN_GLOB CTRL/REL=10% NOM=40U
Tip
See “.PARAMDEX” in the Eldo Reference Manual.
Related Topics
Defining the Levels of Factors for the DEX Analysis
Determining the List of Noise Parameters
Determining the List of Noise Parameters
This example shows how to use the FIND_FACTOR option in the .DEX command to determine
the list of noise parameters prior to any DEX analysis. This list is then used to prepare the
.PARAMDEX statements. Two output files are produced: a .dex file containing formatted data,
and an include file, _paramdex.inc, containing the related .PARAMDEX commands.
Consider the following netlist (from the example filter.cir available in the directory
$MGC_AMS_HOME/examples/dex/):
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Statistical Experimental Design and Analysis
Determining the List of Noise Parameters
* CIRCUIT
V1 1 0 DC 0 AC 1
R1 1 2 ’R1 + D_R1’
R3 2 0 ’R3 + D_R3’
C2 2 INN ’C + D_C’
C3 2 OUT ’C + D_C’
R2 OUT INN ’R2 + D_R2’
Y1 OPAMP1 0 INN OUT 0 PARAM: GAIN=’GAIN + D_GAIN’ P1=’P1 + D_P1’
* DETERMINISTIC PARAMETERS.PARAM R1 = 159K R2 = 3.18MEG R3 = 79.5
+ C = 1U
+ P1 = 10 GAIN = 10E6
* NOISE PARAMETERS
.PARAM D_R1 = AGAUSS( 0, 10.6K, 1)
.PARAM D_R2 = AGAUSS( 0, 0.212MEG, 1)
.PARAM D_R3 = AGAUSS( 0, 5.30, 1)
.PARAM D_C = AGAUSS( 0U, 0.067U, 1)
.PARAM D_P1 = AGAUSS( 0, 0.667U, 1)
.PARAM D_GAIN = AGAUSS( 0, 0.667E6, 1)
Modify the netlist by adding the following .DEX command:
.DEX
+ EXPERIMENT=SCREENING_NOISE
+ DESIGN=ORTHA_2_N
+ RESPONSE=OPGAIN,OPFREQ,OPBW
+ FIND_FACTOR
By running Eldo on the modified netlist, a .dex file is generated containing the list of noise
parameters as follows:
List of candidates for the DEX analysis
---------------------------------------
Noise Factor(s) Dummy Distrib Nominal Dev/Range
Name
Value
D_GAIN SIG=1 N1 Gaussian 0.0000e+00 6.6700e+05
D_P1 SIG=1 N2 Gaussian 0.0000e+00 6.6700e-07
D_C SIG=1 N3 Gaussian 0.0000e+00 6.7000e-08
D_R3 SIG=1 N4 Gaussian 0.0000e+00 5.3000e+00
D_R2 SIG=1 N5 Gaussian 0.0000e+00 2.1200e+05
D_R1 SIG=1 N6 Gaussian 0.0000e+00 1.0600e+04
And the following .PARAMDEX statement is generated in the file filter_paramdex.inc:
.PARAMDEX
+ D_GAIN NOISE/SIG=1.0
+ D_P1 NOISE/SIG=1.0
+ D_C NOISE/SIG=1.0
+ D_R3 NOISE/SIG=1.0
+ D_R2 NOISE/SIG=1.0
+ D_R1 NOISE/SIG=1.0
You can use this generated information to prepare the .PARAMDEX statements.
Eldo® User's Manual, 15.3 571

Statistical Experimental Design and Analysis
Determining the List of Noise Parameters
See Also
• “.DEX” in the Eldo Reference Manual
• “.PARAMDEX” in the Eldo Reference Manual
Related Topics
Reference Factors for the DEX Analysis
Defining the Levels of Factors for the DEX Analysis
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Conducting a Screening Experiment
Guidelines for using the .DEX command and its arguments.
To use the .DEX command, you must provide the following:
• A working netlist.
Statistical Experimental Design and Analysis
Conducting a Screening Experiment
• The factors. In the netlist you must specify the parameters (factors) that will be
considered by the .DEX command when conducting the experiment. Factors are
specified by adding minor modifications to the working netlist, using the .PARAMDEX
command. For more information see “Designing a Screening Experiment” on page 562
and “Selecting the Number of Factors and the Design Matrix” on page 574.
• A response function which defines the list of measures to be considered in the
experiment. These measures are specified by the .EXTRACT and .MEAS commands in
the netlist.
• A type of experiment to be conducted. For more information see “Choosing the Type of
Experiment” on page 573.
• A design matrix which may either be an orthogonal array based on Hadamard matrices
or a full factorial design. For more information see “Selecting the Number of Factors
and the Design Matrix” on page 574.
Tip
For more information on the .DEX command see “.DEX” in the Eldo Reference Manual.
Choosing the Type of Experiment
This section describes the alternatives for the EXPERIMENT option in the .DEX command.
The regression model used in the DEX analysis is:
The y 0 , α’s and the β’s are a set of unknown coefficients.
To estimate the values of these parameters, the DEX analysis collects data on the system under
study. When no distinction can be made among the factors, the y 0 , α, β are estimated within the
same experiment. For this kind of experiment use EXPERIMENT=SCREENING in the .DEX
command.
Eldo® User's Manual, 15.3 573

Statistical Experimental Design and Analysis
Selecting the Number of Factors and the Design Matrix
For integrated circuit design, where the designable and noise variables are defined in separate
spaces, consider using a two-stage strategy. This will enable you to identify the critical noise
factors and critical control factor separately. This is particularly useful when some noise factors,
such as environmental noise factors, have large masking effects.
The phase zero of the response surface study will then involve two steps:
• Conduct a screening experiment for noise factors first by not considering the designable
factors. Use EXPERIMENT=SCREENING_NOISE in the .DEX command. The DEX
analysis runs the experiment using x = x 0 , where x 0 is the experiment center in the space
of control variables. This will give the amplitude of the β’s.
• Next conduct a screening experiment for control factors by not considering the noise
factors. Use EXPERIMENT=SCREENING_CTRL in the .DEX command. The
amplitude of the α’s are then analyzed. The DEX analysis runs the experiment using s =
s 0 , where s 0 is the experiment center in the space of noise variables.
Tip
For further details see “.DEX” in the Eldo Reference Manual.
Selecting the Number of Factors and the Design
Matrix
The .DEX command is compatible with the Multiple Run features. The maximum number of
factors N max is 40,000. However, running very large experiments is not recommended. The
range 7 to 150 is considered to be the ideal number of factors.
Tip
See the command description for “.MPRUN” in the Eldo Reference Manual.
The design matrix used to run the experiment enables you to specify either an orthogonal array
at two levels based on Hadamard matrices (DESIGN=ORTHA_2_N or
DESIGN=ORTHA_2_2N) or a full factorial design (DESIGN=FULL_FACT). If N is the
number of factors, the orthogonal arrays, which have an economical run size, will use about N
runs or 2N runs. However, a full factorial design will use 2 N runs.
Figure 12-4 depicts the geometrical differences between a full factorial design and an
orthogonal array based on Hadamard matrices.
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Statistical Experimental Design and Analysis
Selecting the Number of Factors and the Design Matrix
Figure 12-4. Cuboidal Representation of Two 3-factors Designs
The black bullets indicate that the corners are effectively chosen. The first design is obtained by
setting the argument DESIGN=FULL_FACT and the second by DESIGN=ORTHA_2_N. The
last design is a balanced subset of the full factorial design.
Note
With DEX analysis based on Hadamard matrices, the main effects are, in general, heavily
confounded (or aliased) with two-factor interactions. As such it may be difficult to handle
large numbers of aliased effects and interpret their significance. The main effect analysis may
not explain the variation in user-defined response very well.
See Also
• “.DEX” in the Eldo Reference Manual
• “.EXTRACT” in the Eldo Reference Manual
• “.MEAS” in the Eldo Reference Manual
• “.PARAMDEX” in the Eldo Reference Manual
Related Topics
Designing a Screening Experiment
Viewing the Experiment Results
Example of Conducting an Experiment
Eldo® User's Manual, 15.3 575

Statistical Experimental Design and Analysis
Viewing the Experiment Results
Viewing the Experiment Results
The .dex file contains the results of the experiment. It is a structured text file that is organized
with sections and sub-sections, and enables the user to skip one or more sections at different
levels of detail. To display the results run the service routine named viewdex on the .dex file in
order.
Syntax
viewdex [-l d] -f file.dex
Arguments
• -l d
Where d is the level of detail that users wants to view. The range of levels is 1 to 3, level 1
(default) gives the least amount of data while level 3 gives the most amount of data.
Level 1:
Only the results of the screening experiment are printed for multi and simple response
problems. Default.
Level 2:
In the case of multi-response problems, the results of the screening experiments for
each response are given separately.
Level 3:
The script gives the ordered and unordered data tables (in CSV format) and the design
matrix.
When an outer loop has been performed, the amount of data can be very large. In this case
level 1 only reports simplified results in a table printed at the end of the .dex file.
• -f
Name of the .dex file to be formatted.
See “Example of Analysis Results” on page 581 for an example of the contents of a .dex
file.
Related Topics
Designing a Screening Experiment
Conducting a Screening Experiment
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Statistical Experimental Design and Analysis
Examples of Factor Screening Experiments
Examples of Factor Screening Experiments
This section provides some basic examples netlists which include the design and conducting of
experiments, along with an example of the output that will be used for analysis.
• “Example of Experiment Design” on page 577
This netlist extract, taken from testcase cmos_delay.cir, shows the .PARAMDEX
command specifying the parameters (factors) that will be considered when conducting
the factor screening experiment.
• “Example of Conducting an Experiment” on page 579
This netlist extract, taken from testcase filter.cir, shows how to specify the .DEX
command arguments for a factor screening experiment.
• “Example of Analysis Results” on page 581
This example presents the results of an example experiment, available in the .dex output
file.
Example of Experiment Design
These examples are extracted from the testcase cmos_delay.cir (available in the directory:
$MGC_AMS_HOME/examples/dex/). This circuit contains three groups of parameters:
• The process parameters used in a Level 8 NMOS model, such as the Oxide Thickness
TOX, NMOS Length and Width Reductions (DLN, DWN), and so on.
• A second set of environmental noise parameters such as two supply voltages (VPERI,
VBB) and the temperature TP.
• The designable variables, the length and width of transistors.
Specifying Process Parameters Selectors
Suppose our approach is to assume that process disturbances affect devices within the same chip
in the same way: only inter-die variations exist and intra-die variations are negligible. The set of
process parameters is common to all NMOS and PMOS devices within the same chip. These
statistical definitions can be translated as follows:
.PARAM TOX = AGAUSS( 0.015, 0.0003, 1)
+ DL = AGAUSS( 0.05, 0.0044, 1)
+ DW = AGAUSS( 1.00, 0.044, 1)
+ VFB = AGAUSS( -0.8632, 0.0186, 1)
Then the associated .PARAMDEX statements could be defined as follows:
Eldo® User's Manual, 15.3 577

Statistical Experimental Design and Analysis
Example of Experiment Design
.PARAMDEX
+ DL NOISE/SIG=2.5
+ DW NOISE/SIG=2.5
+ TOX NOISE/SIG=2.5
+ VFB NOISE/SIG=2.5
Note that these statements are equivalent to the following:
.PARAMDEX
+ P(DL) NOISE/SIG=2.5
+ P(DW) NOISE/SIG=2.5
+ P(VFB) NOISE/SIG=2.5
+ P(TOX) NOISE/SIG=2.5
Specifying Model Parameter Selectors
The following example illustrates the use of the constructs M(.,.) and EM(.,.) with the inter and
intra variations. The use of M(.,) is not very useful in this case but we will assume that the
statistical variations were stated as follows:
.PARAM TOX=0.015
.MCMOD NCH TOX LOT/GAUSS=0.0003
.MCMOD PCH TOX LOT/GAUSS=0.0003
There are two independent random variables TOX associated with the PMOS and NMOS
transistor. Two PMOS, or respectively two NMOS, transistors are assumed to be perfectly
tracking each other, but the PMOS and NMOS transistors have independent variations. This is a
very hypothetical situation, since the Oxide Thickness should affect the PMOS and NMOS
transistors in the same way. The associated .PARAMDEX command would be as follows:
.PARAMDEX
+ M(PCH,TOX) SIG=2.5
+ M(NCH,TOX) SIG=2.5
Suppose now we are interested in intra-die variations. The statistical variations can be defined
as follows:
.PARAM TOX=0.015
.MCMOD NCH TOX DEV/GAUSS=0.0003
.MCMOD PCH TOX DEV/GAUSS=0.0003
It follows that the associated .PARAMDEX statements are:
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Statistical Experimental Design and Analysis
Example of Conducting an Experiment
.PARAMDEX
+ EM(MOPA,TOX) SIG=2.5
+ EM(MIPC,TOX) SIG=2.5
+ EM(MIPA,TOX) SIG=2.5
+ EM(MPN0E,TOX) SIG=2.5
+ EM(MPN4A,TOX) SIG=2.5
+ EM(MPN3A,TOX) SIG=2.5
+ EM(MPN2A,TOX) SIG=2.5
+ EM(MPN1A,TOX) SIG=2.5
+ EM(MONA,TOX) SIG=2.5
+ EM(MINC,TOX) SIG=2.5
+ EM(MINA,TOX) SIG=2.5
+ EM(MNN0D,TOX) SIG=2.5
+ EM(MNN4C,TOX) SIG=2.5
+ EM(MNN4B,TOX) SIG=2.5
These statements define a list of independent factors, one for each device. Eldo acts as if private
models were created for each device leaving the original model unchanged.
Related Topics
Example of Conducting an Experiment
Example of Analysis Results
Example of Conducting an Experiment
This netlist is extracted from the testcase filter.cir (available in the directory:
$MGC_AMS_HOME/examples/dex/). Consider the netlist:
* CIRCUIT
V1 1 0 DC 0 AC 1
R1 1 2 'R1 + D_R1'
R3 2 0 'R3 + D_R3'
R2 OUT INN 'R2 + D_R2'
C2 2 INN 'C + D_C'
C3 2 OUT 'C + D_C'
Y1 OPAMP1 0 INN OUT 0 PARAM: P1='P1 + D_P1'
The designable control parameters are defined by:
* DETERMINISTIC PARAMETERS
.PARAM R1 = 159K R2 = 3.18MEG R3 = 79.5
+ P1 = 10
The statistical noise parameters that follow the normal distribution and are defined by:
* NOISE PARAMETERS
.PARAM D_R1 = AGAUSS( 0, 10.6K, 1)
.PARAM D_R2 = AGAUSS( 0, 0.212MEG, 1)
.PARAM D_R3 = AGAUSS( 0, 5.30, 1)
.PARAM D_P1 = AGAUSS( 0, 0.667U, 1)
The response factors are defined within the following statements:
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Statistical Experimental Design and Analysis
Example of Conducting an Experiment
* EXTRACT SECTION
.EXTRACT AC LABEL=OPGAIN MAX(VDB(OUT)) LBOUND=20
.EXTRACT AC LABEL=OPFREQ XMAX(VDB(OUT)) LBOUND=9.95 UBOUND=10.05
The associated .PARAMDEX statements for noise and control parameters could be defined as
below. Here the noise parameters, which follow the normal distribution, are defined as having
levels with a standard deviation of 1.0 around the nominal value:
* NOISE FACTORS.PARAMDEX
+ D_R1 SIG=1.0
+ D_R2 SIG=1.0
+ D_R3 SIG=1.0
+ D_P1 SIG=1.0
The control parameters have levels with a relative perturbation of 20% around nominal values
that are defined by the NOM= argument:
* CONTROL FACTORS
.PARAMDEX
+ R1 CTRL/REL=20% NOM=159K
+ R2 CTRL/REL=20% NOM=3.18MEG
+ R3 CTRL/REL=20% NOM=79.5
+ P1 CTRL/REL=20% NOM=10
The following command conducts the experiment based on the performance responses defined
in the earlier .EXTRACT statements:
.DEX
+ EXPERIMENT=SCREENING
+ DESIGN=ORTHA_2_2N
+ RESPONSE=OPGAIN,OPFREQ
Related Topics
Example of Experiment Design
Example of Analysis Results
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Statistical Experimental Design and Analysis
Example of Analysis Results
Example of Analysis Results
The results of an experiment are available in the .dex file.
This output file contains:
• Ordered Data Table—for each simulated response.
• DEX Mean Table—which provides the ranked list of factors (not including the
interactions). The ranking is from the most important factor to least important factor.
• Formal Test of Significance—based on the Lenth’s method.
• Multi-Responses—a summary of the screening experiments for each response in the
case of multi-responses.
• Unordered Data Table (CSV Table)—giving the simulation results.
The results of an example analysis are presented below. The example used is cmos_ring.cir
(available in the directory: $MGC_AMS_HOME/examples/dex/). Two response functions are
defined which are the oscillation frequency 30 MHz < OSCFREQ < 50 MHz, and the AC
switching power dissipation: ACPOWER < 5 MW.
This analysis is performed with respect to 34 noise factors. Note that the .dex file gives the
name and the properties of each factor. A dummy name is associated to each factor to get more
compact tables. The control factors are designated by C1, C2, C3, ... and the noise factors by
N1, N2, N3, and so on.
Eldo® User's Manual, 15.3 581

Statistical Experimental Design and Analysis
Example of Analysis Results
Factors and Levels
------------------
==> Level values and coded factors
==> Output in the following order:
Distrib ... Statistical distribution of factor (Uniform or Gaussian)
Coding ... Levels are coded with the Std. Deviation
Mult ... Fraction of the Std. Deviation or the Range
Dev/Range ... Std. Deviation or Range
Mean ... Mean value of the statistical distribution
Low/High ... Low and High settings (coded with -1 and +1)
Noise Factor(s) Distrib Coding +/-Mult Dev/Range
N1 - M(SBSIMP,X3U1) Gauss StdDev 1.0e+00 2.8900e-03 ...
N2 - M(SBSIMP,X3MS) Gauss StdDev 1.0e+00 1.4400e+00 ...
N3 - M(SBSIMP,X2MS) Gauss StdDev 1.0e+00 1.4700e+00 ...
N4 - M(SBSIMP,MUS) Gauss StdDev 1.0e+00 2.2100e+01 ...
N5 - M(SBSIMP,X2U1) Gauss StdDev 1.0e+00 2.1400e-03 ...
N6 - M(SBSIMP,X2U0) Gauss StdDev 1.0e+00 7.7600e-04 ...
N7 - M(SBSIMP,X3E) Gauss StdDev 1.0e+00 7.6500e-04 ...
N8 - M(SBSIMP,X2E) Gauss StdDev 1.0e+00 8.2600e-04 ...
N9 - M(SBSIMP,X2MZ) Gauss StdDev 1.0e+00 7.2600e-01 ...
...
N29 - M(SBSIMN,MUZ) Gauss StdDev 1.0e+00 4.6100e+01 ...
N30 - M(SBSIMN,ETA) Gauss StdDev 1.0e+00 5.3200e-03 ...
N31 - M(SBSIMN,K2) Gauss StdDev 1.0e+00 3.7800e-02 ...
N32 - M(SBSIMN,K1) Gauss StdDev 1.0e+00 1.1900e-01 ...
N33 - M(SBSIMN,PHI) Gauss StdDev 1.0e+00 1.0800e-02 ...
N34 - M(SBSIMN,VFB) Gauss StdDev 1.0e+00 8.0600e-02 ...
Ordered Data Table
The result is an ordered data table for each simulated response. This data table answers the
question: What is the best setting (based on the data) for each of the N factors? An ordered data
table is formed by:
• Vertical axis: the ordered (smallest to largest) raw response value for each run in the
experiment.
• Horizontal axis: the corresponding factor index with (at each run) a designation of the
corresponding settings (−1 or +1) for each of the N factors.
This analysis can be found in the .dex file as follows:
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Statistical Experimental Design and Analysis
Example of Analysis Results
Ordered Data Table
------------------
Response Y : OSCFREQ
Mean Value
: 4.8667e+07
Value at nominal point : 4.8667e+07
==> Vertical axis: the ordered raw response
value for each of the 72 runs in the experiment.
Horizontal Axis: the corresponding dummy variable index (1 to 34)
with settings (-1 or +1) for each of the 34 factors.
Run N1 N2 N3 N4 ... N29 N30 N31 N32 N33 N34 Response Y
4 +1 -1 -1 -1 +1 -1 +1 +1 +1 -1 4.1226377e+07
56 -1 +1 +1 -1 +1 -1 +1 +1 +1 +1 4.1369450e+07
31 -1 -1 +1 -1 -1 -1 -1 +1 +1 +1 4.2162628e+07
72 +1 +1 -1 -1 -1 -1 -1 -1 -1 +1 4.2545442e+07
15 -1 -1 +1 -1 -1 +1 +1 -1 +1 +1 4.2712903e+07
61 +1 +1 -1 +1 +1 +1 -1 +1 -1 +1 4.3002165e+07
11 +1 -1 +1 -1 +1 +1 -1 +1 +1 -1 4.3099024e+07
14 -1 +1 -1 +1 +1 +1 -1 +1 +1 -1 4.3174847e+07
19 -1 -1 +1 -1 ... +1 -1 -1 -1 -1 +1 4.3490089e+07
...
DEX Mean Table
A DEX mean table provides the ranked list of factors (not including the interactions). The
ranking is from the most important factor to least important factor. This table is appropriate for
analyzing data from an experiment, with respect to important factors, where the factors are at
two levels. The table gives the mean value and the amplitude of the main effect coefficient (a
line proportional to this magnitude is also printed).
Note
Note that the magnitude represents the absolute value of the coefficient α i .
This qualitative analysis can be found in the .dex file as follows (the central part has been
removed):
Eldo® User's Manual, 15.3 583

Statistical Experimental Design and Analysis
Example of Analysis Results
DEX Mean Table
--------------
Response Y : OSCFREQ
==> Horizontal axis: the mean response for a given setting (- or +)
of a factor, for each of the 34 factors.
Vertical axis: the 34 factors and the two settings (- and +)
within each factor.
Value at nominal point : 4.8667e+07
Mean Value
: 4.8667e+07
Factor Name Sign of Magnitude
effect (percent / exact / cumulative)
N4 M(SBSIMP,MUS) [+] 13.0% 3.6552e+06 13.0%
N27 M(SBSIMN,U1) [-] 12.8% 3.6022e+06 25.8%
N21 M(SBSIMN,MUS) [+] 11.6% 3.2592e+06 37.3%
N32 M(SBSIMN,K1) [-] 9.9% 2.7839e+06 47.2%
N15 M(SBSIMP,K1) [-] 7.8% 2.1921e+06 55.0%
N10 M(SBSIMP,U1) [-] 7.5% 2.1091e+06 62.5%
N17 M(SBSIMP,VFB) [-] 6.0% 1.6999e+06 68.5%
N34 M(SBSIMN,VFB) [-] 5.8% 1.6240e+06 74.3%
N18 M(SBSIMN,X3U1) [+] 3.1% 8.7887e+05 77.4%
N11 M(SBSIMP,U0) [-] 2.8% 7.8008e+05 80.2%
...
N23 M(SBSIMN,X2U0) [-] 0.0% 1.5643e+03 100.0%
N9 M(SBSIMP,X2MZ) [-] 0.0% 7.2275e+02 100.0%
The last column gives the following information: almost 70% of the response’s variability is
explained with the variations of the eight factors M(SBSIM*,MUS), M(SBSIM*,U1),
M(SBSIM*,K1) and M(SBSIM*,VFB) where the ‘*’ character means ‘P’ positive or ‘N” for
negative.
Formal Test of Significance
A formal test of significance is based on the Lenth’s method. This method is usually employed
for unreplicated experiments, where there are no replicated runs and no dispersion modeling is
investigated.
A detailed description of this algorithm can be found in [1].
This quantitative analysis is given as follows:
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Statistical Experimental Design and Analysis
Example of Analysis Results
==> Response Y[1] : OSCFREQ
==> Initial standard error s0 : 5.8724e+05
Pseudo standard deviation PSE : 3.6619e+05
Signifiance level alpha : 0.05
Critical value
: 2.0525e+00
Main Name Accept/Reject Value t(PSE) P-value
Effect
N4 M(SBSIMP,MUS) *** PASS *** 9.9816e+00 0.001
N27 M(SBSIMN,U1) *** PASS *** 9.8368e+00 0.001
N21 M(SBSIMN,MUS) *** PASS *** 8.9002e+00 0.001
N32 M(SBSIMN,K1) *** PASS *** 7.6022e+00 0.001
N15 M(SBSIMP,K1) *** PASS *** 5.9861e+00 0.001
N10 M(SBSIMP,U1) *** PASS *** 5.7594e+00 0.001
N17 M(SBSIMP,VFB) *** PASS *** 4.6422e+00 0.001
N34 M(SBSIMN,VFB) *** PASS *** 4.4348e+00 0.002
N18 M(SBSIMN,X3U1) *** PASS *** 2.4000e+00 0.03
N11 M(SBSIMP,U0) *** PASS *** 2.1302e+00 0.05
N28 M(SBSIMN,U0) 1.7737e+00 0.09
N31 M(SBSIMN,K2) 1.7069e+00 0.1
N29 M(SBSIMN,MUZ) 1.5284e+00 0.2
N1 M(SBSIMP,X3U1) 1.5215e+00 0.2
N12 M(SBSIMP,MUZ) 1.4868e+00 0.2
N16 M(SBSIMP,PHI) 1.3491e+00 0.2
...
Non-expert users should only consider the central column Accept/Reject. Based on our
experience, the Lenth’s method is not very restrictive. Inactive factors can pass the test. We
suggest that misidentifying an inert factor as active should be less important than missing an
important and active factor.
Multi-Responses
In the case of multi-response problems, a summary of the screening experiments is performed
for each response.
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Statistical Experimental Design and Analysis
References
Active effect(s) for 2 response(s) :
N4 - M(SBSIMP,MUS) Rank = 33 Response(s) : OSCFREQ ACPOWER
N27 - M(SBSIMN,U1) Rank = 32 Response(s) : OSCFREQ ACPOWER
N21 - M(SBSIMN,MUS) Rank = 31 Response(s) : OSCFREQ ACPOWER
N32 - M(SBSIMN,K1) Rank = 30 Response(s) : OSCFREQ ACPOWER
N15 - M(SBSIMP,K1) Rank = 29 Response(s) : OSCFREQ ACPOWER
N10 - M(SBSIMP,U1) Rank = 28 Response(s) : OSCFREQ ACPOWER
N17 - M(SBSIMP,VFB) Rank = 27 Response(s) : OSCFREQ ACPOWER
N34 - M(SBSIMN,VFB) Rank = 26 Response(s) : OSCFREQ ACPOWER
N18 - M(SBSIMN,X3U1) Rank = 25 Response(s) : OSCFREQ ACPOWER
N11 - M(SBSIMP,U0) Rank = 24 Response(s) : OSCFREQ ACPOWER
Active effect(s) for 1 response(s) :None
Unimportant effect(s) detected for all responses:
N9 - M(SBSIMP,X2MZ)
N33 - M(SBSIMN,PHI)
N12 - M(SBSIMP,MUZ)
N13 - M(SBSIMP,ETA)
N8 - M(SBSIMP,X2E)
N3 - M(SBSIMP,X2MS)
...
This global analysis based on the Lenth’s method clearly identifies the eight factors
M(SBSIM*,MUS), M(SBSIM*,U1), M(SBSIM*,K1), M(SBSIM*,VFB), and the additional
M(SBSIMN,X3U1), M(SBSIMP,U0) as active factors.
Unordered Data Table (CSV Table)
An unordered data table gives the simulation results. These results are stored in a CSV format
(Comma Separated Values) table. CSV is a delimited data format with fields/columns separated
by the comma character and records/rows separated by new lines.
Related Topics
Example of Experiment Design
Example of Conducting an Experiment
References
Articles referenced in this chapter:
1. C. F. Jeff Wu, Michael Hamada. Experiments: Planning, Analysis, and Parameter
Design Optimization. John Wiley & Sons, 2000.
2. Hedayat, A. and Wallis W.D. Hadamard Matrices and Their Applications. Annals of
Statistics, Vol. 6, No. 6 (Nov., 1978), pp. 1184-1238.
586
Eldo® User's Manual, 15.3

Chapter 13
Optimization
The purpose of optimization is to attain a specified electrical performance for a circuit (for
example a desired frequency response for a filter circuit) by adjusting component parameters of
the circuit (such as resistor or capacitor values, the current gain (β) value of a transistor, widths
and lengths of a MOSFET) to meet this desired performance.
Optimization can be applied to:
• Circuit parameters.
• Model parameters.
• Element parameters.
• Device lengths, widths, areas, and peripheries.
Optimization in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589
Optimization Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589
Optimization Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 591
Eldo Optimization Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 592
Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
Discretized Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
Specifying Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596
Specifying Tracking with Design Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597
Scaling Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599
Design Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603
Specifying Design Objectives Using .EXTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
Specifying Design Objectives Using .OBJECTIVE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608
Types of Design Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610
Design Objectives for Multi-Point Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618
Scaling Design Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621
Optimization Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 622
Eldo Optimizer SQP Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 622
Eldo Optimizer/Search Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626
Conducting an Eldo Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Global and Local Optimization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Continuous and Discrete Optimization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630
Smooth and Non-Smooth Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631
Multiple-Run Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
Optimization of Sweep Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 633
Post-Analysis of Optimization Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
Eldo® User's Manual, 15.3 587

Optimization
Output from the Optimization Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
Explicitly Declaring Results For Graphical Viewing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641
Viewing the ASCII Output File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 642
ASCII Optimization File Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643
Monitoring Design Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653
Final Diagnostic Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 656
Normal and Elastic Modes of Termination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659
Examples of Circuit Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664
Designing a Low Noise Amplifier (LNA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664
Fourband Filter Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 671
MOS Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 675
Robust Optimization Using Corners. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 677
Setup Time Computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 681
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 682
588
Eldo® User's Manual, 15.3

Optimization
Optimization in Eldo
Optimization in Eldo
Eldo contains a general-purpose electrical circuit optimization tool that simultaneously
improves AC, DC, Transient domain, Steady-State, and Modulated Steady-State analyses.
With each run of the optimizer, the adjustable component parameters of the circuit (the design
variables, see “Design Variables” on page 594) are modified in an attempt to reach desired
performance (the design objectives, see “Design Objectives” on page 603). The parameters
relating to the specified electrical performance are extracted and measured (the extracted
measures) to verify whether the desired performance has been met.
The design variables must conform to manufacturing limits, process limits, or discrete device
values (known as constraints). For example, they must be non-negative, or must not violate
upper boundaries. Restrictions and/or inter-relations can also be specified, for example, how
components physically interact with each other to produce non-linear relations.
The process of identifying the design objectives, design variables, and constraints for a specific
problem is known as modeling. The construction of an appropriate model is the first step in the
optimization process. If the model is too simplistic, it will not generate useful insights into the
practical problems. If too complex, it may become difficult to solve.
The optimizer output shows if the target performance (design objectives) has been reached, and
whether it might be possible to improve on the current solution. It also details the values of the
design variables, extracted measures, and constraints for each run.
Optimization Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589
Optimization Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 591
Eldo Optimization Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 592
Optimization Commands
The definition of the design variables, the design objectives and the constraints, along with the
request for optimization, are all specified in the netlist file using simple extensions of the Eldo
commands. The links open the Simulator Commands chapter in the Eldo Reference Manual.
The .PARAMOPT command specifies the design variables and the constraints on them. The
syntax is:
.PARAMOPT VARIABLE_NAME=(
+ [INIT_VALUE,]
+ {LOWER_BOUND | LOWER_PERCENT% },
+ {UPPER_BOUND | UPPER_PERCENT% }
+ [, INCREMENT])
In the following example the .PARAMOPT command is used to specify the optimization
variables, the length l and the width w of a MOS transistor:
Eldo® User's Manual, 15.3 589

Optimization
Optimization Commands
.PARAMOPT
+ L=(10U, 2U, 100U)
+ W=(60U, 2U, 200U)
This statement defines an initial length of 10μm and an initial width of 60μm. The length is
allowed to vary between 2μm and 100μm and the width can vary between 2μm and 200μm.
The .EXTRACT and .MEAS commands can be used to specify design objectives where they are
represented by a single number (scalar version) or represented by a vector of measures. These
are regular .EXTRACT and .MEAS command statements with additional optimization
parameters. The syntax for the .EXTRACT command is:
.EXTRACT
+ [EXTRACT_INFO] [LABEL=NAME] [FILE=FNAME]
+ [VECT] [CATVECT] $MACRO|FUNCTION
+ [OPTIMIZER_INFO]
The .MEAS command (the HSPICE-compatible equivalent of .EXTRACT) shares all of the
same syntax and parameters.
The .OBJECTIVE command can also be used to specify the design objectives. It is dedicated to
optimization and can be used for more complex objectives. The syntax is:
.OBJECTIVE
+ EXTRACT_INFO [LABEL=NAME]
+ {$MACRO|FUNCTION}
+ OBJECTIVE_INFO
+ [SCALING_INFO]
+ [MONITOR_INFO]
+ [PRINT_INFO]
In the following example the design objective is specified using an .OBJECTIVE command. It
shows the optimization of the phase margin for an operational amplifier in closed-loop
configuration:
.OBJECTIVE AC
+ LABEL=phasemarg(XYCOND(VP(out),VDB(out)

Optimization
Optimization Options
.OPTIMIZE
+ [METHOD=DICHOTOMY|SECANT|PASSFAIL|SEARCH]
+ [QUALIFIER=VALUE{, QUALIFIER=VALUE}]
+ [PARAM=LIST_OF_VARIABLES|*]
+ [RESULTS=LIST_OF_MEASURES|*]
+ [OUTER=LIST_OF_PARAMETERS]
Once the design variables and the design objectives have been defined, the .OPTIMIZE
command is added to the netlist file to request the optimization.
After simulating the netlist, run the viewotm command line utility on the optimization output
(.otm file) to display the optimization results. The syntax is:
viewotm [-l 1|2|3] -f file.otm
For further details, see “Viewing the ASCII Output File” on page 642.
See Also
• .EXTRACT in the Eldo Reference Manual
• .OBJECTIVE in the Eldo Reference Manual
• .OPTIMIZE in the Eldo Reference Manual
• .PARAMOPT in the Eldo Reference Manual
Related Topics
Optimization Options
Eldo Optimization Methods
Design Variables
Design Objectives
Optimization Options
The following Eldo options can be specified with the .OPTION command to modify execution
behavior for optimization. The links open the Simulator Options chapter in the Eldo Reference
Manual.
• .OPTION OPSELDO_ABSTRACT generates a summary table of simulations
containing parameter and extract values for each run.
• .OPTION OPSELDO_ALTER forces Eldo to perform optimization on all .ALTER
sections.
• .OPTION OPSELDO_DETAIL specifies the level of detail stored in the generated files.
• .OPTION OPSELDO_NETLIST generates a modified netlist containing the optimized
variable parameter values.
Eldo® User's Manual, 15.3 591

Optimization
Eldo Optimization Methods
• .OPTION OPSELDO_OUTER specifies a reverse behavior of optimization and sweep
simulations.
• .OPTION OPSELDO_OUTPUT specifies the format for optimization results using the
Dichotomy, Secant, and Passfail methods.
• .OPTION PARAMOPT_NOINITIAL enables the .PARAMOPT command to be
specified without an initial value, which is instead taken from the netlist. For example, if
the capacitors CT, CLC and CPASS are specified in the netlist:
.PARAM CT=0.02U CLC=0.001U CPASS=0.3U
with the associated .PARAMOPT statement:
.PARAMOPT
+ CT = (0.001U, 0.05U)
+ CLC = (0.001U, 0.005U)
+ CPASS = ( 0.1U, 1.0U)
.OPTION PARAMOPT_NOINITIAL
The option PARAMOPT_NOINITIAL specifies that the parameter INITIAL_VALUE
is omitted from the .PARAMOPT command and should be taken from the netlist
instead.
Related Topics
Optimization Commands
Eldo Optimization Methods
Design Variables
Design Objectives
Inner and Outer Sweep Parameters
Eldo Optimization Methods
Sometimes you need to be more precise about the underlying method or algorithm used during
the optimization.
The terminology in Table 13-1 enables you to specify the underlying method or algorithm.
Table 13-1. Eldo Optimization Methods
Name Algorithm/Method Terminology
Eldo optimizer/SQP SQP method .OPTIMIZE
Eldo optimizer/Search Dichotomy and inverse
quadratic interpolation
.OPTIMIZE METHOD=SEARCH
592
Eldo® User's Manual, 15.3

Table 13-1. Eldo Optimization Methods (cont.)
Name Algorithm/Method Terminology
Optimization
Eldo Optimization Methods
Eldo optimizer/Passfail Pass or fail technique .OPTIMIZE
METHOD=PASSFAIL
Eldo optimizer/Dichotomy
This chapter focuses primarily on the Eldo optimizer SQP algorithm, and also covers the Eldo
optimizer/Search algorithm.
The other group of methods (Dichotomy, Secant, and Passfail) represent a specific class of
algorithms categorized as Derivative Free Optimization (DFO) algorithms. They enable
optimization in the restricted case of one-dimensional problems.
See Also
• Eldo Optimizer/Dichotomy/Secant/PassFail Parameters in the Eldo Reference Manual
Related Topics
Optimization Commands
Optimization Options
Design Variables
Design Objectives
Eldo Optimizer SQP Algorithm
Eldo Optimizer/Search Algorithm
Dichotomy (or bisection)
algorithm
.OPTIMIZE
METHOD=DICHOTOMY
Eldo optimizer/Secant Hybrid Dichotomy/Secant .OPTIMIZE METHOD=SECANT
Eldo® User's Manual, 15.3 593

Optimization
Design Variables
Design Variables
Design variables represent the vector of the variables x that will be tuned during the
optimization. They are specified through the .PARAMOPT command.
The Eldo simulator is regarded as a black box that provides a vector of extracted measures F(x)
and derivatives F’(x) given the set of design variables x, as shown in Figure 13-1.
Figure 13-1. Simulator as a Black Box
This topic describes design variables in the context of the Eldo simulator, then details how to
specify them.
Discretized Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
Specifying Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596
Specifying Tracking with Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597
Scaling Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599
Discretized Design Variables
This topic explains how the optimizer handles design variables that are restricted to being
members of a finite set of values.
Figure 13-2 illustrates such a situation.
594
Eldo® User's Manual, 15.3

Figure 13-2. Discretization of Design Variables
Optimization
Discretized Design Variables
The continuous box represents the feasible domain specified by the upper and lower bounds,
and the black bullets are the feasible points where the final parameters are allowed to lie.
The Eldo optimizer initially ignores discretization requirements, solving the optimization
problem with real variables. All the design variables are then rounded to the nearest point onto
the grid at the end of optimization.
Note
This strategy is not guaranteed to give solutions that are close to optimal. See “Solving
Problems with Pseudodiscrete Variables” on page 668 for a detailed example.
When the lower bound is a finite number, the set of discretized points are as follows:
{x l (i) , x l (i) + δ i , x l (i) + 2δ i , …}
Where δ i > 0 is the given increment.
When the lower bound is infinite (x l (i) = ∞), the grid is started from the upper bound, if it is
finite. The set of discretized points is then:
{x u (i) , x u (i) + δ i , x u (i) + 2δ i , …}
When a design variable is unbounded (x l (i) = −∞ and x u (i) = ∞), discretization is not considered.
Related Topics
Optimization in Eldo
Design Objectives
Optimization Methods
Conducting an Eldo Optimization
Eldo® User's Manual, 15.3 595

Optimization
Specifying Design Variables
Specifying Design Variables
This topic uses examples to explain how to use the .PARAMOPT statement to specify design
variables. Design variables can be different types of circuit parameters and can take the
following forms:
parameter_name
P(parameter_name)
P(subckt_name, subckt_parameter)
E(device_name, device_parameter)
M(model_name, model_parameter)
EM(device_name, model_parameter)
In our first example, the length and width of a MOS transistor are specified by:
.PARAMOPT
+ L=(10U, 2U, 100U)
+ W=(60U, 2U, 200U)
This .PARAMOPT statement defines an initial length of 10μm and a initial width of 60μm. The
length is allowed to vary between 2μm and 100μm and the width can to take values between
2μm and 200μm.
Suppose an optimization is required on the following circuit:
.MODEL NMOD1.1 NMOS LEVEL=53
+ LMIN=0.1U LMAX=0.2U
+ WMIN=1U WMAX=100U
+ VTH0=0.2
.MODEL NMOD1.2 NMOS LEVEL=53
+ LMIN=0.2U LMAX=0.3U
+ WMIN=1U WMAX=100U
+ VTH0=0.3
.MODEL NMOD1.3 NMOS LEVEL=53
+ LMIN=0.3U LMAX=1U
+ WMIN=1U WMAX=100U
+ VTH0=0.4
VD D 0 DC 1.5
VS S 0 DC 0
VB B 0 DC 0
VG G 0 DC 3
RD1 D D1 1
RD2 D D2 1
M1 D2 G S B NMOD1 W=10U L=0.25U
M2 D1 G S B NMOD1 W=10U L=0.35U
Adding the following commands adjusts the length of M2:
.PARAMOPT E(M2,L)=(0.35U, 0.1U, 1U)
596
Eldo® User's Manual, 15.3

Optimization
Specifying Tracking with Design Variables
The length of M1 and M2 is adjusted with:
.PARAMOPT E(M*,L)=(*, 0.1U, 1U)
The initial values specified on the instances are kept unchanged.
The following command adjusts lengths of M1 and M2, the initial values are both set to
0.35μm.
.PARAMOPT E(M*,L)=(0.35U, 0.1U, 1U)
The following sequence of examples affect model parameter VTH0:
.PARAMOPT EM(M2,VTH0)=(0.3, 0.1, 1)
Adjusts the parameter VTH0 of the model used by device M2. For this type of parameter the
initial value is ignored.
Using wildcards, the parameter VTH0 can be changed for both devices M1 and M2. This is
achieved with:
.PARAMOPT EM(M*,VTH0)=(*, 0.1, 1)
The commands:
and:
.PARAMOPT M(NMOD1.3,VTH0)=(0.3, 0.1, 1)
.PARAMOPT M(NMOD1.*,VTH0)=(0.3, 0.1, 1)
change the parameter VTH0 of the model NMOD1.3 and all models NMOD1.* respectively.
For this type of parameter the initial value is ignored.
See Also
• .PARAMOPT in the Eldo Reference Manual
Related Topics
Discretized Design Variables
Specifying Tracking with Design Variables
Scaling Design Variables
Specifying Tracking with Design Variables
Design variables can track each other during the optimization process. Tracking is specified
through the command:
Eldo® User's Manual, 15.3 597

Optimization
Specifying Tracking with Design Variables
.CORREL EXPR ELEMENT={EXPRESSION}
Where ELEMENT can take the form of:
parameter_name
P(parameter_name)
P(subckt_name, subckt_parameter)
E(device_name, device_parameter)
M(model_name, model_parameter)
EM(device_name, model_parameter)
The character string EXPRESSION can contain references to E(), EM() and M(). These
quantities must be defined in the .PARAMOPT command.
Note
The ELEMENT should not be set as a design variable using the .PARAMOPT command.
Doing so would disable the .CORREL EXPR expression.
In the following case the .CORREL EXPR expression is disabled because P2 has been set as a
design variable with the .PARAMOPT command:
R1 1 0 P1
R2 2 0 P2
.PARAMOPT
+ P1=(1K, 1K, 100K)
+ P2=(5K, 5K, 500K) ! Incorrect
.CORREL EXPR P2=’1.2*P1’
In the following case P2 will not be affected by P1, but will track the value of the resistor R1:
R1 1 0 P1
R2 2 0 P2
.PARAMOPT P1=(1K, 1K, 100K)
.CORREL EXPR P2=E(R1,R)
The .CORREL EXPR command enables you to avoid having to edit files when an optimization
is performed on a non-parametric netlist. For example:
598
Eldo® User's Manual, 15.3

Optimization
Scaling Design Variables
* LCR Parallel Network
VIN 1 0 AC 10
R2 1 2 50
R3 2 3 50K
R5 3 0 50
L1 2 3 100U
C4 2 3 1N
VIN2 a 0 AC 10
RA A B 50
RB B C 50K
RC C 0 50
LA B C 100U
CA B C 1N
.PARAMOPT E(C4,C)=(1N,1N,20N)
.CORREL EXPR E(CA,C)=’1.2* E(C4,C)’
Note
The meaning of .CORREL EXPR is completely different to .CORREL in a Monte Carlo
analysis.
See Also
• .CORREL EXPR in the Eldo Reference Manual
• .PARAMOPT in the Eldo Reference Manual
Related Topics
Discretized Design Variables
Specifying Design Variables
Scaling Design Variables
Scaling Design Variables
This topic considers the effect of widely disparate variable scales on the algorithms and how to
deal with it. For example, you may have a minimization problem in which the first design
variable x (1) is in the range [10 8 , 10 9 ] Hz and the second x (2) in the range [10 −7 , 10 −6 ] seconds.
These ranges are referred to as the scales of the respective variables.
Scaling will affect algorithms when calculating the difference between iterates (the successive
values of design variables taken during optimization). In the above example the second variable
(time) is virtually ignored in any calculation.
The Eldo optimizer SQP method rescales the variables used in the optimization - that is,
changes their units. For example, if the units of x (1) are changed to gigahertz (GHz) and the
units of x (2) are changed to microseconds (μs), then both variables have the range [0.1, 1] and
Eldo® User's Manual, 15.3 599

Optimization
Scaling Design Variables
the scaling problem in computing the differences is eliminated. This corresponds to changing
the design variable to:
where D is a diagonal matrix of scaling.
The Eldo optimizer SQP method uses an affine scaling transformation based on the values of
the upper and lower bounds. If the variable x satisfies the relationship l ≤ x ≤ u, two numbers
can be introduced:
that define the transformation:
With this formula the transformed variable has a range of [-1, 1]. The bounds that correspond to
the change in units must be set on the variable x. The algorithms then operate as if they are
working in the transformed variable space.
When the variables are unbounded below or above, a similar transformation is used by utilizing
the nominal value x 0 . For example, if l = −∞, the transformation is defined as:
When x 0 = u:
A similar transformation is used when u = ∞.
600
Eldo® User's Manual, 15.3

Optimization
Scaling Design Variables
The result of this scaling procedure is described in the output file .otm, in the section headed
Section 2 - Scaling Transformation For Variables. For more information, refer to “Section 2 -
Scaling Transformation For Variables” on page 644.
This scaling strategy is not always appropriate and there are cases that need an alternative
approach. Consider the following example:
* Circuit Statements
.PARAM LOGL={LOG10(150U)}
.PARAM LOGR={LOG10(10)}
.PARAM LOGC={LOG10(10U)}
V1 1 0 AC 1
L1 1 2 5U
L2 2 3 150U
C1 3 0 33U
LA 2 2A {10^LOGL}
CA 2A 2B {10^LOGC}
RA 2B 3 {10^LOGR}
.AC DEC 500 1E2 1E5
* Optimization Commands
.OPTIMIZE
.PARAM LNOM={LOG10(150U)} LMIN={LOG10(150U)} LMAX={LOG10(1)}
.PARAMOPT LOGL=(LNOM,LMIN,LMAX)
.PARAM CNOM={LOG10(10U)} CMIN={LOG10(1P)} CMAX={LOG10(1)}
.PARAMOPT LOGC=(CNOM,CMIN,CMAX)
.PARAM RNOM={LOG10(10)} RMIN={LOG10(1E-3)} RMAX={LOG10(1E+6)}
.PARAMOPT LOGR=(RNOM,RMIN,RMAX)
.OBJECTIVE AC LABEL=Q MAX(W(’VM(3)’))
+ GOAL=MINIMIZE
This example represents a user-defined transformation based on the logarithmic function:
The exponent becomes the parameter to optimize. Consider the third .PARAMOPT command,
the original formulation would have been the following statements:
.PARAM RNOM=10 RMIN=1E-3 RMAX=1E+6
.PARAMOPT R=(RNOM, RMIN, RMAX)
The affine scaling transformation is not appropriate since the upper bound RMAX=1E+6 will
dominate inside the expression of the matrix D:
Eldo® User's Manual, 15.3 601

Optimization
Scaling Design Variables
Related Topics
Discretized Design Variables
Specifying Design Variables
Specifying Tracking with Design Variables
602
Eldo® User's Manual, 15.3

Optimization
Design Objectives
Design Objectives
This topic describes how to specify the design objectives to be considered by the .OPTIMIZE
command when performing an optimization.
Design objectives represent a desired behavior, for example a required frequency response for a
filter circuit. The optimizer adjusts the design variable parameters of the circuit (such as resistor
or capacitor values, the current gain (β) value of a transistor, widths and lengths of a MOSFET)
to meet the desired behavior. They are specified using .EXTRACT statements with additional
optimization parameters, or for more complex objectives the .OBJECTIVE command
(dedicated to optimization) can be used. For example, the objective of fixing the input power
matching of a Low Noise Amplifier (LNA) at a frequency of 2.4GHz to -15 is specified as:
.EXTRACT AC LABEL=S11_dB@2.4GHz
+ YVAL(SDB(1,1),2.4G)
+ GOAL=-15
This section covers:
Specifying Design Objectives Using .EXTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
Specifying Design Objectives Using .OBJECTIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608
Types of Design Objective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610
Design Objectives for Multi-Point Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618
Scaling Design Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621
Eldo® User's Manual, 15.3 603

Optimization
Specifying Design Objectives Using .EXTRACT
Specifying Design Objectives Using .EXTRACT
This section describes an extension of the .EXTRACT command parameters used explicitly for
optimization.
The .EXTRACT command can be used to define two categories of design objectives, as
described in the following sections:
• Those represented by a single number — Scalar Design Objectives.
• Those represented by a vector of measures — Vector Design Objectives.
Note
The .MEAS command (HSPICE-compatible equivalent of .EXTRACT) shares all of the
same syntax and parameters.
604
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Scalar Design Objectives
Optimization
Specifying Design Objectives Using .EXTRACT
The general syntax of the .EXTRACT command for scalar objectives is:
Syntax
.EXTRACT
+ [EXTRACT_INFO] [LABEL=NAME] [FILE=FILE_NAME]
+ [VECT] [CATVECT] $MACRO|FUNCTION
+ [OPTIMIZER_INFO]
Parameters
• [EXTRACT_INFO] [LABEL=NAME] [FILE=FILE_NAME] [VECT] [CATVECT]
$MACRO|FUNCTION
Refer to .EXTRACT in the Eldo Reference Manual for more information.
• OPTIMIZER_INFO:=
GOAL=MINIMIZE|MAXIMIZE [WEIGHT=RVALUE]
| GOAL=RVALUE [WEIGHT=RVALUE]
| GOAL=OPMODE_VALUE
| EQUAL=RVALUE
| {LBOUND=RVALUE | UBOUND=RVALUE}
| LBOUND=RVALUE UBOUND=RVALUE
The OPTIMIZER_INFO parameter describes the optimization. It is ignored if the
.OPTIMIZE command is not specified in the netlist.
A MINIMIZE or MAXIMIZE objective specifies that the extracted measure is to be
minimized or maximized.
The optional WEIGHT parameter is a positive value attached to the design objective and
weights objectives with respect to their relative importance.
The parameter GOAL=RVALUE defines a soft constraint on the measure. The default value
is 0. This does not apply to the passfail method.
The parameter GOAL=OPMODE_VALUE defines a set of hard constraints on the
operating mode of a given device. This “goal” must be specified when the extract function is
defined as OPMODE(DEVICE_NAME).
The LBOUND, UBOUND and EQUAL parameters define hard constraints on the measure.
Note
The additional parameters (GOAL, EQUAL, LBOUND, UBOUND and WEIGHT)
have no effect when the .OPTIMIZE command is not specified in the netlist. The
specification of at least one of the parameters GOAL, EQUAL, LBOUND and/or
UBOUND is mandatory for optimization.
Related Topics
Vector Design Objectives
Eldo® User's Manual, 15.3 605

Optimization
Specifying Design Objectives Using .EXTRACT
Vector Design Objectives
Vector objectives are specified using the FITTING parameter with the .EXTRACT command.
The general syntax of the .EXTRACT command for vector objectives is:
Syntax
.EXTRACT
+ [EXTRACT_INFO] [LABEL=NAME] [FILE=FILE_NAME]
+ [VECT] [CATVECT]
+ FITTING TARGET_NAME $MACRO|FUNCTION
+ [SCALE_INFO] [WEIGHT=RVALUE]
+ [INTERP_INFO | SELECT_INFO]
Parameters
• [EXTRACT_INFO] [LABEL=NAME] [FILE=FILE_NAME] [VECT] [CATVECT]
$MACRO|FUNCTION
Refer to .EXTRACT in the Eldo Reference Manual for more information.
• FITTING TARGET_NAME
Specifies the name of the discretized curve to fit. It can be the name of a previously defined
wave or a reference to a variable in a .DATA statement. For more information run the
example fourband in the directory: $MGC_AMS_HOME/examples/optimizer.
• SCALE_INFO:= [LINEAR|LOG|LOG10]
Specifies the scale (LINEAR, LOG, or LOG10) of the x-axis for the extracted measures.
• INTERP_INFO:= INCR=RVALUE
The INTERP_INFO parameter is used only when goal values are specified through .DATA
statements. INCR=RVALUE specifies the real-valued step of the analysis sweep variable
used for generating goal values through piece wise linear interpolation of data provided by
an associated .DATA command.
• SELECT_INFO:= DEC=RVALUE
Specifies the number of points per decade in the analysis sweep variable used for generating
goal values using a logarithmic interpolation of the data points provided. The corresponding
simulated values are obtained by interpolation of the available simulated values.
Description
Notes:
• You can specify a multi-dimensional specification of GOAL objectives. This is
equivalent to specifying the .EXTRACT FITTING command.
• Coherency is enforced between analysis commands and objective specifications.
• The .OPTIMIZE command is required in the netlist.
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Optimization
Specifying Design Objectives Using .EXTRACT
Examples
Examples of forbidden situations.
Example 1
The situation in the following example is detected and forbidden. Here the analysis command
should be driven by the values of VDS and VGS specified in the .DATA construct. The use of
.DATA constructs is then restricted.
DC Operating Point analysis is performed for every value of VDS from 0 to 40 with a step
increment of 1, and every value of VGS between 4 and 16 with a step increment of 2.
.DC VDS 0 40 1 VGS 4 16 2
Three design objectives are defined for the variable IDS through the .DATA statement labeled
MOSFIT, corresponding to the values of VGS equal to 4 and the values of VDS equal to 1, 2,
and 3 respectively. The current through voltage source VDRAIN is optimized to fit the values
of IDS. The values of VDS and VGS for the measurements correspond to the simulation points
on a short range as specified in the .DC command.
.EXTRACT DC LABEL=FIT_IDS
+ FITTING
+ MOSFIT(IDS) I(VDRAIN)
.DATA MOSFIT
+ VDS VGS IDS
+ 1.000E+00 4.000E+00 1.574E+00
+ 2.000E+00 4.000E+00 1.806E+00
+ 3.000E+00 4.000E+00 1.826E+00
.ENDDATA
Example 2
Consider the next example where interpolation is required to obtain the values for the measures
required for optimization.
Interpolation for measures is forbidden with optimization, since this technique introduces
additional errors that cannot be bounded, and provides non-smooth measurements. When
optimization is required, all simulation points must be included in the set of simulation points.
A small signal analysis is performed for frequencies in the range [100 kHz, 1 GHz] with 2
points per decade. The voltage magnitude at node 16 VM(16) is optimized to fit the values of
the data labelled V16 in the statement .DATA VFIT.
Eldo® User's Manual, 15.3 607

Optimization
Specifying Design Objectives Using .OBJECTIVE
.AC DEC 2 100k 1g
.EXTRACT AC LABEL=FIT_VM16
+ FITTING
+ VFIT(V16) VM(16)
.DATA VFIT
+ FREQ V16
+ 100K 200
+ 30Meg 200
+ 1G 1m
.ENDDATA
There are three measurement points defined at 100 kHz, 30 MHz and 1 GHz respectively. The
values of VM(16) at these frequencies would need to be obtained by interpolation of the values
simulated according to the .AC analysis command.
Related Topics
Scalar Design Objectives
Specifying Design Objectives Using .OBJECTIVE
The .OBJECTIVE command is dedicated to optimization, based on the .EXTRACT construct.
Some restrictions are imposed and the semantics are different in some situations. The
specification of design objectives is simplified.
Tip
Refer to .OBJECTIVE in the Eldo Reference Manual for a complete description of the
command syntax and parameters.
The .OBJECTIVE command should be used rather than .EXTRACT for the following reasons:
• Some notions, such as scope, are not clearly defined in relation to the .EXTRACT
command. For example, when several .ALTER blocks are used with optimization, the
.EXTRACT commands are simply added to each .ALTER block. By default,
.OBJECTIVE commands have a local scope.
• It makes it easier to separate the optimization block, the circuit statements, and the plot
statements.
• In the .chi file, it is difficult to print the values of objectives as they are effectively
processed in the optimizer.
• The dump of the results into a file (using the FILE parameter) is not of great use and
vector optimization makes the results difficult to read.
608
Eldo® User's Manual, 15.3

Notes
Optimization
Specifying Design Objectives Using .OBJECTIVE
• For backward compatibility, the equivalent of the .OBJECTIVE command can be
specified with the .EXTRACT command.
Related Topics
Optimization Methods
Specifying Design Objectives Using .EXTRACT
Design Objectives for Multi-Point Simulation
Scaling Design Objectives
Eldo® User's Manual, 15.3 609

Optimization
Types of Design Objective
Types of Design Objective
This section describes the different types of design objectives that will be considered by the
.OPTIMIZE command when conducting an optimization.
It covers:
Minimization and Maximization Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610
Goal Values Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 612
Range Constraints Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 614
Objectives for Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616
Minimization and Maximization Objectives
This topic explains how to specify design objectives that minimize or maximize extracted
measures.
Note
Optimization in Eldo always minimizes. Maximizing f(x) is handled as minimizing -f(x).
Objectives that minimize measures are specified using the .OBJECTIVE command as follows:
* Minimize or Maximize statements
.OBJECTIVE EXTRACT_INFO LABEL=f_m
+ {$MACRO|FUNCTION}
+ GOAL=MINIMIZE
+ [WEIGHT=MU_M]
The optional weight μ m is a positive number, defaulting to one.
Multiple Specifications of Minimization Objectives
The syntax enables .OBJECTIVE command statements to be specified multiple times in the
netlist. If several objectives are qualified as GOAL=MINIMIZE (or MAXIMIZE), a weighted
objective function is built as the summation of all these particular measures. The optimizer
minimizes a unique objective that is the weighted sum of the whole objectives. Consider the
following:
* Aggregation of two Minimize statements
.OBJECTIVE EXTRACT_INFO_1 LABEL=F_M_1
+ {$MACRO|FUNCTION}
+ GOAL=MINIMIZE WEIGHT=MU_M_1
.OBJECTIVE EXTRACT_INFO_2 LABEL=f_M_2
+ {$MACRO|FUNCTION}
+ GOAL=MINIMIZE WEIGHT=MU_M_2
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Optimization
Types of Design Objective
These statements, where two design objectives are minimized, define a bi-criterion problem or
a vector-valued objective function (f m (1) , f m (2) ). The technique used, known as scalarization, is
a standard approach for finding the solution to a vector optimization problem. Applied to this
simple problem, it leads to the minimization of the global objective function:
F = μ m (1) f m
(1)
+ μ m (2) f m
(2)
The optimization method considers a unique problem that is the aggregation of two concurrent
problems.
In practice you need to experiment with the different choices of weights with successive
adjustments. This technique is explained in “Role of the Weight Values on Minimization
Objectives” on page 611.
Effect of Multiple Sweeps on Minimization Objectives
When multiple sweeps or multiple step increments on circuit parameters are present in the
netlist, an extracted measure qualified as GOAL=MINIMIZE (or MAXIMIZE) must be handled
as a multi-dimensional object. Consider the following statements where P parameters have been
specified:
* Design parameters specification
.STEP PARAM OMEGA_J ! for all j in {1, ..., P}
* Minimize or Maximize statements
.OBJECTIVE EXTRACT_INFO LABEL=f_m
+ {$MACRO|FUNCTION}
+ GOAL=MINIMIZE
+ WEIGHT=MU_M
As above, the technique of scalarization is used, replacing the minimization of the
vector-valued function by the minimization of the sum of the components of f m . The optimizer
then forms and minimizes the function:
The extracted measure f m can be considered as a group of functions to be minimized. In these
cases the weight value applies to all functions in the group implying that all functions have the
same relative importance.
Role of the Weight Values on Minimization Objectives
The values μ
(i)
m are positive weight values attached to each design objective. Increase the
weight value μ
(i)
m if you want the objective f (i) m (x) to be a lower value.
Eldo® User's Manual, 15.3 611

Optimization
Types of Design Objective
The ratio μ m
(i)
/ μ m
(j)
can be interpreted as the relative weight of the ith objective compared with
the jth objective. This is useful when you want to alter weights to get lower values of a chosen
objective, for example the kth. To find an optimal point which trades off the kth objective,
increase the weight on the kth objective.
Related Topics
Specifying Design Objectives Using .EXTRACT
Specifying Design Objectives Using .OBJECTIVE
Design Objectives for Multi-Point Simulation
Scaling Design Objectives
Goal Values Objectives
This topic explains how to specify design objectives that define goal values on extracted
measures. With this type of design objective the extracted measure aims to get as close as
possible to a goal value r.
Objectives that define goals values on measures are specified using the .OBJECTIVE command
as follows:
* Goal values on measures
.OBJECTIVE EXTRACT_INFO LABEL=F_R
+ {$MACRO|FUNCTION}
+ GOAL=R
+ [WEIGHT=MU_R]
The optional weight μ r is a positive number, defaulting to one.
Multiple Specifications
If multiple objectives are qualified as GOAL=R, a weighted objective function is built using the
non-linear least squares approach, that is by minimizing the squared difference between the
actual value of the measure f r and the goal value r:
μ r (f r − r) 2
Consider the following example:
* Aggregation of two Minimize statements
.OBJECTIVE EXTRACT_INFO_1 LABEL=F_R_1
+ {$MACRO|FUNCTION}
+ GOAL=R_1 WEIGHT=MU_R_1
.OBJECTIVE EXTRACT_INFO_2 LABEL=F_R_2
+ {$MACRO|FUNCTION}
+ GOAL=R_2 WEIGHT=MU_R_2
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Optimization
Types of Design Objective
This leads to the minimization of the global objective function:
F = μ r (1) (f r
(1)
− r (1) ) 2 + μ r (2) (f r
(2)
− r (2) ) 2
In practice you need to experiment with different choices of weights by successive adjustments
(refer to “Role of the Weight Values on Minimization Objectives” on page 611).
Effect of Multiple Sweeps and Step Increments
The combination of optimization with goal values and multiple .STEP commands is supported.
Consider the following statements where P parameters have been specified:
* Design parameters specification
.STEP PARAM OMEGA_1
.STEP PARAM OMEGA_2
*...
.STEP PARAM OMEGA_P
* Goal statement
.OBJECTIVE EXTRACT_INFO LABEL=F_R
+ {$MACRO|FUNCTION}
+ GOAL=R
+ WEIGHT=MU_R
As above, the technique of scalarization is used, replacing the minimization of a vector-valued
function by the minimization of the sum of the components of f r . The optimizer then forms and
minimizes the function:
Note
The weight number applies to all functions in the group, however, it is possible to associate
a weight to each component of f r . This can done with the .DATA command. Refer to
“Design Objectives for Multi-Point Simulation” on page 618 for more information.
Related Topics
Minimization and Maximization Objectives
Range Constraints Objectives
Objectives for Operating Modes
Eldo® User's Manual, 15.3 613

Optimization
Types of Design Objective
Range Constraints Objectives
This topic explains how to specify design objectives that define bounds on extracted measures.
These types of objectives are called equality constraints or range constraints and correspond to
relations such as l≤ f i (x) ≤ u.
Equality constraints are range constraints with equal lower and upper bounds: l=u.
Objectives that define ranges on measures are specified using the .OBJECTIVE command by:
* Range constraint
.OBJECTIVE EXTRACT_INFO LABEL=F_I
+ {$MACRO|FUNCTION}
+ LBOUND=L UBOUND=U
When the objective f i does not need to be bounded by a lower or an upper value, the parameters
may be omitted. For example, if a design objective must be positive f i ≥ 0 (its lower bound is 0),
you can specify the following:
* Positive objective
.OBJECTIVE EXTRACT_INFO LABEL=F_I
+ {$MACRO|FUNCTION}
+ LBOUND=0.0
The Eldo Optimizer SQP Algorithm handles them directly as hard constraints. These objectives
must be satisfied at the solution of the problem.
Notes
• The iterates (the successive values of design parameters taken during optimization) may
not satisfy the constraints. If the optimization problem appears to be feasible, the
constraints will be satisfied at the solution, or in the vicinity of a solution.
• In general, inequality constraints are more relevant than equality constraints as
equalities are more difficult to satisfy. Consider the objective of fixing the input power
matching of a low noise amplifier at a frequency of 2.4GHz:
.EXTRACT AC LABEL=S11_dB@2.4GHz YVAL(SDB(1,1),2.4G)
+ GOAL=-15
A more appropriate objective is to specify a tolerance on the target value, for example
±1dB.
The Eldo optimizer SQP method does not enable you to specify a tolerance on equality
constraints. Instead you can combine GOAL objectives to center the design and range
constraints with the same objective in separate statements.
• The limitation above also means that equalities and inequalities are mutually exclusive.
The parameter EQUAL cannot appear inside the same objective statement as the
parameters LBOUND and UBOUND.
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Optimization
Types of Design Objective
• A constraint of the form f > 0 is difficult to handle in an active set method such as the
Eldo optimizer SQP algorithm. This is because the feasible region is not closed and the
constraint cannot be active at a solution.
Constraints of this type can be included via the transformation f(x) ≥ ε > 0. If the
constraints are active, you can solve a sequence of problems in which ε → 0. This
prevents f(x) from being evaluated at an infeasible point where it is not defined.
Multiple Specifications
Multiple range constraints can be specified. For example, if the netlist consists of two
statements such as:
* Aggregation of two range constraints
.OBJECTIVE EXTRACT_INFO_1 LABEL=F_I_1
+ {$MACRO|FUNCTION}
+ LBOUND=L_1 UBOUND=U_1
.OBJECTIVE EXTRACT_INFO_2 LABEL=F_I_2
+ {$MACRO|FUNCTION}
+ LBOUND=L_2 UBOUND=U_2
These objectives will be optimized jointly, meaning that a vector of design variables x has to
satisfy the system of inequalities:
This approach consists of defining a unique optimization problem that is the aggregation of all
the constraint statements.
Effect of Multiple Sweeps and Step Increments
Optimizations can be specified where range constraints are combined with multiple .STEP
commands. Consider the following statements where P parameters have been specified:
* Design parameters specification
.STEP PARAM OMEGA_1
.STEP PARAM OMEGA_2
*...
.STEP PARAM OMEGA_P
* Range cosntraint statement
.OBJECTIVE EXTRACT_INFO LABEL=f_i
+ {$MACRO|FUNCTION}
+ LBOUND=L
+ UBOUND=U
The optimizer forms a group (or system) of inequalities as shown below:
Eldo® User's Manual, 15.3 615

Optimization
Types of Design Objective
Related Topics
Minimization and Maximization Objectives
Goal Values Objectives
Objectives for Operating Modes
Objectives for Operating Modes
You can optimize the operating mode of transistors and bipolars in your circuit. The syntax of a
single statement is given as follows:
* OPMODE constraint statement
.OBJECTIVE EXTRACT_INFO LABEL=f_op
+ OPMODE(DEVICE_NAME)
+ GOAL=OPMODE_NAME
The goal is not specified as a value, it is a string. The different modes are recalled here:
• GOAL=SATURATION (MOS and BJT)
• GOAL=LINEAR (MOS and BJT)
• GOAL=ON (only BJT)
• GOAL=OFF (only BJT)
• GOAL=SUBTHRESHOLD (only MOS)
For a transistor, these modes can be expressed as numerical relations (constraints) between the
voltages VGS, VT, VDS, and VDSAT. For example, the LINEAR mode is characterized with the
two following constraints: VGS ≥ VT and VDS ≤ VDSAT. The same applies to the other modes.
There is no “goal value” for this objective, it is attempted to find a feasible configuration which
satisfies the OPMODE constraints. It is very likely that there is an infinite number of circuits
which are feasible. This means you must introduce additional objectives to optimize the circuit,
the role of these constraints is to force the circuit into a good operation mode.
Consider the following inverter example, the two transistors are “symmetric,” and must be
mutually in opposite configuration or state (linear and subthreshold):
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Optimization
Types of Design Objective
*OPMODE on NMOS and PMOS device
.MODEL MODN NMOS LEVEL=60 VERSION=4.3
.MODEL MODP PMOS LEVEL=60 VERSION=4.3
.PARAM VDD = 5
VDD VDD 0 VDD
Vin VG 0 VIN
M1 VOUT VG 0 0 MODN W=10U L=3U
M2 VOUT VG VDD VDD MODP W=10U L=3U
.DC
.EXTRACT DC LABEL=ID1 I(M1.D)
.EXTRACT DC LABEL=ID2 I(M2.D)
.EXTRACT DC LABEL=VT1 VT(M1)
.EXTRACT DC LABEL=VG1 VG(M1)
.EXTRACT DC LABEL=VT2 VT(M2)
.EXTRACT DC LABEL=VG2 VG(M2)
.EXTRACT DC LABEL=VIN V(VG, 0)
.EXTRACT DC LABEL=VOUT V(VOUT, 0)
.OPTIMIZE
.PARAMOPT VIN=(0,-10,10)
.EXTRACT LABEL=DC1 DC OPMODE(M1) GOAL=SUBTHRESHOLD
.EXTRACT LABEL=DC2 DC OPMODE(M2) GOAL=LINEAR
.END
Related Topics
Minimization and Maximization Objectives
Goal Values Objectives
Range Constraints Objectives
Design Objectives for Multi-Point Simulation
Eldo® User's Manual, 15.3 617

Optimization
Design Objectives for Multi-Point Simulation
Design Objectives for Multi-Point Simulation
This section explains how to specify design objectives based on multi-point simulations for
small-signal analysis and transient analysis. It is not relevant for DC-based design objectives.
It starts by explaining the notion of implicit and explicit data points for multi-point simulations,
then describes how to specify design objectives for multi-point analysis. This section covers:
Implicit and Explicit Data Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618
Specifying Design Objectives with Explicit Data Points . . . . . . . . . . . . . . . . . . . . . . . . . 619
Implicit and Explicit Data Points
Restrictions ensure a reasonable connection is maintained between simulation statements and
optimization objectives. These limitations are based on two categories of multi-point analysis:
analysis with implicit data points, and analysis with explicit data points:
• Transient analysis may have implicit data points where Eldo computes the data points
for accuracy. For example:
.TRAN TPRINT TSTOP [TSTART [HMAX]]
For transient and the small-signal analyses, time and frequency are implicit data points.
• Transient and AC analyses may alternatively have explicit data points where the data
points are specified. For example:
.TRAN DATA=DATA_NAME
The explicit case is favored because it enables the simulation and the optimization commands to
refer to the same list of data. For transient and the small-signal analyses, frequency and time
must be included in the explicit set of simulation data points when optimization is required.
These limitations are related to the algorithm implemented in the Eldo optimizer SQP method.
For more information refer to the topic “Smooth and Non-Smooth Problems” on page 631.
Related Topics
Specifying Design Objectives Using .EXTRACT
Specifying Design Objectives Using .OBJECTIVE
Types of Design Objective
Specifying Design Objectives with Explicit Data Points
Scaling Design Objectives
618
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Optimization
Design Objectives for Multi-Point Simulation
Specifying Design Objectives with Explicit Data Points
This topic describes how to specify design objectives when simulation points are explicitly
specified. It first considers data-driven AC and transient analyses, and then parameter- and listdriven
AC analysis, and transient analysis in HSPICE compatibility mode.
Data-Driven Analysis
Consider data-driven AC and transient analyses where the command matches one of the
following:
.AC DATA=data_name [SWEEP DATA=data_name]
.AC DATA=data_name [SWEEP param_name TYPE nb start stop]
.AC DATA=data_name [SWEEP param_name start stop incr]
.TRAN DATA=data_name [SWEEP DATA=data_name]
.TRAN DATA=data_name [SWEEP param_name TYPE nb start stop]
.TRAN DATA=data_name [SWEEP param_name start stop incr]
In these cases, a GOAL or EQUAL objective statement has the following syntax:
. DATA=OMEGA_DATA(OMEGA)
.DATA OMEGA_DATA
+ OMEGA GOAL_VAL WEIGHT_VAL TYP_VAL
+ OMEGA1 GOAL_VAL1 WEIGHT_VAL1 TYP_VAL1
*... ... ... ...
+ OMEGAP GOAL_VALP WEIGHT_VALP TYP_VALP
.ENDDATA
.OBJECTIVE
+ EXTRACT_INFO [LABEL=NAME]
+ {$MACRO|FUNCTION}
+ OBJECTIVE_INFO
+ [SCALE_INFO]
where the parameter OMEGA is the keyword TIME or FREQ, and:
and:
OBJECTIVE_INFO:=
{GOAL=OMEGA_DATA(GOAL_VAL)|RVALUE} | {EQUAL=OMEGA_DATA(GOAL_VAL)|RVALUE}
[ WEIGHT=OMEGA_DATA(WEIGHT)|RVALUE]
SCALE_INFO:=
TYPVAL=OMEGA_DATA(TYP_VAL) | RVALUE
Using the same .DATA statement in the analysis and the objective statement ensures data
coherency. A scalar value (denoted by RVALUE) can be specified for the GOAL, EQUAL,
WEIGHT and TYPVAL parameters.
Eldo® User's Manual, 15.3 619

Optimization
Design Objectives for Multi-Point Simulation
Note
When WEIGHT and TYPVAL are scalar values, they apply to all lines.
An objective statement with the parameters LBOUND or UBOUND type has the following
syntax:
with:
and:
. DATA=OMEGA_DATA
.DATA OMEGA_DATA OMEGA L_VAL U_VAL WEIGHT_VAL TYP_VAL
+ OMEGA1 L_VAL1 U_VAL1 WEIGHT_VAL1 TYP_VAL1
*...
+ OMEGAP L_VALP U_VALP WEIGHT_VALP TYP_VALP
.ENDDATA
.OBJECTIVE
+ EXTRACT_INFO [LABEL=NAME]
+ {$MACRO|FUNCTION}
+ OBJECTIVE_INFO
+ [SCALE_INFO]
OBJECTIVE_INFO:=
{{LBOUND=OMEGA_DATA(L_VAL)|RVALUE} | {UBOUND=OMEGA_DATA(U_VAL)|RVALUE}}
| {LBOUND=OMEGA_DATA(L_VAL)|RVALUE} {UBOUND=OMEGA_DATA(U_VAL) | RVALUE}
[WEIGHT=OMEGA_DATA(WEIGHT_VAL) | RVALUE]
SCALE_INFO:=
TYPVAL={OMEGA_DATA(TYP_VAL) | RVALUE}
Other Types of Analysis
Consider parameter- and list-driven AC analysis where the command syntax matches one of the
following:
.AC TYPE NB FSTART FSTOP [SWEEP DATA=DATA_NAME]
.AC TYPE NB FSTART FSTOP [SWEEP PARAM_NAME TYPE NB START STOP]
.AC TYPE NB FSTART FSTOP [SWEEP PARAM_NAME START STOP INCR]
.AC LIST {LIST_OF_FREQUENCIES} [SWEEP DATA=DATA_NAME]
.AC LIST {LIST_OF_FREQUENCIES} [SWEEP PARAM_NAME TYPE NB START STOP]
.AC LIST {LIST_OF_FREQUENCIES} [SWEEP PARAM_NAME START STOP INCR]
Alternatively consider transient analysis in HSPICE compatibility mode where the command
matches one of the following:
.TRAN INCR1 T1 [{INCRn Tn}] [TSTART=VAL] [SWEEP DATA=DATA_NAME]
.TRAN INCR1 T1 [{INCRn Tn}] [SWEEP PARAM_NAME TYPE NB START STOP]
.TRAN INCR1 T1 [{INCRn Tn}] [SWEEP PARAM_NAME START STOP INCR]
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Optimization
Scaling Design Objectives
In these cases the objective statement parameters GOAL, EQUAL, LBOUND, UBOUND,
WEIGHT and TYPVAL must be a scalar value or a constant waveform. Refer to “Specifying
Design Objectives Using .OBJECTIVE” on page 608 for more details on these parameters.
When waveforms are used in OBJECTIVE_INFO, the value of the objectives (goal and bounds)
are sampled values of the waveform at simulation points.
It is possible to mix scalar values and waveforms. Specifying LBOUND as a scalar means that
this bound is global.
Related Topics
Implicit and Explicit Data Points
Scaling Design Objectives
Consider the scale of the design objectives, particularly in relation to the stopping conditions
and the computation of derivatives. Differing sizes among the component functions of an
extracted measure F can cause the same types of problems as differing sizes among the
optimization variables.
For instance, if the algorithm requires a decrease in the merit function, and it is clear that if the
units of two component functions of F(x) are widely different, then the smaller component
function is virtually ignored. For this reason, the Eldo optimizer algorithms also use a positive
diagonal scaling matrix Df on the design objectives F(x), which works as D does on x.
The diagonal matrix Df is chosen so that all the components of Df . F(x) will have a similar
magnitude. You can specify an initial Df using the parameter TYPVAL. The algorithm then
sets:
The result of this scaling procedure is described in the output file .otm, in the section headed
Section 1- Scaling Transformation Design Objectives. Refer to “ASCII Optimization File
Contents” on page 643 for more information.
Related Topics
Specifying Design Objectives Using .EXTRACT
Specifying Design Objectives Using .OBJECTIVE
Types of Design Objective
Design Objectives for Multi-Point Simulation
Eldo® User's Manual, 15.3 621

Optimization
Optimization Methods
Optimization Methods
This section provides an overview of the SQP and Search .OPTIMIZE methods and their
parameters:
• Eldo Optimizer SQP Algorithm
• Eldo Optimizer/Search Algorithm
The other group of methods (Dichotomy, Secant, and Passfail) represents a specific class of
algorithms categorized as Derivative Free Optimization (DFO) algorithms. They enable
optimization in the restricted case of one-dimensional problems. Refer to Eldo Optimizer/
Dichotomy/Secant/PassFail Parameters in the Eldo Reference Manual to set-up a measurement
with Eldo using these methods.
Tip
Refer to .OPTIMIZE in the Eldo Reference Manual for a complete description of the
command syntax and parameters.
See also:
• “Optimization in Eldo” on page 589
• “Design Variables” on page 594
• “Conducting an Eldo Optimization” on page 629
• “Post-Analysis of Optimization Simulations” on page 639
• “Examples of Circuit Optimization” on page 664
Eldo Optimizer SQP Algorithm
The Eldo optimizer SQP method optimizer is based on a Sequential Quadratic Programming
method (SQP), using an active-set algorithm for solving large-scale quadratic programming
problems.
The active-set algorithm (proposed by Fletcher [2]) is efficient for solving a large class of
smooth optimization problems belonging to the following list:
• Unconstrained and bound constrained problems (using only the statements
GOAL=MINIMIZE|MAXIMIZE and GOAL=RVALUE).
• Systems of non-linear equations (using only the statement EQUAL=RVALUE).
• General (equality and inequality) constrained problems.
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Optimization
Eldo Optimizer SQP Algorithm
Refer to Nocedal and Wright [5], and Fletcher [3] for recent books giving a broader view of
optimization techniques. For more advanced books consult Bonnans, Gilbert, Lemarechal and
Sagastizabal [1] and Gill, Murray and Wright [4].
The design variables are denoted by:
x =(x (1) , x (2) , ... , x (N) )
a vector of real numbers of dimension N. Therefore the space of variables is denoted by R N . The
scalar product is denoted by:
onto the space R Ν , and its associated norm is ||u||.
A simplified structure of the kth iteration can be depicted as:
1. Step Computation: determine a direction of search s k (by solving a tangent quadratic
subproblem (QP) k
2. Step Assessment: find α k > 0 to minimize a chosen merit function x → Φ(x) along the
line α→ x k + αs k
3. Update: x k+1 = x k + α k s k
This approach is referred to as a descent method since the search direction s k satisfies a descent
property:
where the vector:
represents the gradient of the chosen merit function. The role of the line search algorithm is to
dampen the displacement s k .
During the optimization process, simulations are required at two distinct stages:
• The computation of derivatives of the extracted measures involved in the problem
statement.
• The step assessment procedure, or line search algorithm.
Eldo® User's Manual, 15.3 623

Optimization
Eldo Optimizer SQP Algorithm
Role of Tolerances in the Eldo Optimizer SQP Method
This topic describes the role of the parameters TOL_GRAD, TOL_FEAS and TOL_OPT.
For more information on these parameters, see Eldo Optimizer/SQP Parameters in the Eldo
Reference Manual.
Suppose a value of x that is a local minimizer of f(x) in the interval a ≤ x ≤ b is to be obtained:
Minimize: f(x)
Subject to: a ≤ x ≤ b
Or using a SPICE formulation:
.OPTIMIZE
* Minimize Statement
.OBJECTIVE EXTRACT_INFO LABEL=F
+ {$MACRO|FUNCTION}
+ GOAL=MINIMIZE
* Design variable specification
.PARAMOPT X=(X0, A, B)
The optimality conditions OPTIM(x) in the definition of the TOL_GRAD parameter are listed
in Table 13-2:
Table 13-2. Optimality Conditions
OPTIM(x) x
f’(x)
a < x < b
min(f’(x), 0) x = a
max(f’(x),0) x = b
Consider the first case in Figure 13-3. The minimum is the point x = b. The blue vector
represents the derivative f’(x) at point b. The derivative f’(x) is negative, so max(f’(x), 0) = 0. A
zero or very small OPTIM(x) indicates that the point x is an optimum. The number TOL_GRAD
is used in the stopping test of the Eldo optimizer SQP method. The point x is optimal when the
absolute value of OPTIM(x) is less than TOL_GRAD.
Consider the second case in Figure 13-3. Point y is an unconstrained minimizer of f, since it lies
strictly in the interval [a, b]. The optimality condition is then OPTIM(y) = f’(y) which is the
slope of f at point y. Here OPTIM(y) equals zero.
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Eldo® User's Manual, 15.3

Figure 13-3. Illustration of Optimality Conditions
Optimization
Eldo Optimizer SQP Algorithm
Note
Previous definitions of the optimality conditions related only to bound constraint
minimization problems. The conditions OPTIM(x) have been extended to more general
problems that the Eldo optimizer SQP method can handle.
In many cases the function values are the result of extensive computation, possibly involving an
iterative procedure that can provide a few digits of precision at reasonable cost.
Suppose that a constraint function c (i) (x) is computed for some relevant x and the first six digits
are known to be correct. A constraint is considered as active at its upper bound (or lower bound)
if the difference between the values c (i) (x) and c (i) u (or c (i) l respectively) is less than some
tolerance of order 1.0 × 10 −6 .
This tolerance, δ, specifies how accurately the constraints are satisfied. It defines the maximum
absolute violation in non-linear constraints at a feasible point. A constraint is considered
satisfied if its violation does not exceed the tolerance δ.
The feasible region for the constraints c l (i) ≤ c (i) (x) ≤ c u (i) is shown in Figure 13-4.
Figure 13-4. Illustration of Constraints
The constraints are considered satisfied if c (i) (x) lies in the region 2, 3 or 4, and inactive if c (i) (x)
lies in region 3. The constraint c (i) l ≤ c (i) (x) is considered active in region 2, and violated in
region 1. Similarly, c (i) (x) ≤ c (i) u is active in region 4, and violated in region 5. For equality
constraints c
(i)
l = c (i) u , regions 2 and 4 are the same, and region 3 is empty. The default value is
appropriate when the constraints contain data about the accuracy.
Eldo® User's Manual, 15.3 625

Optimization
Eldo Optimizer/Search Algorithm
Note
Specifying an appropriate tolerance on feasibility TOL_FEAS may lead to several savings
by enabling the optimization procedure to terminate when the difference between function
values along the search direction becomes as small as the absolute error in the values.
Computation of Finite-Difference Derivatives
One of the most demanding phases in terms of simulation is the computation of derivatives. The
Eldo optimizer uses finite differences; an approach to calculating the approximate derivatives
coming from Taylor’s theorem. Like many software tools, the Eldo optimizer performs
automatic calculation of finite differences whenever the simulator is unable to supply the code
to compute exact derivatives.
A popular formula for approximating the partial derivative ∂F/∂x at a given point is forward
differences or one-sided differences. The parameter h f controls the interval used to estimate the
gradients of the function F by forward differences:
One-sided difference estimates are used to ensure feasibility with respect to an upper or lower
bound on x. If x is close to an upper bound, the trial intervals will be negative. The final interval
is always positive.
• An approximation to the derivative of F is obtained by evaluating the function F at N + 1
points and performing some elementary arithmetic.
• The resulting gradient estimates should be accurate to O(h f ) unless the functions are
badly scaled.
Related Topics
Eldo Optimizer/Search Algorithm
Eldo Optimizer/Search Algorithm
The Search method is efficient for solving minimization optimization problems that are onedimensional.
This method belongs to the class of derivative free optimization (DFO) algorithms that are
dedicated to solving problems having one variable and one extracted measure. The Dichotomy
and Secant methods also belong to this class. The search method runs faster than the Dichotomy
method and is more robust than the modified Dichotomy (the Eldo optimizer/Secant) method.
Search is based on two distinct algorithms: FIND_ZERO and FIND_MINIMUM.
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Optimization
Eldo Optimizer/Search Algorithm
The algorithm FIND_ZERO aims to find a solution to:
Find x such that F(x) = 0, where a ≤ x ≤ b.
Using a SPICE formulation:
.OPTIMIZE METHOD=SEARCH
* Design variable specification
.PARAMOPT X=(X0, A, B)
* Goal value
.OBJECTIVE LABEL=F_R GOAL=R
Note
Specifying a weight number with WEIGHT=μ r is allowed, however, it is not considered. A
warning message is generated.
F(x) = f r (x) − r defines the difference between the actual measure f r and the goal value r.
The search method enables you to specify an initial guess point to locate an interval for a
solution if one has not been specified:
• When the interval [a, b] is not known, a guess point x0 must be specified with the
.PARAMOPT command: .PARAMOPT x=(x0,*,*). The method initially invokes a
search phase to find an interval for locating a solution.
• When the interval [a, b] is specified, the guess point is not used and the method directly
starts the search for a solution.
The FIND_ZERO algorithm uses a combination of dichotomy, secant, and inverse quadratic
interpolation methods. It defines a zero as a point where the function crosses the x-axis. Points
where the function touches but does not cross (see Figure 13-5) the x-axis are not valid zeros.
For example, F(x) = x 2 is a parabola that touches the x-axis at (0, 0). Since the function never
crosses the x-axis, no zero is found. For functions with no valid zeros, FIND_ZERO executes
until an undefined value is detected.
Figure 13-5. Non-Valid and Valid Zeros
Eldo® User's Manual, 15.3 627

Optimization
Eldo Optimizer/Search Algorithm
The algorithm FIND_MINIMUM attempts to return a value of x that is a local minimizer of F(x)
in the interval a ≤ x ≤ b:
Minimize F(x) = 0, where a ≤ x ≤ b.
The algorithm is based on the golden section search and parabolic interpolation techniques.
Related Topics
Eldo Optimizer SQP Algorithm
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Conducting an Eldo Optimization
Optimization
Conducting an Eldo Optimization
This section discusses specific types of optimization problem and explains the options available
to influence the behavior of the optimizer in each of these cases. It covers:
Global and Local Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Continuous and Discrete Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630
Smooth and Non-Smooth Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631
Multiple-Run Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
Optimization of Sweep Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 633
Global and Local Optimization
The fastest optimization algorithms only search for a local solution at a point at which the
objective function is smaller than all other feasible points in its vicinity. They do not always
find the best of all such minima, that is the global solution. Practical methods for finding global
optima are currently too expensive in all but the most specialized cases.
Figure 13-6 shows local and global solutions.
Figure 13-6. Different Types of Minima
General non-linear problems may possess local solutions that are not global solutions. Global
solutions are highly desirable, however, they are usually difficult to identify and even more
difficult to locate. Unless very strong assumptions are made about the functions that define the
optimization problem in question, characterizations of global minima are almost impossible.
Note
The Eldo Optimizer SQP Algorithm is based on Newton iterations. It is not able to combine
local and global searches, and only finds local solutions.
Related Topics
Design Variables
Design Objectives
Eldo® User's Manual, 15.3 629

Optimization
Continuous and Discrete Optimization
Optimization Methods
Post-Analysis of Optimization Simulations
Examples of Circuit Optimization
Continuous and Discrete Optimization
In some optimization problems, the variables can only take integer or discrete real values. The
obvious strategy is to ignore the integrality requirement, solving the problem with real
variables. However, rounding all the components to the nearest integer is not guaranteed to
provide an optimal solution. Problems of this type should be handled using discrete
optimization tools. The mathematical formulation is changed by adding the constraint “x i is an
integer for all i in K, where K is a subset of {1, ..., N}”.
Continuous optimization problems are easier to solve. The smoothness of the functions makes it
possible to use function and constraint information at a particular point x to deduce a function’s
behavior at all points close to x.
The same statement cannot be made about discrete problems where nearby points may have
markedly different function values. Moreover, the set of possible solutions is too large to make
an exhaustive search for the best value in this finite set. Models that contain some variables
which are allowed to vary continuously and others that can attain only integer values are
referred to as mixed-integer programming problems (MIP).
The Eldo optimizer can only handle non-linear problems (NLP) with continuous variables. The
increment parameter in the .PARAMOPT command is used to define a grid of feasible integer
points with uniform steps. A strategy is used which ignores the discretization requirement—it
solves the problem with real variables and then rounds all the components to the nearest point
onto the grid at the end of optimization. This strategy is based on the assumption that the
increment value is sufficiently small. The problem solved by the optimizer is a continuous
relaxation of the original MIP problem where the constraints of integrality on variables are
simply relaxed.
Related Topics
Global and Local Optimization
Smooth and Non-Smooth Problems
Multiple-Run Compatibility
Optimization of Sweep Simulations
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Smooth and Non-Smooth Problems
Optimization
Smooth and Non-Smooth Problems
When the functions corresponding to the design objectives do not have continuous derivatives
or are not continuous at all, methods for smooth problems (such as the Eldo optimizer SQP
algorithm) will encounter difficulties.
Figure 13-7. Examples of Non-Smooth Problems
It is assumed that the functions are continuous, with continuous derivatives on some domain (or
sufficiently smooth). Figure 13-7 illustrates some of these difficulties:
• Noisy function
The overall trend is plotted with dashed lines. It is related to the effect of features such
as adaptive algorithms and stopping tests in iterative methods inside the simulation. The
noise is not stochastic in such situations.
The Eldo optimizer SQP method will fail to make any progress because local descent
directions may point uphill.
• Non-smooth minimum (not differentiable)
Functions such as ABS(.), MIN(.) or MAX(.) that are not differentiable in the common
sense can represent minor difficulties when you only want to improve the current
solution rather than optimization at full-blown optimality.
• Discontinuous
This leads to serious difficulties. It usually involves functions that are not numerical in
nature, or the discontinuities may be the result of features such as table look-ups and
switches.
• Undefined
Eldo® User's Manual, 15.3 631

Optimization
Multiple-Run Compatibility
This leads to serious difficulties. It may be the result of unexpected failures of the
simulation or undefined extracted measures.
Related Topics
Global and Local Optimization
Continuous and Discrete Optimization
Multiple-Run Compatibility
Optimization of Sweep Simulations
Multiple-Run Compatibility
The .OPTIMIZE command is compatible with the multiple-run features (.MPRUN). If
.OPTIMIZE is specified together with option OPSELDO_ALTER, Eldo emulates a .MPRUN
command using all the default values. If the netlist contains a .MPRUN command, then Eldo
uses the parameter values specified in the netlist.
Related Topics
Global and Local Optimization
Continuous and Discrete Optimization
Smooth and Non-Smooth Problems
Optimization of Sweep Simulations
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Optimization of Sweep Simulations
Optimization
Optimization of Sweep Simulations
The following topics explain how the optimizer behaves during a sweep analysis, and the
options available to influence that behavior. They introduce the notion of sweep parameters and
their role in the optimization process.
The circuit parameters that are to be adjusted (such as width and length for MOS) should be
considered separately from those associated with DC multi-point, transient, small-signal,
frequency, or parametric analysis. The former are known as design variables and the latter
design parameters.
During a sweep analysis, the design parameters are a real-valued set Ω of user-defined
discretizations. These are known as sweep parameters and are denoted by the Greek letter ω.
Sweep parameters ω vary only within the simulator. They are not affected by the optimization
algorithm. The parameter set Ω can be discretized using .TEMP, .DATA, and .STEP
commands. For example, the Voltage-Temperature parameters temperature-voltage (TEMP,
PVDD):
.STEP TEMP -25 150 5
.STEP PARAM PVDD 2.7 3.3 0.1
define a cartesian product or a box Ω = [-25, 150] × [2.7, 3.3] in the 2-dimensional space R 2 .
An example of a 2-dimensional domain Ω is shown in Figure 13-8. It is obtained from the
multi-step specification:
* Sweep parameters
.STEP PARAM OMEGA_1 omega1_start omega1_end omega1_step
.STEP PARAM OMEGA_2 omega2_start omega2_end omega2_step
Figure 13-8. Discretization of Design Parameters
Eldo® User's Manual, 15.3 633

Optimization
Optimization of Sweep Simulations
The extracted measure F is a bidimensional object of size defined by the range of the .STEP
statements. Given the values of the variables x (fixed during each simulation), the simulator
returns a value f = f(x; ω (1) , ω (2) ) for each discretized point (ω (1) , ω (2) ) of the domain Ω.
See also:
• “Global and Local Optimization” on page 629
• “Continuous and Discrete Optimization” on page 630
• “Smooth and Non-Smooth Problems” on page 631
• “Multiple-Run Compatibility” on page 632
Inner and Outer Sweep Parameters
Consider the following minimization problem with respect to the x variable, where the design
parameter ω belongs to the interval Ω = [ω start , ω end ].
A formal circuit formulation example is:
.PARAMOPT X=(XINIT, XL, XU)
.STEP PARAM OMEGA OMEGA_START OMEGA_END OMEGA_INCR
.OBJECTIVE
+ EXTRACT_INFO LABEL=f
+ {$MACRO|FUNCTION}
+ GOAL=MINIMIZE
.OPTIMIZE
The strings XINIT, XL, and XU represent: the initial value of the design variable x, its lower
bound, and its upper bound. Refer to “Specifying Design Variables” on page 596 for more
information.
The example optimization statements can be understood in two different ways:
• The optimizer seeks the smallest value of the function:
such that the value of x is within the interval [x l , x u ]. This case is represented in the right
branch of Figure 13-9. Here the design parameter ω is handled as an inner sweep
parameter.
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Optimization
Optimization of Sweep Simulations
• The optimizer seeks the smallest value of f(x, ω i ) with respect to the fixed design
variables x for each of the discretized values within the interval Ω = [ω start , ω end ]. This
case is represented in the left branch of Figure 13-9. Here the design parameter ω is
handled as an outer sweep parameter.
Figure 13-9. Inner and Outer Sweep Parameters
Related Topics
Specifying Outer Design Parameters
Hierarchy and Depth of Sweep Parameters
Specifying Outer Design Parameters
You can specify a design parameter as outer using the OUTER parameter in the .OPTIMIZE
command or the OPSELDO_OUTER option. The former provides better control over the outer
parameters.
Eldo® User's Manual, 15.3 635

Optimization
Optimization of Sweep Simulations
Using the OUTER Parameter To Specify Outer Design Parameters
By default, the parameters specified with a .PARAM command are inner design parameters.
Use the OUTER parameter in the .OPTIMIZE command to specify one or more parameters as
outer. The command syntax is:
.OPTIMIZE
+ [QUALIFIER=VALUE {, QUALIFIER=VALUE}]
+ [PARAM=LIST_OF_VARIABLES|*]
+ [RESULTS=LIST_OF_MEASURES|*]
+ [OUTER=LIST_OF_PARAMETERS|*]
There are some rules associated to the OUTER parameter:
• The order of the design variables specified within the list of parameters
LIST_OF_PARAMETERS has no precedence over the order specified in the netlist.
• The OUTER parameter is not considered when the OPSELDO_OUTER is active and all
the parameters are outer.
• The OUTER parameter specification is not valid for .STEP commands using the library
(corners) or temperature sweeps variants.
For example:
.OPTION OPSELDO_OUTER
.STEP PARAM P1
.STEP PARAM P2
Both parameters are outer parameters:
.STEP PARAM P1
.STEP PARAM P2
.OPTIMIZE OUTER=P2
The parameter P2 is the only candidate for the outer loop.
If the parameter of the .OPTIMIZE command is:
.OPTIMIZE OUTER=P2,P1
Then the parameter P1 would still be the outer-most within the outer loop as this is the order of
the .STEP PARAM commands.
A full optimization is performed for each outer design parameter.
Using the OPSELDO_OUTER Option To Specify Outer Design Parameters
It is also possible to reverse the behavior of optimization and sweep simulations using the
OPSELDO_OUTER option. When specified, the sweep on all design parameters becomes outer
with respect to the optimization process. An outer sweep is performed on the complete set of the
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Optimization
Optimization of Sweep Simulations
parameters involved in the .STEP, .DATA and .TEMP commands, and a sequence of
optimizations is launched, one for each of the discretized values in the sweep domain.
Note
When the OPSELDO_OUTER is active, the OUTER parameter in the .OPTIMIZE
command is ignored.
Related Topics
Inner and Outer Sweep Parameters
Hierarchy and Depth of Sweep Parameters
Hierarchy and Depth of Sweep Parameters
The hierarchy (or the default order of precedence) of the commands that define the variation of
the parameters is given by the following:
• Several .ALTER blocks with the label denoted by A 1 , A 2 , and so on.
• A .TEMP command or a .STEP command on temperature:
.TEMP T1 T2 ...
.STEP TEMP T_START T_STOP T_INCR
• A .STEP command using different variants of libraries (or corners K):
.LIB mylib TYP
.STEP LIB(mylib) K1 K2 ...
• A .STEP command on circuit parameters:
.STEP PARAM ALPHA ALPHA_START ALPHA_STOP ALPHA_INCR
• Multiple sweeps or nested sweeps on parameters, and a parameter sweep in the analysis
command. These parameters are denoted by a, b, and so on. The cases of DC, AC and
transient analyses are represented by the command syntax:
.{AC | TRAN} SWEEP DATA=DATA_SWEEP
.DC SWEEP DATA=DATA_SWEEP
where a two parameter sweep is defined with:
Eldo® User's Manual, 15.3 637

Optimization
Optimization of Sweep Simulations
.DATA DATA_SWEEP ALPHA BETA
+ ALPHA1 BETA1
+ ALPHA2 BETA1
*...
+ ALPHAM BETA1
+ ALPHA1 BETA2
*...
+ ALPHAM BETA2
*...
+ ALPHAM BETAP
.ENDDATA
• A DC data-driven analysis:
.DC DATA=DATA_SWEEP
• Transient and frequency analyses. The time and frequency parameters are denoted by
the symbol ω.
A design objective F can be represented as a family of real-valued functions of variables x. This
family is parameterized with points that were denoted by A, T, K, α, β, ..., ω.
The parameter ω is the inner-most parameter and the .ALTER label A is the outer-most
parameter.
This convention aims to fit with the order of the simulations. The simulator provides this
hierarchy to the optimizer for specifying the depth of a design parameter. It is used in printing
routines and in optimization algorithms.
You can change the depth of a design parameter defined in a .STEP PARAM or .STEP TEMP
command. Refer to “Inner and Outer Sweep Parameters” on page 634 for more information.
When at the same hierarchical level, the order of precedence of the design parameters is defined
by the simulator. For example, when the netlist contains the following statements, the parameter
α will be the outer-most and β the inner-most:
.STEP PARAM ALPHA
.STEP PARAM BETA
Related Topics
Inner and Outer Sweep Parameters
Specifying Outer Design Parameters
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Optimization
Post-Analysis of Optimization Simulations
Post-Analysis of Optimization Simulations
After the optimization has been conducted, the next step is to recognize whether it has
succeeded in its task of finding a solution.
The only way to check for success is to measure optimality and feasibility at the final solution.
If the optimality measure is less than the specified tolerance, the current point is considered as
optimal. For more information please refer to “Role of Tolerances in the Eldo Optimizer SQP
Method” on page 624.
This can be accomplished by analyzing the results of the optimization. There are two areas to be
analyzed:
• Whether the current set of variables are a solution to the problem. If the optimal
conditions are not satisfied, these may provide some useful information on how the
current estimate of the solution can be improved. Think of this as a global score of the
optimization run.
• The values of the extracted measures printed at the end of the process. This represents
the post-optimization analysis.
This section explains:
Output from the Optimization Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
Explicitly Declaring Results For Graphical Viewing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641
Viewing the ASCII Output File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 642
ASCII Optimization File Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643
Monitoring Design Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653
Final Diagnostic Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 656
Normal and Elastic Modes of Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659
Output from the Optimization Process
The results of an optimization are provided in two ways, ASCII and graphical outputs:
• ASCII Output (.otm)
The .otm optimization output file is useful for recognizing whether an optimization has
succeeded in its task of finding a solution. It is a structured text file separated into
sections and subsections. It uses a technique known as folding, enabling you to filter out
one or more sections. You can get a better overview of the results text by folding lines of
a section to omit them.
By default, the output file is generated in the same directory from where eldo is run and
is named .otm, where is the name of the simulation
command file.
Eldo® User's Manual, 15.3 639

Optimization
Output from the Optimization Process
For example, executing the following command:
eldo lnaopt.cir
generates an optimization output file named: lnaopt.otm
Refer to “Viewing the ASCII Output File” on page 642.
Note
Section 2 - Status Of Variables and Section 3 - Status Of Objectives can also be
found in a section called Results of Optimization that is towards the end of the
standard Eldo simulation log file (.chi).
• Graphical Output
The optimizer also produces binary waveform files (.swd and .wdb). These contain
extracted waves generated during the optimization process which can be viewed using
the EZwave viewer. These implicitly declared waves have the same name as the extract
label they refer to. They represent extract results versus the index of the run.
Use the .PLOT command to explicitly declare results for graphical viewing.
Related Topics
Design Variables
Design Objectives
Optimization Methods
Conducting an Eldo Optimization
Examples of Circuit Optimization
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Optimization
Explicitly Declaring Results For Graphical Viewing
Explicitly Declaring Results For Graphical Viewing
Use the .PLOT command to explicitly declare results for graphical viewing.
Syntax
.PLOT OPT WOPT(label_name) [(LOW, HIGH)] [(VERSUS)]
+ {OVN [(LOW, HIGH)]} [(SCATTERED)]
Parameters
• OPT
Specifies an optimization analysis. The waves produced by this analysis can only be
specified using the keyword WOPT.
• WOPT
Only available for extracting waves generated during an optimization process. These are
implicitly declared waves which have the same name as the extract label they refer to. They
represent extract results versus the index of the run.
Examples
.EXTRACT tran label=FOO yval(v(node),3n) !Define the extract
.PLOT OPT WOPT(FOO)
Related Topics
Output from the Optimization Process
Viewing the ASCII Output File
ASCII Optimization File Contents
Monitoring Design Objectives
Final Diagnostic Conditions
Normal and Elastic Modes of Termination
Eldo® User's Manual, 15.3 641

Optimization
Viewing the ASCII Output File
Viewing the ASCII Output File
The ASCII results from the optimizer output file (.otm) can be viewed by running the utility
named viewotm. This utility can be invoked from the command line as follows:
Syntax
viewotm [-l d] -f file.otm
Parameters
• -l d
Specifies the level of detail to view, from 1 to 5. Level 1 (default) gives the least detail while
level 5 gives the most.
-l 1
A summary of the results of the optimization is displayed (merit function, values of
the variables, and the objectives)
-l 2
Some additional information relating to the initialization phase is displayed.
-l 3, 4, or 5
The information displayed is progressively more detailed.
When an outer loop has been performed, the amount of data can be very large. In this case
level 1 only reports the simplified results in a table at the end of the .otm file. An example is
given in “Solving Problems with Pseudodiscrete Variables” on page 668.
• -f
Name of the .otm file to be displayed.
Related Topics
Output from the Optimization Process
Explicitly Declaring Results For Graphical Viewing
ASCII Optimization File Contents
Monitoring Design Objectives
Final Diagnostic Conditions
Normal and Elastic Modes of Termination
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Optimization
ASCII Optimization File Contents
ASCII Optimization File Contents
This section describes the content of the optimization file (.otm) in detail. The file is divided
into main sections, each with their own subsections:
• Initialization of Problem Data
• Optimization Phase
• Optimization Results
• Optimization Results with Respect to the Outer Loop
The level of the output is controlled by the parameter PRN_VAL (see “Specifying Design
Objectives Using .OBJECTIVE” on page 608).
Initialization of Problem Data
The first section of the optimization file (.otm), related to the initialization of problem data, is
divided into further subsections.
Section 1 - Scaling Transformation For Design Objectives
• Formula — Scaling formula, for example: Scaled Obj = DF * Simulated Obj.
• Type — Type of objective.
• Name — Label given to the objective.
• DF Factor — Magnitude factor.
• Weight — Weighting number.
• Rel Wght — Relative weight.
Eldo® User's Manual, 15.3 643

Optimization
ASCII Optimization File Contents
Figure 13-10. Scaling Transformation For Design Objectives Output
Section 2 - Scaling Transformation For Variables
• Formula — Scaling formula, for example: Scaled Var = D * Prob Var - C.
• Name — Label given to the design variable.
• Init Value — Initial value of the variable.
• Increment — Uniform increment on the grid.
• Scal Value — Scaled value.
• D Factor — Amplitude factor.
• C Parameter — Centering parameter.
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ASCII Optimization File Contents
Figure 13-11. Scaling Transformation for Variables Output
Note
The example in Figure 13-11 is cropped for readability.
Related Topics
Optimization Phase
Optimization Results
Optimization Results with Respect to the Outer Loop
Optimization Phase
The second section of the optimization file (.otm) is related to the optimization phase.
• Algorithm — Optimization algorithm.
• Control parameters — Control parameters for the optimization.
• Number of connected simulators — Number of simulators that are in use.
• Dimension of the aggregated problem
o
o
o
o
o
o
Number of variables — Number of design variables.
Fixed variables — Number of variables which are fixed.
Bounded variables — Number of design variables which are bounded.
Number of goals — Number of objective goals.
Equality constraints — Number of goals which are equality constraints.
Inequality constraints — Number of goals which are inequality constraints.
Eldo® User's Manual, 15.3 645

Optimization
ASCII Optimization File Contents
• Iter — Major iteration number.
• Simul — Cumulative number of simulations performed at the current iteration.
• LS Step — The step length α k taking the direction s k at the kth iteration. This step length
is used to update the current iterate with the formula: x k+1 = x k + α k s k .
• Merit Function — Value of the merit function.
• Feas — Measure of feasibility. Will be small in the vicinity of a solution.
• Optim — Measure of optimality. Will be small in the vicinity of a solution.
• Slack — Norm of the slack variables added to the range constraints to prevent a
potential inconsistency.
Figure 13-12. Optimization Phase Output
Related Topics
Output from the Optimization Process
Explicitly Declaring Results For Graphical Viewing
Viewing the ASCII Output File
Initialization of Problem Data
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Optimization
ASCII Optimization File Contents
Optimization Results
Optimization Results with Respect to the Outer Loop
Optimization Results
The third section of the optimization file (.otm), related to the optimization results, is divided
into further subsections.
Section 1 - Statistics and Diagnostics
• Number Of Iterations — Total number of iterations of the optimization.
• Number Of Simulations — Total number of simulations during the optimization.
• Merit Function — Final value of the merit function.
• Optimality — Final measure of optimality.
• Feasibility — Final measure of feasibility.
• Final Diagnostics — Finishing status code.
• Final running mode — Indication of whether the optimization ran normally.
• Global elapsed time — Time the optimization took to run.
Figure 13-13. Statistics and Diagnostics Output
Eldo® User's Manual, 15.3 647

Optimization
ASCII Optimization File Contents
Section 2 - Status Of Variables
• Name — Name of the design variable.
• Status — Status of the design variable from:
o
o
o
o
o
FR — Always free
FX — Always fixed
LWR — At lower bound
UPR — At upper bound
BND — Free and bounded
• Init Value — Initial continuous value of the design variable.
• Final Value — Best continuous value of the design variable found so far.
• Lower Bound — Lower bound of the design variable.
• Upper Bound — Upper bound of the design variable.
• Discr Value — Discretized value of the design variable.
Figure 13-14. Status of Variables Output
Note
The example in Figure 13-14 is cropped for readability.
Section 3 - Status Of Objectives
• Type — Type of objective.
• Name — Name of the objective.
• Init Value — Initial value of the objective.
• Opt Value — Current value of the objective.
• Rel Wght — Relative weight.
• Rel Chg — Relative change from initial value (as a percentage).
• Goal Objectives and Equality Constraints
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o
o
Goal Value — Goal value of the objective.
Abs Error — Absolute error of the objective from the goal value.
• Inequality Constraints
o
o
o
Violation — Indication of a violation on the constraint.
Lower Bnd — Lower bound on objective.
Upper Bnd — Upper bound on objective.
Optimization
ASCII Optimization File Contents
The inequality constraints (with LBOUND and UBOUND parameters) are printed with an
additional status represented by a symbol “***” if the constraint violation is non zero. This
symbol is printed to indicate that the initial or the final objectives are not satisfied.
Figure 13-15. Status of Objectives Output
Note
The example in Figure 13-15 is cropped for readability.
Section 4 - Analysis Of Last Simulation
• Type — Type of design objective.
• Name/Index — Label given to the d=objective.
Eldo® User's Manual, 15.3 649

Optimization
ASCII Optimization File Contents
• Opt/Final Value — Final value of the objective.
• Discr Value — Objective value after discretization.
• Rel Diff — Relative difference between final and discretization value (as a percentage).
• Goal Objectives and Equality Constraints
o
o
Opt/Final Err — Error value of the goal.
Discr Err — Error after discretization.
• Inequality Constraints
o
o
o
o
Opt/Final Viol — Indicates a violation on the constraint.
Discr Viol — Indicates a violation after discretization.
Lower Bnd — Lower bound on the objective.
Upper Bnd — Upper bound on the objective.
Figure 13-16. Analysis Of Last Simulation Output
Note
The example in Figure 13-16 is cropped for readability.
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Optimization
ASCII Optimization File Contents
Related Topics
Initialization of Problem Data
Optimization Phase
Optimization Results with Respect to the Outer Loop
Optimization Results with Respect to the Outer Loop
The fourth section of the optimization file (.otm) is related to the optimization results with
respect to the outer loop.
• Run — Run number.
• Iter — Major iteration number.
• Simul — Cumulative number of simulations performed at the current iteration.
• Merit Function — Value of the merit function.
• Feas — Measure of feasibility. Will be small in the vicinity of a solution.
• Optim — Measure of optimality. Will be small in the vicinity of a solution.
• Slack — Norm of the slack variables added to the range constraints to prevent a
potential inconsistency.
• Outer Parameters — Values of the outer parameters for this run. Displayed only when
outer loops are performed.
Figure 13-17. Optimization Results with Respect to the Outer Loop Output
Note
The example in Figure 13-17 is cropped for readability.
Eldo® User's Manual, 15.3 651

Optimization
ASCII Optimization File Contents
Related Topics
Initialization of Problem Data
Optimization Phase
Optimization Results
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Optimization
Monitoring Design Objectives
Monitoring Design Objectives
The information in the .otm file can be enriched. Additional columns labelled with the name of
a design objective can be printed during the optimization process, enabling you to monitor the
optimization process more closely.
This is achieved through specifying the parameter MONIT_VAL=QUALIFIER within the
.OBJECTIVE command. This parameter specifies how the current values of a design objective
are printed during optimization. Multiple options are allowed and these should be separated by
commas. The default value is MEAN.
Note
When a design objective is represented by a single value, this value is printed as a raw
number.
This section uses examples to examine:
Monitoring Goal Value Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653
Monitoring Minimize and Maximize Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 654
Monitoring Bound Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655
Monitoring Goal Value Objectives
Consider the GOAL objective statement for example:
.OBJECTIVE DC LABEL=FIT_IDRAIN I(V101)
+ GOAL=DATA_D25X25(IDS) TYPVAL=1E-4 MONIT_VAL=ERRMEAN
The output would look like:
The options that are available are:
• MONIT_VAL=MEAN, the printed value will be the sum , which is the
mean value of the functions f (k) r (x).
Eldo® User's Manual, 15.3 653

Optimization
Monitoring Design Objectives
• MONIT_VAL=MAX or MONIT_VAL=MIN, the printed value will be the maximum
Max{f r (k) (x)} or the minimum Min{f r (k) (x)}.
• MONIT_VAL=ERRMEAN, the printed value will be the sum
of the squared residuals.
• MONIT_VAL=ERRMAX or MONIT_VAL=ERRMIN, the printed value will be the
maximal error function Max{|f (k) r (x) − r (k) |} or the minimal error function Min{|f (k) r (x) −
r (k) |}.
Related Topics
Design Objectives
Output from the Optimization Process
Explicitly Declaring Results For Graphical Viewing
Viewing the ASCII Output File
ASCII Optimization File Contents
Final Diagnostic Conditions
Normal and Elastic Modes of Termination
Monitoring Minimize and Maximize Objectives
When the design objectives are specified as MINIMIZE and MAXIMIZE there is no error
function associated with the objectives.
Consider the following netlist as a basic example:
* Design parameter (temperature)
.STEP TEMP -25 150 5
* Design variable specification
.PARAMOPT x = (x0,a,b)
* Minimization
.OBJECTIVE EXTRACT_INFO LABEL=f_m {$MACRO|FUNCTION}
+ GOAL=MINIMIZE MONIT_VAL=ERRMEAN
This will minimize the functions f m (x; T k ) with respect to design variable x which is subject to
the constraints a ≤ x ≤ b, where T k represents a point of discretization in the temperature interval
[-25, 150].
You can monitor the mean value or the max/min values of these types of objectives:
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Optimization
Monitoring Design Objectives
• MONIT_VAL=MEAN, the printed value will be the sum .
• MONIT_VAL=MAX or MONIT_VAL=MIN, the printed value will be the maximum
Max{f r (k) (x)} or the minimum Min{f r (k) (x)}.
Related Topics
Monitoring Goal Value Objectives
Monitoring Bound Objectives
Optimization Methods
Monitoring Bound Objectives
Consider the case of objectives bound by inequality constraints. The notion of error functions
can be extended to this case. These functions are called the violation associated to a constraint.
Consider a group of range constraints:
l (k) ≤ f r (k) (x) ≤ u (k)
the maximum violations v u and v l are defined as follows:
v u (k) = max{0, f i (k) (x) − u (k) }
and
v l (k) = max{0, l (k) − f i (k) (x)}
These numbers are always positive v l, u ≥ 0. This is summarized in the following list:
• MONIT_VAL=MEAN, the printed value will be the sum:
• MONIT_VAL=MAX or MONIT_VAL=MIN, the printed value will be:
The maximum Max{f r (k) (x)} or the minimum Min{f r (k) (x)}.
• MONIT_VAL=ERRMEAN, the printed value will be the mean value of the constraint
violations:
Eldo® User's Manual, 15.3 655

Optimization
Final Diagnostic Conditions
• MONIT_VAL=ERRMAX or MONIT_VAL=ERRMIN, the printed value will be:
The maximal constraint violation Max k {v
(k)
l + v (k) u } or the minimal constraint violation
Min k {v
(k)
l + v (k) u }.
Related Topics
Monitoring Goal Value Objectives
Monitoring Minimize and Maximize Objectives
Optimization Methods
Final Diagnostic Conditions
When the optimizer has finished, a status code is printed in the optimization results. It is
essential to check the value of this code (and its associated message) and the effective results of
optimization (design variables and objectives).
The final diagnostics indicate the final status of the optimizer before it exits. These messages
and their meaning are described in Table 13-3:
Table 13-3. Optimization Result Status Code
Code Message and meaning
0 The optimization seems to be successful. The required accuracy has been achieved.
The iterates have converged to a point that satisfies the optimality conditions to
the accuracy requested by the optional parameters TOL_OPT or TOL_GRAD and
TOL_FEAS (refer to “Optimization Methods” on page 622). The user should
verify whether the following two conditions have been satisfied:
• The final values of Optimality are significantly small.
• The final values of Feasibility are significantly small. This is set to zero if there
are no equality or inequality constraints.
1 Optimization was not successful. The maximum number of simulation runs has
been reached.
The limiting number of iterations, determined by the optional parameter
MAX_ITER has been reached.
Check the iteration log contained in the .otm file. If the optimizer appears to be
making progress, MAX_ITER may be too small. If so, increase its value and rerun
the optimizer, possibly using the values of the design variables obtained so far (this
can be considered as a warm start).
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Code
Table 13-3. Optimization Result Status Code (cont.)
Message and meaning
Optimization
Final Diagnostic Conditions
2 The current point cannot be improved. A sufficient decrease in the merit function
could not be attained during the last line search. This may occur because the user
has requested an overly stringent accuracy.
A sufficient decrease in the merit function could not be attained during the final
line search. This sometimes occurs because an overly stringent accuracy has been
requested, that is, TOL_OPT is too small. In this case verify the following to
determine whether or not the final solution is acceptable:
• The final values of Optimality are significantly small.
• The final values of Feasibility are significantly small. This is set to zero if there
are no equality or inequality constraints.
An additional status code may be raised, of value: 0, 6, or 11.
4 Optimization was not successful. The maximum number of simulation runs has
been reached.
The limiting number of simulations, determined by the optional parameter
MAX_SIMUL has been reached.
6 The current point is feasible and quite optimal, however, the required accuracy has
not been achieved. The optimizer is within 1e-2 of satisfying the TOL_OPT (or
TOL_GRAD) optimality tolerance.
The optimizer is within 1x10 −2 of satisfying the TOL_OPT (or TOL_GRAD)
optimality tolerance. For the next runs, check that TOL_OPT is not too small.
7 The objective function may be unbounded on the feasible set. Alternatively, it may
happen that the scaling of the problem is very poor.
To avoid this situation, if the MINIMIZE or MAXIMIZE objectives are close to
singularities, define bounds on some variables. Also use an appropriate scaling of
the design objectives.
8 The simulation process stopped the optimization. The optimization was
abandoned.
This message is raised only after an interrupt message (Ctrl+C).
9 The current point cannot be improved. The problem is too hard to solve. Try with
another starting point.
This has to be considered as a failure of the optimizer regarding the treatment of
constraint feasibilities. Please refer to “Normal and Elastic Modes of Termination”
on page 659. Check that the final solution is not an acceptable point for the
problem.
10 The current point cannot be improved. The Hessian matrix has been reset too many
times. It indicates that the line search failed to find a sufficiently better point for a
large number of iterations.
This message should appear very rarely. This is an algorithmic weakness of the
method implemented in the Eldo optimizer SQP method. Try to start the
optimization from a different point.
Eldo® User's Manual, 15.3 657

Optimization
Final Diagnostic Conditions
Code
Table 13-3. Optimization Result Status Code (cont.)
Message and meaning
11 The starting point cannot be improved. It may happen that the derivative are
inaccurate or the starting point is already critical.
Check that the objectives to optimize are well-defined at the starting point.
12 The current point cannot be improved. The last QP step was too poor to allow a
sufficient progress of the iterations.
This may indicate that the extracted measures and their derivatives have a low
precision at the current point.
13 Optimization was not successful. Either the objective function or the constraints
seem to be undefined at the starting point. The optimization was abandoned.
The current version of the Eldo optimizer SQP method cannot handle problems
where the objectives returned by Eldo (at the first iterate) have the UNDEF value.
Try to eliminate such cases by using a two-stage approach.
14 Please refer to code 2.
15 Please refer to code 2.
Related Topics
Output from the Optimization Process
Explicitly Declaring Results For Graphical Viewing
Viewing the ASCII Output File
ASCII Optimization File Contents
Monitoring Design Objectives
Normal and Elastic Modes of Termination
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Optimization
Normal and Elastic Modes of Termination
Normal and Elastic Modes of Termination
The SQP algorithm is able to make explicit allowance for infeasible constraints when
computing the incremental steps obtained from a sequence of sub-problems. This phenomenon
is referred to as local infeasibility.
In constrained optimization, a situation where no feasible solution exists can occur. In this case
the constraints are inconsistent and the problem is infeasible. If all the constraints are bounds on
the variables x
(i)
l ≤ x (i) ≤ x
(i)
u it is simple to determine whether a feasible point exists, since the
(i)
ith is only inconsistent when x l > x (i) u . Such infeasibilities are automatically trapped when
parsing the .PARAMOPT command.
Conversely, with general constraints there are no simple characteristics that identify whether a
feasible solution exists.
This section describes how the algorithm performs a shift of bounds on objectives to make a
locally infeasible problem feasible. It handles:
Constraint Violations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659
Slack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 661
Constraint Violations
The following simple example illustrates one possible situation.
Consider the optimization problem with two variables x 1 and x 2 :
.PARAMOPT X1=(4, 0, *)
.PARAMOPT X2=(7, 0, *)
.OBJECTIVE DC LABEL=C (X1 + X2) UBOUND=-1
These statements define two bound constraints on the variables x 1 ≥ 0 and x 2 ≥ 0, and the linear
constraint on the measure x 1 + x 2 ≤ -1.
By considering the graphical representation displayed in the left part of Figure 13-18, you can
see that they define two disjoint sets of points. The optimization problem is thus infeasible.
Eldo® User's Manual, 15.3 659

Optimization
Normal and Elastic Modes of Termination
Figure 13-18. Illustration of Constraint Violations
To cope with this issue, the SQP optimizer can run in one of two different modes:
• normal mode
• elastic mode
The algorithm automatically enters the ‘elastic’ mode when a situation of infeasibility is
detected. This mode performs a shift of the bounds on constraints.
In our example, add a positive number v ≥ 0 to the upper bound UBOUND such that x 1 + x 2 ≤ -
1 + v then try to minimize the value of v, the constraint violation. This numerical modification is
graphically displayed in the right part of Figure 13-18, where the green colored area represents
the non empty feasible domain. It is clear that v = 1 is the smallest of the violation such that
there exist a feasible point.
If this simple problem is solved with the SQP optimizer, the .otm file gives the following results
for the optimized variable:
Section 2 - Status Of Variables
-------------------------------
Name Status Init Value Final Value Lower Bound
X1 BND 4.0000e+00 0.0000e+00 0.0000e+00
X2 BND 7.0000e+00 0.0000e+00 0.0000e+00
The final value of the parameters is (0,0).
The final status of the objective is given by:
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Optimization
Normal and Elastic Modes of Termination
Section 3 - Status Of Objectives
--------------------------------
*** Inequality Constraints in simulator id(0)
Type Name Init Value Opt Value Violation
UPR CONSTR1 *** 1.1000e+01 1.0000e-06 *** 1.0000e+00
The optimal value is 1.0×10 −6 and the violation (or equivalently the value of the additional
variable v) is shown in the last column as being the strictly positive value 1.0.
Note
This approach has very interesting properties. For instance, the optimal solution often
violates only a small number of the constraints and a point that satisfies many of the
constraints is computed, that is, a large subset of constraints that are feasible have been
identified. This is more informative than finding that the constraints are mutually feasible (this
approach is closely related to the L1-norm regularization technique).
Related Topics
Slack
Slack
For this next example, consider the following problem with two variables. The aim is to
minimize some function f(x 1 , x 2 ) subject to the constraints:
• (x 1 + 1) 2 + x 2 2 ≥ 0.75 which defines a disk centered at (-1, 0) with radius √3/2.
• (x 1 − 1) 2 + x 2 2 ≤ 0.75 which defines the symmetrical disk centered at (1, 0).
Figure 13-19 illustrates this situation.
Eldo® User's Manual, 15.3 661

Optimization
Normal and Elastic Modes of Termination
Figure 13-19. Illustration of Slack
It is clear that there is no feasible solution. Running the Eldo optimizer on this example:
.PARAMOPT X1=(-2, *, *)
.PARAMOPT X2=(-2, *, *)
.OBJECTIVE DC LABEL=CIRCLE1 ( (X1-1)**2 + X2**2 ) UBOUND=0.75
.OBJECTIVE DC LABEL=CIRCLE2 ( (X1+1)**2 + X2**2 ) UBOUND=0.75
gives the following output:
==> Starting Optimization...
Iteration 0: Feas = 1.2e+01, Optim = 6.0e+00
Iter Simul LS Step Merit Function Feas Optim Slack
1 10 1.0e+00 6.3505943e-01 1.2e+00 6.0e-04 0.0e+00
2 16 3.3e-01 1.7787634e+00 3.9e-01 7.8e-01 0.0e+00
3 22 1.9e-01 4.3108310e+00 2.9e-01 9.0e-01 0.0e+00
4 28 3.4e-02 3.7393098e+01 2.5e-01 1.3e+00 0.0e+00
5 34 3.7e-04 6.5283185e+03 2.5e-01 1.9e+00 0.0e+00
6 40 1.0e-00 1.5304677e+04 2.5e-01 2.0e+00 3.5e+00
7 46 2.2e-01 1.5238534e+04 5.1e-03 7.7e+03 3.6e-01
8 53 1.3e-02 1.4929878e+04 5.1e-03 7.5e+03 3.5e-01
9 61 9.9e-01 1.5000628e+04 1.1e-02 1.9e+03 3.5e-01
Iter Simul LS Step Merit Function Feas Optim Slack
10 65 1.0e+00 1.5000626e+04 4.1e-04 2.8e+01 3.5e-01
11 69 1.0e+00 1.5000625e+04 1.2e-07 1.4e+01 3.5e-01
==> End Of The Optimization Phase
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Optimization
Normal and Elastic Modes of Termination
The column Slack is the value of the global constraint violation — the norm of the artificial
variables (v 1 , v 2 ) added to the upper bound UBOUND for each constraint. The constraints
become:
• (x 1 + 1) 2 + x 2
2
≥ 0.75 + v 1 .
• (x 1 − 1) 2 + x 2
2
≤ 0.75 + v 2 .
The value of the slack becomes strictly positive after the 6th iteration. This phenomenon can be
interpreted as follows:
• After the 6th iteration the algorithm detected that the problem is locally infeasible.
• Two artificial variables are then introduced such that the constraints become consistent.
Graphically, this can be interpreted as increasing the radius of the two circles such that
they do intersect.
• The goal of the algorithm is then to find a solution point such that the constraint
violation is minimized.
The final solution is given in the following output:
Section 2 - Status Of Variables
-------------------------------
Name Status Init Value Final Value
X1 FR -2.0000e+00 -5.0009e-07
X2 FR -2.0000e+00 1.6166e-05
Section 3 - Status Of Objectives
--------------------------------
*** Inequality Constraints in simulator id(0)
Type Name Init Value Opt Value Violation
UPR CIRCLE1 *** 1.3000e+01 1.0000e+00 *** 2.5000e-01
UPR CIRCLE2 *** 5.0000e+00 1.0000e-00 *** 2.5000e-01
Constraint violations have been minimized. The actual value of the violation is v 1 = 0.25 for the
first constraint and v 2 = 0.25 for the second. The solution point is approximately the origin (0,
0). The algorithm automatically increased the radius of each circle such that the feasible domain
becomes a non empty set. The feasible set reduces to the singleton (0, 0).
Related Topics
Constraint Violations
Eldo® User's Manual, 15.3 663

Optimization
Examples of Circuit Optimization
Examples of Circuit Optimization
A number of example files are provided to illustrate the Eldo Optimizer.
See Table 13-4 for filenames and descriptions of the example files provided in your installed
directory: $MGC_AMS_HOME/examples/optimizer/
Table 13-4. Basic Examples of Circuit Optimization
Example File name Description
Designing a Low Noise Amplifier
(LNA)
lnaopt.cir
Optimization using AC, Noise and
SST analyses
Fourband Filter Optimization fourband.cir Optimization of a filter response
MOS Characterization nmos.cir Double DC sweep optimization and
ALTER blocks
Robust Optimization Using Corners aop_optim.cir Optimization of a 2-stage operational
amplifier using ALTER blocks
Setup Time Computation
Optimization of the setup time
computation of a flip-flop
Designing a Low Noise Amplifier (LNA)
Netlist file: lnaopt.cir
The Low Noise Amplifier (LNA) architecture is a fully balanced dual-gain amplifier for
achieving gain, linearity, and the noise specifications for a Zero-IF receiver architecture. Output
power matching is not required since the output load is given by the integrated mixer.
This example will show how the Eldo optimizer can be used for a LNA. The architecture of the
LNA is based on the 2.45GHz Switched-Gain CMOS LNA [6]. The high-gain stage is a fully
balanced cascade configuration with an integrated LC tank as the load. This design reduces the
Miller effect and improves isolation (-S12). The low-gain stage consists of two NMOS devices
used as switches to achieve the required linearity and insertion loss.
The main characteristics are: Voltage Gain (AV), Input Power Matching (S11), Noise Figure
(NF), and Input Third Order Intercept Point (IIP3). The circuit parameters are:
• Input Network Model (CPIN1, CPIN2, LSIN, CSIN).
• Source Inductor (associated with serial resistance).
• NMOS Width (composed of 10mm length fingers).
The input network consists of a serial capacitor (CSIN) used to isolate the LNA DC from the
input. A p-network (consists of CPIN1, CPIN2, LSIN) enables simultaneous input power and
noise matching. Changing the source inductor (LS) and the width of the NMOS through the
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Optimization
Designing a Low Noise Amplifier (LNA)
number of fingers (N1) will improve noise matching, input power matching, and linearity
characteristics such as IIP3 (the current and the load values are fixed to 6mA and 200Ω
respectively).
Analyses
Using a single testbench, different analyses were simulated to extract the following key
specifications:
• An AC analysis to extract Return Loss and the Voltage Gain.
• A NOISE analysis for extracting the Noise Figure.
• A multi-tone SST analysis for the IIP3.
* Parameters
.PARAM VG=0.6 VD=1.8
.PARAM FUND1=2.45G FUND2=2.46G PIN=-50
.PARAM IS=6m ROUT=200 RS=LS/1N
VIN IN 0 RPORT=50 IPORT=1 AC 1 FOUR FUND1 FUND2 PDBM (1,0) PIN -90
+ (0,1) PIN -90
VOUT OUT 0 RPORT=ROUT IPORT=2
* Analyses
.DC
.AC LIN 11 2G 3G
.SST FUND1=FUND1 NHARM1=5 FUND2=FUND2 NHARM2=5
.NOISE V(OUT) VIN 10
.SNF INPUT=(VIN) OUTPUT=(VOUT)
* Plots
.PLOT AC SDB(1,1)
.PLOT NOISE DB(SNF) DB(NFMIN)
.DEFWAVE AV_DB=VDB(OUT)-VDB(IN)
.PLOT AC W(AV_DB)
The .DEFWAVE command was used to define the voltage gain (dB).
Design Variables
For the optimization analysis, each parameter has an initial value, together with lower and upper
bounds. For example, the capacitor CPIN1 has an initial value of 0.1p with lower and upper
bounds of 0.10p and 10p respectively. Our problem has bound constraints on the variables.
The variables LS and N1 are specified using the fourth parameter of the .PARAMOPT
command. It means that these parameters are allowed to lie only on a discretized grid (the fourth
parameter gives the step of this grid). Refer to “Eldo Optimization Methods” on page 592 for
more information, and also the “Solving Problems with Pseudodiscrete Variables” on page 668.
The design variables are specified as:
Eldo® User's Manual, 15.3 665

Optimization
Designing a Low Noise Amplifier (LNA)
.PARAMOPT
+ CPIN1=(0.1P,0.10P,10P)! 0.1x10-12 ≤ CPIN1 ≤ 10x10-12
+ CPIN2=(0.1P,0.10P,10P)! 0.1x10-12 ≤ CPIN2 ≤ 10x10-12
+ LSIN=(0.1N,0,30N)! 0 ≤ LSIN ≤ 30x10-9
+ CSIN=(1P,0.10P,10P)! 0.1x10-12 ≤ CSIN ≤ 10x10-12
+ LS=(0.25N,0,3N,0.25N)! 0 ≤ LS ≤ 3x10-9
+ N1=(30,10,50,5)! 10 ≤ N1 ≤ 50
The degenerative integrated inductor (LS) would typically come from a design kit library. In
our context, it is useful to specify the unit step (0.25n) to obtain the optimal matching inductor.
Design Objectives and Extracted Measures
To specify design objectives, the keyword GOAL is used on the .EXTRACT command, this
describes the ideal target that the user would like to reach for this specification with the
optimization process.
* AC Analysis
.EXTRACT AC LABEL=AV_dB@2.4GHz YVAL(WR(AV_DB),2.4G) GOAL=20
.EXTRACT AC LABEL=AV_dB@2.5GHz YVAL(WR(AV_DB),2.5G) GOAL=20
.EXTRACT AC LABEL=S11_dB@2.4GHz YVAL(SDB(1,1),2.4G) GOAL=-15
.EXTRACT AC LABEL=S11_dB@2.5GHz YVAL(SDB(1,1),2.5G) GOAL=-15
* Noise Analysis
.EXTRACT NOISE LABEL=NF_dB@2.4GHz YVAL(DB(SNF),2.4G) GOAL=MINIMIZE
.EXTRACT NOISE LABEL=NF_dB@2.5GHz YVAL(DB(SNF),2.5G) GOAL=MINIMIZE
.EXTRACT NOISE LABEL=NFMIN_dB@2.4GHz YVAL(DB(NFMIN),2.4G) GOAL=MINIMIZE
.EXTRACT NOISE LABEL=NFMIN_dB@2.5GHz YVAL(DB(NFMIN),2.5G) GOAL=MINIMIZE
The specified design objectives are for an optimization problem having four GOAL objectives
and four MINIMIZE objectives.
Optimization Process
The optimization process stops when the accuracy on the design variables need not be improved
further, or more precisely, when the current point satisfies the optimality condition. This
optimality property can be checked in the Eldo optimizer output (.otm file):
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Optimization
Designing a Low Noise Amplifier (LNA)
Optimization Results
====================
Section 1 - Statistics and Diagnostics
--------------------------------------
==> Number Of Iterations 84
Number Of Simulations 850
Merit Function
Optimality
Feasibility
4.8781332e+00
7.55e-03
0.00e+00
The term Optimality was denoted by OPTIM(x) in the definition of the TOL_GRAD parameter
of the .OPTIMIZE command. A small value indicates that the optimality condition is satisfied.
The term Merit Function is the value of the function minimized during the optimization process.
This function can be considered as a global score associated to the final iterate, that is, it gives
the distance of the final solution to the ideal solution (which may not exist). For the LNA
problem, the ideal solution would have given a Merit Function value close to 4.0, since the four
error functions coming from the objectives AV_DB@2.4GHZ, AV_DB@2.5GHZ,
S11_DB@2.4GHZ and S11_DB@2.5GHZ would be exactly zero, and the four MINIMIZE
objectives should be close to 1.0.
Optimization Results
The design variables found by the optimizer provide a voltage gain close to 20dB, a return loss
of 12dB, and an IIP3 of 1.2dBm. Note that the value of the Noise Figure (NF) is not so similar
to the value of the Minimum Noise Figure (NFMIN). Thus the noise matching can be improved,
however, this maybe at the expense of S11 matching by using different weighting numbers for
each of the objectives.
Table 13-5 gives the results of optimization for the GOAL objectives:
Table 13-5. Results of Optimization for GOAL Objectives
Name
Initial Value Current Value Goal Value
AV_DB@2.4GHZ 11.9 20.1 20.0
AV_DB@2.5GHZ 11.7 19.6 20.0
S11_DB@2.4GHZ -0.82 -15.1 -15.0
S11_DB@2.5GHZ -0.88 -15.1 -15.0
The results reported in the previous table have been obtained with the default values (1.0) of the
WEIGHT parameters.
The results for MINIMIZE objectives are shown in Table 13-6:
Eldo® User's Manual, 15.3 667

Optimization
Designing a Low Noise Amplifier (LNA)
Table 13-6. Results of Optimization for MINIMIZE Objectives
Name Initial Value Current Value
NF_DB@2.4GHZ 3.03 1.41
NF_DB@2.5GHZ 3.06 1.41
NFMIN_DB@2.4GHZ 1.01 0.97
NFMIN_DB@2.5GHZ 1.06 1.03
Solving Problems with Pseudodiscrete Variables
As with many problems in circuit design, some of the variables are restricted to being members
of a finite set of values. These variables were LS, the NMOS source inductor, and N1, the
number of fingers in the NMOS. The LNA problem illustrates the distinction between the two
types of discrete variables that may be encountered in practical problems. Some of the
techniques in this topic are freely adapted from the book of Gill, Murray and Wright [4].
First consider the LNA problem with respect to the variable LS (assuming N1 is fixed at its
initial value of 30 for now). The problem is a mixed continuous-discrete problem since the LS
inductor comes from a design kit library which restricts the values to specific sizes. Such
variables are termed pseudodiscrete, since the solution to the continuous problem (in which the
variables are not subject to discrete restrictions) is well defined.
The other category of discrete variables is represented by the variable N1 where there is no
physical meaning of a non-integer value.
In our case, the definition of the NMOS model parameters used in the design kit library makes
the LNA problem a problem with continuous variables. For example, the parameter WR, which
represents the width offset for the channel resistance (RDS) calculation, is redefined as follows:
.PARAM WR=’(C1 + C2*Lm - C3*N1)’
The symbols C1, C2 and C3 refer to some constant factors which are not specified here. The
parameter Lm is simply the length of the transistor. This definition of the WR parameter does
not use the discrete nature of the N1 parameter. During the evaluation of this expression, the
value of N1 is considered to be a floating number. The problem is implicitly reformulated as
continuous.
The situation is more difficult to handle when the integer part of N1 is used explicitly in the
previous expression:
WR=’(C1 + C2*Lm - C3*TRUNC(N1))’
Such situations should be avoided wherever possible.
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Optimization
Designing a Low Noise Amplifier (LNA)
Our problem with pseudodiscrete variables can be solved by utilizing the solution of the
continuous problem. The results of the optimization are summarized in the .otm file, and the
information shown in Table 13-7 can be extracted:
Table 13-7. Extracted Information from .otm File
Name Initial Value Final Value Discretized value Increment
LS 2.5x10 −10 1.5352x10 −9 3.0x10 −9 1.5x10 −9
CPIN1 1.0x10 −13 0.0 0.0 0.0
CPIN2 1.0x10 −13 8.7506x10 −14 2.234x10 −13 0.0
CSIN 1.0x10 −12 1.0x10 −12 1.0x10 −12 0.0
LSIN 1.0x10 −10 1.3651x10 −8 1.3651x10 −8 0.0
N1 30 18.453 20 5
The optimal N1 value when handled as a continuous variable is 18.453, and the optimal discrete
value is unlikely to be very different. This will be confirmed by the next two experiments. The
first experiment represents a general approach for handling optimization problems with
pseudodiscrete variables, while the second illustrates a “well-defined” problem.
N1 was defined as the variable that must assume one of the integer values {10, 15, 20, ..., 50}.
Let N1 C denote the value of N1 at the solution of the continuous problem, which is supposed to
be unique. Suppose that N1 C satisfies: ns < N1 C < ns+1
The value of the merit function Fmerit at the continuous solution is a lower bound on the value
of Fmerit at any solution to the discrete problem. If the variable N1 is a value other than N1 C ,
the merit function will be larger than Fmerit at the continuous solution, irrespective of the other
variables (LS, CPIN1, CPIN2, ...).
The next stage is to fix the pseudodiscrete variables at either n s or n s+1 by combining the values
in Table 13-8:
Table 13-8. Combinations of N1 and LS Values
Name s s+1
N1 15 20
LS 1.5x10 −9 1.75x10 −9
The problem is then solved again, minimizing with respect to the remaining continuous
variables, and using the old optimal values as the initial estimate of the new solution.
Eldo® User's Manual, 15.3 669

Optimization
Designing a Low Noise Amplifier (LNA)
Solving the restricted problem should require only a fraction of the effort needed to solve the
continuous problem, as shown in Table 13-9, because the number of variables is smaller and the
solution should be close to the solution of the continuous problem.
Table 13-9. Results of Restricted Problem
Run Fmerit Nb Iter Nb Simul
N1=20, LS=1.5x10 -9 4.9403493 16 130
N1=20, LS=1.75x10 -9 5.4893925 16 131
N1=15, LS=1.5x10 -9 5.4792729 57 467
N1=15, LS=1.75x10 -9 5.0082957 40 329
The value of the merit function Fmerit at the continuous solution is a lower bound on the
restricted solutions. This value was given above and is 4.8781332. The solution obtained for the
run with N1 = 20 and LS =1.5x10 −9 will be a satisfactory solution. The extra computation cost
in solving the additional restricted problems associated with the discrete variables is likely to be
a fraction of the cost to solve the original full continuous problem. If not, this implies that the
discrete solution differs substantially from the continuous solution.
Example of Solving a Pseudodiscrete Variable Problem
The following experiment can be considered a complete enumeration procedure where all the
possible combinations of the discrete values of N1 and LS were tested.
Note
This kind of process is very costly and inefficient and given only for illustrative purposes.
The following statements were used:
.PARAM LS=0.25n
.PARAM N1=30
.STEP PARAM LS 0 3n 0.25n
.STEP PARAM N1 10 50 5
.OPTIMIZE OUTER=LS,N1
This outer loop results shown at the end of the .otm file (some columns were removed to
simplify the results) were:
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Optimization
Fourband Filter Optimization
Optimization Results With Respect To The Outer Loop
===================================================
Run Iter Simul Merit Function Optim Outer Parameters
...
1 22 177 5.0741859e+01 6.4e-04 LS: 0.0000e+00 N1: 1.0000e+01
2 11 97 6.7559608e+01 1.5e-03 LS: 0.0000e+00 N1: 1.5000e+01
3 26 205 6.2095585e+01 2.3e-04 LS: 0.0000e+00 N1: 2.0000e+01
4 33 274 5.2472654e+01 1.1e-01 LS: 0.0000e+00 N1: 2.5000e+01
5 31 242 4.1993472e+01 9.3e-02 LS: 0.0000e+00 N1: 3.0000e+01
The plot shown in Figure 13-20 extracts the optimal value of the merit function F merit after
solving each problem associated to a restricted problem with fixed values N1 and LS. It shows
that there is a narrow area along the line N1 = 20 where this function takes its minimal values.
This means that the assumption of a well-defined problem having continuous and
pseudodiscrete variables is reasonable.
Figure 13-20. Plotted Values of the Merit Function
Related Topics
Minimization and Maximization Objectives
Goal Values Objectives
Inner and Outer Sweep Parameters
Fourband Filter Optimization
Netlist file: fourband.cir
Eldo® User's Manual, 15.3 671

Optimization
Fourband Filter Optimization
This example illustrates the fitting of a filter response. It illustrates the influence of the initial
point in circuit optimization and the relative robustness of the optimizer.
Figure 13-21. Filter Response
A set of eighteen circuit parameters is to be optimized such that the voltage at node 12 follows
the curve response given in Figure 13-21. This plot also shows the initial response.
Analyses
A single AC analysis is performed, driven by .DATA command.
.AC DATA=DATA_FOURBAND
.DATA DATA_FOURBAND
+ FREQ VDB12
+ 1.122E+02 -8.326E+00
+ 1.166E+02 -7.435E+00
+ 1.212E+02 -6.566E+00
*...
+ 8.913E+04 -4.212E-01
+ 9.261E+04 -4.213E-01
+ 9.624E+04 -4.215E-01
.ENDDATA
Design Variables
The design variables are resistor and capacitor values of the circuit. The initial (or nominal)
values are given below.
The capacitors CT, CLC and CPASS have been specified separately to illustrate the effect of the
initial conditions on the optimizer (refer to “Global and Local Optimization” on page 629 for
more information).
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Optimization
Fourband Filter Optimization
.PARAM
+ R2=10K CL=0.01U R2B=8K
+ CTB=0.01U CLB=0.01U R2C=12K CTC=0.002U
+ R2D=12K CTD=800P CLD=150P
+ CACT1=0.02U CACT2=0.02U
+ RPASS=4K RACT1=50K RACT2=180K
.PARAM CT=0.02U CLC=0.001U CPASS=0.3U
with the associated .PARAMOPT statements:
.PARAMOPT
+ R2 = ( 5K, 20K)
+ CT = (0.001U, 0.05U)
+ CL = (0.001U, 0.05U)
+ R2B = ( 3K, 10K)
+ CTB = (0.001U, 0.05U)
+ CLB = (0.001U, 0.05U)
+ R2C = ( 5K, 20K)
+ CTC = (0.001U, 0.01U)
+ CLC = (0.001U, 0.005U)
+ R2D = ( 5K, 20K)
+ CTD = ( 100P, 1000P)
+ CLD = ( 10P, 500P)
+ CPASS = ( 0.1U, 1.0U)
+ CACT1 = (0.001U, 0.05U)
+ CACT2 = (0.001U, 0.05U)
+ RPASS = ( 1K, 5K)
+ RACT1 = ( 20K, 100K)
.OPTION PARAMOPT_NOINITIAL
The option PARAMOPT_NOINITIAL specifies that the parameter INITIAL_VALUE is
omitted from the .PARAMOPT command and should be taken from the netlist instead.
Design Objectives
The optimization will be performed on a single design objective which aims to improve the
match of the constructed model (or the target curve) with the actual measurements. The
differences between the model and the measured values are combined in a global error function
(using the least squares approach).
The objective statement is:
.OBJECTIVE AC LABEL=RESPVDB12
+ VDB(12) GOAL=DATA_FOURBAND(VDB12)
Former releases of the Eldo optimizer used the equivalent (but less explicit) FITTING
construct:
.EXTRACT AC LABEL=RESPVDB12 FITTING
+ DATA_FOURBAND(VDB12) VDB(12)
Eldo® User's Manual, 15.3 673

Optimization
Fourband Filter Optimization
Optimization Results
The optimization was performed on a 32-bit Linux machine and the results generated during the
optimization process are shown in Table 13-10:
The minimum and maximum errors give the range of the residuals (difference between the
target and the measured values) after optimization. The global error represents the error
function minimized by the optimizer (this value may differ with the merit function of the
optimizer).
In Figure 13-21 the optimized response was not plotted since the target and the output responses
were the same.
Modified Initial Values
Table 13-10. Values Extracted from fourband.otm File
Minimum Error Global Error Maximum Error
Test 1 1.7×10 −6 1.6×10 −6 7.3×10 −3
Test 2 1.4×10 −4 1.2×10 −2 4.3×10 −1
Now consider the following modified initial values of the capacitors CT, CLC and CPASS:
.PARAM CT=0.002U CLC=0.0001U CPASS=1.0U
The corresponding response is plotted in Figure 13-22.
Figure 13-22. Optimized Response
The minimum and maximum errors are stored in Table 13-10.
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Optimization
MOS Characterization
Related Topics
Optimization Options
Specifying Design Variables
Vector Design Objectives
Goal Values Objectives
MOS Characterization
Netlist file: nmos.cir
This example illustrates the combination of a double DC sweep and ALTER blocks for the
optimization of I-V data for a Level 3 MOS model. The data consists of drain characteristics
(IDS versus VDS and VGS) with two different choices of the length parameter L.
The data is stored in two separate .DATA statements (d25x25.dat and d25x2p5.dat files). The
I-V curves are shown in Figure 13-23 at the initial point of optimization.
Figure 13-23. Illustration of I-V characteristics
Circuit Statements
The circuit and the model statement are given below. The circuit is a simple single transistor
circuit. The parameters VDS, VGS and VBS are the names of the sweep parameters used in the
parametric DC analyses.
Eldo® User's Manual, 15.3 675

Optimization
MOS Characterization
* CIRCUIT STATEMENTS
VDS 104 0 VDS
VGS 102 0 VGS
VBS 103 0 VBS
M25X25D1 101 102 0 103 NMOS W=25U L=25U NRS=0.12 NRD=0.12
V101 104 101 0
* THE MODEL
.MODEL NMOS NMOS(LEVEL=3 TOX=2.0E-8 NSUB=1E16
+ LD=LD VTO=VTO GAMMA=GAMMA UO=UO VMAX=VMAX
+ THETA=THETA ETA=ETA KAPPA=KAPPA)
Design Variables
This example performs optimization of the level 3 parameters: LD, VTO, GAMMA, UO,
VMAX, THETA, ETA, and KAPPA. The corresponding statements are:
.PARAM
+ LD=1E-7 VTO=1.0 GAMMA=0.6 UO=600 VMAX=1E5
+ THETA=0.1 ETA=0.01 KAPPA=1
.OPTION PARAMOPT_NOINITIAL
.PARAMOPT
+ LD = ( 1E-9, 5E-7)
+ VTO = ( 0, 2)
+ GAMMA = ( 0.1, 2)
+ UO = ( 300, 900)
+ VMAX = ( 1E4, 1E7)
+ THETA = ( 1E-6, 2)
+ ETA = ( 1E-4, 2)
+ KAPPA = ( 1E-6, 1E3)
ALTER Blocks and Design Objectives
In our example the netlist consists of two blocks, the second is defined with a .ALTER
command.
The first .OBJECTIVE command has a local scope. This means that the expression I(V101) is
computed in a specific simulation context. This context is related to a ALTER block (the first
block may be considered as the root block or nominal case).
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Optimization
Robust Optimization Using Corners
* DRAIN CHARAC W=25U L=25U AT VBS=0.0
.INCLUDE d25x25.dat
.DC DATA=DATA_D25X25 ! DATA DRIVEN ANALYSIS
.OBJECTIVE DC LABEL=FIT_IDRAIN I(V101) ! DOUBLE DC SWEEP OPTIMIZATION
+ GOAL=DATA_D25X25(IDS) TYPVAL=1E-4
* DRAIN CHARAC W=25U L=2.5U AT VBS=0.0
.ALTER DRAIN 25X2P5 AT VBS=0
M25X25D1 101 102 0 103 NMOS W=25U L=2.5U NRS=0.12 NRD=0.12
.INCLUDE d25x2p5.dat
.DC DATA=DATA_D25X2P5
.OBJECTIVE DC LABEL=FIT_IDRAIN I(V101)
+ GOAL=DATA_D25X2P5(IDS) TYPVAL=1E-3
The parameter TYPAL has been used to globally rescale the objectives (the extracted measures
and the associated target values), such that the low current data is not dominated by others data.
Optimization Results
The optimization was performed on a 32-bit Linux machine and the results generated during the
optimization process are shown in Table 13-11:
Table 13-11. Nmos Example Results
Minimum Error Global Error Maximum Error
Length L=25U 0.0 1.1×10 −18 3.5×10 −9
Length L=2.5U 0.0 6.4×10 −17 3.0×10 −8
These values are the result of a synthetic problem. The circuit parameters were fixed, the data
was then generated, and the circuit was optimized after performing a perturbation of the initial
point. This is why the global error is so small. The residuals are almost zero. This is not the case
with realistic data where the physical measurements involve some variability in the current
curves.
Related Topics
Optimization Options
Inner and Outer Sweep Parameters
Robust Optimization Using Corners
Netlist file: aop_optim.cir
Eldo® User's Manual, 15.3 677

Optimization
Robust Optimization Using Corners
This example illustrates the combination of optimization and .ALTER commands. For this
purpose a new architecture based on the concepts of multi-context of simulation and multinetlist
optimization has been developed.
Nominal optimization focuses on finding the best design variable values for one nominal
operating condition of the circuit. Typically the power supply, the ambient temperature, and the
process technology are given their nominal value, and the best value of design variables is
found by the optimizer.
However, if the circuit has to operate under a variety of operating conditions, nothing
guarantees that these will always be optimal design variable values if they are simply set to
these optimal nominal values. Maybe if the power supply level is slightly changed, the circuit
will fail.
Robust optimization focuses on finding the set of design variable values that fulfill the
specifications across a certain range of operating conditions. For example, robust optimization
would be performed on a circuit that must operate between 1.7 and 1.9V, a temperature range of
-25C to 100C, and accommodate variations in the process (defined by the corner device model
libraries). The optimization targets might have upper or lower bounds on certain characteristics
(for example the DC consumption has to be lower than 50μA, in all operating conditions). They
might be set as targets for the average value of a given specification.
Operating conditions are defined with .ALTER commands in Eldo. In each .ALTER command
the operating conditions (typically the power supply level and the temperature) and the corner
device model library, are defined. The optimization commands (design variables definition,
design objective definitions, and the optimize command) from the main netlist are then
interpreted to span the main netlist conditions and the various combinations defined through the
.ALTER sections.
Note
These types of optimizations are usually more costly than simple nominal optimizations.
Eldo can distribute the simulations on multi-processor machines to accelerate the process.
Circuit Statements
The following netlist is available in the directory $MGC_AMS_HOME/examples/optimizer
678
Eldo® User's Manual, 15.3

Optimization
Robust Optimization Using Corners
* 2-STAGES OPAMP - TYPICAL MODEL FOR 3.3V
M16 VDD BIAS M17D VDD PCH_33 W=’WS*4.8U’ L=0.8U
M17 M17D M17D VSS VSS NCH_33 W=’WS*3.2U’ L=0.8U
M15 M15D M17D VSS VSS NCH_33 W=’WS*3.2U’ L=0.8U
M13 M13D M17D VSS VSS NCH_33 W=’WS*3.2U’ L=0.8U
M14 VDD M15D M15D VDD PCH_33 W=’WS*1U’ L=0.8U
M12 VDD M13D M13D VDD PCH_33 W=’WS*4.8U’ L=0.8U
M3 VDD M13D M1D VDD PCH_33 W=’WS*4.8U’ L=0.8U
M4 VDD M13D M2D VDD PCH_33 W=’WS*4.8U’ L=0.8U
M11 VDD M13D OUT VDD PCH_33 W=’WS*16U’ L=0.8U
M1 M1D INP COM COM NCH_33 W=’WS*0.8U’ L=0.6U
M2 M2D INN COM COM NCH_33 W=’WS*0.8U’ L=0.6U
M9 COM M17D VSS VSS NCH_33 W=’WS*3.2U’ L=0.8U
M5 M2D M15D M7D VDD PCH_33 W=’WS*2.4U’ L=0.8U
M6 M1D M15D M8D VDD PCH_33 W=’WS*2.4U’ L=0.8U
M7 M7D M7D VSS VSS NCH_33 W=’WS*1.6U’ L=0.8U
M8 M8D M7D VSS VSS NCH_33 W=’WS*1.6U’ L=0.8U
CX M8D OUT C_COMP ! LOUSY COMPENSATION CAP.
CL OUT 0 1P ! LOAD CAP.
M10 OUT M8D VSS VSS NCH_33 W=’WS*13U’ L=0.8U
.CONNECT OUT INN ! FOLLOWER CONNECTION
.OP
.TRAN 1N 400N
.PLOT TRAN V(INP) V(OUT)
.OPTION TUNING=VHIGH NOASCII NOMOD
VDD VDD 0 1.65V
VSS VSS 0 -1.65V
VINP INP 0 PULSE -0.9 0.9 10N 1N 1N 200N 400N AC 1 0
VB BIAS 0 0.55V
* TYPICAL MODEL FOR 3.3V DEVICES
.LIB ./cln90g_lk.eldo TT_33
.ALTER Sections
The following corners are used:
Eldo® User's Manual, 15.3 679

Optimization
Robust Optimization Using Corners
* SS_33 : Slow NMOS Slow PMOS model for 3.3V devices
.ALTER SS_33 : SLOW NMOS SLOW PMOS MODEL
.LIB ./cln90g_lk.eldo SS_33
* FF_33 : Fast NMOS Fast PMOS model for 3.3V devices
.ALTER FF_33 : FAST NMOS FAST PMOS MODEL
.lib ./cln90g_lk.eldo FF_33
* SF_33 : Slow NMOS Fast PMOS model for 3.3V devices
.ALTER FS_33 : FAST NMOS SLOW PMOS MODEL
.LIB ./cln90g_lk.eldo FS_33
* FS_33 : Fast NMOS Slow PMOS model for 3.3V devices
.ALTER FS_33 : SLOW NMOS FAST PMOS MODEL
.LIB ./cln90g_lk.eldo SF_33
Analyses and Design Objectives
Two analyses were specified to define the following design objectives:
• A transient analysis to extract the output voltage.
.EXTRACT TRAN LABEL=RSLOPE SLOPE(V(OUT),0,0,140N)
+ GOAL=80.0E6 WEIGHT=1000.0
• A DC analysis for extracting the IDS current.
.PARAM SCAL_I=1E4 ! INVERSE OF TYPICAL VALUE
.EXTRACT DC LABEL=SCAL_IBIAS SCAL_I*ID(M16)
+ GOAL=MINIMIZE WEIGHT=1.0
The constant parameter SCAL_I was used to rescale the extracted measure IBIAS. The values
taken by RSLOPE and SCAL_IBIAS have the same order of magnitude. The specified weight
for the measure RSLOPE was introduced to find a solution that minimize the rise time at the
expense of larger IBIAS values. Users can experiment with different choices of weights.
Design Variables and the Optimization
A shrink parameter WS is used for the width of each MOS instantiated in the netlist. The
capacitor is also optimized:
.PARAMOPT
+ WS=(2,0.5,4)
+ C_COMP=(1p,0.01p,100p)
This example must be run with the following commands:
.OPTIMIZE TOL_OPT=1E-2
.OPTION OPSELDO_ALTER
where the option OPSELDO_ALTER informs Eldo that optimization must be performed on all
.ALTER sections. The results of the optimization are placed in the optimization file with the
extension .otm.
680
Eldo® User's Manual, 15.3

Optimization
Setup Time Computation
Related Topics
Optimization Options
Specifying Design Variables
Scaling Design Objectives
Setup Time Computation
The goal here is to use Eldo to compute the setup time of a flip-flop. The definition of setup
time is: time between input and the clock (TIC) so that propagation time between clock and
output (TCO) is 10% above nominal value (computed when there is a large time between input
and the clock).
If the nominal value of TCO is already known, this gives:
TCO_TARGET= 1.1 * TCO_NOMINAL
A very general method, available even with older versions of Eldo, would be to sweep TIC,
measure TCO, adjusting the value of TIC so that TCO=TCO_TARGET.
.PARAM TIC=200n
.STEP PARAM TIC 205N 195N 0.1N
.EXTRACT LABEL=TCO
+ (XUP(V(Q),0.48,200n,300n,1) - XUP(V(CP),0.48,200n,300n,1))
.EXTRACT SWEEP xycond(XAXIS, meas(TCO)=1.1*TCO_NOMINAL)
Simulation time can be improved with the use of .OPTION AUTOSTOP=2. Accuracy is
proportional to the parameter sweep increment, and simulation time is proportional to the
number of steps in the swept interval.
The PASSFAIL optimization method is useful for this example. It computes the maximum
value for which an extract can be measured. This is not exactly the definition of set-up,
however, it can be used as a first step, this would give:
.OPTIMIZE METHOD=PASSFAIL RESULTS=TCO
.PARAMOPT TIC=(201N,199N,205N)
The DICHOTOMY method is also useful. It finds the value of an optimization variable so that
one extract yields a target value, provided that the extracted values for the Min and Max values
of the optimization variable bracket the target.
In this example, the Min value of the optimization parameter TIC has been computed with the
PASSFAIL method, this will give:
.EXTRACT TRAN LABEL=DCP
+ (XUP(V(Q),0.48,200N,300N,1) - XUP(V(CP),0.48,200N,300N,1))
+ GOAL={1.1*TCO_NOMINAL}
.PARAMOPT TIC=(201N,200.07N,205N) !MIN provided by PASSFAIL
Eldo® User's Manual, 15.3 681

Optimization
References
You can combine both PASSFAIL and DICHOTOMY methods in one step with the following
syntax:
.OPTIMIZE METHOD=DICHOTOMY
.EXTRACT tran LABEL=DCP
+ (XUP(V(Q),0.48,200N,300N,1) - XUP(V(CP),0.48,200N,300N,1))
+ GOAL={1.1*TCO_NOMINAL}
.PARAMOPT TIC=(201N,195N,205N)
The secant method search algorithm is more advanced than the dichotomy method. Many
problems suitable for dichotomy (one design parameter, one target) are actually relatively
linear, that is, the target value is almost proportional to the design variable. In these conditions,
using the dichotomy method is clearly suboptimal in terms of the number of iterations required.
Using the secant method will greatly diminish the number of iterations. This feature is useful if
you want to accelerate your setup/hold simulations.
Related Topics
Eldo Optimization Methods
Specifying Design Variables
Specifying Design Objectives Using .EXTRACT
References
Articles referenced in this chapter:
1. J.F. Bonnans, J. Ch. Gilbert, C. Lemarechal, C. Sagastizabal. Numerical Optimization
-Theoretical and Practical Aspects. Springer Verlag, Berlin, 2003.
2. R. Fletcher. A general quadratic programming algorithm. Journal of the Institute of
Mathematics and its Application, 7, 76-91, 1971.
3. R. Fletcher. Practical Methods of Optimization (second edition). John Wiley & Sons,
Chichester, 1987.
4. P. E. Gill, W. Murray, and M. H. Wright. Practical Optimization. Academic Press, New
York, 1981.
5. J. Nocedal and S. W. Wright. Numerical Optimization. Springer Series in operations
Research, Springer, New York, 1999.
6. R. Point, M. Mendes and W. Foley. A differential 2.4GHz Switched-Gain CMOS LNA
for 802.11b and Bluetooth. 2002 IEEE Radio and Wireless Conference.
682
Eldo® User's Manual, 15.3

Chapter 14
Working with S, Y, Z Parameters
A set of commands in Eldo enables you to extract large signal S parameters (Scattering),
Y parameters (Admittance) or Z parameters (Impedance) in the frequency domain for a
specified circuit. The circuit can have any number of ports.
Eldo enables the simulation of circuits including any number of N-port blocks described by a
frequency tabulation of their S, Y, or Z parameters. It does so by reading the S, Y, Z,
G (Hybrid-G), H (Hybrid-H), T (Transfer scattering), or A (chain or ABCD) parameter data
from a Touchstone® or CITIfile format file.
Simulation Setup for S, Y, Z Parameter Extraction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 684
S, Y, Z Parameter Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 685
Matrix (G, H, T, A) Parameter Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 687
Output File Specification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 688
Simulating a Block Defined by S Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 691
Transient Simulation of Circuits Characterized in the Frequency Domain . . . . . . . . . . . . 691
Technical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692
Implementation Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 695
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 696
Basic Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Detailed Functionality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Instantiating a Block Defined by S, Y, Z Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 699
Touchstone Data File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705
CITIfile Data File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708
Instantiating a Block Defined by X-Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 710
Eldo® User's Manual, 15.3 683

Working with S, Y, Z Parameters
Simulation Setup for S, Y, Z Parameter Extraction
Simulation Setup for S, Y, Z Parameter
Extraction
Special sources must be added at each port of the circuit to be analyzed. The number of the port
and the reference impedance for S parameters must be specified in the Eldo control file as a
source as follows:
Tip
See also “Independent Voltage Source” and “Independent Current Source” in the Eldo
Reference Manual.
Syntax
Voltage Source
Vyy NP NN IPORT=VAL [RPORT=VAL] [CPORT=VAL] [LPORT=VAL] [MODE=KEYWORD]
Vyy NP NN IPORT=VAL ZPORT_FILE=filename [CPORT=VAL] [LPORT=VAL]
+ [MODE=KEYWORD]
Current Source
Iyy NP NN IPORT=VAL [RPORT=VAL] [CPORT=VAL] [LPORT=VAL] [MODE=KEYWORD]
Iyy NP NN IPORT=VAL ZPORT_FILE=filename [CPORT=VAL] [LPORT=VAL]
+ [MODE=KEYWORD]
Parameters
• yy
Required. Name of the port.
• NP
Required. Name of the positive node.
• NN
Required. Name of the negative node.
• IPORT
Required. This is a strictly positive number that is unique and is used as the port number:
this number is used for naming the outputs (for instance, .PLOT AC S(1,2)). An error
message will be issued if two port instances have the same value for IPORT, or if an IPORT
is missing (for example maximum IPORT number found in the netlist is 4, and there is no
instance with IPORT 3).
• RPORT
Value of the reference impedance in Ohms. Default value is 50Ω.
• CPORT
Capacitor placed in series (for V source) or parallel (for I source) with RPORT. Defaults to
0, in which case it behaves like a zero voltage source (that is, CPORT would have no effect).
684
Eldo® User's Manual, 15.3

Working with S, Y, Z Parameters
S, Y, Z Parameter Extraction
• LPORT
Inductor placed in series (for V source) or parallel (for I source) with RPORT. Defaults to 0.
• ZPORT_FILE=filename
Specifies the Touchstone file containing the complex port impedances from which the
S parameters are extracted.
The port impedance file should be 1-port. The Z-parameters represent a passive load and
does not contain the source. For example:
# Hz Z RI R 50
!Freq.[Hz] R[ohm] I[ohm]
1800000000 50 0
1801000000 50 0
3600000000 50 0
3602000000 50 0
5400000000 50 0
5403000000 50 0
6000000000 50 0
• MODE=SINGLE|COMMON|DIFFERENTIAL
Mixed-mode S parameter selection.
SINGLE specifies the port as single ended, it is dedicated to S parameter extraction.
Default.
COMMON and DIFFERENTIAL specify that the port is not single ended. Such ports are
split into two linked sources that are either common (same amplitude and same phase) or
differential (same amplitude but opposite phases). During S parameter extraction a “nonsingle
ended” port is equally common and differential depending on which display is
required. During simulation (DC, AC or TRAN) this port is either common or differential
depending on the specified mode keyword.
Note
Port numbers in Vyy instances should range from 1 to the total number of ports without
discontinuity. The simulation parameters FMIN, FMAX, and Number of frequency points
for the analysis are specified with a .AC command.
S, Y, Z Parameter Extraction
Once the simulation has been setup, S, Y, Z parameters can be extracted during simulation by
use of the .PRINT and .PLOT commands as described in the following subsections.
Tip
See “Simulation Setup for S, Y, Z Parameter Extraction” on page 684.
Eldo® User's Manual, 15.3 685

Working with S, Y, Z Parameters
S, Y, Z Parameter Extraction
S Parameter Extraction
.PLOT AC SR(i, j)
.PRINT AC SI(i, j)
.PRINT AC SM(i, j)
.PLOT AC SDB(i, j)
.PRINT AC SP(i, j)
.PRINT AC SGD(i, j)
Mixed-Mode S Parameter Extraction
Mixed-mode S parameters can be extracted using the following syntax:
S[mn]TYPE(i,j)
TYPE can be one of the following:
R Real partM MagnitudeI Imaginary partDB Magnitude (dB)P PhaseGD Group Delay
mn specifies the mode of ports i and j respectively, can be one of the following:
cc common-commondd differential-differentialdc differential-commoncd commondifferentialsc
single-commonsd single-differentialcs common-singleds different-singless
single-single. Default.
The default mixed-mode for S parameter extraction is single-single. If no mixed extension is
specified on the output the default will change depending on how ports 1 and 2 are setup. The
default rule is shown in Table 14-1.
Table 14-1. Mixed-Mode S Parameter Extraction Default Rule
Port 1 Port 2 Default Available quantities
Single Single SS S[ss](1,1)
S[ss](1,2)
S[ss](2,1)
S[ss](2,2)
Single Balanced SD Sss(1,1)
Ssd(1,2) Ssc(1,2)
Sds(2,1) Scs(2,1)
Sdd(2,2) Sdc(2,2) Scd(2,2) Scc(2,2)
Balanced Balanced DD Sdd(1,1) Sdc(1,1) Scd(1,1) Scc(1,1)
Sdd(1,2) Sdc(1,2) Scd(1,2) Scc(1,2)
Sdd(2,1) Sdc(2,1) Scd(2,1) Scc(2,1)
Sdd(2,2) Sdc(2,2) Scd(2,2) Scc(2,2)
686
Eldo® User's Manual, 15.3

The default mixed-mode can be set using the .LIN command, with syntax:
.LIN mixedmode2port=dd|dc|ds|cd|cc|cs|sd|sc|ss
Example
V1 in1 in2 iport=1 MODE=single
V2 in4 in5 iport=2 MODE=differential
.PLOT AC Sdb(1,1) Sscm(1,2) Ssdp(1,2) Sddr(2,2) Scdi(2,2)
Y Parameter Extraction
.PLOT AC YR(i, j)
.PRINT AC YI(i, j)
.PRINT AC YM(i, j)
.PLOT AC YDB(i, j)
.PRINT AC YP(i, j)
.PRINT AC YGD(i, j)
Z Parameter Extraction
.PLOT AC ZR(i, j)
.PRINT AC ZI(i, j)
.PLOT AC ZM(i, j)
.PLOT AC ZDB(i, j)
.PRINT AC ZP(i, j)
.PRINT AC ZGD(i, j)
Where Sxx(i, j), (Yxx(i, j), Zxx(i, j)) give the influence of port j on port i.
Working with S, Y, Z Parameters
Matrix (G, H, T, A) Parameter Extraction
Table 14-1. Mixed-Mode S Parameter Extraction Default Rule (cont.)
Port 1 Port 2 Default Available quantities
Balanced Single DS Sdd(1,1) Sdc(1,1) Scd(1,1) Scc(1,1)
Sds(1,2) Scs(1,2)
Ssd(2,1) Ssc(2,1)
Sss(2,2)
Matrix (G, H, T, A) Parameter Extraction
Once the simulation has been setup, then G, H, T, A parameters can be extracted during an AC
or FSST simulation by use of the .PRINT and .PLOT commands as described in the following
subsections.
Tip
See “Simulation Setup for S, Y, Z Parameter Extraction” on page 684.
Eldo® User's Manual, 15.3 687

Working with S, Y, Z Parameters
Output File Specification
G Parameter Extraction
.PLOT AC GR(i, j)
.PRINT AC GI(i, j)
.PRINT AC GM(i, j)
.PLOT AC GDB(i ,j)
.PRINT AC GP(i, j)
.PRINT AC GGD(i, j)
H Parameter Extraction
.PLOT AC HR(i, j)
.PRINT AC HI(i, j)
.PRINT AC HM(i, j)
.PLOT AC HDB(i ,j)
.PRINT AC HP(i, j)
.PRINT AC HGD(i, j)
T Parameter Extraction
.PLOT AC TR(i, j)
.PRINT AC TI(i, j)
.PRINT AC TM(i, j)
.PLOT AC TDB(i ,j)
.PRINT AC TP(i, j)
.PRINT AC TGD(i, j)
A Parameter Extraction
.PLOT AC AR(i, j)
.PRINT AC AI(i, j)
.PRINT AC AM(i, j)
.PLOT AC ADB(i ,j)
.PRINT AC AP(i, j)
.PRINT AC AGD(i, j)
Where Sxx(i, j), (Yxx(i, j), Zxx(i, j)) give the influence of Port j on Port i.
Output File Specification
For S, Y, Z parameter output file specification use the .FFILE command.
Note
See the .FFILE command in the Eldo Reference Manual.
Two-port noise parameters NFMIN_MAG, GAMMA_OPT_MAG, PHI_OPT and RNEQ are
automatically written to the specified output file when a .NOISE command is specified in the
netlist and the circuit to be analyzed is a two-port circuit.
688
Eldo® User's Manual, 15.3

Working with S, Y, Z Parameters
Output File Specification
Examples
r1 1 2 100k
c1 2 0 10pf
V1 1 0 iport=1 rport=100
V2 2 0 iport=2 rport=20
.ac dec 10 1 100meg
.plot ac sdb(2,1)
.Ffile S sb1.par khz ri
In this example, the S parameters of an RC circuit are extracted between 1Hz and 100MHz with
10 points per decade. The reference impedance is 100 for port1 and 20 for port2. The magnitude
of S21 is plotted in dB, and the extracted S parameters are stored in the file sb1.par with the
frequency in kHz. The data is stored in the form of the Real and Imaginary parts.
V1 1 0 iport=1 rport=50
R1 1 n1 1k
C1 n1 0 100p
R2 n1 2 1k
Rc1 n1 0 100k
V2 2 0 iport=2 rport=50
.ac lin 21 1meg 21meg
.noise v(n1) V1 3
.plot noise rneq gopt bopt nfmin_mag
.ffile Z Z.par kHz ma
In this example the Z parameters are being extracted between 1MHz and 21MHz with 21
analysis points. The extracted Z parameters are stored in the file Z.par with the frequency in
kHz. The data is stored in the form of the Magnitude Angle. As the circuit is a two-port circuit
and there is a .NOISE command specified in the netlist then the two-port noise parameters are
also stored in the output file. The output file is shown below:
! Data from test
# KHZ Z DB R 5.000000E+01
!
1.0000000000000000E+03 6.5542511585029786E+01 -5.7202544106307606E+01
6.4035302689753806E+01 -8.9088186330215692E+01 6.4035302689753806E+01
-8.9088186330215706E+01 6.5542511585029786E+01 -5.7202544106307606E+01
...
2.1000000000000000E+04 6.0025369785355387E+01 -4.3338006361865595E+00
3.7592014242230192E+01 -8.9956576643609139E+01 3.7592014242230199E+01
-8.9956576643609139E+01 6.0025369785355402E+01 -4.3338006361865711E+00
! Noise Data: Nfmin(dB) GammaOpt PhiOpt Rneq/R0
1.0000000000000000E+03 5.2661113010469025E+00 9.6890047604421903E-01
1.7851510536508835E+02 4.8497683522933400E+01
...
2.1000000000000000E+04 2.8441528902447214E+01 9.0554147314402922E-01
1.7956971588917614E+02 3.5225984336136335E+03
Eldo® User's Manual, 15.3 689

Working with S, Y, Z Parameters
Output File Specification
In the following example the S parameters of the block TWO_PORT_SUBCKT are being
extracted between 10kHz and 10MHz with 10 analysis points per decade. The Touchstone file
Z1.par defines the complex impedance of the source at port 1. The extracted S parameters are
stored in the file subckt.par with the frequency in kHz. The data is stored in the form of the
Magnitude Angle.
Vin 1 0 iport=1 zport_file="Z1.par"
Xsub1 1 0 2 0 TWO_PORT_SUBCKT
Vout 3 0 iport=2 rport=50
.ac dec 10 10000 10meg
.plot sdb(1,2) sdb(1,1) sdb(2,2) sdb(2,1)
.ffile S subckt.par KHZ MA
690
Eldo® User's Manual, 15.3

Working with S, Y, Z Parameters
Simulating a Block Defined by S Parameters
Simulating a Block Defined by S Parameters
The large signal S parameters model a component’s behavior in the frequency domain. Eldo
simulates the circuit using the included S-parameter data for any number of N-port blocks.
Transient Simulation of Circuits Characterized in the Frequency Domain . . . . . . . . . 691
Technical Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692
Implementation Issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 695
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 696
Basic Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Detailed Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Instantiating a Block Defined by S, Y, Z Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . 699
Touchstone Data File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705
CITIfile Data File Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708
Instantiating a Block Defined by X-Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 710
Transient Simulation of Circuits Characterized in
the Frequency Domain
Traditionally, high frequency circuits are characterized and simulated in the frequency domain.
This is because of the difficulty of handling extremely short rise times of the order of picoseconds
and the simplicity of frequency measurement.
Today with the technological advent in high frequency circuits, there is a vital need to simulate
circuits in the time domain using electrical simulators. This is needed to simulate, for example,
a linear (lossy and maybe coupled) interconnection having a non-linear termination. Such
problems may be solved in the frequency domain using harmonic balance. If we are interested
in using pulse stimuli, the circuit must be analyzed in the time domain. Another example is the
microwave simulation of passive elements, either discrete or integrated. A user defined passive
element may be simulated by extracting its scattering (S) parameters using a standard Electro-
Magnetic (EM) solver and then using this file as an input to an S-Model. This procedure enables
the user to simulate this passive element in Eldo either with or without other linear or non-linear
elements.
The main object of the S-model GenLib library is to enable the transient analysis of precharacterized
(in the frequency domain) linear high frequency circuits with any other non-linear
components. The circuit is usually characterized by its scattering parameters. S-model also
enables the simulation of circuits characterized using their admittance (Y) or impedance (Z)
parameters. The pre-characterized circuit may have any number of ports. The following
paragraph gives a brief technical presentation of matrix representation of linear circuits.
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Working with S, Y, Z Parameters
Technical Background
Technical Background
A two port network is completely presented by its Z, Y, h or S matrix.
As an example, consider the impedance Z matrix:
It is clear that this matrix relates the currents and voltages at the terminals of a given block:
An equivalent presentation is:
In this case, we use the S matrix or scattering parameters. a 1 and b 1 present the normalized
incident and reflected waves at port 1. a 2 and b 2 present the corresponding waves at port 2.
There are direct relationships between a 1 , b 1 , a 2 , b 2 and the corresponding I 1 , V 1 , I 2 , V 2 .
In the case of a two port network, the I and V as a function of a and b is given by the following:
For the same case, a and b as a function of I and V is given by the following:
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Working with S, Y, Z Parameters
Technical Background
where R 1 and R 2 are the reference impedances of ports 1 and 2 respectively.
The S parameters are widely used to characterize high frequency circuits, mainly because they
present no difficulty in measurements while the other parameters are difficult to measure. The
scattering parameters are not unique; they are defined for a given reference impedance for each
port. The reference impedance R 0 is usually 50Ω for all ports to facilitate measurement
(standard coaxial cable has 50Ω characteristic impedance).
In general, an n-port circuit has an n × n scattering matrix of the following form:
Mixed-Mode S Parameters
Bockelman and Eidenstadt 1 developed a theory for combined differential and common
normalized power waves (in terms of even and odd mode). Then it is now possible to
characterize multiport networks at high frequencies, especially such device which are simulated
by common-mode or differential-mode source, by using the extended S parameter definition.
This adaptation, called “mixed-mode S parameter”, addresses differential and common-mode
operation, as well as the conversion between the two modes operation.
According with this new definition, we can see that a two port S parameters form a 4x4 matrix
containing the mixed-mode S parameters (differential-mode, common mode and cross-mode
S parameters). Consider the following differential circuit, each port can support the propagation
of differential-mode and common-mode waves:
1.David E. Bockelman William R. Eisenstadt, “Combined Differential and Common-Mode Scattering
Parameters: Theory and Simulation” July 1995.
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Working with S, Y, Z Parameters
Technical Background
Figure 14-1. Mixed-Mode S Parameters
The response of this differential circuits to a stimulus can be expressed with the mixed-mode
S parameter matrix:
where the partition labeled are the differential-mode S parameters, are the commonmode
S parameter, and and the cross-mode S parameters. The and are the
normalized differential-mode stimulus and response waves; and are the normalized
common mode stimulus and response waves. The definition of these normalized waves are:
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Working with S, Y, Z Parameters
Implementation Issues
In general, an n-port has a 2n x 2n mixed-mode S parameter matrix of the following form:
Implementation Issues
Eldo uses three methods to simulate an S-model given by S, Y, or Z parameters. These methods
are briefly described below:
• Complex Pole Fitting (CPF) technique is a method based on complex-pole fitting of the
original dependence. During an initial “fitting” stage, the model’s given dependence is
represented as a sum of simple first-order components, each one defined by its complex
pole and residue. The result of fitting is re-usable; once generated, the list of poles and
residues is stored in a *.pls file and can be used repeatedly for simulations without the
need to re-fit. This file has the same name and location as the original data (Touchstone)
file.
The representation of frequency dependence created by fitting enables fast and accurate
transient simulation of the S-model. Simulation progresses linearly in time, using an
effective, recursive, convolution-based algorithm. Although poles/residues can be used
to build an equivalent circuit, this is not needed or recommended, for performance
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Working with S, Y, Z Parameters
Applications
reasons: the model-evaluation time in CPF is less by a factor of 5-7 than that for the
equivalent circuit built from the same poles.
Due to the very nature of fitting, the CPF method always results in a causal solution. It
also has a delay-extraction capability useful when simulating transmission lines or
connectors.
• Digital Signal Processing (DSP) technique is an alternative approach that transforms the
frequency-domain data into time domain parameters via inverse FFT, Hilbert transform
and convolution. Important modifications were made to these basic algorithms to enable
both periodic and non-periodic dependencies, to ensure the causality of the system, to
account for singularities in matrix representation and to ensure high-speed convolution.
If the circuit frequency response is naturally periodic (as for delay-containing operators)
and is given only in a fraction of a single period, the DSP method is recommended to
ensure accurate simulation. In this case, the last point given in the input data file should
correspond to the half-period of the dependence.
• System identification (SI) technique is a third method that represents S parameters in the
form of a rational function in ‘s’ (Laplace variable). These functions are then converted
into systems of linear differential equations so that Eldo can solve them during the
transient analysis.
With the above three methods, Eldo can efficiently solve a wide variety of problems. Frequency
dependencies can be either quite smooth or with a large number of sharp resonant peaks (up to
many hundred). The user may specify input data either with equidistant frequency points,
starting from zero or not; or give them in any other way, (for example, logarithmically spaced)
relevant to the method of data acquisition.
Of course, one can expect accurate simulations only if the original data is complete and
accurate. The frequency dependence given should completely encompass the range of interest,
from the lowest to the highest operation frequency. For example, high accuracy at DC is
unlikely if the data starts from non-zero frequency. Similarly, accurate simulation of short
transitions, lasting for hundred ps, is impossible if the highest point is far below tens of GHz.
Also, the data points should be given with good resolution, sufficient to reproduce the shape of
the dependencies. For example, many more points are needed to describe a dependence with
many sharp peaks than for a smooth one, even if they are both defined in the same frequency
range. Finally, the input data should be causal, so that the real and imaginary parts of the
frequency dependence satisfy the dispersion Kronig-Kramers relation. In reality, data becomes
slightly non-causal due to unavoidable measurement/simulation errors, especially (typically) at
higher frequencies. However, serious measurement errors (like taking the negated phase) cause
catastrophic non-causality that will lead to improper simulation results.
Applications
S parameters can originate from the following:
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• Simulation of passive networks using an electromagnetic solver.
Working with S, Y, Z Parameters
Basic Functionality
• Measurements from a passive network (interconnects, transmission lines, passive filters,
and so on).
• Frequency-domain simulation of passive networks (AC analysis).
• Data sheets of active or passive devices.
The major applications of S-model are as follows:
• Transient simulation of microwave linear circuits originally described by its response in
frequency domain.
• Transient simulation of interconnects together with non-linear drivers/loads, either for
VLSI or GaAs integrated circuits, using either their calculated or measured scattering
parameters.
• Lossy transmission-line transient simulation in the presence of either linear or non-linear
drivers/loads.
• Transient simulation of arbitrary (or user-defined) passive microwave circuits after
extracting their S parameters (using a standard electromagnetic solver).
Basic Functionality
The S-model implemented in Eldo is a building block that makes possible DC, AC, and
transient simulation of circuits with any number of N-ports described by their S (Scattering), Y
(Admittance), or Z (Impedance) parameters, in the form of tabulated data in the frequency
domain.
The tabulated data is contained in an ASCII data file in the Touchstone® format. This format is
briefly described in “Touchstone Data File Format” on page 705. When giving the instance of
the model in the Eldo netlist file, you can specify the data file either by setting an index
associated with the file’s name, or by explicitly defining the name of the file. The optimal of the
three algorithms discussed above, Complex Pole Fitting (CPF), Digital Signal Processing
(DSP), and System Identification (SI), is selected by the internal Eldo monitor that enables great
flexibility of simulation. You can also specify this method directly.
Detailed Functionality
Eldo supports S parameters as follows:
• Simulation of N-ports with no restriction on N. N is determined automatically by the
Eldo parser according to the number of pins.
• Any number of instances of the same model, any number of different models.
• All SST, PSS and MODSST simulation types are supported.
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Working with S, Y, Z Parameters
Detailed Functionality
• DC Simulation.
• AC Simulation. When the CPF algorithm is chosen either by the monitor or the user, the
frequency response of the system is computed based on the found poles/residues, to
enable smooth and causal simulation results. In the case of the DSP method, AC
simulation is performed by interpolation and extrapolation of the tabulated parameters,
with the response made symmetrical around the maximal tabulated frequency point, and
the obtained spectrum is made periodic. With the SI algorithm, AC simulation produces
the frequency response of the transfer function that best fits the tabulated frequency
points. If AC simulation is performed without transient simulation and without any
method forced by the user, the response is obtained through interpolation of the given
frequency-domain data points.
• Transient Simulation. Transient simulation is obtained through the application of the
most appropriate of the CPF, DSP, or SI algorithms.
• Input data can be specified as S, Y, Z, G, H, T or A parameters.
• Tabulated data may have linear, logarithmic, or irregular distribution in its frequency
range. Frequency values may start from 0 Hz or any positive value. Any number of
points is allowed.
• The choice of the CPF, DSP, or SI algorithm can be forced through a parameter of the
model. All algorithms allow any kind of spacing. However, since internally DSP
requires linearly spaced K 2 +1 data points starting at zero frequency, it uses interpolation
and extrapolation of the input data to satisfy this requirement.
• Simulation is possible with the Eldo default options.
• For an N-port block (N>1), port impedances can be identical, or different for each port.
• Speed-optimized CFAS model.
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Working with S, Y, Z Parameters
Instantiating a Block Defined by S, Y, Z Parameters
Instantiating a Block Defined by S, Y, Z Parameters
To instantiate S, Y, Z parameters use the Yname FBLOCK command.
Syntax
.MODEL FBLOCK MACRO LANG=C
YNAME FBLOCK PARAM:
+ [M=VAL]
+ [IDX_M=VAL]
+ [NO_DELAY=VAL]
+ [GROUPFIT=VAL]
+ [SYMMETRY=VAL]
+ [FORCE_PASSIVITY=VAL]
+ [FORCE_REFIT=VAL]
+ [EXTRAP_TO_DC=VAL]
+ [FORCE_TOUCH_DC=0|1]
+ [POLE_REDUCTION=VAL]
+ [HIGH_PRECISION=VAL]
+ [MAXROW=VAL]
+ [MAXCOL=VAL]
+ [IDX_F=VAL]
+ [SINGLE_REFERENCE_NODE=VAL]
+ [STRING: FILENAME]
+ PIN: IP1 IN1 ... IPN INN
Parameters
• .MODEL
The first line (.MODEL) is the reference to the C-FAS model, where the entity is called
FBLOCK. The other lines are the model parameters.
Note
The .MODEL line is optional. This declaration is not a requirement of Eldo when
referencing embedded Eldo FBLOCK models.
• PARAM:
This keyword precedes the list of parameters, (those shown in brackets are optional). Most
of the options, except for M, IDX_M and NO_DELAY, are specific to the CPF method.
• M=val
Device multiplier parameter, simulating the effect of multiple S-block elements in parallel.
Default value is 1.
• IDX_M=val
Parameter that forces a specific algorithm to be used:
IDX_M=0 specifies the CPF algorithm (default).
IDX_M=1 specifies DSP.
IDX_M=2 specifies SI.
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Working with S, Y, Z Parameters
Instantiating a Block Defined by S, Y, Z Parameters
• NO_DELAY=val
Used to enable or prevent delay extraction in the CPF or DSP methods. NO_DELAY=0
enables delay extraction, NO_DELAY=1 disables it. The default value is 0.
• GROUPFIT=val
Used in CPF to force group fitting instead of individual for every matrix component. As a
rule, with this option, fitting requires less effort but this might compromise accuracy. The
default value is 0, corresponding to individual fitting.
• SYMMETRY=val
The default assumption (SYMMETRY=1) made in CPF on the fitting stage is that the
original S (or Y or Z) matrix is symmetric. Matrix symmetry is a valid assumption as long as
the S-model describes a reciprocal subcircuit. We cannot simply rely on symmetry of the
matrices in the input data. Very often, the input matrices generated by field-solvers or
measured from reciprocal systems, are not strictly symmetric, however they should be
handled as symmetric. Set to 0 to disable the default assumption.
• FORCE_PASSIVITY=val
Enables or disables each of the two different types of passivity enforcement available in the
CPF method. These types are (1) pre-fit passivity enforcement, in which the original
sampled data is worked with to make it “passive,” and (2) post-fit enforcement, in which
poles/residues are corrected in such a way as to make the approximation strictly passive.
FORCE_PASSIVITY=0 means there is no passivity enforcement.
FORCE_PASSIVITY=1 activates pre-fit passivity enforcement.
FORCE_PASSIVITY=2 activates post-fit enforcement.
FORCE_PASSIVITY=3 (default) activates them both.
Pre-fit passivity enforcement is recommended for all passive devices. It removes occasional
passivity violations from the input data (which may result from measurement errors).
However, even for the passive data created by pre-fit passivity enforcement, fitting may still
result in a non-passive model if this data is defined within a limited frequency range (typical
case). With two different methods of passivity enforcement, you can determine the true
reason for non-passivity: poor accuracy of the input data or fitting errors. The reason for
both could be incomplete frequency range, non-causality, or insufficient resolution of the
input data. For causal, accurate, and smooth input data, fitting accuracy is quite high.
By default, Eldo performs a passivity check on the Touchstone file S parameter data. When
non-passivity is detected, data passivity will be enforced and a corresponding information
message will be issued. After the fitting of the S parameter data a new passivity check is
performed on the fitting results. If passivity violation is detected then passivity of the fitting
is enforced and a message is again issued.
Warning message examples:
o non-passive data found:
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Working with S, Y, Z Parameters
Instantiating a Block Defined by S, Y, Z Parameters
"Warning 1824: OBJECT "YNPORT0": Input data non-passive:
overshoot 1.018228e+00 at freq = 2.254981e+07"
o
pre-fit passivity enforcement:
"Warning 1822: OBJECT "YNPORT0": Enforcing passivity of input
data."
o
post-fit passivity enforcement:
"Warning 1823: OBJECT "YNPORT0": Enforcing post-fit global
passivity."
If non-reciprocal linear active devices (such as amplifiers or filters) are to be simulated, both
SYMMETRY and FORCE_PASSIVITY should be disabled.
• FORCE_REFIT=val
Set to 1 to force fitting in CPF regardless as to whether the corresponding .pls file is already
present or not. This might be needed if you want to redo fitting with different options, such
as FORCE_PASSIVITY. However, you should be careful in using such an option, it should
be disabled after the desired fit is built. The default value is 0, disabled.
• EXTRAP_TO_DC=val
Set to 1 to restore a missing point at zero frequency (DC) by extrapolating the curve from
low frequency points given in the Touchstone file. Compared to the default case
(EXTRAP_TO_DC=0) it enables, as a rule, to achieve better accuracy in DC simulation
when the point at zero frequency is not given. If the DC point is present in the input data,
this option has no effect unless incorrect DC data has been detected in the S parameter .par
or .snp file; in which case EXTRAP_TO_DC is automatically enabled and a warning
generated; see the FORCE_TOUCH_DC description.
• FORCE_TOUCH_DC=val
Set to 1 to force DC data to be used from the S parameter .par or .snp file. The default value
is 0, disabled. If incorrect DC data has been detected in the S parameter file a warning is
generated:
+ In , DC value seems to be incoherent.
+ It is ignored and its value is extrapolated (EXTRAP_TO_DC set to
1).
+ To force its use, set the parameter FORCE_TOUCH_DC to 1 in the
+ corresponding FBLOCK.
The DC value is ignored and EXTRAP_TO_DC is automatically enabled for the
corresponding FBLOCK. If, despite this recommendation, you choose to force the incorrect
DC data to be used (FORCE_TOUCH_DC=1) this value can lead to incorrect results.
• POLE_REDUCTION=val
Default value is 1. Enables the mode of transient simulation in which some of the fitted
poles (that are too fast, too slow or too small) are removed to speed-up the solution. This
mode typically gives up to 30-50% reduction in solution time when the step of the transient
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Working with S, Y, Z Parameters
Instantiating a Block Defined by S, Y, Z Parameters
solution is fixed. The decision about pole reduction is made from considering the solution
step (pole is too “fast”), or the duration of the simulation interval (pole is too “slow”).
Therefore, the set of actually used poles is defined “dynamically” from considering the
parameters of the .TRAN command. The generated list of poles/residues (*.pls) file remains
unaffected. Pole reduction does not considerably affect the solution accuracy. However, if
the precise simulation is needed, the option can be disabled by setting
POLE_REDUCTION=0.
• HIGH_PRECISION=val
Set to 1 to increase the fitting accuracy by enabling more poles than in regular mode (with
default value 0). This option can be useful for verification purposes, for example if a
“reference solution” is required. However, it is not recommended if the input data itself is
not very accurate. Also, since high-precision fitting produces more poles, it makes
simulation slower.
• MAXROW=val
Sets the limit (val/2) to the frequency points of the original dependence used in fitting. The
default value is 40000, corresponding to 20,000 points.
• MAXCOL=val
Sets the limit (val/2) to the maximal order of complexity for fitting in CPF. The default
value is 1500, corresponding to an order of complexity of 750. For very complicated (sharp,
irregular) dependencies it is sometimes reasonable to reduce the order of complexity,
especially if we have reasons not to entirely trust the input data at higher frequencies. As a
rule, reducing the order of complexity is a better strategy than reducing the number of points
to consider (MAXROW).
• IDX_F=val
Defines the index (integer number) VAL associated with the S parameter file (IDX_F=VAL
implies that the input parameter file is named sbVAL.par). Alternative way of defining the
input data file; see also the STRING: keyword.
• SINGLE_REFERENCE_NODE=val
Set to 1 to support a single reference node. When the number of pins of the FBLOCK model
is even, Eldo considers that each port has two pins. When the number of pins is odd, Eldo
considers the reference pin is the same for all ports (and it is the last pin). Specify
SINGLE_REFERENCE_NODE=1 to enable the FBLOCK model to consider the last pin as
the common reference pin for all ports if the number of ports is the number of pins−1.
• STRING:
Used to define the name of the touchstone file, CITIfile, or poles/residues file (.pls),
containing the input data. Path definition is allowed. Another way of defining the data file is
using the IDX_F parameter under the keyword PARAM: together with all the other
parameters, not under the STRING: keyword. If not specified, sbVAL.par is used by
default, where VAL is defined by IDX_F, or the number of ports otherwise.
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Working with S, Y, Z Parameters
Instantiating a Block Defined by S, Y, Z Parameters
• PIN: IP1 IN1 ... IPN INN
Required. The 2×N pins of the N-port model will be connected to nodes IP1 IN1 ... IPN
INN. Any number of ports can be specified.
Description
Any model may be instantiated as many times as required with the same or different input data
file.
Any FBLOCK instance will contribute to the global noise results of .NOISE and .SSTNOISE. If
the Touchstone format file contains noise parameters then they will be used to compute the
noise contribution, otherwise the simulator will use the Twiss formula.
Twiss Formula
Where:
C y = Noise Correlation Matrix
k = Boltzmann Constant
t = Temperature
Y = Y Parameter Matrix
H = Hermitian Matrix (complex conjugate transpose)
The FBLOCK file parameter is searched with the same methodology as searching library files,
see “Search Path Priorities” on page 133. This means that if the FBLOCK file is not found in the
current directory, the library where the corresponding FBLOCK instance was found is searched
first if FBLOCK was actually read from a library. If not found, the directories are searched in
the order specified by the option SEARCH.
Examples
In this example, a block ytline is defined. By default, the CPF method runs. Delay extraction is
allowed (if feasible), fit is set to individual, the model is assumed symmetric, passivity
enforcement is set for pre-fit stage; refit, extrapolation to DC, and high precision flags are
disabled, and the parameters MAXCOL, MAXROW are set to their default values, 1500 and
40,000 respectively. The file name is given in conventional form, by using the keyword
“string:”.
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Working with S, Y, Z Parameters
Instantiating a Block Defined by S, Y, Z Parameters
.model dio D rs=4.68 bv=6.1 cjo=246p
.model Fblock macro lang=c
vin 1 0 dc 5 ac 1 pulse(0 5 1n 1n 1n 5n 10n)
rin 1 2 50
ytline Fblock param:
+ force_passivity=1
+ string: C:\s-parameterdata\lowpassfilter.s2p
+ pin: 2 0 3 0
dout 3 0 dio
.ac dec 10 1 10meg
.tran 10n 100n
.plot ac vdb(2) vdb(3)
.plot tran v(1) v(2) v(3)
.end
In this example, a block y2port refers to an S parameter file sb4.par (defined with idx_f=4).
Here, the S-block is described as a subcircuit. The DSP method is chosen and delay extraction is
prevented.
.subckt sparam_2p p1 p2 grnd
.model Fblock macro lang=c
y2port FBLOCK param:
+ idx_f=4
+ idx_m=1
+ no_delay=1
+ pin: p1 grnd p2 grnd
.ends sparam_2p
Related Topics
Touchstone Data File Format
CITIfile Data File Format
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Working with S, Y, Z Parameters
Touchstone Data File Format
Touchstone Data File Format
Input or output for: Eldo and Eldo RF; output generated by the .FFILE command
Eldo fully supports Touchstone® versions v1 and v2 formats for reading and writing. When
reading, the format is automatically detected.
Note
See the .FFILE command in the Eldo Reference Manual.
Format
The Touchstone data format file is an ASCII text file in which data appears line by line: N lines
for each data point of N ports. The data points are stored in increasing order of frequency.
The first of the N lines consist of a frequency value and N pairs of values for S, Y, Z, G, H, T or
A parameters. The (N-1) following lines contain N pairs of values. Values are separated by one
or more spaces or tabulations.
Tip
Touchstone data format files follow general syntax rules. The standard is available from the
EDA Industry Working Groups website:
Touchstone version 1:
http://www.eda.org/pub/ibis/connector/touchstone_spec11.pdf
Touchstone version 2:
http://www.eda.org/pub/ibis/touchstone_ver2.0/touchstone_ver2_0.pdf
• Comment lines begin with an exclamation mark (!).
• The first uncommented line in the Touchstone data file must be an option specification
line that begins with the pound sign (#) followed by a space. The option line is formatted
as follows:
# [Hz|kHz|MHz|GHz] [S|Y|Z|G|H|T|A] [RI|MA|DB] [R Val|R1 Val1 ... Rn
Valn]
Parameters
• [Hz|kHz|MHz|GHz]
Frequency Unit (Hz, kHz, MHz, GHz). Default value is Hz.
• [S|Y|Z|G|H|T|A]
Parameter type (S, Y, Z, G, H, T, A). Default value is S.
• [RI|MA|DB]
Data format (MA, DB, RI). Default value is RI. MA means Magnitude-angle in Volts, and
phase in degrees. DB means Magnitude in dB, and phase in degrees. RI means Real and
Imaginary parts.
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Working with S, Y, Z Parameters
Touchstone Data File Format
• [R Val|R1 Val1 ... Rn Valn]
Reference impedance of each port (when all the ports have the same reference impedance
you can specify a single value). Default value is all ports with the same 50 W reference
impedance.
Note
The two-port noise parameters (NFMIN, GAMMA_OPT_MAG, PHI_OPT, RNEQ) can be
included in the Touchstone data file when you have specified a .NOISE command in the
netlist and when the circuit to be analyzed is a two-port circuit. NFMIN is the minimal noise
figure of the two-port. GAMA_OPT is the magnitude of the optimal reflection coefficient
associated with the minimum noise figure. PHI_OPT is the angle of the optimal reflection
coefficient associated with the minimum noise figure. RNEQ is the equivalent noise resistance.
Examples
Touchstone data file option line example:
# khz s ri r 50
Frequency values are in kHz, the data is S parameter data, they are stored in the format Real and
Imaginary part, and the reference impedance is 50Ω for each port.
Example S parameters for three ports:
F
SR11 SI11 SR12 SI12 SR13 SI13
SR21 SI21 SR22 SI22 SR23 SI23
SR31 SI31 SR32 SI32 SR33 SI33
Two ports may be represented in matrix or single line format, but with a different parameter
order (S12 and S21 are swapped). For example:
Two ports in single line format:
Freq S11 S21 S12 S22
Two ports in matrix format:
Freq S11 S12
S21 S22
Mixed-Mode S Parameter Extraction
When extracting mixed-mode S parameters the contents of the Touchstone output data file
changes. For example the file header for a 2-port network may be as follows:
! Data from foo
! S11 = SDD11
! S12 = SDS12
! S13 = SDC11
# HZ S RI R1 1.000000E+01 R2 1.000000E+00
706
Eldo® User's Manual, 15.3

Working with S, Y, Z Parameters
Touchstone Data File Format
Related Topics
CITIfile Data File Format
Instantiating a Block Defined by S, Y, Z Parameters
Instantiating a Block Defined by X-Parameters
Eldo® User's Manual, 15.3 707

Working with S, Y, Z Parameters
CITIfile Data File Format
CITIfile Data File Format
Input for: Eldo and Eldo RF
CITIfile stands for Common Instrumentation Transfer and Interchange file format. Eldo
partially supports CITIfile versions A.01.00 and A.01.01 formats for reading only. When
reading, the format is automatically detected.
Format
The CITIfile data format file is an ASCII text file in which data appears line by line: N lines for
each data point of N ports. The data points are stored in increasing order of frequency.
Tip
CITIfile data format files follow general syntax rules. The standard is available from the
Agilent website:
http://edadocs.software.keysight.com/display/ads2009U1/
Working+with+Data+Files#WorkingwithDataFiles-CITIfileDataFormat
• A typical CITIfile package is divided into two parts:
o
o
The header is made up of keywords and setup information.
The data usually consists of one or more arrays of data.
• The length of a line within a CITIfile package should not exceed 80 characters. This
allows instruments which may have limited RAM to define a reasonable input buffer
length.
• Keywords are always at the beginning of a new line. The end of a line is as defined by
the file system or transfer mechanism being used.
• Arrays of data start after the BEGIN keyword, and the END keyword follows the last
data element in an array.
Parameters
Keyword
CITIFILE
NAME
VAR
CONSTANT
Table 14-2. CITIfile Data Format Supported Keywords
Limitations / Requirements
Only A.01.00 and A.01.01 revisions are supported.
Keywords after NAME are ignored.
Only FREQ and MAG keywords supported.
VAR FREQ MAG is mandatory.
Supported:
NBR_OF_PORTS (mandatory).
NORMALIZATION (optional, only the value “1” is supported).
708
Eldo® User's Manual, 15.3

VAR_LIST_BEGIN /
VAR_LIST_END
SEG_LIST_BEGIN /
SEG_LIST_END
DATA
BEGIN / END
#KEYWORD
(user-defined keyword)
Related Topics
Touchstone Data File Format
Instantiating a Block Defined by S, Y, Z Parameters
Instantiating a Block Defined by X-Parameters
Only MAG format supported (revision A.01.00).
List of FREQ associated values in ascending order.
Working with S, Y, Z Parameters
CITIfile Data File Format
Table 14-2. CITIfile Data Format Supported Keywords (cont.)
Keyword
Limitations / Requirements
Only one SEG in the block allowed (revision A.01.00).
List of FREQ associated values.
Supported:
• S[i,j], Y[i,j], Z[i,j], G[i,j], H[i,j], T[i,j], A[i,j] (mandatory):
• RI, MAGANGLE, DB supported.
• Any order for [i,j] supported.
• DATA S/Y/Z/G/T/A line number should correspond to the
number of ports (#lines = nb_ports×nb_ports).
• PORTZ[i] (user-defined keyword, optional, 50Ω by default):
• RI supported (real format only: ", 0").
• Any order for [i] supported.
• All values in a BEGIN/END block should be identical (same
value for all frequencies).
• DATA PORTZ line number should match number of ports
(#lines = nb_ports).
Data should be complex (2 values per line).
Number of lines should correspond to FREQ.
Any line starting with # is ignored (considered as comment).
Eldo® User's Manual, 15.3 709

Working with S, Y, Z Parameters
Instantiating a Block Defined by X-Parameters
Instantiating a Block Defined by X-Parameters
X-parameters can be used in an XBLOCK, similar to the S parameters FBLOCK syntax. They
can be used in Eldo RF SST analysis or Eldo Classic DC, AC, and noise analyses.
Tip
The X-parameters parser is based on the GMDIF version 2.0 file format:
http://edocs.soco.agilent.com/display/ads2009U1/
Working+with+Data+Files#WorkingwithDataFiles-XparameterGMDIFFormat
Syntax
.MODEL XBLOCK MACRO LANG=C
XNAME XBLOCK PARAM:
+ [M=VAL]
+ [SINGLE_REFERENCE_NODE=VAL]
+ STRING: FILENAME
+ PIN: IP1 IN1 ... IPN INN
Parameters
• .MODEL
The first line (.MODEL) is the reference to the model, where the entity is called XBLOCK.
The other lines are the model parameters.
Note
This .MODEL line is optional. This declaration is not a requirement of Eldo when
referencing embedded Eldo XBLOCK models.
• PARAM:
This keyword precedes the list of optional parameters.
• M=val
Device multiplier parameter, simulating the effect of multiple X-block elements in parallel.
Default value is 1.
• SINGLE_REFERENCE_NODE=val
A single reference node is supported. When the number of pins of the XBLOCK model is
even, Eldo considers that each port has two pins. When the number of pins is odd, Eldo
considers the reference pin is the same for all ports (and it is the last pin). Specify
SINGLE_REFERENCE_NODE=1 to enable the XBLOCK model to consider the last pin as
the common reference pin for all ports if the number of ports is the number of pins−1.
• STRING: filename
Used to define the name of the touchstone file, or poles/residues file (.pls), containing the
input data. Path definition is allowed.
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Eldo® User's Manual, 15.3

Working with S, Y, Z Parameters
Instantiating a Block Defined by X-Parameters
• PIN: IP1 IN1 ... IPN INN
The 2×N pins of the N-port model will be connected to nodes IP1 IN1 ... IPN INN.
Description
X-parameter files are identified with the .xnp extension (where n represents the number of
ports). To compute accurate results, it is recommended to adapt output ports, that is, to match
the port impedances with the port impedances used while generating X parameters.
• Transient, SSTAC and SSTNOISE simulations are not supported.
• Multi-tone extraction/simulation is not supported.
• Memory effects are not supported.
• X-parameter blocks do not generate noise.
Eldo RF generates X-parameter data in the Generic MDIF (GMDIF) version 2.0 file format,
with the .XFILE command similar to the S parameters .FFILE command. See Generating
X-Parameters in the Eldo RF User’s Manual.
Eldo® User's Manual, 15.3 711

Working with S, Y, Z Parameters
Instantiating a Block Defined by X-Parameters
712
Eldo® User's Manual, 15.3

Chapter 15
Aging and Reliability Simulation
Reliability models are implemented in the Eldo UDRM (User Defined Reliability Model)
interface.
The objective of aging and reliability simulation is to be able to model the gradual damage,
which occurs to the devices in a certain design causing degradation in the performance of that
design. It is required to evaluate the amount of degradation occurring in a certain period of
operation and examine the circuit performance after this period. The modeled damage could
follow one or more of several damage mechanisms, which show gradual degradation in device
performance.
The reliability simulations follows the model defined by the user using the UDRM interface.
Degradation effects supported are: Hot-Carrier degradation, and NBTI (Negative Bias
Temperature Instability) degradation.
Tip
Refer to Eldo UDRM User’s Manual for more information.
Running Reliability Simulation in Eldo
Reliability simulation in Eldo can be used with any normal netlist provided that it contains a
.TRAN or .SST analysis. This .TRAN or .SST analysis is the analysis used for all the fresh and
aged simulations, and its outputs are also available for all the fresh and aged simulations.
The reliability simulation is invoked and controlled through the Eldo reliability commands,
summarized in Table 15-1. Clicking on a command link in the table will open the description
inside the Eldo Reference Manual.
Table 15-1. Eldo Reliability Commands
Command
Description
.AGE
Age analysis
.AGE_LIB
Define functions for reliability
.AGE_SENSITIVITY Provide information about the stress sensitivity
.AGEMODEL Reliability model parameter declaration
.SETKEY
Set reliability model key (password)
Eldo® User's Manual, 15.3 713

Aging and Reliability Simulation
Running Reliability Simulation in Eldo
Command
.USEKEY
Table 15-1. Eldo Reliability Commands (cont.)
Description
Use reliability model key (password)
Tip
For further information on usage, and the implementation of reliability models, see the Eldo
UDRM User’s Manual.
714
Eldo® User's Manual, 15.3

Chapter 16
Electrothermal Simulation
This chapter describes the electrothermal simulation available in Eldo.
Electrothermal Simulation Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 715
Specifying an Electrothermal Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 716
Verilog-A Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 720
Reporting and Sorting Thermal Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 723
Electrothermal Simulation Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 724
Electrothermal Simulation Overview
Eldo supports fully coupled electrothermal simulation. In high voltage/power applications, the
control of the temperature and its propagation throughout the circuit and the system become
critical. Using a global uniform temperature for the entire IC is no longer accurate enough.
Devices consuming power tend to heat, and this heat propagates to the devices in the vicinity,
through thermal coupling. The temperature at which a device operates (for example a simple
resistor, a DMOS, or bipolar device) modifies its electrical characteristics. Some particular
characteristics might have exponential dependencies with the temperature, such as leakage
currents.
As the electrical characteristics change, so does the dissipated power, and thus the heat, and so
on. Everything (the electrical performance and the temperature) becomes tightly coupled and
interacting, and cannot be calculated in isolation. The electrical and thermal equations must
truly belong to the same system for accurate resolution.
Eldo solves this problem by allowing the local temperature of devices or entire cells
(subcircuits, in SPICE terminology) to be true variables of the system. Temperatures are solved
simultaneously with the voltages and the currents through the devices. This is called true
electrothermal simulation.
This flow requires the inclusion of an estimated thermal network in the simulation netlist. This
network is typically composed of thermal resistors and capacitors. The thermal network
depends on the layout (the physical distance between the heating devices) and on the materials
used in the process.
Figure 16-1 shows the electrothermal simulation flow in Eldo.
Eldo® User's Manual, 15.3 715

Electrothermal Simulation
Specifying an Electrothermal Simulation
Figure 16-1. Electrothermal Simulation Flow
Related Topics
Specifying an Electrothermal Simulation
Electrothermal Simulation Example
Specifying an Electrothermal Simulation
The implementation of electrothermal simulation in Eldo is subcircuit-based.
You specify the .TEMPNODE command inside the subcircuit for which the
electrothermal effect is to be monitored. This is the internal definition syntax. The voltage value
on the specified node represents the temperature increase of the corresponding subcircuit with
respect to the global circuit temperature. Eldo computes the power dissipated by the active
devices present in the subcircuit containing .TEMPNODE commands. This power, formally
equivalent to a current source, is dissipated in the thermal network attached to the thermal net,
resulting in a new temperature value of the subcircuit. Eldo continues iterations until
convergence is achieved.
Examples of Setting up Electrothermal Simulation
For example, starting from a normal subcircuit:
.subcircuit mybjt c b e
.model bjt50 bjt level=…
Q1 c b e bjt50
.ends
Enable electrothermal simulation with the following simple addition (th node on subcircuit and
.TEMPNODE command):
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Eldo® User's Manual, 15.3

Electrothermal Simulation
Specifying an Electrothermal Simulation
.subcircuit mybjt c b e th
.model bjt50 bjt level=…
Q1 c b e bjt50
.tempnode th
.end
Anything connected on the thermal nodes is treated as a thermal device (not electrical) and part
of the thermal network (not part of the electrical network).
The thermal node does not have to be the last connection in the list. For example, you can
alternatively specify:
.subcircuit mybjt2 th c b e
.model bjt50 bjt level=…
Q1 c b e bjt50
.tempnode th
.end
Blocks (subcircuit instances) are connected using the same convention as in regular SPICE. For
example:
X1 out1 inp em th1 mybjt
X2 out2 inm em th2 mybjt
Rth th1 th2 10
The Rth thermal resistor creates a thermal coupling between transistors X1 and X2, connecting
their respective thermal nodes th1 and th2 together. As th1 and th2 are connected to the thermal
node (th) of the X1 and X2 blocks, they are no longer treated as regular electrical connections
(by contrast, out1 and out2 are) carrying an electrical voltage. Instead, they carry at all times the
temperature elevation of the X1 and X2 blocks. The temperature elevation is always measured
with respect to the global temperature (27 °C by default in Eldo), and can be interpreted in
degrees Kelvin or Celsius as it is a delta.
You can use the subcircuit X instance parameter STATUS_TEMPNODE to control the
temperature inheritance for that instance. For example:
.subckto foo a b c
.tempnode c
R1 a b 1 tc1 = 0.1
X1 a b foo2 status_tempnode=0
.ends
Because STATUS_TEMPNODE is set to 0, devices in X1 do not contribute to the power of
instance foo. X1 does not inherit the temperature of instance foo, devices in X1 are supposed to
be at the temperature of the circuit (.TEMP command). When STATUS_TEMPNODE is 1
(default), X1 contributes to the power and inherits the temperature of the instance foo. Setting
STATUS_TEMPNODE=2 provides an intermediate case: X1 inherits the temperature of the
instance foo, but does not contribute to the power of X1.
Eldo® User's Manual, 15.3 717

Electrothermal Simulation
Specifying an Electrothermal Simulation
Alternative Syntax for External Definition
The thermal node can be defined external to the subcircuit definition. This means thermal
analysis can be used without modifying the structure of your design kits (schematics, symbols,
models). This is different to the internal definition where you can only define the thermal node
of a subcircuit by adding the command inside its definition.
You specify the .TEMPNODE SUBCKT=subckt THNODE=node external to the subcircuit
definition, not internal. It creates a thermal node named node in the subcircuit. Because it is an
internal node, the instantiations of the subcircuit do not need to change. Its hierarchical name
must be used to connect it to a thermal network.
Electrothermal Simulation Outputs
Additional outputs are available when using electrothermal simulation. You can easily plot the
dissipated power, the local time-varying temperature of the blocks, and the temperature
elevations. For example:
• Instantaneous power:
.plot tran pow(X1) pow(X2)
• Instantaneous temperature, in degrees Celsius:
.plot tran temp(X1) temp(X2)
• Temperature change (from the global temperature):
.plot tran V(th1) V(th2)
Electrothermal Simulation Modes
To select the accuracy of the electrothermal simulation, specify option ETMODE=0|1|2.
When ETMODE=1, default, Eldo makes the assumption that the temperature evolves at a
slower rate than electrical quantities to perform a faster simulation. When this assumption is
true (which is the case in real circuits), results are accurate. If this assumption is not true
(generally for ideal circuits), select ETMODE=2 to obtain accurate results. Specifying
ETMODE=0 deactivates electrothermal simulation.
Notes
• For internal definition syntax, there can be only one .TEMPNODE command per
.SUBCKT: all devices in a subcircuit share the same temperature node, hence the same
temperature.
• For internal definition syntax, the node specified on the .TEMPNODE command is
usually a node at the interface of the .SUBCKT definition, to connect a thermal network
between subcircuits. This is not mandatory: thermal devices can be connected from
outside using full-hierarchical names (for example R1 x1.x2.thn x1.x3.thn 1).
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Eldo® User's Manual, 15.3

Electrothermal Simulation
Specifying an Electrothermal Simulation
• Subcircuit X instances inside a .SUBCKT inherit the .TEMPNODE of the parent, unless
a new .TEMPNODE is specified on the .SUBCKT definition of the child, or the
parameter STATUS_TEMPNODE= 0 is specified on the X instance (to disable the
electrothermal effect for that instance).
• You can use the subcircuit X instance parameter STATUS_TEMPNODE to disable (0)
or enable (1—default) the temperature inheritance for that instance. Alternatively, you
can select an intermediate case (2) where the subcircuit instance inherits the temperature
as computed by the electrothermal simulation, but the instance does not contribute to the
electrothermal power. This is useful in applications using LED models where the
forward current is split into two components: one component contributes to dissipation
(self-heating), the other current component is associated with light output without any
contribution to heating; but both components depend on the local junction temperature.
• Temperature-dependent parameters present inside a .SUBCKT with .TEMPNODE are
re-evaluated at each iteration, and their values are propagated.
• DTEMP specifications on devices inside an electrothermal subcircuit are ignored (Eldo
computes the DTEMP value).
• For external definition syntax, if there are multiple .TEMPNODE commands specified
for the same subcircuit only the last one is used, the others are ignored.
• For external definition syntax, if the thermal pin of a subcircuit instance is connected to
nothing or to ground, then electrothermal simulation is disabled on this subcircuit
instance.
• For external definition syntax, the subcircuit name can contain wildcards. In this case, a
thermal node is created for each subcircuit matching the regular expression.
• For external definition syntax, when using wildcards, it is advised to carefully select
subcircuits where the thermal node will be really connected to a thermal network. For
example, it is not advised to specify:
Limitations
.TEMPNODE subckt=* thnode=th
when only a few subcircuits will be connected to a thermal network. Adding a dangling
thermal node on subcircuits where electrothermal simulation will not be activated has a
negative impact on performance.
• For Monte Carlo analysis: DEV is not allowed on parameters used on .SUBCKT with
.TEMPNODE, however DEVX is allowed.
• Electrothermal simulation is disabled when performing AC analysis: but DCOP done
prior to AC does take into account electrothermal effects.
• Electrothermal simulation is disabled when either IEM or RF analyses are found in the
circuit.
Eldo® User's Manual, 15.3 719

Electrothermal Simulation
Verilog-A Support
• Eldo Premier is not able to deactivate, on the resistors belonging to the thermal network,
the automatic MINRVAL=1e-3 added by default with option PREMIER_MODE=2. If
the thermal network has resistors with very small values (below 1e-3 Ohm), it is advised
to explicitly set the MINRVAL option to avoid them being removed.
Related Commands
• .TEMPNODE command in the Eldo Reference Manual.
• .REPORT_HEATING command in the Eldo Reference Manual.
• .SUBCKT command in the Eldo Reference Manual.
• Subcircuit Instance in the Eldo Reference Manual.
Related Topics
Reporting and Sorting Thermal Contributors
Electrothermal Simulation Example
Verilog-A Support
Electrothermal simulation supports Verilog-A models. The power contribution of Y instances
are taken into account. Eldo simulates Verilog-A models in an electrothermal simulation, in the
same way as for SPICE devices.
For Verilog-A devices, the analog kernel parameter system function $temperature, returns the
local temperature in (Kelvin units) of the given subcircuit. Verilog-A devices that have
temperature dependency are then impacted by any temperature variation inside the surrounding
subcircuit. In a standard (non-electrothermal) simulation, the $temperature will always return
the ambient temperature of the circuit.
To simulate coupled electrothermal effects in Eldo, a thermal node for a given subcircuit is
defined and connected to a thermal network in two ways using the .TEMPNODE command:
internal definition inside the subcircuit and external definition outside the subcircuit. The
electrical behavior of all instances inside such a subcircuit that are temperature dependent, are
affected by the local temperature of this subcircuit. The total power dissipated by the
instantiated devices, contributes to the heating in the connected thermal network.
• Explicit .TEMPNODE specification:
In the same as for Eldo devices, a Verilog-A model can be instantiated in a subcircuit
that contains a .TEMPNODE command that describes the additional thermal port. The
thermal port must be connected explicitly to the thermal network to enable
electrothermal simulation.
In the first example below, a SPICE resistor is replaced by a Verilog-A instance.
• Implicit .TEMPNODE specification:
720
Eldo® User's Manual, 15.3

The .TEMPNODE statement can also be specified outside the subcircuit.
Electrothermal Simulation
Verilog-A Support
In the second example below, a SPICE resistor is replaced by a Verilog-A instance.
• Case of $temperature specified in @initial_step
Examples
To avoid multiple evaluations of some variables, the @initial_step of a Verilog-A model
is commonly used. In a standard (non electrothermal) simulation, the temperature of the
circuit is supposed to be constant during the entire simulation.
For electrothermal simulation, Eldo allows the update of the local temperature without
modifying the model. All variables that are dependent of the temperature and are present
only in the initial step statement, are updated at each temperature variation inside the
surrounding subcircuit.
This reduces the evaluation cost of the resistor model with $temperature in the @initial
step compared to the first model.
In the third example below, resistor1 and resistor2 give the same electrothermal
simulation results.
Examples of .TEMPNODE specifications with Verilog-A models:
• Explicit .TEMPNODE specification—a SPICE resistor is replaced by the Verilog-A
instance xra:
* Verilog-A Electrothermal simulation example
* I(V1) = -2.5607996733E-02
* TEMP(X1) = 4.6050301765E+01 Celsius
.hdl resistor.va
.SUBCKT test a b thn
.tempnode thn
xra a b resistor RS=1k tc1 = 0.1
.ENDS
.option numdgt = 10
v1 a 0 100
* instantiate the thermal subcircuit:
* 3 pins to connect
x1 a b thn test
r2 b 0 1k
* connect the explicit thermal node
* to the thermal network
rthn thn 0 10
.op
.extract dc i(v1)
.extract dc TEMP(x1)
.end
Eldo® User's Manual, 15.3 721

Electrothermal Simulation
Verilog-A Support
• Implicit .TEMPNODE specification—a SPICE resistor is replaced by the Verilog-A
instance xra:
*Verilog-A Electrothermal simulation example
* I(V1) = -2.5607996733E-02
* TEMP(X1) = 4.6050301765E+01 Celsius
.hdl resistor.va
.SUBCKT test a b
xra a b resistor RS=1k tc1 = 0.1
.ENDS
.tempnode subckt=test thnode=thn
.option numdgt = 10
v1 a 0 100
* instantiate the thermal subcircuit:
* 2 pins to connect
x1 a b test
r2 b 0 1k
* connect the implicit thermal node
* to the thermal network
rthn x1.thn 0 10
.op
.extract dc i(v1)
.extract dc TEMP(x1)
.end
• An example of the $temperature function usage is shown in the small resistor code
below. In this model, the temperature is evaluated at each iteration and the value of the
resistor updated accordingly. This may have a certain cost.
`include "disciplines.h"
module resistor1 (a,b);
electrical a , b;
inout a,b;
parameter real RS = 0;
parameter real TC1 = 0;
real rtval;
analog begin
rtval = RS*(1.0 + TC1*($temperature - 300.15));
I(a,b)

Electrothermal Simulation
Reporting and Sorting Thermal Contributors
`include "disciplines.h"
module resistor2 (a,b);
electrical a , b;
inout a,b;
parameter real RS = 0;
parameter real TC1 = 0;
real rtval;
analog begin
@(initial_step) begin
rtval = RS*(1.0 + TC1*($temperature - 300.15));
end
I(a,b)

Electrothermal Simulation
Electrothermal Simulation Example
Related Commands
• .REPORT_HEATING command in the Eldo Reference Manual.
Related Topics
Electrothermal Simulation Example
Electrothermal Simulation Example
This example verifies the electrothermal simulation.
* Electrothermal simulation example
.SUBCKT test a b thn
.tempnode thn
ra a b 1k tc1 = 0.1
.ENDS
.option numdgt = 10
v1 a 0 100
x1 a b thn test
r2 b 0 1k
rthn thn 0 10
.op
.extract dc i(v1)
.extract dc TEMP(x1)
.alter
x1 a b 0 test
.temp '27 + 1.9050301766E+01'
.end
The .TEMPNODE command specifies node thn as the thermal net on which power dissipation
will be monitored. The thermal net here is a single resistor, rthn, it emulates how the power
generated by devices attached to node thn is dissipated to the thermal ground 0. The syntax
TEMP(x) is used to plot/extract the actual temperature value of an X instance or the temperature
of a device.
The .ALTER statement reruns Eldo with a modified netlist. The solution of the previous
simulation gives 19.05, this value is used to define a .TEMP, and the thermal effect is disabled
by connecting the thermal net to 0 (3rd pin of subcircuit test), and extract values I(V) obtained
in the first run when electrothermal was active must be identical to the extract obtained in the
ALTER run where the TEMP is explicitly defined and electrothermal disabled.
An equivalent example, using the alternative syntax to define the thermal node external to the
subcircuit definition is as follows.
724
Eldo® User's Manual, 15.3

Electrothermal Simulation
Electrothermal Simulation Example
* Electrothermal simulation example - syntax 2 (external definition)
.SUBCKT test a b
ra a b 1k tc1 = 0.1
.ENDS
.tempnode subckt=test thnode=thn
.option numdgt = 10
v1 a 0 100
x1 a b test
r2 b 0 1k
rthn x1.thn 0 10
.op
.extract dc i(v1)
.extract dc TEMP(x1)
.end
The .TEMPNODE command specifies a thermal node thn in the subcircuit test. Its hierarchical
name x1.thn is used to connect it to a thermal network. The thermal net here is a single resistor,
rthn, it emulates how the power generated by devices attached to node thn is dissipated to the
thermal ground 0. The syntax TEMP(x) is used to plot/extract the actual temperature value of an
X instance or the temperature of a device.
Related Topics
Electrothermal Simulation Overview
Specifying an Electrothermal Simulation
Eldo® User's Manual, 15.3 725

Electrothermal Simulation
Electrothermal Simulation Example
726
Eldo® User's Manual, 15.3

Chapter 17
IBIS Models Support in Eldo
This chapter provides a brief introduction and background to IBIS, lists the current state of IBIS
support in Eldo, and provides the syntax and its description for simulating either individual IBIS
buffers or entire components. General notes and options related to the IBIS support in Eldo are
also described, and some illustrative examples provided. Finally, the chapter ends with some
examples. It is not intended to provide a detailed description of the IBIS standard in this chapter.
Introduction to IBIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 728
IBIS Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 728
Using IBIS Models in Eldo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 728
IBIS Resources on the Web . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729
IBIS File Types and Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729
Checking IBIS Files with the Golden Parser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731
IBIS Device Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 732
Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 733
Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 744
Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745
Electrical Board Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 748
IBIS AMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 748
IBIS Support in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 749
Backward Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 749
Analysis Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 749
Digital Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750
IBIS Model Syntax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 751
IBIS Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 752
IBIS Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 765
IBIS Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773
IBIS Electrical Board Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777
Supported Keywords and Sub-Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 780
IBIS Algorithmic Model Interface (AMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 787
IBIS Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790
Example 1—Single-Ended Tx-Rx System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790
Example 2—Pseudo-Differential Tx-Rx System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 792
Example 3—Package Parasitics Cross Talk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 794
Example 4—Simultaneous Switching Output Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 796
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IBIS Models Support in Eldo
Introduction to IBIS
Introduction to IBIS
I/O Buffer Information Specification (IBIS) is an ANSI/EIA-656 standard that is developing a
specified industry standard method to electronically transport input/output buffers modeling
data between semiconductor vendors, EDA tool vendors and end customers.
Eldo supports IBIS version 5.0.
IBIS Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 728
Using IBIS Models in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 728
IBIS Resources on the Web. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729
IBIS File Types and Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729
Checking IBIS Files with the Golden Parser. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731
IBIS Background
IBIS was originally developed by Intel ® Corporation in the early 1990s. With the participation
of more companies and industry members, IBIS Open Forum was created to promote the IBIS
development and to make sure that standard exists. In 1995 the IBIS Open Forum teamed with
the EIA. Since then the EIA/IBIS Open Forum oversaw all technical developments of IBIS.
The IBIS committee provides a new version every one or two years. Each version adds more
features that the EDA tool vendors should support, and describes how the related input data is
formatted. The latest IBIS standard is IBIS version 5.0 which was ratified by the EIA IBIS Open
Forum on August 29, 2008. The previous standard, IBIS version 4.2, was ratified by the EIA
IBIS Open Forum on June 2, 2006 and formally ratified as ANSI/EIA-656-B on September 1,
2006.
IBIS is a behavioral model that describes the electrical characteristics of the I/O buffers using
V/I and V/T tables. It has the advantage of not showing any proprietary information. Moreover,
the use of behavioral simulation, instead of transistor level simulation, helps in accelerating the
signal integrity analysis and the overall design cycle. It is important to note that IBIS does not
provide the models themselves but describes how the input data to the EDA tool is formatted.
An IBIS file contains data not only about individual buffers but also about an entire component
(IC) including pin-to-buffer mapping and package parasitics.
Related Topics
Using IBIS Models in Eldo
Using IBIS Models in Eldo
Using IBIS in Eldo is similar to using other SPICE elements, such as transistors. You specify a
name for the buffer, the nodes to which the buffer is connected to the rest of the circuit, and
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IBIS Models Support in Eldo
IBIS Resources on the Web
parameters to refer to a model for the buffer and the IBIS file where the model is located. In
Eldo you specify the name of the IBIS element with the prefix _IO_.
Eldo can simulate IBIS devices either individually or in the overall component. Eldo supports
external models/circuits written in SPICE or Verilog-A. External models/circuits written in
VHDL-AMS and Verilog-AMS can be simulated using Questa ADMS. Eldo is compatible with
HSPICE syntax, under option compat, except for multilingual model Support.
Related Topics
IBIS Device Standards
IBIS Support in Eldo
IBIS Examples
IBIS Resources on the Web
The best way to learn about IBIS is to review the IBIS specification, published papers and
sample models. Extensive IBIS information is available on the web as follows:
• Official IBIS Open Forum website:
http://www.eda.org/ibis/
• Mentor Graphics Visual IBIS Editor:
http://www.mentor.com/pcb/downloads/visual_ibis_editor/
Through these web sites you can: receive technical support; review articles, presentations and
FAQs; find links to most public IBIS models from semiconductor and connector supplier
sources; get free tools and documents that help create an IBIS model; and retrieve the IBIS
specifications.
Related Topics
Introduction to IBIS
IBIS File Types and Structures
There are three supported file types within the IBIS modeling framework:
• IBIS files, *.ibs
The IBIS file is the main file that contains the basic information about the component(s)
and their internal buffers. The .ibs file also contains information about the package
electrical characteristics (package model).
• Package files, *.pkg
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IBIS Models Support in Eldo
IBIS File Types and Structures
Advanced package models can be either placed inside the .ibs file itself or in a package
file (.pkg).
• Electrical board description files, *.ebd
An electrical board description file (.ebd file) is defined to describe the connections of a
board level component between the board pins and its components on the board.
The IBIS files contain the same basic information and can be thought of as having three main
sections:
• Header section—contains information about the IBIS version, the file name, and the
process or organization responsible for the information.
• Component section—describes the component name, pinout, pin to buffer mapping, and
package electrical characteristics.
• Model section—describes the behavior of each unique buffer used in a component.
An IBIS .ibs file consists of:
• File Header Section
• [Component]
• [Model]
• [Define Package Model]
• [End]
A package .pkg file consists of:
• File Header Section
• [Define Package Model]
• [End]
An electrical board description file .ebd file consists of:
• File Header Section
• [Begin Board Description]
• [End]
Related Topics
IBIS Buffers
IBIS Component
IBIS Package
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IBIS Models Support in Eldo
Checking IBIS Files with the Golden Parser
IBIS Electrical Board Description
Checking IBIS Files with the Golden Parser
The golden parser is a syntax-checking program that aids the development and verification of
IBIS data files.
It is available in executable format, compiled for a variety of operating systems, free of charge
through the IBIS website:
http://www.eigroup.org/ibis/tools.htm
The latest version of this parser, ibischk5 v5.0.7, is integrated inside Eldo. The golden parser
produces warnings and errors which are displayed in the Eldo output by default when an IBIS
file is incorporated in the simulation netlist.
Related Topics
IBIS Support in Eldo
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IBIS Models Support in Eldo
IBIS Device Standards
IBIS Device Standards
The following sections describe the IBIS device standards:
Buffers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 733
Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 744
Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745
Electrical Board Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 748
IBIS AMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 748
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IBIS Models Support in Eldo
Buffers
Buffers
IBIS is a modeling technique that provides a simple table-based buffer model for semiconductor
devices. IBIS models can be used to characterize I/V output curves, rising/falling transition
waveforms, and package parasitic information of the device. There are four types of buffer in
IBIS:
• “Single-Ended Buffers” on page 735
• “Pseudo-Differential Buffers” on page 739
• “True Differential Buffers” on page 741
• “Series Buffers” on page 742
IBIS also defines a global list of port names with fixed functionality that can be applied to all
types of buffers. Eldo uses the same port naming and definition for the buffer equivalent
subcircuit. Table 17-1 lists the port names and their descriptions. Port names starting with “A”
are used to define analog ports while those starting with “D” are used to define digital ports.
Table 17-1. List of Predefined Port Names and their Descriptions
Port Name Description
A_signal I/O signal port for a model unit
A_signal_pos Non-inverting port of a differential model
A_signal_neg Inverting port of a differential model
A_pos
Non-inverting port for series or series switch models
A_neg
Inverting port for series or series switch models
A_puref Voltage reference port for pull-up structure
A_pcref Voltage reference port for power clamp structure
A_pdref Voltage reference port for pull-down structure
A_gcref Voltage reference port for ground clamp structure
A_gnd
Global reference voltage port
D_drive Digital input to a model unit
D_enable Digital enable for a model unit
D_receive Digital receive port of a model unit, based on data on A_signal (and/
or A_signal_pos and A_signal_neg)
D_switch Digital input for control of a series switch model
Table 17-2 lists all the available buffer types, assigns a number for each type, lists nodes used
by buffer type, and provides the min/max number needed for each buffer type. “[ ]” is used to
Eldo® User's Manual, 15.3 733

IBIS Models Support in Eldo
Buffers
denote optional nodes. Pseudo-differential buffers are recognized as a separate buffer type by
the IBIS standard and are constructed from two single-ended buffers. Therefore, pseudodifferential
buffer nodes can be obtained from their single-ended version by replacing
“a_signal” with “a_signal_pos” and “a_signal_neg”. PN is used to denote the power nodes,
which are:
• a_pcref - a_gcref for Input, Input_ECL, Terminator, and Input_diff buffers.
• a_pcref - a_gcref - a_puref - a_pdref for other types.
Table 17-2. Buffer Types and Port Names Used
Type Number Nodes (in order) Min/Max
Input 1 a_signal - [d_receive] - [PN] 1/4
Output 2 a_signal - d_drive - [PN] 2/6
I/O 3 a_signal - d_drive - d_enable - [d_receive] - [PN] 3/8
3-state 4 a_signal - d_drive - d_enable - [PN] 3/7
Open_drain 5 a_signal - d_drive - [PN] 2/6
I/O_open_drain 8 a_signal - d_drive - d_enable - [d_receive] - [PN] 3/8
Open_sink 7 a_signal - d_drive - [PN] 2/6
I/O_open_sink 8 a_signal - d_drive - d_enable - [d_receive] - [PN] 3/8
Open_source 9 a_signal - d_drive - [PN] 2/6
I/O_open_source 10 a_signal - d_drive - d_enable - [d_receive] - [PN] 3/8
Input_ECL 11 a_signal - [d_receive] - [PN] 1/4
Output_ECL 12 a_signal - d_drive - [PN] 2/6
I/O_ECL 13 a_signal - d_drive - d_enable - [d_receive] - [PN] 3/8
3-state_ECL 14 a_signal - d_drive - d_enable - [PN] 3/7
Series 15 a_pos - a_neg 2
Series_switch 16 a_pos - a_neg - [d_switch] 2/3
Terminator 17 a_signal - [PN] 1/3
Input_diff 18 a_signal_pos - a_signal_neg - [d_receive] - [PN] 2/5
Output_diff 19 a_signal_pos - a_signal_neg - d_drive - [PN] 3/7
I/O_diff 20 a_signal_pos - a_signal_neg - d_drive - d_enable 4/9
- [d_receive] [PN]
3-state_diff 21 a_signal_pos - a_signal_neg - d_drive - d_enable
- [PN]
4/8
734
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IBIS Models Support in Eldo
Buffers
Single-Ended Buffers
A number of single-ended buffer types are supported.
Input and Input_ECL buffers
Figure 17-1 shows the model of an Input buffer (receiver). It has two sets of I-V curves, a
ground clamp and a power clamp, and the die capacitance C_comp. Two thresholds are defined,
Vinl and Vinh, that determine the buffer’s digital output, d_receive.
Figure 17-1. Input Buffer Model Building Blocks
The following relation gives the digital output for the non-inverting buffers:
Vd_receive =
1.0 V if Va_signal > Vinh
0.5 V if Vinl < Va_signal < Vinh
0.0 V if Va_signal < Vinh
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IBIS Models Support in Eldo
Buffers
If Vinl and Vinh are not specified in the IBIS file, the default values of Vinl = 0.8 V and
Vinh = 2.0 V are assumed for an Input buffer and Vinl = -1.475 V and Vinh = -1.165 V are
assumed for an Input_ECL buffer.
Terminator Buffers
A Terminator is an input-only model that can have analog loading effects on the circuit being
simulated, but has no digital output. The Terminator model is shown in Figure 17-2. It may
contain termination elements like Rgnd, Rpower, Rac, and Cac in addition to the usual clamping
diodes circuitry.
Figure 17-2. Terminator Buffer Model Building Blocks
Output and Output_ECL buffers
Figure 17-3 shows the model of an Output buffer (driver). It has four sets of I-V curves, a
ground clamp, a power clamp, a pull-up network and a pull-down network, and the die
capacitance C_comp. In addition, the transient switching characteristics of the pull-up and pulldown
networks are also defined.
736
Eldo® User's Manual, 15.3

Figure 17-3. Output Buffer Model Building Blocks
IBIS Models Support in Eldo
Buffers
IBIS provides two ways for defining the switching characteristics:
• If the output switching (V-T) waveform of a buffer can be approximated by a linear
ramp then the V-T data may be reported as a rising and falling ramp rate (dV/dt) by
using the [Ramp] keyword.
• Using the [Rising Waveform] and [Falling Waveform] keywords if the output switching
waveform of the buffer is significantly non-linear.
In both cases the transient current is considered to be a factor from the DC (steady state) current
and this factor is calculated from the provided switching data. There are two factors; k_pullup
and k_pulldown. These factors range from 0, representing a switched off pull-up/pull-down
network, to 1, representing a fully switched on network. The switching starts when d_drive
crosses 0.5 V and according to the buffer polarity, inverting or non-inverting, the appropriate
network is switched on or off.
Output_ECL buffer differs from Output buffer in that the a_pdref is internally connected to the
a_puref; that is, pull-up and pull-down share the same power reference. Output and
Output_ECL buffers also differ in the conventions related to the [Pulldown], [Temperature
Range], [Pin Mapping] keywords and the measuring conditions of the switching characteristics.
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IBIS Models Support in Eldo
Buffers
I/O and I/O_ECL Buffers
Figure 17-4 shows the model of an I/O buffer. The d_enable signal determines if the buffer will
operate as an Input or Output buffer. If the buffer is active low, then it will behave as an Output
buffer if d_enable < 0.5 V and as an Input buffer otherwise. If the buffer is active high, then it
will behave as an Output buffer if d_enable > 0.5 V and as an Input buffer otherwise.
Figure 17-4. I/O Buffer Model Building Blocks
When behaving as an Output buffer, I/O_ECL buffer differs mainly from I/O buffer in that the
a_pdref is internally connected to the a_puref; that is, pull-up and pull-down share the same
power reference. I/O and I/O_ECL buffers also differ in the conventions related to [Pulldown],
[Temperature Range], [Pin Mapping] keywords and the measuring conditions of the switching
characteristics. Otherwise, if behaving as an Input buffer, I/O and I/O_ECL buffers differ in the
default values of Vinl and Vinh (see “Input and Input_ECL buffers” on page 735 for details).
3_state and 3_state_ECL Buffers
The model of a 3_state buffer is show in Figure 17-5. The 3_state buffer is very similar to the I/
O buffer but does not have a digital output. It either works as an output buffer when enabled or
high impedance when not enabled. The high impedance state is described by the Power Clamp,
GND Clamp and die capacitance, C_comp.
738
Eldo® User's Manual, 15.3

Figure 17-5. 3_state Buffer Model Building Blocks
IBIS Models Support in Eldo
Buffers
3_state_ECL buffer differs mainly from 3_state buffer in that the a_pdref is internally
connected to the a_puref; that is, pull-up and pull-down share the same power reference. 3_state
and 3_state_ECL buffers also differ in the conventions related to [Pulldown], [Temperature
Range], [Pin Mapping] keywords and the measuring conditions of the switching characteristics.
Buffers with Open Drain, Sink, or Source
The open drain and open sink are buffers that do not include a pull-up network; that is, the
output can sink current only. Earlier IBIS versions used the term “open drain”, however, this
may be confusing for NMOS and PMOS networks, and so the term “open sink” is now used to
describe a buffer that can sink current only. The “open drain” terminology is retained for
backward compatibility.
The open source buffer is a buffer that does not include a pull-down network; that is, the output
can source current only.
Pseudo-Differential Buffers
The [Diff Pin] keyword in the IBIS file is used to create a pseudo-differential buffer from two
already existing single-ended buffers.
A pseudo-differential input buffer consists of two single-ended input buffers as shown in
Figure 17-6. The digital outputs of these two single-ended buffers are tied together and labeled
by d_receive. One single-ended buffer’s input is taken to be the non-inverting input
Eldo® User's Manual, 15.3 739

IBIS Models Support in Eldo
Buffers
(a_signal_pos) while the second one is taken to be the inverting input (a_signal_neg). The
differential input threshold is denoted by Vdiff and is provided under the [Diff Pin] keyword in
the IBIS file.
Figure 17-6. Pseudo-Differential Input Buffer Consisting of Two Single-Ended
Input Buffers
The digital output d_receive is given by:
d_receive =
• 1 V if a_signal_pos - a_signal_neg > V diff
• 0 V if a_signal_pos - a_signal_neg < V diff
The pseudo-differential output buffer consists of two single-ended output buffers as shown in
Figure 17-7. One single-ended buffer’s output is taken to be the non-inverting output
(a_signal_pos) while the second one is taken to be the inverting output (a_signal_neg). The
differential delay between the two outputs is denoted by tdelay and provided under the [Diff
Pin] keyword in the IBIS file.
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IBIS Models Support in Eldo
Buffers
Figure 17-7. Pseudo-Differential Output Buffer Consisting of Two Single-Ended
Output Buffers
The two inputs are tied together and the overall differential buffer has one input and two
outputs. Positive differential delay means the non-inverting output is delayed with respect to the
inverting output. Inverting differential delay means inverting output is delayed with respect to
the non-inverting output.
True Differential Buffers
The native IBIS does not support true differential buffers, they are only supported using the
external model format created using SPICE or Verilog-A.
SPICE or Verilog-A formatted models are pure analog. Eldo is responsible for handling the A/D
and D/A conversions as shown in Figure 17-8. Specification of these A/D and D/A blocks are
defined in the IBIS file.
Eldo® User's Manual, 15.3 741

IBIS Models Support in Eldo
Buffers
Figure 17-8. Example Analog-Only Model init Using an I/O Buffer
Series Buffers
Series and Series_switch buffers can be passive circuits containing various combinations of
inductors, resistors and capacitors, as well as the steady state I-V characteristics of non-linear
devices such as diodes and transistors.
Series and Series_switch are identical in their elements, the only difference is that the latter one
can be switched ON or OFF. The IBIS specifications do not define the transition characteristics
of a Series_switch. Switches are assumed to either be ON or OFF during a simulation, and I-V
characteristics could be defined for either or both states. Switching does not occur during
simulation, but you must decide whether the element is ON or OFF before the simulation starts.
The electrical models for the Series / Series_switch are:
• R Series, L Series, Rl Series, C Series, Lc Series and Rc Series
These enable IBIS to model simple passive models and/or parasitics. The model is
shown in Figure 17-9.
Figure 17-9. Simple Passive Modeling
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IBIS Models Support in Eldo
Buffers
• Series Current
under which the data points define the I-V tables for voltages measured at Pin 1 with
respect to Pin 2. The model is shown in Figure 17-10. Currents are considered positive if
they flow into Pin 1.
Figure 17-10. Series Current Modeling
• Series MOSFET
under which the data points define the I-V tables for voltages measured at Pin 2 for a
given Vds setting. Currents are considered positive if they flow into Pin 1. The model is
shown in Figure 17-11.
Figure 17-11. Series MOSFET Modeling
Related Topics
IBIS Buffers
Supported Keywords and Sub-Parameters
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IBIS Models Support in Eldo
Package
Package
IBIS has many ways for package modeling, differing in their complexity and accuracy. The
simplest, least accurate, way is to assume all the package pins are identical and uncoupled.
The common package parasitics, R_pkg, L_pkg and C_pkg shown in Figure 17-12, are defined
under the [Package] keyword in the IBIS file. Each pin is assumed to have parasitic resistance
R_pkg, inductance L_pkg, and capacitance C_pkg. Unique parasitics R_pin, L_pin and C_pin
can also be defined separately for each pin under the [Pin] keyword.
Figure 17-12. Common Package Parasitics
More advanced package modeling can be achieved using the [Package Model] keyword, where
you can refer to a package model inside the .ibis file or in a .pkg file. You can model the
package as coupled pins and give the resistance, inductance and capacitance matrices (RLC
matrices) elements of the package pins network. These matrices assume the Maxwellian format.
Another way of modeling is to divide the package into stub sections and define the electrical
parameters for each section. The stub represents the physical connection between the package
pin and the die pad. Each section is described in terms of its L/R/C per unit length and the Fork
and Endfork subparameters allow any path to branch. For example, this can describe the
parasitics of the wire bond between the die pad and the package pin. This stub can be treated as
lumped or distributed elements depending on whether the section length is 0 or not.
Related Topics
IBIS Package
Supported Keywords and Sub-Parameters
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IBIS Models Support in Eldo
Component
Component
Eldo can simulate IBIS devices either individually or in the overall component. The component
simulation means creating all the buffers inside the component, connecting these buffers to the
appropriate nodes and power buses, creating the package parasitics and connecting buffer die
pads to the package parasitics.
Several keywords and sub-parameters in the IBIS file are used in a component simulation in
addition to that used in the individual buffer simulation:
• [Pin Mapping] is used to define the buffers sharing the same power/ground bus.
See “Pin Mapping” on page 745.
• [Series Pin Mapping] is used to join two die pads by a series buffer and [Series Switch
Groups] is used to define switching combinations of series switches.
See “Series Pin Mapping and Series Switch Groups” on page 746.
• [Circuit Call] and [Node Declarations] create subcircuits from external circuit models
written in SPICE or Verilog-A language, and make their interconnections.
See “Node Declarations and Circuit Call” on page 747.
• [Package Model] defines an advanced package model, taking coupling effects into
account.
Pin Mapping
When the input of a buffer(s) changes from High to Low, the output driver current (Ldi/dt)
creates a fluctuation between the core ground and power buses. This creates a pulse that can
affect static buffer(s) output, causing the receiver(s) to switch inappropriately. A similar effect
occurs when the input of a buffer(s) changes from Low to High. The difference between the
core ground and power is referred to as “ground bounce.” The amount of ground bounce is
dependent on the number of outputs changing state at the same time and thus the ground bounce
may also be called “simultaneous switching output noise” (SSON).
The [Pin Mapping] keyword, in the IBIS file, contains information on how power supplies are
connected to individual buffers or groups of buffers that can be used for predicting SSON. The
bus connections (from buffer nodes to supply or ground nodes) described by [Pin Mapping] are
assumed as ideal shorts, and do not override parasitic information given for power and/or
ground pins. Figure 17-13 indicates how the model is constructed, the [Pin Mapping] contains
information about the bus connection from buffer nodes to supply/ ground nodes. For example,
pins 8 and 12 are connected to the Power bus; pins 10 and 38 are connect to the Ground bus; and
the models with signal terminals connected to pins 35 and 40 use these buses for their voltage
supplies.
Eldo® User's Manual, 15.3 745

IBIS Models Support in Eldo
Component
Figure 17-13. [Pin Mapping] Model Construction
Series Pin Mapping and Series Switch Groups
[Series Pin Mapping] enables modeling of elements in series with a signal path. They are
particularly useful for modeling elements placed between the terminals of differential buffers.
However, the [Series Pin Mapping] keyword can generally be used to connect series elements
between the die pads of any buffers inside the component.
Figure 17-14 indicates how the model is constructed.
746
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IBIS Models Support in Eldo
Component
Figure 17-14. Series Pin Mapping
IBIS defines two categories of series elements; series and series switch. Series and series switch
are identical in their elements. The only difference is that series switch can be switched ON or
OFF. Series switches are divided into groups, and the group name to which the series switch
belongs to, is defined in the function_table_group column in the IBIS file. The [Series Switch
Groups] keyword is used to define switching combinations of series switch groups. You can
specify the state of some groups to be ON and it is implicitly assumed that unspecified groups
are OFF, or vice versa.
Node Declarations and Circuit Call
The [External Circuit] keyword enables you to define any block behavioral models, written in
SPICE or Verilog-A, with any number of ports and with any functionality.
The connectivity of these blocks to each other, to die nodes or die pads, must be defined using
the [Node Declaration] and [Circuit Call] keywords. Only one [Node Declarations] keyword is
permitted for each [Component] keyword. Multiple [Circuit Call] keywords may appear under a
[Component] using the same [External Circuit] name if multiple instantiations of an [External
Circuit] are needed.
Related Topics
IBIS Component
Supported Keywords and Sub-Parameters
Eldo® User's Manual, 15.3 747

IBIS Models Support in Eldo
Electrical Board Description
Electrical Board Description
A “board level component” is a term describing a printed circuit board (PCB) or substrate which
can contain components or even other boards, and which can connect to another board through a
set of user visible pins. The electrical connectivity of such a board level component is referred
to as an Electrical Board Description (EBD). An EBD file (.ebd) describes the connections of a
board level component between the board pins and its components on the board. An .ebd file is
intended to be a stand-alone file, not referenced by or included in any .ibs or .pkg files.
The IBIS EBD describes the connection between the user accessible pins of a board level
component and other pins of the board or pins of the ICs mounted on that board. Each pin-tonode
connection is divided into one or more cascaded sections, where each section is described
in terms of its L/R/C per unit length. The Fork and Endfork subparameters allow any path to
branch to multiple nodes, or another pin. A path description is required for each pin whose
signal name is not GND, POWER or NC.
Related Topics
IBIS Electrical Board Description
Supported Keywords and Sub-Parameters
IBIS AMI
Eldo supports the IBIS Algorithmic Model Interface (AMI). IBIS AMI addresses the modeling
of the advanced Serializer-Deserializer (SERDES) devices. For more details about AMI please
refer to the IBIS v5.0 specifications document.
Related Topics
IBIS Algorithmic Model Interface (AMI)
748
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IBIS Models Support in Eldo
IBIS Support in Eldo
IBIS Support in Eldo
Eldo uses the latest IBIS parser to support IBIS files up to and including IBIS version 5.0.
Eldo can simulate IBIS devices either individually or in the overall component. See “Supported
Keywords and Sub-Parameters” on page 780 for further information.
Backward Compatibility
Beginning the AMS2010.1 release, an improved algorithm is available for over-clocking
switching and uses default values for IBIS instance keywords, c_fixture=yes and
keep_monotonic=no, which provides results with better matching to transistor level results.
For backward compatibility use the Eldo option or IBIS instance keyword IEVER, which may
be used to switch back to older Eldo IBIS behavior as follows:
• IEVER=1
Switch back to the behavior prior to AMS2007.2. In this implementation most IBIS v2.1
features are supported, but it uses different algorithms and components than the current
implementation.
• IEVER=2
Switch back to the behavior prior to, and including, AMS2009.2. This implementation is
the same as the current one, but an alternate algorithm is used for over-clocking
switching, with default values c_fixture=no and keep_monotonic=yes.
Note
The backward compatibility option IEVER does not affect the parser version used. In all
cases the latest parser version is used to parse IBIS files.
Analysis Types
IBIS specifications provide data about the large signal behavior of the I/O buffers and their
switching characteristics. However, no data about the frequency domain behavior is provided.
Therefore, IBIS simulation can be performed in either the DC or Transient domain.
IBIS simulation is supported in Eldo using:
• DC analysis
• Transient analysis
Eldo® User's Manual, 15.3 749

IBIS Models Support in Eldo
Digital Levels
Digital Levels
IBIS defines both analog and digital ports.
Table 17-3 and Table 17-4 show the different digital ports logic levels and the corresponding
analog levels.
Table 17-3. Digital Port Logic Levels
Analog Input Digital Input: d_drive, d_enable and d_switch
Vin > 0.5V Logic "1"
Vin < 0.5V Logic "0"
Table 17-4. Analog Levels
Digital Output: d_receive Analog Output
Logic "1”
1.0 V
Logic "0”
0.0 V
Logic "X”
0.5 V
Related Topics
IBIS Device Standards
IBIS Model Syntax
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IBIS Models Support in Eldo
IBIS Model Syntax
IBIS Model Syntax
The following topics describe the IBIS model syntax in Eldo:
IBIS Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 752
IBIS Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 765
IBIS Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773
IBIS Electrical Board Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777
Supported Keywords and Sub-Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 780
IBIS Algorithmic Model Interface (AMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 787
Eldo® User's Manual, 15.3 751

IBIS Models Support in Eldo
IBIS Buffers
IBIS Buffers
You can reference an IBIS buffer by a model name, or a pin of component.
Syntax
Single-Ended Buffer
_IO_xx ASG [DDR] [DEN] [DRX] [PCR GCR PUR PDR] file="path"
+ model="model_name"|pin="pin_name" [component="component_name"]
+ [device=type_name|type_number] [limit_k_factors=POWER|NO|YES]
+ [corner=TYP|MIN|MAX|FAST|SLOW] [warn=ON|OFF] [nowarn] [power=ON|OFF]
+ [c_comp_pu=value] [c_comp_pd=value]
+ [c_comp_pc=value] [c_comp_gc=value]
+ [use_fall_wvf=0|1|2] [use_rise_wvf=0|1|2]
+ [k_pulldown=node] [k_pullup=node]
+ [model_selector='msel_1=mdl_1 [,..., msel_n=mdl_n]'] [msel_mode=value]
+ [package=0|1|2|3|OFF|CMPNT|PIN|PKGMOD] [pkg_model="pkg_model_name"]
+ [rx_logic=0|1]
+ [para_begin param1=value1 param2=value2 ... para_end]
+ [eldova=ON|OFF] [em_libname="logical_lib_name"]
+ [table_tune=value]
+ [logic_one=value] [logic_zero=value]
+ [c_fixture=YES|NO]
+ [keep_monotonic=YES|NO]
+ [switch_isso=ON|OFF] [switch_composite_current=ON|OFF]
+ [check_model_spec=ON|OFF] [ibischk_soft=NO|YES]
Pseudo-Differential Buffer
_IO_xx ASP ASN [DDR] [DEN] [DRX] [PCR GCR PUR PDR] file="path"
+ component="component_name" pin="pin_name" inv_pin="inv_pin_name"
+ [limit_k_factors=POWER|NO|YES] [corner=TYP|MIN|MAX|FAST|SLOW]
+ [warn=ON|OFF] [nowarn] [power=ON|OFF]
+ [c_comp_pu=value] [c_comp_pd=value]
+ [c_comp_pc=value] [c_comp_gc=value]
+ [use_fall_wvf=0|1|2] [use_rise_wvf=0|1|2]
+ [model_selector='msel_1=mdl_1 [,..., msel_n=mdl_n]'] [msel_mode=value]
+ [package=0|1|2|3|OFF|CMPNT|PIN|PKGMOD] [pkg_model="pkg_model_name"]
+ [para_begin param1=value1 param2=value2 ... para_end]
+ [eldova=ON|OFF] [em_libname="logical_lib_name"]
+ [table_tune=value]
+ [logic_one=value] [logic_zero=value]
+ [add_series_terminator=YES|NO|IFA]
+ [c_fixture=YES|NO]
+ [keep_monotonic=YES|NO]
+ [switch_isso=ON|OFF] [switch_composite_current=ON|OFF]
+ [check_model_spec=ON|OFF] [ibischk_soft=NO|YES]
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IBIS Models Support in Eldo
IBIS Buffers
True Differential Buffer
_IO_xx ASP ASN [DDR] [DEN] [DRX] [PCR GCR PUR PDR] file="path"
+ model="model_name"|pin="pin_name" [inv_pin="inv_pin_name"]
+ [component="component_name"]
+ [device=type_name|type_number] [corner=TYP|MIN|MAX|FAST|SLOW]
+ [warn=ON|OFF] [nowarn] [power=ON|OFF]
+ [model_selector='msel_1=mdl_1 [,..., msel_n=mdl_n]'] [msel_mode=value]
+ [package=0|1|2|3|OFF|CMPNT|PIN|PKGMOD] [pkg_model="pkg_model_name"]
+ [para_begin param1=value1 param2=value2 ... para_end]
+ [eldova=ON|OFF] [em_libname="logical_lib_name"]
+ [table_tune=value]
+ [add_series_terminator=YES|NO|IFA] [ibischk_soft=NO|YES]
Series Buffer
_IO_xx APV ANV [DST] file="path"
+ model="model_name"
+ [device=type_name|type_number] [corner=TYP|MIN|MAX|FAST|SLOW]
+ [warn=ON|OFF] [nowarn]
+ [ss_state=ON|OFF] [all_sm=YES|NO]
+ [keep_vds_monotonic=NO|YES] [keep_vgs_monotonic=NO|YES]
+ [model_selector='msel_1=mdl_1 [,..., msel_n=mdl_n]'] [msel_mode=value]
+ [para_begin param1=value1 param2=value2 ... para_end]
+ [eldova=ON|OFF] [em_libname="logical_lib_name"] [ibischk_soft=NO|YES]
Parameters
Some parameters are part of the IBIS standard, please refer to description in “IBIS Device
Standards” on page 732.
• _IO_xx
IBIS instance name.
• ASG
Name of the a_signal node.
• ASP
Name of the a_signal_pos node.
• ASN
Name of the a_signal_neg node.
• DDR
Name of the d_drive node.
• DEN
Name of the d_enable node.
• DRX
Name of the d_receive node.
Eldo® User's Manual, 15.3 753

IBIS Models Support in Eldo
IBIS Buffers
• APC
Name of the a_pcref node.
• AGC
Name of the a_gcref node.
• APU
Name of the a_puref node.
• APD
Name of the a_pdref node.
• APV
Name of the a_pos node.
• ANG
Name of the a_neg node.
• DST
Name of d_switch node, this node is used only for Series_Switch buffers that reference an
external model.
Note
Buffer external nodes should be listed in order, depending on the type of the buffer
model. A list of the buffer model types and corresponding ports are in Table 17-2.
• file="path"
Specifies the path to the file that contains an IBIS formatted model.
This can be the full path (for example, /user/test/Models/model.ibs), a relative path, or just a
file name. Both / and \ are acceptable as separators in the path name for the UNIX and
Windows platforms. Avoid any spaces between the quotes and the file name/path. An Eldo
option IBIS_SEARCH_PATH is available to specify the path to the directory to search for
the IBIS files.
• model="model_name"
Specifies an IBIS model name within the specified IBIS file, it can be either a model name
or a model selector name. Model name is case-sensitive.
• pin="pin_name"
Specifies a pin name within the specified component.
Note
The keywords pin and model are exclusive. It is an error to specify both these
keywords in the same _IO_ card.
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IBIS Models Support in Eldo
IBIS Buffers
• inv_pin="inverting_pin_name"
Specifies a pin name within the specified component; this is to be used with the pseudo/true
differential buffers. Pin name and inverting pin name must match a differential pins pair
under [Diff Pin] IBIS keyword.
• component="component_name"
Specifies a component name within the specified IBIS file. The component name is casesensitive.
Component name must be specified if pin name or inverting pin name is specified,
while it is optional if you specify a model name.
• device="type_name|type_number"
Specifies the desired buffer type to be used; this is to check the buffer type assignment in the
IBIS instance against the buffer type given in the IBIS file. A list with buffer types and
numbers are given in Table 17-2.
• limit_k_factors=POWER|NO|YES
POWER
Prevent current flow in the power terminals, a_puref and a_pdref, from being nonmonotonic.
This is the default.
NO
Keep the scaling factors as calculated.
YES
Limit the switching scaling factors between 0 and 1.
Switching scaling factors are extracted from the rising/falling waveforms, and used to
modulate the output current of the buffer while switching.
o
o
Scaling factor 0 indicates fully off for the working network.
Scaling factor 1 indicates fully on.
Sometimes these factor values exceed one or become negative, causing a negative slope,
that may lead to some convergence problems.
Note
The POWER setting helps to avoid non-convergence issues whilst keeping the
correct buffer behavior on the a_signal terminal.
• corner=TYP|MIN|MAX|FAST|SLOW
Specifies the IBIS corner to be used to extract the data from the IBIS file. The default is
corner=TYP—if any data is missing under the Min or Max columns in the IBIS file then
the Typ column value will be used instead. When corner=TYP, MIN, or MAX, simulation
will extract the data under the corresponding Typ, Min, and Max columns in the IBIS file.
When corner=FAST or SLOW, corner uses combinations from data under the Min and
Max columns; FAST is the same as MAX, and SLOW is the same as MIN except for
parameters listed in Table 17-5.
Eldo® User's Manual, 15.3 755

IBIS Models Support in Eldo
IBIS Buffers
Table 17-5. Exceptions to Fast=Max, Slow=Min Rule
Parameter/Data Fast Slow
C_comp Min Max
[Cac] Min Max
[Gnd Clamp Reference] Min Max
[Pulldown Reference] Min Max
[Package] Min Max
• power=ON|OFF
When power=ON (the default), the reference voltage sources are connected to the buffer
reference ports a_pcref, a_gcref, a_puref, a_pdref internally. When power=OFF you are
responsible for connecting the voltage sources externally, if you set power=OFF but do not
specify the power nodes in the _IO_ card, then OFF will be ignored and internal references
will be created.
Power nodes can be specified when power=ON to enable you to print/plot the values of
voltage sources connected to these nodes internally, in this case you must not connect
external voltage sources to these nodes.
• warn=ON|OFF
Specifies if the warning message generated for this instance should be printed: ON, or
suppressed: OFF. Setting warn=OFF is equivalent to using the keyword nowarn. The
default setting is ON.
• nowarn
This is equivalent to warn=OFF.
• c_comp_pu=value, c_comp_pd=value, c_comp_pc=value, c_comp_gc=value
These four keywords are optional. If one of these keywords is specified with a non-zero
value; the c_comp capacitor will be split up to four parts. Values are dimensionless numbers
between 0 and 1, and the sum of them should be equal to 1. The default is zero for the
unspecified values.
• use_fall_wvf= 0|1|2, use_rise_wvf= 0|1|2
0
Use the ramp for the falling/rising transitions.
1
Use one waveform for the falling/rising transitions.
2
Use two waveforms for the falling/rising transitions.
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IBIS Models Support in Eldo
IBIS Buffers
The default behavior is to use the first two waveforms if more than one waveform is
specified in the IBIS model, use one waveform if only one is specified, and to use ramp if no
waveforms are specified.
• k_pulldown="node", k_pullup="node"
The purpose of these keywords is to display the values of the pull-up and pull-down
coefficients of the device as a function of time as the device goes through rising or falling
transitions.
• msel_mode=value
The value indicates a model order under the [Model Selector] keyword in the IBIS file. If
the value given is greater than the model selector list, then the first model will be selected.
The default is 1.
• model_selector='mod_sel1=mod_name1 [, mod_sel2=mod_name2 ,...]'
Used to select models for some or all model selectors in the given IBIS file. model_selector
has a higher precedence over msel_mode.
• package=0|1|2|3|OFF|CMPNT|PIN|PKGMOD
Specifies the package modeling type to be used for package parasitics.
0 or OFF
No package is added.
1 or CMPNT
RLC components defined under [Package] keyword are added, this is the default
when specifying model name.
2 or PIN
RLC components defined under [Pin] are added, this is the default when specifying
pin name.
3 or PKGMOD
A package model will be used. This is the default.
Note
For a single buffer and package=PKGMOD; if the package model is defined in
matrix form Eldo issues a warning and sets package=PIN.
If no data is available for the selected packaging type, then the data in the lower type
will be used.
• ss_state=ON|OFF
For Series Switch buffers, if ss_state=ON, then Eldo will use the data under the [On]
keyword: setting it to OFF, the data under [Off] keyword will be used. The default is ON.
Eldo® User's Manual, 15.3 757

IBIS Models Support in Eldo
IBIS Buffers
• all_sm=YES|NO
For Series/Series_Switch buffers; setting all_sm to NO makes Eldo use only the first
non-zero Vds table to generate the current of Series MOSFET elements in the Series buffer.
The default is YES.
• keep_vds_monotonic=NO|YES
For Series/Series_Switch buffers; setting keep_vds_monotonic to YES will keep the Ids
current monotonic versus Vds values for a given Vgs. Default is NO.
• keep_vgs_monotonic=NO|YES
For Series/Series_Switch buffers; setting keep_vgs_monotonic to YES will keep the Ids
current monotonic versus Vgs values for a given Vds. Default is NO.
• rx_logic=0|1
For Input or IO buffers; if the input voltage on a_signal port is between Vinl and Vinh
thresholds then rx_logic will control the output voltage on the d_receive port. When
rx_logic=0 (default), the voltage on the d_receive port will be 0.5V (representing logic
"X"). When rx_logic=1, the voltage on the d_receive port will have the same value (state) as
the previous time step.
Note
If there are hysterises thresholds (Vinl+, Vinl-, Vinh+, and Vinh-) under the
[Model Spec] keyword, then rx_logic has no effect.
• para_begin param1=value1 param2=value2 ... para_end
For IBIS buffers that reference an external model, the parameter names and values specified
between keywords para_begin/para_end will be passed to the external model module.
• eldova=ON|OFF
For IBIS models that reference an external model in Verilog-A, Eldo will use its Verilog-A
compiler to handle these models if eldova=ON. Setting eldova=OFF enables these models
to be simulated with Questa ADMS. The default is ON.
• em_libname="logical_lib_name"
For IBIS models that reference external models written in any AMS language, this keyword
is optionally used. If no library is specified, the default work library will be used, specified
with the vasetlib command or the -lib option of the vasim command. Otherwise, the
specified logical_lib_name library is used.
• table_tune=value
Controls Eldo time step when the IBIS buffer is switching to obtain accurate output
waveforms. Table_tune accepts non-negative values. Default value is 8.
Setting a value of 1 forces Eldo to take into account all the switching waveform points, 2 to
take one point into account and skip the next, 3 skips two points, but takes into account the
third, and so on. Setting a value of 0 makes Eldo control the time step regardless of the
switching waveform.
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IBIS Models Support in Eldo
IBIS Buffers
Note
The actual time step will be the minimum among the time step of the current IBIS
buffer, time steps of other IBIS buffers, and the time step forced by Eldo.
HMIN is always set as the lower limit for the time step.
• logic_one=value|logic_zero=value
Define the voltage level accepted by IBIS buffers for digital ports, logic_one default is 1.0,
and logic_zero default is 0.0. logic_one must be greater than logic_zero by at least 200mV.
The input voltage is considered ‘logic 1’ if it is greater than (logic_one + logic_zero)/2, and
considered ‘logic 0’ if it is below this value.
Note
These levels are defined for native IBIS buffers and do not apply to external models.
• add_series_terminator=YES|NO|IFA
Used with the pseudo/true differential buffers to enable/disable creation of series models
across the differential buffers die pads. Default is NO. IFA is the same as YES but does not
produce warning messages if there is no series models defined under [Series Pin Mapping]
for the differential buffers pins.
• c_fixture=YES|NO
Enable/disable using rising or falling waveforms that have a c_fixture sub-parameter with a
non-zero value. Setting to NO makes Eldo discard these waveforms; YES (default) to use
these waveforms.
• keep_monotonic=YES|NO
Used to control Eldo behavior with non-monotonic data. Setting to YES Eldo fixes the nonmonotonic
data provided in the tables, setting to NO (default) Eldo keeps the nonmonotonic
tables data as is. This keyword affects the data under [GND Clamp], [POWER
Clamp], [Pullup] and [Pulldown] IBIS keywords.
• switch_isso=ON|OFF
Switch ON or OFF the effect of SSO (Simultaneous Switching Output) on the driver
current. The SSO effect is modeled in the IBIS file under the [ISSO PD] and [ISSO PU]
keywords. The default is ON.
• switch_composite_current=ON|OFF
Switch ON or OFF the effects of the power reference terminal current modeled by the
[Composite Current] keyword. The default is ON.
• check_model_spec=ON|OFF
Switch ON or OFF checking of the buffer input/output signals according to subparameters
given under the [Model Spec] keyword. The following subparameters are supported:
D_overshoot_area_h, D_overshoot_area_l, D_overshoot_ampl_h, and
D_overshoot_ampl_l. The default is ON.
Eldo® User's Manual, 15.3 759

IBIS Models Support in Eldo
IBIS Buffers
• ibischk_soft=NO|YES
Used to control the golden parser (ibischk) reporting of IBIS version compatibility errors.
Setting to NO means the IBIS version number is checked for compatibility. Only the first
digit of the version number is checked, for example 4.x. Setting to YES releases ibischk
constraints on the IBIS version number. Default is NO.
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IBIS Models Support in Eldo
IBIS Buffers
Examples
IBIS File Example
[IBIS Ver] 3.2
[Comment Char] |_char
[File Name] dummy.ibs
|
.
.
.
|
[Component] Test_Component
[Manufacturer] None
[Package]
| typ min max
R_pkg 0.020 0.017 0.025
L_pkg 0.998nH 0.881nH 1.069nH
C_pkg 0.146pF 0.118pF 0.205pF
|
|**********************************************************
|
[Pin] signal_name model_name R_pin L_pin C_pin
|
1 NC NC 0.019 1.069n 0.162p
2 in MS_In 0.018 0.881n 0.121p
3 out+ MS_Out 0.017 1.031n 0.205p
4 out- MS_Out 0.017 1.031n 0.205p
|
[Model Selector] MS_In
Input_33
Vcc = 3.3 V
Input_50
Vcc = 5.0 V
|
[Model Selector] MS_Out
Output_33
Vcc = 3.3 V
Output_50
Vcc = 5.0 V
|
[Diff Pin] inv_pin vdiff tdelay_typ tdelay_min tdelay_max
|
3 4 150mV -1ns 0ns -2ns
|
[Series Pin Mapping] pin_2 model_name
|
3 4 Series1
|
|**********************************************************
| Model Input_33
|**********************************************************
|
[Model] Input_33
Model_type Input
Vinl = 0.99
Vinh = 2.31
|
| variable typ min max
C_comp 1.27p 0.95p 1.59p
|
[Temperature Range] 25 85 -40
Eldo® User's Manual, 15.3 761

IBIS Models Support in Eldo
IBIS Buffers
[Voltage Range] 3.3 3.0 3.6
|
.
.
.
|
|**********************************************************
| Model Input_50
|**********************************************************
|
[Model] Input_50
Model_type Input
Vinl = 1.2
Vinh = 3.5
|
| variable typ min max
C_comp 1.27p 0.95p 1.59p
|
[Temperature Range] 25 85 -40
[Voltage Range] 5.0 4.5 5.5
|
.
.
.
|
|**********************************************************
| Model Output_33
|**********************************************************
|
[Model] Output_33
Model_type Output
|
| variable typ min max
C_comp 1.27p 0.95p 1.59p
|
[Temperature Range] 25 85 -40
[Voltage Range] 3.3 3.0 3.6
|
.
.
.
|
|**********************************************************
| Model Output_50
|**********************************************************
|
[Model] Output_50
Model_type Output
|
| variable typ min max
C_comp 1.27p 0.95p 1.59p
|
[Temperature Range] 25 85 -40
[Voltage Range] 5.0 4.5 5.5
|
.
.
.
762
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
IBIS Buffers
|
|**********************************************************
| Model Series1
|**********************************************************
|
[Model] Series1
Model_type Series1
|
| variable R(typ) R(min) R(max)
[R Series] 8ohm 6ohm 12ohm
|
| variable L(typ) L(min) L(max)
[L Series] 5nH NA NA
| variable R(typ) R(min) R(max)
[Rl Series] 4ohm NA NA
|
.
.
.
|
[End]
The preceding IBIS file example is referenced in the following netlist examples.
Netlist 1
_IO_input1_bymodel IN D_OUT1
+ file="dummy.ibs" model="Input_33"
+ device=input ! or device=1
The above netlist calls the buffer by its model name. It instantiates an input buffer
input1_bymodel and connects its analog input to node IN and its digital output to node
D_OUT1. The buffer description is in the IBIS file dummy.ibs located in the same directory as
the netlist. The buffer model, named Input_33, is picked up from the IBIS file.
Note that the component name is not specified; therefore Eldo will not add any package
parasitics to the buffer analog input pin. The corner is not specified, therefore the typical data
will be used for this buffer by default. The power keyword is not specified, therefore Eldo
connects the reference voltage sources to the buffer reference ports.
Netlist 2
_IO_input1_bypin IN D_OUT2 PC GC
+ file="dummy.ibs"
+ component="Test_Component" pin="2"
+ model_selector='MS_In=Input_50' ! equal to msel_mode=2
The above netlist calls the buffer by its pin name. It instantiates an input buffer input1_bypin
and connects its analog input to node IN and its digital output to node D_OUT2. The buffer
description is in the IBIS file dummy.ibs located in the same directory as the netlist. It belongs to
the component Test_Component. The buffer model, named MS_In (the one associated with pin
Eldo® User's Manual, 15.3 763

IBIS Models Support in Eldo
IBIS Buffers
2), is picked up from the IBIS file. The MS_In model has a model selector statement in the IBIS
file. The netlist selects the Input_50 model for MS_In.
The package keyword takes the default of 2 because the buffer is instantiated by pin name.
Therefore Eldo will add the package parasitics associated with pin 2 under the [Pin] keyword,
R=0.018 L=0.881n C=0.121p, to the buffer analog input pin. The corner is not specified,
therefore the typical data will be used for this buffer by default. The power keyword is not
specified, therefore Eldo connects the reference voltage sources to the buffer reference ports. In
this case the nodes PC and GC only have the role of enabling you to plot/print the voltage
reference values.
Netlist 3
* make pseudo-differential buffer for pin 3 and pin 4
_IO_out_diff OUTp OUTn d_CTRL
+ file="dummy.ibs" component="Test_Component"
+ pin="3" inv_pin="4"
The above netlist instantiates the pseudo-differential buffer associated with pins 3 and 4. The
non-inverting pin of the buffer is connected to node OUTp, inverting pin to node OUTn, and the
digital input to node d_CTRL. The buffer description is in the IBIS file dummy.ibs located in the
same directory as the netlist. It belongs to the component Test_Component.
The package keyword takes the default of 2 because the buffer is instantiated by pin name.
Therefore Eldo will add the package parasitics associated with pin 3 and 4 under the [Pin]
keyword, R=0.017 L=1.031n C=0.205p, to the buffer analog input pins. The corner is not
specified, therefore the typical data will be used for this buffer by default. The power keyword
is not specified, therefore Eldo connects the reference voltage sources to the buffer reference
ports.
Netlist 4
*connect series buffer between 3 and 4
_IO_ser OUTp OUTn
+ file="dummy.ibs" model="Series1"
The above netlist instantiates the series buffer associated with pins 3 and 4. It is connected to
nodes OUTp and OUTn. The buffer description is in the IBIS file dummy.ibs located in the
same directory of the netlist. The buffer model is Series1. The corner is not specified, therefore
the typical data will be used for this buffer by default.
Note that any series buffer has no package associated with it.
Related Topics
Buffers
Supported Keywords and Sub-Parameters
764
Eldo® User's Manual, 15.3

IBIS Component
Instantiates an IBIS component name within the specified IBIS file.
Syntax
IBIS Models Support in Eldo
IBIS Component
_IO_xx file="path" component="component_name"
+ [limit_k_factors=POWER|NO|YES] [corner=TYP|MIN|MAX|FAST|SLOW]
+ [warn=ON|OFF] [nowarn]
+ [model_selector='msel_1=mdl_1 [,..., msel_n=mdl_n]'] [msel_mode=value]
+ [package=0|1|2|3|4|OFF|CMPNT|PIN|PKGMOD|MIX]
+ [pkg_model="pkg_model_name"]
+ [ss_group='ON|OFF G1 [,..., Gn]'] [nopseudo]
+ [use_fall_wvf=0|1|2] [use_rise_wvf=0|1|2]
+ [c_comp_pu=value] [c_comp_pd=value] [c_comp_pc=value]
+ [c_comp_gc=value] [all_sm=YES|NO]
+ [keep_vds_monotonic=NO|YES] [keep_vgs_monotonic=NO|YES]
+ [rx_logic=0|1]
+ [eldova=ON|OFF] [em_libname="logical_lib_name"]
+ [table_tune=value]
+ [logic_one=value] [logic_zero=value]
+ [c_fixture=YES|NO]
+ [keep_monotonic=YES|NO]
+ [switch_isso=ON|OFF] [switch_composite_current=ON|OFF]
+ [check_model_spec=ON|OFF] [ibischk_soft=NO|YES]
Parameters
Some parameters are part of the IBIS standard, please refer to description in “IBIS Device
Standards” on page 732.
• _IO_xx
IBIS instance name.
• file="path"
Specifies the path to the file that contains an IBIS formatted model.
This can be the full path (for example, /user/test/Models/model.ibs), a relative path, or just a
file name. Both / and \ should be acceptable as separators in the path name (for the UNIX
and NT versions). Avoid any spaces between the quotes and the file name/path. An Eldo
option IBIS_SEARCH_PATH is available to specify the path to the directory to search for
the IBIS files.
• component="component_name"
Specifies a component name within the specified IBIS file. The component name is casesensitive.
• limit_k_factors=POWER|NO|YES
POWER
Prevent current flow in the power terminals, a_puref and a_pdref, from being nonmonotonic.
This is the default.
NO
Eldo® User's Manual, 15.3 765

IBIS Models Support in Eldo
IBIS Component
Keep the scaling factors as calculated.
YES
Limit the switching scaling factors between 0 and 1.
Switching scaling factors are extracted from the rising/falling waveforms, and used to
modulate the output current of the buffer while switching.
o
o
Scaling factor 0 indicates fully off for the working network.
Scaling factor 1 indicates fully on.
Sometimes these factor values exceed one or become negative, causing a negative slope,
that may lead to some convergence problems.
Note
The POWER setting helps to avoid non-convergence issues whilst keeping the
correct buffer behavior on the a_signal terminal.
• corner=TYP|MIN|MAX|FAST|SLOW
Specifies the IBIS corner to be used to extract the data from the IBIS file. The default is
corner=TYP—if any data is missing under the Min or Max columns in the IBIS file then
the Typ column value will be used instead. When corner=TYP, MIN, or MAX, simulation
will extract the data under the corresponding Typ, Min, and Max columns in the IBIS file.
When corner=FAST or SLOW, corner uses combinations from data under the Min and
Max columns; FAST is the same as MAX, and SLOW is the same as MIN except for
parameters listed in Table 17-5.
• warn=ON|OFF
Specifies if the warning message generated for this instance should be printed (ON), or
suppressed (OFF). Setting warn=OFF is equivalent to using the keyword nowarn. The
default setting is ON.
• nowarn
This is equivalent to warn=OFF.
• msel_mode=value
The value indicates a model order under the [Model Selector] keyword in the IBIS file. If
the value specified is greater than the model selector list, then the first model will be
selected. The default is 1.
• model_selector='mod_sel1=mod_name1 [, mod_sel2=mod_name2 ,...]'
This keyword can be repeated more than once. model_selector is used to select models for
some or all model selectors in the given IBIS file. model_selector has a higher precedence
over msel_mode.
• package=0|1|2|3|4|OFF|CMPNT|PIN|PKGMOD|MIX
This keyword specifies the package modeling type to be used for package parasitics.
766
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
IBIS Component
0 or OFF
No package is added.
1 or CMPNT
RLC components defined under [Package] keyword are added.
2 or PIN
RLC components defined under [Pin] are added.
3 or PKGMOD
A package model will be used. This is the default.
4 or MIX
A package model will be used, and RLC parasitics are added as defined under [Pin]
section for pins that are not defined in the package model.
Note
If no data is available for selected packaging type, then the data in the lower type
will be used.
• pkg_model="package_model_name"
Specifies an IBIS package model name within the specified IBIS file. The package model
name must match one defined for this component under [Package Model] or [Alternate
Package Models] keywords. If pkg_model is not specified, the one under [Package Model]
will be used. “package_model_name” is case-sensitive.
• ss_group='ON|OFF G1 [,G2, ...]'
Sets the On/Off state for the series switch buffers created according the info under [Series
Pin Mapping] keyword.
You can set the logical state of this set of groups by type ON|OFF in the beginning of the
set, and then follow it by the groups’ names that will take this state. The specified set of
groups must match one of these under [Series Switch Groups] keyword or its
complementary. If ss_group is not specified Eldo will take the first set of groups under
[Series Switch Groups] keyword to set the logical state for the series switch buffers.
• nopseudo
When specified Eldo does not generate pseudo-differential buffers for the pseudodifferential
pins, and generates single-ended buffers instead.
By default Eldo generates pseudo or true differential buffers as defined under [Diff Pin]
keyword.
Note
The following keywords are used in the generated buffers if applicable.
Eldo® User's Manual, 15.3 767

IBIS Models Support in Eldo
IBIS Component
• c_comp_pu=value, c_comp_pd=value, c_comp_pc=value, c_comp_gc=value
These four keywords are optional. If one of these keywords is specified with a non-zero
value; c_comp capacitor will be split up to four parts. Values are dimensionless numbers
between 0 and 1, and sum of them should be equal to 1. The default is 0 for the unspecified
values.
• use_fall_wvf= 0|1|2, use_rise_wvf= 0|1|2
0
Use the ramp for the falling/rising transitions.
1
Use one waveform for the falling/rising transitions.
2
Use two waveforms for the falling/rising transitions.
The default behavior is to use the first two waveforms if more than one waveform is
specified in the IBIS model, use one waveform if only one is specified, and to use ramp if no
waveforms are specified.
• all_sm=YES|NO
For Series/Series_Switch buffers. Setting all_sm to NO makes Eldo use only the first
non-zero Vds table to generate the current of Series MOSFET elements in the Series buffer.
The default is YES.
• keep_vds_monotonic=NO|YES
For Series/Series_Switch buffers. Setting keep_vds_monotonic to YES will keep the Ids
current monotonic versus Vds values for a given Vgs. Default is NO.
• keep_vgs_monotonic=NO|YES
For Series/Series_Switch buffers. Setting keep_vgs_monotonic to YES will keep the Ids
current monotonic versus Vgs values for a given Vds. Default is NO.
• rx_logic=0|1
For Input or IO buffers; if the input voltage on a_signal port is between Vinl and Vinh
thresholds then rx_logic will control the output voltage on the d_receive port. When
rx_logic=0 (default), the voltage on the d_receive port will be 0.5V (representing logic
"X"). When rx_logic=1, the voltage on the d_receive port will have the same value (state) as
the previous time step.
Note
If there are hysterises thresholds (Vinl+, Vinl-, Vinh+, and Vinh-) under the
[Model Spec] keyword, then rx_logic has no effect.
768
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
IBIS Component
• eldova=ON|OFF
For external models and external circuits written in Verilog-A. Eldo will use its Verilog-A
compiler to handle these models if eldova=ON. Setting eldova=OFF enables these models
to be simulated with Questa ADMS. The default is ON.
• em_libname="logical_lib_name"
Can be used for external models and external circuits written in any AMS language. The
specified logical_lib_name library is used as the work library. If no library is specified, the
default work library will be used, specified with the Questa ADMS vasetlib command or the
vasim -lib command.
• table_tune=value
Controls Eldo time step when the IBIS buffer is switching to obtain accurate output
waveforms. Table_tune accepts non-negative values. Default value is 8.
Setting a value of 1 forces Eldo to take into account all the switching waveform points, 2 to
take one point into account and skip the next, 3 skips two points, but takes into account the
third, and so on. Setting a value of 0 makes Eldo control the time step regardless of the
switching waveform.
Note
The actual time step will be the minimum among the time step of the current IBIS
buffer, time steps of other IBIS buffers, and the time step forced by Eldo.
HMIN is always set as the lower limit for the time step.
• logic_one=value|logic_zero=value
Define the voltage level accepted by IBIS buffers for digital ports, logic_one default is 1.0,
and logic_zero default is 0.0. logic_one must be greater than logic_zero by at least 200mV.
The input voltage is considered ‘logic 1’ if it is greater than (logic_one + logic_zero)/2, and
considered ‘logic 0’ if it is below this value.
Note
These levels are defined for native IBIS buffers and do not apply to external models.
• c_fixture=YES|NO
Enable/disable using rising or falling waveforms that have a c_fixture sub-parameter with a
non-zero value. Setting to NO makes Eldo discard these waveforms; YES (default) to use
these waveforms.
• keep_monotonic=YES|NO
Used to control Eldo behavior with non-monotonic data. Setting to YES Eldo fixes the nonmonotonic
data provided in the tables, setting to NO (default) Eldo keeps the nonmonotonic
tables data as is. This keyword affects the data under [GND Clamp], [POWER
Clamp], [Pullup] and [Pulldown] IBIS keywords.
Eldo® User's Manual, 15.3 769

IBIS Models Support in Eldo
IBIS Component
• switch_isso=ON|OFF
Switch ON or OFF the effect of SSO (Simultaneous Switching Output) on the driver
current. The SSO effect is modeled in the IBIS file under the [ISSO PD] and [ISSO PU]
keywords. The default is ON.
• switch_composite_current=ON|OFF
Switch ON or OFF the effects of the power reference terminal current modeled by the
[Composite Current] keyword. The default is ON.
• check_model_spec=ON|OFF
Switch ON or OFF checking of the buffer input/output signals according to subparameters
given under the [Model Spec] keyword. The following subparameters are supported:
D_overshoot_area_h, D_overshoot_area_l, D_overshoot_ampl_h, and
D_overshoot_ampl_l. The default is ON.
• ibischk_soft=NO|YES
Used to control the golden parser (ibischk) reporting of IBIS version compatibility errors.
Setting to NO means the IBIS version number is checked for compatibility. Only the first
digit of the version number is checked, for example 4.x. Setting to YES releases ibischk
constraints on the IBIS version number. Default is NO.
Description
Equivalent subcircuit
Eldo uses the data under the [Component] keyword to generate buffers, interconnections,
package parasitics, and SPICE subcircuits or Verilog-A modules that represent external circuit
calls. Each component pin that references a model name or model selector name will be
associated with a buffer. The pins that are used as differential pairs under the [Diff Pin]
keyword will be connected to differential buffers, the other pins will be connected to singleended
buffers.
Series/Series_Switch models will be created according to the data under the [Series Pin
Mapping] keyword. Power interconnections are done according to the data under the [Pin
Mapping] keyword if available; otherwise internal source references are created for each buffer.
Package parasitics are added according to the package modeling type specified by the package
keyword, and the data available about the package model.
External nodes naming rules
Component pins that reference anything other than “NC” reserved keywords as the model name
will be added to the Eldo netlist as external nodes for the component equivalent subcircuit. If
the pin references an “NC” reserved keyword, but is used by the package model or exists in the
pin mapping of the series buffers, it will be added to the netlist also.
Additional nodes are also added to make access for buffers input, output, and control signals.
These additional nodes should be connected to ground if they will not be used.
770
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
IBIS Component
The naming rules for the buffers and external nodes are:
• Component pins:
_
• Control nodes:
__
Buffer names are as follows:
• Single-Ended Buffer:
• Differential Buffer:
__diff
• Series Buffer:
Examples
____sers
This example uses the same IBIS file as that used in “IBIS Buffers” on page 752.
Netlist
_IO_comp1 file="dummy.ibs"
+ component="Test_component"
.connect _IO_comp1_2_d_receive _IO_comp1_3_4_diff_d_drive
The above netlist instantiates the entire component Test_component located in the IBIS file
dummy.ibs. The component instance is given the name _IO_comp1. It is composed of an input
buffer, a pseudo-differential buffer, and a series buffer (as shown in Figure 17-15). The digital
output of the input buffer _IO_comp1_2_d_receive and the digital input of the differential
output buffer _IO_comp1_3_4_diff_d_drive are connected in the netlist using the .connect
statement.
Eldo® User's Manual, 15.3 771

IBIS Models Support in Eldo
IBIS Component
Figure 17-15. Test_component Example
Figure 17-15 shows the Test_component of the dummy.ibs IBIS file in “IBIS Buffers” on
page 752. The component is instantiated with the name _IO_comp1. The digital output of the
input buffer and the digital input of the output buffer are connected in the netlist by the user.
Related Topics
Component
Supported Keywords and Sub-Parameters
772
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
IBIS Package
IBIS Package
Instantiates an IBIS package model name within the specified IBIS file.
Syntax
_IO_xx file="path" pkg_model="package_model_name"
+ [ibischk_soft=NO|YES]
Parameters
• _IO_xx
IBIS instance name.
• file="path"
Specifies the path to the file that contains an IBIS formatted model.
This can be the full path (for example, /user/test/Models/model.ibs), a relative path, or just a
file name. Both / and \ should be acceptable as separators in the path name (for the UNIX
and NT versions). Avoid any spaces between the quotes and the file name/path. An Eldo
option IBIS_SEARCH_PATH is available to specify the path to the directory to search for
the IBIS files.
• pkg_model="package_model_name"
Specifies an IBIS package model name within the specified IBIS file. package_model_name
is case-sensitive.
• ibischk_soft=NO|YES
Used to control the golden parser (ibischk) reporting of IBIS version compatibility errors.
Setting to NO means the IBIS version number is checked for compatibility. Only the first
digit of the version number is checked, for example 4.x. Setting to YES releases ibischk
constraints on the IBIS version number. Default is NO.
Description
Equivalent subcircuit
For each IBIS instance that represents an IBIS package model, Eldo will create an equivalent
subcircuit that contains sets of loss-less/lossy transmission lines and/or discrete RLC
components.
Naming rules
External nodes of the equivalent subcircuit will be generated automatically by Eldo. Each pin in
the package model will be represented by two external nodes; one at the die-pad side and the
other one at the package-pin side. The naming of these pins follows the rules below:
• Node at die side:
Eldo® User's Manual, 15.3 773

IBIS Models Support in Eldo
IBIS Package
__DIEPAD
• Node at package side:
_
774
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
IBIS Package
Examples
Package File Example
[IBIS Ver] 4.0
[File Name] package_model_4pins.pkg
[File Rev] 1.0
[Define Package Model] pm1
[Manufacturer] ST None
[OEM] Unknown
[Description] None
[Number Of pins] 4
[pin Numbers]
pin1
pin2
pin3
pin4
[Model Data]
[Inductance Matrix] Sparse_matrix
|
[Row] pin1
pin1 418n
pin2 125n
|
[Row] pin2
pin2 418n
pin3 125n
|
[Row] pin3
pin3 418n
|
[Row] pin4
pin4 418n
|
[Capacitance Matrix] Sparse_matrix
|
[Row] pin1
pin1 94p
pin2 -22p
|
[Row] pin2
pin2 94p
pin3 -22p
|
[Row] pin3
pin3 94p
|
[Row] pin4
pin4 94p
|
[Resistance Matrix] Sparse_matrix
|
[Row] pin1
pin1 15
|
[Row] pin2
pin2 15
|
Eldo® User's Manual, 15.3 775

IBIS Models Support in Eldo
IBIS Package
[Row] pin3
pin3 15
|
[Row] pin4
pin4 15
|
[End Model Data]
[End Package Model]
[End]
The preceding package file example is referenced in the following netlist example.
Netlist
_IO_pkg1
+ file="package_model_4pins.pkg"
+ pkg_model="pm1"
The above netlist instantiates the IBIS package located in the package_model_4pins.pkg IBIS
file. The package model name is pm1. It is a four-pin package as shown in Figure 17-16. This
package is described, in the package file, using the RLC matrix representation that accounts for
the coupling between the pins. You can access the nodes that reside either inside or outside the
package as shown.
Figure 17-16. Package Model Example
Figure 17-16 shows the package of the package_model_4pins.pkg IBIS file given in the above
package file example. The package is instantiated with the name _IO_pkg1.
Related Topics
Package
Supported Keywords and Sub-Parameters
776
Eldo® User's Manual, 15.3

IBIS Electrical Board Description
IBIS Models Support in Eldo
IBIS Electrical Board Description
Instantiates an IBIS Electrical Board Description (EBD) model name within the specified IBIS
file.
Syntax
_IO_xx file="path" ebd_model="ebd_model_name"
+ [ref_des_map='ref_des_1=instance_1 [,..., ref_des_n=instance_n]']
+ [ibischk_soft=NO|YES]
Parameters
• _IO_xx
IBIS instance name.
• file="path"
Specifies the path to the file that contains an IBIS formatted model.
This can be the full path (for example, /user/test/Models/model.ibs), a relative path, or just a
file name. Both / and \ should be acceptable as separators in the path name (for the UNIX
and NT versions). Avoid any spaces between the quotes and the file name/path. An Eldo
option IBIS_SEARCH_PATH is available to specify the path to the directory to search for
the IBIS files.
• ebd_model="ebd_model_name"
Specifies an IBIS Electrical Board Description (EBD) model name within the specified IBIS
file. ebd_model_name is case-sensitive.
• ref_des_map='ref_des_1=instance_1 [,…, ref_des_n=instance_n]'
Maps an IBIS buffer component to a reference designator, where:
o
o
instance_n is the name of the Eldo IBIS instance used to describe an IBIS
component.
ref_des_n is the reference designator visible in the Node sub-parameter of the [Path
Description] keyword in the EBD file.
Note
Reference designator name and instance name are case insensitive.
ref_des_map can be repeated more than once in the _IO_ card.
If a reference designator is repeated in the ref_des_map, then the instance assigned to
that reference designator will be that of the last one.
• ibischk_soft=NO|YES
Used to control the golden parser (ibischk) reporting of IBIS version compatibility errors.
Setting to NO means the IBIS version number is checked for compatibility. Only the first
Eldo® User's Manual, 15.3 777

IBIS Models Support in Eldo
IBIS Electrical Board Description
digit of the version number is checked, for example 4.x. Setting to YES releases ibischk
constraints on the IBIS version number. Default is NO.
Description
Equivalent subcircuit
For each IBIS instance that represents an IBIS EBD model, Eldo will create an equivalent
subcircuit that contains sets of loss-less/lossy transmission lines and/or discrete RLC
components.
Naming rules
External nodes of the equivalent subcircuit will be generated automatically by Eldo. Each pin in
the EBD model, and each component pin, will be connected to the node in the netlist. The
naming of these pins follows the rules below:
• Board pins:
_
• Component nodes:
_
Note
If a reference designator name is used within the IBIS file, but not mapped in the
IBIS instance then the name used in the EBD file will be used without mapping.
778
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
IBIS Electrical Board Description
Examples
Example EBD File
|
[Ibis Ver] 3.2
[File Name] ebd.ebd
[File Rev] 0
[Source] None
|
[Begin Board Description] EBD1
[Manufacturer] None
[Number Of Pins] 5
[Pin List] signal_name
1 S1
2 NC
3 POWER
4 GND
5 S2
[Path Description] 1 | S1
Pin 1
Len = 0.66 L = 1.33333e-08 C = 2.08333e-12 /
Len = 2.00 L = 1e-08 C = 1.77778e-12 /
Node u1.1
Node u1.2
Len = 0.50 L = 1e-08 C = 1.77778e-12 /
Node u2.1
[Path Description] 5 | S2
Pin 5
Len = 0.70 L = 1.33333e-08 C = 2.08333e-12 /
Len = 1.25 L = 1e-08 C = 1.77778e-12 /
Node u2.2
|
[Reference Designator Map]
u1 ebd.ibs component1
u2 ebd.ibs component1
[End Board Description]
[End]
The preceding EBD file example is referenced in the following netlist example.
Eldo® User's Manual, 15.3 779

IBIS Models Support in Eldo
Supported Keywords and Sub-Parameters
Netlist
_IO_cmpnt1
+ file="ebd.ibs"
+ component="component1"
.connect _io_cmpnt1_1_d_drive vdd ! ignored
.connect _io_cmpnt1_1_d_enable vss ! input buffer
.connect _io_cmpnt1_1_d_receive _io_cmpnt1_2_d_drive
.connect _io_cmpnt1_2_d_enable vdd ! output buffer
_IO_cmpnt2
+ file="ebd.ibs"
+ component="component1"
.connect _io_cmpnt2_1_d_drive vdd ! ignored
.connect _io_cmpnt2_1_d_enable vss ! input buffer
.connect _io_cmpnt2_1_d_receive _io_cmpnt2_2_d_drive
.connect _io_cmpnt2_2_d_enable vdd ! output buffer
_IO_ebd1 file="ebd.ebd"
+ ebd_model="EBD1"
+ ref_des_map='u1=_IO_cmpnt1'
+ ref_des_map='u2=_IO_cmpnt2'
The netlist above instantiates two components and an EBD model. The components are located
in the IBIS file ebd.ibs, and the EBD model is located in an EBD file ebd.ebd. The EBD model
used is EBD1, specified within the [Begin Board Description] and [End Board Description]
keywords. The ref_des_map statements inform Eldo that _IO_cmpnt1 in the netlist corresponds
to u1 in the EBD file, and that _IO_cmpnt2 corresponds to u2.
The example files are provided in the installed AMS tree: $MGC_AMS_HOME/examples/ibis/
ebd.cir
Figure 17-17 shows the connections between the IBIS components as described in the EBD file
and the netlist.
Figure 17-17. Electrical Board Description Example Connections
Related Topics
Electrical Board Description
Supported Keywords and Sub-Parameters
Supported Keywords and Sub-Parameters
Eldo can simulate IBIS devices either individually or in the overall component.
780
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
Supported Keywords and Sub-Parameters
Table 17-6 lists the supported keywords and sub-parameters in the current Eldo release. The
IBISver column refers to the IBIS version in which the keyword/sub-parameter was introduced
or modified.
Table 17-6. Supported Keywords and Sub-Parameters
Keyword Sub-parameter IBISver
[Package] R_pkg, L_pkg & C_pkg 1.0
[Pin]
model_name 1.0
R_pin, L_pin, C_pin 1.0
[Diff Pin]
inv_pin 2.1
vdiff 3.1
tdelay_typ 2.1
tdelay_max 2.1
tdelay_min 2.1
[Voltage Range] 1.0
[Pullup Reference] 2.1
[Pulldown Reference] 2.1
[POWER Clamp Reference] 2.1
[GND Clamp Reference] 2.1
[Pulldown] 1.0
[Pullup] 1.0
[POWER Clamp] 1.0
[GND Clamp] 1.0
[ISSO PD] 5.0
[ISSO PU] 5.0
[Ramp]
dV/dt_r 1.0
dV/dt_f 1.0
R_load 2.1
[Rising Waveform] 1 1000 Pts 4.0
Eldo® User's Manual, 15.3 781

IBIS Models Support in Eldo
Supported Keywords and Sub-Parameters
Table 17-6. Supported Keywords and Sub-Parameters (cont.)
Keyword Sub-parameter IBISver
[Falling Waveform] 1 1000 Pts 4.0
C_fixture 2 2.0
R_fixture 2.0
V_fixture 2.0
V_fixture_min 2.1
V_fixture_max 2.1
[Composite Current] 5.0
[Model]
Model_type 4.1
Polarity 1.0
Enable 1.0
Vinl 2.0
Vinh 2.0
C_comp 1 1.0
[Model Spec]
C_comp_pullup 3 4.0
C_comp_pulldown 3 4.0
C_comp_power_clamp 3 4.0
C_comp_gnd_clamp 3 4.0
Vinh 3.2
Vinl 3.2
Vinh+ 3.2
Vinh- 3.2
Vinl+ 3.2
Vinl- 3.2
D_overshoot_area_h 5.0
D_overshoot_area_l 5.0
D_overshoot_ampl_h 5.0
782
Eldo® User's Manual, 15.3

D_overshoot_ampl_l 5.0
[Rgnd] 2.1
[Rpower] 2.1
[Rac] 2.1
[Cac] 2.1
[R Series] 3.2
[L Series] 3.2
[C Series] 3.2
[Lc Series] 3.2
[Rc Series] 3.2
[Series Current] 3.2
[Series MOSFET] 3.2
Vds 3.2
[On] 3.2
[Off] 3.2
[Series Switch Groups] On, Off 3.2
[Series Pin Mapping]
pin_2 3.2
model_name 3.2
function_table_group 3.3
[Model Selector] 3.2
[Submodel]
Submodel_type 3.2
Dynamic_clamp 3.2
Bus_hold 3.2
[Submodel Spec] 3.2
V_trigger_r 3.2
V_trigger_f 3.2
Off_delay 3.2
[GND Pulse Table] 3.2
IBIS Models Support in Eldo
Supported Keywords and Sub-Parameters
Table 17-6. Supported Keywords and Sub-Parameters (cont.)
Keyword Sub-parameter IBISver
Eldo® User's Manual, 15.3 783

IBIS Models Support in Eldo
Supported Keywords and Sub-Parameters
Table 17-6. Supported Keywords and Sub-Parameters (cont.)
Keyword Sub-parameter IBISver
[POWER Pulse Table] 3.2
V_trigger_r 3.2
V_trigger_f 3.2
[Pin Mapping]
pulldown_ref 2.1
pullup_ref 2.1
gnd_clamp_ref 2.1
power_clamp_ref 2.1
[Driver Schedule]
Model_name 3.2
Rise_on_dly 3.2
Rise_off_dly 3.2
Fall_on_dly 3.2
Fall_off_dly 3.2
[External Model] [End ...] 4.1
Language 4.1
SPICE 4.1
Verilog-A 4.2
Ports 4.1
d_control 4.1
d_drive 4.1
d_enable 4.1
d_receive 4.1
a_puref 4.1
a_pdref 4.1
a_pcref 4.1
a_gcref 4.1
a_signal 4.1
d_switch 4.1
a_gnd 4.1
784
Eldo® User's Manual, 15.3

a_pos 4.1
a_neg 4.1
a_signal_pos 4.1
a_signal_neg 4.1
D_to_A 4.1
A_to_D 4.1
[External Circuit] [End ...] 4.1
[Node Declarations] [End ...] 4.1
[Circuit Call] [End ...] 4.1
Signal_pin 4.1
Diff_signal_pins 4.1
Series_pins 4.1
Port_map 4.1
CIRCUITCALL (reserved word) 4.1
[Package Model] 2.1
[Define Package Model] 2.1
[Manufacturer] 2.1
[OEM] 2.1
[Description] 2.1
[Number Of Sections] 3.0
[Number Of Pins] 2.1
[Pin Numbers] 2.1
Len 3.0
R 3.0
L 3.0
C 3.0
Fork 3.0
EndFork 3.0
[Model Data] [End ...] 2.1
[Resistance Matrix] 2.1
IBIS Models Support in Eldo
Supported Keywords and Sub-Parameters
Table 17-6. Supported Keywords and Sub-Parameters (cont.)
Keyword Sub-parameter IBISver
Eldo® User's Manual, 15.3 785

IBIS Models Support in Eldo
Supported Keywords and Sub-Parameters
Table 17-6. Supported Keywords and Sub-Parameters (cont.)
Keyword Sub-parameter IBISver
[Inductance Matrix] 2.1
[Capacitance Matrix] 2.1
[Bandwidth] 2.1
[Row] 2.1
Banded_matrix 2.1
Sparse_matrix 2.1
Full_matrix 2.1
[Begin Board Description] 3.0
[Manufacturer] 3.0
[Number Of Pins] 3.0
[Pin List] 3.0
signal_name 3.0
[Path Description] 3.0
Len 3.0
R 3.0
L 3.0
C 3.0
Fork 3.0
EndFork 3.0
Node 3.0
Pin 3.0
[Reference Designator Map] 3.0
Related Topics
IBIS Device Standards
IBIS Model Syntax
1.Eldo ignores waveforms that have L_fixture sub-parameter with non-zero values.
2.Eldo ignores waveforms that have C_fixture sub-parameter with non-zero values;
to enable using these waveforms set IBIS instance keyword C_fixture=yes.
3.Partially supported. If the value of C_comp is zero with any of these keywords
specified, then all four values are summed up and used as the C_comp value.
786
Eldo® User's Manual, 15.3

IBIS Algorithmic Model Interface (AMI)
IBIS AMI models can be used in Eldo using the following syntax:
Syntax
_IO_xx mode=AMI
+ tx_file="tx_file_name.ibs"
+ [rx_file="rx_file_name.ibs"]
+ tx_model="tx_model_name"
+ [rx_model="rx_model_name"]
+ impulse_matrix="impulse_matrix_file"
+ [row_size=value]
+ [aggressors=value]
+ sample_interval=value
+ bit_time=value
+ input_waveform="input_wave_file"
Parameters
IBIS Models Support in Eldo
IBIS Algorithmic Model Interface (AMI)
• _IO_xx
IBIS instance name.
• mode=AMI
Specifies IBIS AMI mode.
• tx_file="tx_file_name.ibs"
IBIS filename that contains the TX IBIS model.
• rx_file="rx_file_name.ibs"
IBIS filename that contains the RX IBIS model.
• tx_model="tx_model_name"
IBIS model name that references the algorithmic model for the TX. The model name should
match one of the models in tx_file.
• rx_model="rx_model_name"
IBIS model name that references the algorithmic model for the RX. The model name should
match one of the models in rx_file.
• impulse_matrix="impulse_matrix_file"
References a file that contains the channel impulse response matrix. As defined in the IBIS
specifications, the impulse values are in Volts and are uniformly spaced in time. The sample
spacing is given by the parameter sample_interval.
The impulse matrix is stored in a single dimensional array of floating point numbers which
is formed by concatenating the columns of the impulse response matrix, starting with the
first column and ending with the last column. The matrix elements can be identified using:
impulse_matrix[idx] = element (row, col)
idx = col × number_of_rows + row
Eldo® User's Manual, 15.3 787

IBIS Models Support in Eldo
IBIS Algorithmic Model Interface (AMI)
row = row index , ranges from 0 to row_size−1
col = column index, ranges from 0 to aggressors
The first column of the impulse matrix is the impulse response for the primary channel. The
rest are the impulse responses from aggressor drivers to the victim receiver.
Values in the files are in the following form, and comments are not allowed in this file:
1.0e0
1.0005
.
.
.
2.5e-1
• row_size=value
The number of rows in impulse_matrix. It is a non-zero integer value. Default value is 1.
• aggressors=value
The number of aggressors in the impulse_matrix. It is a non-negative integer number.
Default value is 0. If both row_size and aggressors are provided their product should match
the number of values given in the impulse_matrix file.
• sample_interval=value
This is the sampling interval of the impulse_matrix and the input_waveform.
• bit_time=value
The bit time in the input_waveform.
• input_waveform="input_wave_file"
References a file that contains the test waveform. The waveform values are in Volts and are
uniformly spaced in time. The sample spacing is given by the parameter sample_interval.
Values in the files are in the following form, and comments are not allowed in the file:
1.0e0
1.00
.
.
.
0.00
0.00
0.00001
0.75
.
.
.
1.00
Description
When instantiating an IBIS instance in the AMI mode, Eldo loads the AMI shared library, calls
the AMI API functions and passes to them the impulse matrix and the other required
788
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IBIS Models Support in Eldo
IBIS Algorithmic Model Interface (AMI)
parameters. According to the values of the AMI reserved parameters Use_Init_Output and
GetWave_Exists, Eldo convolves the input waveform with the channel impulse matrix and
passes the output to the AMI_GetWave API function.
Eldo adds a .TRAN command and plots the final output waveform. The output waveform is
provided in both differential and single-ended form. The name of the differential wave is
_ami_out. The single ended wave names are _ami_out_diff
and _ami_out_inv.
The IBIS receiver buffer may be added to obtain the output after the digital level.
For more details about the AMI API functions and the reserved parameters, please refer to the
IBIS v5.0 specification document.
Examples
Example netlist:
* AMI Netlist
_IO_ami MODE=ami
+ tx_file="tx.ibs" tx_model="TX"
+ rx_file="rx_ibs" rx_model="RX"
+ impulse_matrix="impulse.txt"
+ sample_interval=1e-9 bit_time=64e-9
+ input_waveform="wave.txt"
* differential RX buffer
_IO_RX _IO_ami_ami_out_diff _IO_ami_ami_out_inv out
+ file="rx.ibs" model="RX"
.plot tran "out"
.end
Related Topics
IBIS AMI
Eldo® User's Manual, 15.3 789

IBIS Models Support in Eldo
IBIS Examples
IBIS Examples
A number of example files are provided to illustrate using IBIS in Eldo. The example files are
available in your installed directory: $MGC_AMS_HOME/examples/ibis/
Example 1—Single-Ended Tx-Rx System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790
Example 2—Pseudo-Differential Tx-Rx System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 792
Example 3—Package Parasitics Cross Talk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 794
Example 4—Simultaneous Switching Output Noise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 796
Example 1—Single-Ended Tx-Rx System
Netlist file: single_tx_rx.cir
IBIS file: tx_rx.ibs
This example deals with a simple arrangement of a single-ended output buffer (Tx),
transmission line, and a single-ended input buffer (Rx). This arrangement can be used for
transmission line analysis mismatch as well as to assure that the Rx correctly recognizes the
logic associated with the received signal levels.
Figure 17-18. Single-Ended Tx-Rx System
The transmission line has characteristics: impedance Z0=50Ω and signal delay TD=0.2ns.
Netlist Explanation
_IO_Tx out d_drive
+ file="tx_rx.ibs"
+ component="transceiver"
+ model="OUT"
The above lines instantiate an IBIS output buffer Tx with output connected to out and digital
input connected to d_drive. The output buffer is located in the tx_rx.ibs IBIS file within the
transceiver component.
TL out 0 in 0 Z0=50 TD=0.3ns
Instantiates an ideal transmission line connected between the nodes out and in with ground
reference. The transmission line has 50 Ω characteristics impedance and 0.3ns time delay.
790
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
Example 1—Single-Ended Tx-Rx System
_IO_Rx in d_receive
+ file="tx_rx.ibs"
+ component="transceiver"
+ model="IN"
Instantiates an IBIS input buffer Rx with input connected to in and its digital output connected
to d_receive. The input buffer is located in the tx_rx.ibs IBIS file within the transceiver
component.
Rterm d_receive 0 1e6
Connects a 1MΩ resistor between the digital output d_receive of the input buffer and ground.
This has no impact on the results but avoids having a node with less than two connections.
.param VHI=1.0
.param VLO =0.0
.param TDELAY=0
.param TRISE=10p
.param TFALL=Trise
.param TSAMPLE=5n
vstim d_drive 0 pattern 1 0 0 10p 10p 5n 0 1 R
Instantiates the stimulus vstim for the system. The source is connected between the nodes
d_drive and ground. It is defined using the pattern function with high voltage level of 1V, low
voltage level of 0V, 0 starting delay time, 10ps rise and fall times, 5ns sample time, and finally
it periodically alternates between 0 and 1.
The next part of the netlist specifies the simulation control directives indicating what type of
simulation Eldo should perform on the circuit.
.tran 10p 20n
Specifies a transient analysis be performed lasting 20ns with a plotting increment of 10ps.
.option step=10p
Imposes a time step of 10ps.
.plot tran v(d_drive) v(out) v(in) v(d_receive)
Specifies voltage/time plots of the voltages at nodes out, d_drive, in and d_receive.
Eldo® User's Manual, 15.3 791

IBIS Models Support in Eldo
Example 2—Pseudo-Differential Tx-Rx System
Simulation Results
Figure 17-19. Single-Ended Tx-Rx System Simulation Results
Ringing is clearly observed in the waveform at the receiver side. This is due to the mismatch
between the TL Z0 and the Rx input impedance (ringing also means a mismatch exists between
the Tx output impedance and the TL Z0). However, the Rx recognizes the signal logic levels
and the digital output (d_receive) is given correctly without any undesired transitions due to the
received signal ringing.
Related Topics
Example 2—Pseudo-Differential Tx-Rx System
IBIS Examples
Example 2—Pseudo-Differential Tx-Rx System
Netlist file: diff_tx_rx.cir
IBIS file: diffsource.ibs
This example deals with a simple arrangement of a pseudo-differential output buffer (Tx),
transmission line and a pseudo-differential input buffer (Rx). Same as example#1, this
arrangement can be used for transmission line analysis mismatch as well as to assure that the
differential Rx correctly recognizes the logic associated with the received differential signal
levels.
792
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
Example 2—Pseudo-Differential Tx-Rx System
Netlist Explanation
_IO_DIFFOUT OUTp OUTn D_drive
+ file="diffsource.ibs"
+ component="diffsource"
+ pin="1" inv_pin="2"
The above lines instantiate an IBIS differential output buffer diffout with non-inverting output
connected to outp, inverting output connected to outn and digital input connected to d_drive.
The output buffer is located in the diffsource.ibs IBIS file within the diffsource component. The
differential buffer is recognized from the pin and inv_pin keywords. Pin names given using
these keywords must match those in the diffsource.ibs IBIS file under the [Diff_pin] keyword.
TLp outp 0 inp 0 Z0=50 TD=0.3ns
TLn outn 0 inn 0 Z0=50 TD=0.3ns
Instantiates a pair of ideal transmission lines, one of them connected between the nodes outp
and inp with ground reference, and the second one connected between the nodes outn and inn
with ground reference. Both transmission lines have 50Ω characteristics impedance and 0.2ns
time delay.
_IO_DIFFIN INp INn D_receive
+ file="diffload.ibs"
+ component="diffload"
+ pin="1" inv_pin="2"
Instantiates an IBIS differential input buffer diffin with non-inverting input connected to inp,
inverting input connected to inn and digital output connected to d_receive. The input buffer is
located in the diffload.ibs IBIS file within the diffload component. The differential buffer is
recognized from the pin and inv_pin keywords. Pin names given using these keywords must
match those in the diffload.ibs IBIS file under the [Diff_pin] keyword.
Rterm D_receive 0 1e6
Connects a 1MΩ resistor between the digital output d_receive of the input buffer and ground.
This has no impact on the results avoids having a node with less than two connections.
.param VHI=1.0
.param VLO =0.0
.param TDELAYL=0
.param TRISE=300p
.param TFALL=Trise
.param TSAMPLE=3000p
vin d_drive 0 pattern VHI VLO TDELAYL TRISE TFALL TSAMPLE 1011010001 R
Instantiates the stimulus vin for the system. The source is connected between the nodes d_drive
and ground. It is defined using the pattern function with high voltage level of 1V, low voltage
level of 0V, 0 starting delay time, 300ps rise and fall times, 3ns sample time, and having the
pattern 1011010001.
Eldo® User's Manual, 15.3 793

IBIS Models Support in Eldo
Example 3—Package Parasitics Cross Talk
The next part of the netlist specifies the simulation control directives indicating what type of
simulation Eldo should perform on the circuit.
.tran 10p 40n
Specifies a transient analysis be performed lasting 40 ns with a plotting increment of 10 ps.
.plot tran v(d_drive) v(outp) v(outn) v(inp) V(inn) v(d_receive)
Specifies voltage/time plots of the voltages at nodes d_drive, outp, outn, inp, inn and d_receive.
Simulation Results
Figure 17-20. Pseudo-Differential Tx-Rx System Simulation Results
Related Topics
Example 3—Package Parasitics Cross Talk
IBIS Examples
Example 3—Package Parasitics Cross Talk
Netlist file: pkg_cross_talk.cir
IBIS file: tx_rx.ibs
This example deals with the simulation of an entire component and observation of the effect of
cross talk between the pins of the package. This is one of the important issues in signal integrity
analysis.
794
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
Example 3—Package Parasitics Cross Talk
Netlist Explanation
_IO_Trx
+ file="tx_rx.ibs"
+ component="transceiver"
+ package=3
The above lines instantiate an IBIS component. Component instantiation means all the buffers
inside the component as well as coupling between pins can be simulated. The component is
named transceiver and located in the tx_rx.ibs IBIS file. The package parameter in the _IO
element specifies the package modeling type to be used. In our case, package=3 means that the
advanced package model, located in the tx_rx.ibs IBIS file under [Define package model] will
be used.
vp _IO_Trx_5 0 pwl (0 0 1n 0 1.6n 3.3 8n 3.3 8.6n 0)
Instantiates the stimulus vp which is a pulse waveform connected between pin 5 of the IBIS
component and ground. It is important to note that all other component pins exist in the
simulation but left unconnected here. A warning will appear about these unconnected pins.
vcc _IO_TRX_4 0 3.3
.connect _IO_TRX_1_d_drive 0
.connect _IO_TRX_2_d_drive 0
.connect _IO_TRX_3_d_drive 0
.connect _IO_TRX_8 0
Rterm1 _IO_TRX_5_d_receive 0 1e6
Rterm2 _IO_TRX_6_d_receive 0 1e6
Rterm3 _IO_TRX_7_d_receive 0 1e6
The above lines have no impact on the simulation results. They are used to avoid warnings
about nodes that have less than two connections. A voltage source vcc is connected between the
node _IO_TRX_4 and ground. The digital inputs of the output buffers (_IO_TRX_1_d_drive,
_IO_TRX_2_d_drive and _IO_TRX_3_d_drive) are tied to ground using the .connect
statement. Also the node _IO_TRX_8 is connected to ground. Then 1MΩ resistors are
connected between the digital outputs of the input buffers (_IO_TRX_5_d_receive,
_IO_TRX_6_d_receive and _IO_TRX_7_d_receive) and ground.
The next part of the netlist specifies the simulation control directives indicating what type of
simulation Eldo should perform on the circuit.
.tran 1p 14n
Specifies a transient analysis be performed lasting 14ns with a plotting increment of 1ps.
.option step=1p
Imposes a time step of 1ps. This small time step is imposed to capture the ringing that will occur
on pin 6 due to both capacitive and inductive coupling with pin 5.
.plot tran v(_IO_TRX_5) v(_IO_TRX_6)
Eldo® User's Manual, 15.3 795

IBIS Models Support in Eldo
Example 4—Simultaneous Switching Output Noise
Specifies voltage/time plots of the voltages at both pin 5 and 6 of the IBIS component.
Simulation Results
Figure 17-21. Package Parasitics Cross Talk
There is both capacitive and inductive coupling between pins 5 and 6. This coupling results in a
ringing effect on pin 6.
Related Topics
Example 4—Simultaneous Switching Output Noise
IBIS Examples
Example 4—Simultaneous Switching Output Noise
Netlist file: sson.cir
IBIS file: tx_rx_pm.ibs
This example deals with the simulation simultaneous switching output noise (SSON). The [Pin
Mapping] keyword in the IBIS file contains information on how power supplies are connected
to individual buffers or groups of buffers; it can be used for predicting SSON.
796
Eldo® User's Manual, 15.3

IBIS Models Support in Eldo
Example 4—Simultaneous Switching Output Noise
Figure 17-22. Component Internal Connection
Netlist Explanation
_IO_comp
+ file="tx_rx_pm.ibs"
+ component="transceiver_pm"
+ package=1
The above lines instantiate an IBIS component. The component is named transceiver_pm and
located in the tx_rx_pm.ibs IBIS file. Package=1 means that package parasitics provided in the
IBIS file under [Package] keyword, where package pins are assumed uncoupled, will be used.
vcc _IO_comp_4 0 3.3
.connect _IO_comp_8 0
Connects the power supply of the component. Note, the power supply should be connected
manually when the component has a [Pin Mapping] keyword. A DC voltage source of 3.3V is
connected to pin 4 of the component and pin 8 is connected to ground.
vin1 _IO_comp_5 0 0
vin2 _IO_comp_6 0 3.3
.param VHI=3.3
.param VLO =0.0
.param TDELAYL=1n
.param TRISE=0.1n
.param TFALL=Trise
.param TSAMPLE=5n
vin3 _IO_comp_7 0 pattern VHI VLO TDELAYL TRISE TFALL TSAMPLE 0 1 1 0 R
Defines the inputs of the component input buffers. Pin 5 is connected to 0 voltage, pin 6 is
connected to a DC voltage of 3.3 V and pin 7 is connected to the stimulus of the system vin3. It
Eldo® User's Manual, 15.3 797

IBIS Models Support in Eldo
Example 4—Simultaneous Switching Output Noise
is defined using the pattern function with high voltage level of 3.3V, low voltage level of 0V,
1ns starting delay time, 0.1ns rise and fall times, 5ns sample time and have the pattern 0110.
.connect _IO_comp_5_d_receive _IO_comp_1_d_drive
.connect _IO_comp_6_d_receive _IO_comp_2_d_drive
.connect _IO_comp_7_d_receive _IO_comp_3_d_drive
Connects the input buffers digital output to the output buffers digital input.
The next part of the netlist specifies the simulation control directives indicating what type of
simulation Eldo should perform on the circuit.
.tran 10p 50n
Specifies a transient analysis be performed lasting 50ns with a plotting increment of 10ps.
.option step=10p
Imposes a time step of 10 ps.
.plot tran v(_IO_comp_1) v(_IO_comp_2) v(_IO_comp_3)
Specifies voltage/time plots of the voltages at pins 1, 2, and 3 of the IBIS component.
Simulation Results
Figure 17-23. Simultaneous Switching Output Noise (SSON) Simulation Results
A difference is observed in the results from the case when package=1 was set (compare yellow
and blue waveforms). The time varying signal at OUT1 and OUT2 is not only due to IR and
LdI/dt voltage drops on the supply pin, but in addition has the capacitive and inductive coupling
between the package pins.
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IBIS Models Support in Eldo
Example 4—Simultaneous Switching Output Noise
Related Topics
IBIS Examples
Eldo® User's Manual, 15.3 799

IBIS Models Support in Eldo
Example 4—Simultaneous Switching Output Noise
800
Eldo® User's Manual, 15.3

Chapter 18
Eldo Control Language
This chapter details the Eldo Control Language—the set of syntax and design approaches that
enable both an explicit control flow for complex, multiple-netlist simulations, and to extract
simulation results into a user-defined output format.
Overview of the Eldo Control Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 802
Eldo Control Language Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 803
Eldo Control Language Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 806
Testbenches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 809
Testbench Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 809
Testbench Instantiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811
Rules for Testbench Location Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 813
Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814
Task Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814
Task Instantiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 817
Statement Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820
Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 839
Defining and Running Simulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 841
Library of Functions for Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 854
Simulation Dynamic Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1014
Extended Simulation Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1024
Parallel Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1039
Statistical Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1058
Advanced Simulation Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1114
Examples Using ECL as an Alternative to Standard Eldo Commands . . . . . . . . . . . . . 1123
.STEP Alternative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1123
.EXTRACT Alternative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1125
.PRINTFILE Alternative #1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1127
.PRINTFILE Alternative #2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1129
.OPTIMIZE Alternative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1131
.MPRUN with Monte Carlo Analysis Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1133
Eldo® User's Manual, 15.3 801

Eldo Control Language
Overview of the Eldo Control Language
Overview of the Eldo Control Language
The Eldo Control Language extends the raw capabilities of Eldo by adding support for
sequential operations, results-based decision taking, and the arbitrary formatting of simulation
results.
In its classical mode of operation, Eldo reads in a netlist that contains both the circuit element
description and a number of commands. The commands usually start with a “.”; for example
.TRAN, .STEP, .EXTRACT, and so on. The relative position of the commands is unimportant;
Eldo uses its own hard-coded internal logic to decide the sequence in which to execute the
commands, between which there is virtually no communication. Eldo also decides how to
format the results of the various commands it executes.
In many cases, the Eldo default logic is sufficient for a designer to achieve the required
simulation results. For situations where more custom control is required, the Eldo Control
Language enables a designer to bypass the hard-coded execution logic and formatting, and
implement whatever sequence of simulation commands is required, from very simple ones to
full algorithms. In addition, the formatting of the results can be freely defined.
The Eldo Control Language is based on two fundamental structures: testbenches and tasks.
• A testbench is a reusable parameterized block of simulator commands that can be
instantiated in the netlist to simulate. It is comparable to the notion of a macro from a
classical programming language, such as C, or comparable to #define in Eldo, when
using the -E/-EE command-line argument, see “Directives Interpreted using the C Pre-
Processor (-E/-EE Arguments)” on page 126.
• A task is a sequence of instructions that specifies which netlists are to be simulated and
what to do with their results. The netlists simulated by the tasks are typically created by
instantiating testbenches with different parameter values. Inside a task, conditions can
be tested, multiple simulations can be launched through for and while loops, their results
(typically the .EXTRACT/.MEAS and the waveforms) easily retrieved and tested for,
and output files printed in arbitrary formats. Any simulation plan exceeding the hardcoded
capabilities of Eldo can be implemented.
The power of the Eldo Control Language is that it is implemented directly within Eldo. This
means that the Eldo Control Language “knows” the syntax and semantics of analog simulation;
it knows what a simulation netlist is, and what .EXTRACT/.MEAS or waveforms are, and thus
can interface directly with these objects.
See also:
• “Testbenches” on page 809
• “Tasks” on page 814
Eldo Control Language Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 803
Eldo Control Language Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 806
802
Eldo® User's Manual, 15.3

Eldo Control Language Examples
Eldo Control Language
Eldo Control Language Examples
A number of example files are provided to illustrate the Eldo Control Language.
See Table 18-1 for directory names and descriptions of the example files provided in your
installed directory: $MGC_AMS_HOME/examples/ecl/
Table 18-1. Eldo Control Language Example Files
Example Dir Description
01-open_loop_gain Typical example of what can be done with the Control Language:
- the netlist first contains the circuit of an operational amplifier;
- then, some parametrized testbenches have been defined;
- and last, the task specifies which simulations to perform with which
testbenches to instantiate.
02-hello_world Most basic example: a task printing “Hello world.”
03-facto
Basic example of a recursive task to compute factorial(10) to show how to
use task input and output parameters.
04-complex
Example of a task using complex numbers. First, the task runs an AC
simulation and then processes a complex result (gain and phase at 1Hz) of
this simulation to display its value.
05-max_gain Example of a task processing waveforms. First, the task runs an AC
simulation and gets a waveform (gain of amplifier) result from this
simulation and then iterates through this waveform to find its maximum
value.
06-max_overshoot Example of a task processing waveforms using some pre-defined
functions. First the task runs a transient simulation and gets a waveform
(output of the amplifier) result from this simulation and then calls the max
function to find its maximum value to compute the overshoot.
07-write_hello_world Basic example of a task writing “Hello world” in a file.
08-rc
Short example to show how to get simulation results from a task. First the
task runs the simulation of a RC circuit, and then some results (parameter
values, extract values, waveforms) are retrieved back in the task so that
they can be processed and so that some specific values can be printed on
the standard output.
09-rc_pulse
Short example to show how to get vector simulation results from a task.
First the task runs the simulation of a RC circuit with a pulse input, and
then some vector results are retrieved back in the task so that they can be
processed and printed on the standard output.
10-rc_step
Another short example to show how to get vector simulation results from a
task. First the task runs the simulation of a RC circuit for different values
of the resistance, and then some vector results are retrieved back in the
task so that they can be processed and printed on the standard output.
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Eldo Control Language
Eldo Control Language Examples
Example Dir
11-rc_alter
12-rc_compounds
13-dichotomy
14-setup
15-rf_vco
16-jitter
17-calibration
18-measure_tprop
19-overshoot
20-osc_freq_callback
21-printfile_csv
Table 18-1. Eldo Control Language Example Files (cont.)
Description
Example of how to process simulation results when the netlist contains
some .ALTER commands. First the task runs the simulation of a RC
circuit where the value of the resistance is modified using .ALTER
commands, and then some vector results are retrieved back in the task so
that they can be processed and printed on the standard output.
Example of how to process compound waveform simulation results in a
task. Two task are defined. The first shows a complicated way to process
compound waveforms by calling pre-defined functions directly on the
compound waveform (it is more complicated because the task has to
process vector results). The second task first calls the compoundcontent
function to have a direct access to each wave composing the compound
waveform; then it is easier to use the pre-defined functions on each single
waveform.
Example of a task implementing a dichotomy to find out which value of
VD yields a requested IDS current. Many simulations are run
successively.
Example of a task running many simulations to compute the setup time for
different values of temperature and VDD. Sequential and parallel versions
are provided.
Example of a task running steady-state and Monte Carlo analyses. The
first simulation computes for which value of the VCONTROL source
voltage the steady-state regime corresponds to a given fundamental
oscillation frequency. The second simulation runs a Monte-Carlo analysis
to find out the standard deviation of the fundamental frequency for the
previously calculated value of the VCONTROL source voltage.
Example of a jitter estimation for different corners. Output is written into
the file jitter.results.
Example of a task searching the required eps value to reach x% accuracy
compared to a golden result.
Short example of a netlist defining and instantiating testbenches. This
example shows how testbenches can be used without tasks to create
reusable blocks of element descriptions or simulator commands.
Short example of a netlist defining and instantiating testbenches.
Example of using a callback function to detect the time when an oscillator
has reached its expected frequency.
Example of generating a .csv file. The DC offset of an operational
amplifier is computed for different values of vdd and is printed into a .csv
file that can be loaded later in EZwave for example.
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Eldo® User's Manual, 15.3

Example Dir
22-plot_mos_
operating_regions
23-plot_mos_ids_
sat_versus_w_l
24-plot_bandwidth
25-step_alternative
26-extract_alternative
27-printfile_
alternative
28-optimize_
alternative
29-
list_mc_stat_params
Eldo Control Language
Eldo Control Language Examples
Table 18-1. Eldo Control Language Example Files (cont.)
Description
Example describing how to create a waveform to plot the content of a
vector versus another one. In this example, the goal is to plot the
saturation drain current versus the drain-to-source voltage and the limit
between linear and saturation regions depending on the gate-to-source and
the drain-to-source voltages. The creation of the waveforms is done in the
last statements of the task. All the processing before it is done to compute
the values to plot. First, the threshold gate-to-source voltage is computed;
then, the gate-to-source voltage is increased logarithmically from this
threshold voltage and for each value, the saturation current and the
saturation drain-to-source voltages are computed.
Example showing how to create a new data type (size) to be able to plot a
waveform with an x-axis scaled in μm. The purpose of this example is to
plot the saturation drain current versus the MOS gate width and the MOS
gate length.
Example showing how to create a new data type having enumerated
values to display graphically the bandwidth of a RLC circuit.
Example showing how the step loops available inside ECL can be used as
an alternative to the regular .STEP command in Eldo. See “.STEP
Alternative” on page 1123. Sequential and parallel versions are provided.
Example showing how the ECL can be used as an alternative to the regular
.EXTRACT commands in Eldo to print results in a custom format. See
“.EXTRACT Alternative” on page 1125.
Example showing how the ECL can be used as an alternative to the regular
.PRINTFILE command in Eldo to print results inside a file. Also look at
example 21-printfile_csv for another example of a .PRINTFILE command
alternative. See “.PRINTFILE Alternative #1” on page 1127.
Example showing how the ECL can be used as an alternative to the regular
.OPTIMIZE command in Eldo to automatically resimulate a design, with
optimized parameter values, without having to re-invoke Eldo. See
“.OPTIMIZE Alternative” on page 1131.
Example showing how to list all the statistical parameters specified in the
netlist. This list is displayed on the standard output. Functions used in this
example: _simu_set_mc_flow, _simu_get_nb_stat_params,
_simu_get_stat_param_name, _simu_get_stat_param_distrib,
_simu_get_stat_param_nom, _simu_get_stat_param_dev and
_simu_get_stat_param_nb_draw.
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Eldo Control Language
Eldo Control Language Limitations
Example Dir
30-modify_mc_distrib
31-mcconv_mcsens
32-
find_important_stat_p
arams
33-
para_find_important_s
tat_params
Table 18-1. Eldo Control Language Example Files (cont.)
Description
Example showing how the distribution of a statistical parameter can be
modified. This example uses _simu_lock_stat_param to keep only one
statistical parameter (found using _simu_get_stat_param_netlist_dev) to
see the impact on the results of the modification of its distribution. The
distribution is modified so that each sampled value is greater than twice
the half-range of the distribution (_simu_get_random is called until
getting such a value and the value is set using
_simu_set_stat_param_sampling_val).
After running, the impact on the result can be seen in
modify_mc_distrib.wdb. The first waveform is the default result
(simulation using the initial gaussian distribution) and the second result is
the result of the simulation using the modified distribution.
Example showing how to monitor the evolution of the average, deviation,
and sensitivities of an extract. This data is displayed on the standard
output. This example uses avg, std, _simu_get_mcsens to compute the
statistical data, and mcconv to stop the simulation once the extract has
converged.
Example showing how to run an ECL Monte Carlo simulation of a 1-bit
adder netlist to find the most important parameters acting on the
propagation delay. Then the width of the corresponding MOS is increased
to see how it impacts this delay. These results are displayed on the
standard output. This example uses _simu_run(mode="nom") to run the
nominal simulation to get the default delay, _simu_run(mode="mc 20") to
run multiple times 20 Monte Carlo simulations until mcconv returns that
the interesting extract has converged, and _simu_get_mcsens to get the
important parameters.
Same example as before but using parallel runs.
Related Topics
Examples Using ECL as an Alternative to Standard Eldo Commands
Eldo Control Language Limitations
The Eldo Control Language has some limitations to consider.
• Netlists containing .MPRUN commands (multiple run of simulations) are fully
supported by Eldo Control Language, including with LSF (Load Sharing Facility) and
OGE (Oracle Grid Engine) dispatchers. If a netlist containing a .MPRUN command is
simulated in a Control Language task, then the Eldo process simulating this netlist will
effectively run multiple simulations on multiple processors or on many machines.
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Eldo Control Language
Eldo Control Language Limitations
The .MPRUN command is not supported at the task level but at the testbench level. ECL
sequential loop statements are not supported; the .MPRUN command has no effect on
the ECL statements: for, step, and while. For example, it is not possible to distribute
each simulation executed inside a sequential “for” loop. For a given simulation (run
from an ECL task), if the netlist to simulate contains a .MPRUN command and a .MC
command for example, then the Monte Carlo runs of this simulation will be distributed
as usual. See the “.MPRUN with Monte Carlo Analysis Example” on page 1133.
Simulations executed inside ECL parallel loop statements can be distributed using the
.ELDO_CL_MPRUN command.
• The .AGE and .DEX commands are supported inside testbenches even if they are
directly instantiated in the netlist.
• The Eldo Control Language is supported by Eldo Premier, with limitations. The
functionality described in “Simulation Dynamic Control” on page 1014 is not supported.
• Eldo Interactive mode is not compatible with the Eldo Control Language: it does not
support netlists containing tasks. Netlists containing only testbench instantiations,
without any tasks can however be run using the Eldo Interactive mode.
• Eldo Control Language may sometimes generate large .wdb files; especially when a task
runs a simulation creating many waveforms and if all these waveform results are saved
into task local variables, the main .wdb file can be much larger than the temporary .wdb
file generated during the simulation. One of the following options can be used to solve
this possible issue:
o
o
.option KEEP_ELDO_CL_TEMP_WAVES=0
For more details on this option, see the “wdb File” section in “Simulation” on
page 1114. This is the preferred solution, but the disadvantage is that waveforms that
need to be saved to be visualized have to be saved explicitly using the “Functions
Operating on wdb Files” described in “Library of Functions for Tasks” on page 854.
.option USE_ELDO_CL_SAFE_WAVE_CP=0
This option deactivation has two major disadvantages:
• Possible impact on the execution speed of Eldo Control Language tasks: the
execution of a task running many simulations generating waveforms will be
longer (if these waveform results are saved into task local variables for each
simulation).
• In some cases the Eldo Control Language won’t be able to generate a compound
waveform simulation result (FAILED TO GET WAVE error). This will happen,
for example, with AC simulations when trying to generate a vdb or vp
waveform, for example:
.plot ac w_db=vdb(out) w_p=vp(out)
Workaround: replace the .PLOT command with a v complex waveform plot:
Eldo® User's Manual, 15.3 807

Eldo Control Language
Eldo Control Language Limitations
.plot ac w=v(out)
The gain and phase waveforms should be computed from the complex waveform
inside the task (if post-processing is needed). Nevertheless it can be worth
deactivating this option in case a simulation command fails because of an
unexpected error related to a waveform result.
• Eldo Control Language is not supported on Windows.
Related Topics
Overview of the Eldo Control Language
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Eldo Control Language
Testbenches
Testbenches
A testbench is a sequence of parameterized simulator commands or circuit element descriptions,
which can be viewed as the encapsulation of a set of commands or element descriptions that are
necessary within a specific context. For example, to perform a slew-rate characterization, it may
be necessary to instantiate the loading capacitor with a certain capacitance value, to define the
slope of a PWL input signal as a specific value, and to run a transient simulation of a certain
duration. These sets of commands can be reused in multiple simulations, and each time the
parameterized parts can receive different values. A complete simulation is defined by
assembling one or more testbenches, typically with the base netlist. This assembly process is
explicit.
This section contains:
Testbench Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 809
Testbench Instantiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811
Rules for Testbench Location Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 813
Testbench Definition
A testbench definition starts with the .define_testbench keyword, and finishes with a
.end_define_testbench command. A testbench accepts input arguments. The number of
arguments is not limited; a testbench may have no arguments at all.
Tip
See “.DEFINE_TESTBENCH” in the Eldo Reference Manual.
A testbench is a set of simulator commands or circuit element descriptions that can be
parametrized using the arguments of the testbench.
A testbench can be considered as a user-defined macro. When instantiated, the testbench call is
simply replaced with its content, where all occurrences to testbench arguments are replaced
with their instantiation value.
A testbench may be instantiated in either of the following ways:
• In the netlist (or in another testbench) using a . command,
which then appears as an additional Eldo command in a regular Eldo netlist.
• From the simulation function used in a task (in which case the calling syntax uses
parenthesis and comma-separated arguments—similar to classical programming) to
request to instantiate the testbench into the netlist that will be simulated (see “Defining
and Running Simulations” on page 841).
A testbench may call another testbench defined in the same netlist/file as itself, or in another
netlist/file (as long as it is included in the main netlist with a .INCLUDE or a .LIB command).
Eldo® User's Manual, 15.3 809

Eldo Control Language
Testbench Definition
Note
The Eldo Control Language is case-sensitive.
Examples
Here is an example of a simple testbench:
.define_testbench tran_options
.option eps=1e-8 hmax=10p reltol=1e-7 gear
.end_define_testbench
This testbench definition creates a user-defined simulator command named .tran_options that
can be used (instantiated) in the base netlist. This testbench has no parameters; instantiating it in
the base netlist or in a simulation run from a task would be equivalent to using the following in
the netlist:
.option eps=1e-8 hmax=10p reltol=1e-7 gear
Note
It is forbidden to use the names of existing simulator commands (such as .ALTER, .STEP,
and so on) as testbench names. Note also that a testbench definition can be added anywhere
in the base netlist, or in files included by the base netlist.
Here is another example of a testbench:
.define_testbench measure_tprop
+ (cload_val=1p, trise=10n, signal="out")
.tran 0 10n
cload signal gnd cload_val
VD D gnd PULSE 0V 1.8V 0n trise trise 50n 100n
.extract tran label=tp xup(V(signal),1.8/2)-xup(V(D),1.8/2)
.extract tran label=avgivdd average(i(vdd))
.end_define_testbench
This example shows a (partially) parameterized testbench. The load capacitance on the
specified node and the rise time of the input signal are parameterized, and may be defined at
instantiation time. The measured propagation time (tp) and the average current consumption
(avgivdd) are .EXTRACT results; their computed values can be returned to the calling task (in
the case that this testbench was instantiated in a simulation run from a task; see “Defining and
Running Simulations” on page 841).
Note
All parameters have a default value, which is mandatory.
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Eldo Control Language
Testbench Instantiation
This measure_tprop example testbench is only partially parameterized. To be usable, the node
gnd must exist, and the circuit must have a D input and a VDD power supply. Otherwise all of
these elements would be dangling, or creating an error at simulation time. It is up to the designer
to parameterize any piece of the testbench that may potentially vary; nothing is imposed.
Here is another example, which is self-explanatory:
.define_testbench transient (vpulse=1)
.connect out inn ! follower connection
vinp inp 0 DC 0 PULSE 0 vpulse 0n 1n 1n 10n 20n
.tran 1n 50n
.extract tran label=overshoot max(V(out))-vpulse
.end_define_testbench
Related Topics
Testbench Instantiation
Rules for Testbench Location Resolution
Testbench Instantiation
A testbench definition will have no impact on the simulation of the netlist if the testbench is not
instantiated. It only creates a user-defined macro that can be reused elsewhere.
The testbench name must be prefixed with a “.” if it is instantiated directly in the netlist (but not
if it is used for a simulation inside a task). Testbench parameters may be given specific values
during instantiation; if not, their default value will be used.
Examples of instantiations of the testbenches defined above:
.tran_options
.measure_tprop trise=1n cload_val=2p
.transient
Note
The Eldo Control Language is case-sensitive; in the example above, trying to instantiate
.measure_tprop Trise=1n Cload_Val=2p will generate an error.
Give special consideration when choosing the names of testbench parameters. The substitution
of the occurrences of a testbench parameter name with its instantiation value is really text
replacement, everywhere a token matches the parameter name in the testbench definition. For
example, in the measure_tprop example above, it would have been wrong to call the cload_val
parameter cload because the name of the capacitor on the second line is also cload. If cload_val
had been called cload, instantiating the testbench would have included the line 1p out gnd 1p
but not cload out gnd 1p.
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Eldo Control Language
Testbench Instantiation
Testbenches may be nested, or more precisely, it is possible to instantiate a testbench inside
another testbench. It is not permitted for a testbench to instantiate itself.
Limitation: SPICE parameters can be used to set values to testbench parameters when
instantiating a testbench in the netlist if they are declared before the testbench instantiation. For
example:
.param p1 = 1
Example
.tb_1(param1=p1)
.define_testbench tran_setup (duration=1n)
.option eps=1e-8 hmax=10p reltol=1e-7 gear
.tran 0 duration
.end_define_testbench
.define_testbench measure_tprop
+ (cload_val=1p, trise=10n, signal="out")
.tran_setup duration=100n
cload signal gnd cload_val
VD D gnd PULSE 0V 1.8V 0n trise trise 50n 100n
.extract tran label=tp xup(V(signal),1.8/2)-xup(V(D),1.8/2)
.extract tran label=avgivdd average(i(vdd))
.end_define_testbench
In the example above, the tran_setup testbench is instantiated inside the measure_tprop
testbench.
Note
It is not permitted to define a “local” testbench inside another testbench.
A special testbench is automatically defined during elaboration. It consists of the part of the
netlist that contains no task definition or testbench, and it is included by default in any
simulation run from a task.
Related Topics
Defining and Running Simulations
Rules for Testbench Location Resolution
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Eldo Control Language
Rules for Testbench Location Resolution
Rules for Testbench Location Resolution
When a testbench is instantiated in a netlist or in a task simulation command, the location of its
definition must be resolved; in other words, Eldo must be able to locate the definition of the
testbenches. The standard Eldo .LIB or .INCLUDE commands can be used so that the testbench
definition can be indirectly found if it was not directly added in the base netlist.
Example
• File util_dev.cir
This file contains a testbench defining a voltage amplifier:
.define_testbench amp (in=1, out=0, vdd=10)
* .MODEL definition
.model q2n2222 npn is=1.9e-14 bf=150 vaf=100 ikf=.175
+ ise=5e-11 ne=2.5 br=7.5 var=6.38 ikr=.012 isc=1.9e-13
+ nc=1.2 rc=.4 cje=26p tf=.5e-9 cjc=11p tr=30e-9 xtb=1.5
+ kf=3.2e-16 af=1.0
* Circuit definition
c30 in 31 47u
r30 31 33 390
r31 vdd 33 50k
r32 33 0 15k
q30 out 33 0 q2n2222
r33 vdd out 750
.end_define_testbench
• File netlist.cir
The main netlist: a low-pass filter incorporating a voltage amplifier:
.include util_dev.cir
r1 1 2 10
l1 2 3 1.3m
c1 3 0 100n
r2 4 0 50k
* Testbench instantiation
.amp in=3 out=4 vdd=9
vb 9 0 5
v1 1 0 ac 1
* Commands
.ac dec 10 1 1g
.plot ac vdb(3) vdb(4) (-250,50)
.plot ac vp(3) vp(4) (-200,200)
.end
Related Topics
Defining and Running Simulations
Eldo® User's Manual, 15.3 813

Eldo Control Language
Tasks
Tasks
This section details the scripting constructs available within the Eldo Control Language.
In this section:
Task Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814
Task Instantiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 817
Statement Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820
Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 839
Defining and Running Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 841
Library of Functions for Tasks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 854
Simulation Dynamic Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1014
Extended Simulation Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1024
Parallel Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1039
Statistical Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1058
Advanced Simulation Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1114
Task Definition
Tasks are defined as a sequence of statements, and are similar to functions in C. As opposed to
simulator commands in a regular Eldo netlist (for example, .TRAN, .AC, .OPTION, and so on)
which are executed more-or-less in parallel, statements inside a task are executed sequentially,
much like in most sequential programming languages.
A task may return nothing, in which case it is similar to a “void” C function. A task that returns
a value is a function.
A task definition starts with the .define_task keyword, and finishes with a .end_define_task
command. A task can accept input and output arguments (except when called from the netlist, in
which case the concept of an output argument is meaningless). The number of arguments is not
limited; a task may have no arguments at all. The names of output arguments must be prefixed
with a “@”. See Example Two.
Tip
See “.DEFINE_TASK” in the Eldo Reference Manual.
The statements inside a task are executed sequentially whenever the task is called, using the
. command. A task can be considered a user-defined (sequential)
simulation command.
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Eldo Control Language
Task Definition
A task (in other words, the sequence of statements inside the task) is never executed until it is
called. There is no such thing as a predefined automatically-executed “main” task as in C.
A task may be called in either of the following ways:
• From within another task (in which case the calling syntax uses parenthesis and commaseparated
arguments – similar to classical programming).
• From the netlist using a . command, which then appears as an
additional Eldo command in a regular Eldo netlist (a sequence of .
calls from the .cir netlist is supported).
A task may call another task defined in the same netlist/file as itself, or in another netlist/file (as
long as it is included in the main netlist with a .INCLUDE or a .LIB command).
Note
The Eldo Control Language is case-sensitive.
Examples
Example One
• Definition of a task printing “Hello world.” on the standard output:
.define_task hello_world
fprint (stdout, "Hello world.\n")
.end_define_task
See the fprint function for more information.
Example Two
• Definition of a task running some simulations:
Eldo® User's Manual, 15.3 815

Eldo Control Language
Task Definition
.define_task opamp (n=10)
set vdd[]=1.65 open_lg[]=60
set vx=0 i=0 max_olg=60 i_max_olg=1 vdd_max=1.5 ovs=0
// for each value of VDD from 1.5V to 1.8V, find out the DC
// offset, then inject it into a .AC simulation that computes the
// open loop gain, and store this gain in open_lg[] vector
for (type=step, param=i, start=1, stop=n, step=1)
vdd[i] = 1.5 + (i-1) * (1.8-1.5) / (n-1)
simulation(
+ powersupply(pvdd = vdd[i]),
+ follower(),
+ vx = @vout_follower)
simulation(
+ powersupply(pvdd = vdd[i]),
+ ac_open_loop(vout_follower = vx),
+ open_lg[i] = @open_loop_gain)
endstep
// find out for which value of VDD the open loop gain is maximal
i_max_olg = open_lg.imin
max_olg = open_lg[i_max_olg]
for (i=open_lg.imin + 1; i max_olg)
i_max_olg = i
max_olg = open_lg[i]
endif
endfor
vdd_max = vdd[i_max_olg]
// finally run a single transient simulation for this value of
// VDD which maximizes the open loop gain and extract the
// overshoot :
simulation(
+ powersupply(pvdd = vdd_max),
+ transient(),
+ ovs=@overshoot)
fprint (stdout, \
"Max. open loop gain : %.5g for VDD = %.5g. Corresponding
overshoot is : %.5g\n",\
max_olg, vdd_max, ovs)
.end_define_task
See “Variables” on page 821, “Flow Control Statements” on page 835, “Defining and
Running Simulations” on page 841, and the fprint function for more information on the
concepts used in the example.
816
Eldo® User's Manual, 15.3

Eldo Control Language
Task Instantiation
Related Topics
Task Instantiation
Statement Overview
Defining and Running Simulations
Task Instantiation
A task has to be instantiated to be executed. Tasks may be instantiated directly inside the netlist,
or also inside other tasks (in which case they will be executed only if the calling task is
instantiated in the netlist). Tasks can even be recursive.
For an example of this, see Example Three.
To instantiate a task in the netlist file, its name must be prefixed with a '.' and no parenthesis nor
comma must be specified to separate the input arguments, as if it was a user-defined command.
Contrary to testbenches or usual commands, tasks have precedence over everything else. As
soon as some tasks are instantiated in the netlist file, only instantiated tasks will be executed. If
the file also contains a circuit description and usual simulation commands, they will be ignored
(except if an instantiated task performs a simulation with the simulation command; see
“Defining and Running Simulations” on page 841 for more information).
Task Input Parameters
Task input parameters may be given specific values during instantiation. If not, their default
values will be used. See “Examples” on page 818.
Task Output Parameters
If output parameters were defined for a task, their result values (that is to say the values they
have at the end of the execution of the task) can be used by the calling task: they are usually
directly saved inside some local variables of the calling task. Task output parameters are not
passed by reference, but by value: when the task having output parameters is executed, its
output parameters are not references to local variables of the calling task; on the contrary, they
really have a value of their own, which can be accessed at the end of the execution of the task by
the calling task, using the '@' operator.
For example, if the definition of a task is:
.define_task task_name(input_param1=default_value1, ...
+ @output_param1=default_value2, ...)
...
output_param1 = final_value1
.end_define_task
then its instantiation inside another task is:
Eldo® User's Manual, 15.3 817

Eldo Control Language
Task Instantiation
set local_variable1 = 0
...
task_name(input_param1=input_param_value1, ...
+ local_variable1 = @output_param1, ...)
It is even possible to specify more complex expressions using these output parameters:
task_name(input_param1=input_param_value, ...
+ local_variable1 = 1 + @output_param1,
+ local_variable2 = @output_param1 - @output_param2, ...)
Note
The values of output parameters can only be used when a task is instantiated inside another
task; it is not possible when a task is instantiated directly in the netlist.
Examples
Example One
• Example of instantiation in the netlist of the tasks defined in “Task Definition” on
page 814:
.hello_world
.opamp n=10
Example Two
• Example of instantiations in another task of the tasks defined in “Task Definition” on
page 814:
.define_task my_example
hello_world()
opamp (n=10)
.end_define_task
Example Three
• Example of a recursive task with output argument:
818
Eldo® User's Manual, 15.3

Eldo Control Language
Task Instantiation
.define_task facto (n = 1, @res = 0)
set loc_res = 0
if (n

Eldo Control Language
Statement Overview
Statement Overview
This section details the fundamental building blocks of ECL statements:
Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820
Line Breaks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820
Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 821
Flow Control Statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 835
Comments
Single line comments inside tasks are introduced with a double slash or an asterisk:
// this is a single line comment
* this is also a single line comment
End-of-line comments inside tasks are introduced with a double slash:
set a = 3 // this is an end-of-line comment
Multi-line comments can use the /* */ construct:
/*
this is a multiple
line comment
*/
Line Breaks
Generally, a statement must be written on a single line. However it is possible to break a line
explicitly using either of the following:
• A backslash “\” at the very end of the first part of the broken line.
• A “+” sign at the beginning of the second part of the broken line.
Note
Either a “\” or a “+” must be used, not both. Note also that no character must be
present after the “\”, especially not a space.'
For an example of line-breaking, see Example Two in “Task Definition” on page 814.
Related Topics
Task Definition
Task Instantiation
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Eldo® User's Manual, 15.3

Eldo Control Language
Statement Overview
Variables
Several simple variable types are available. The simplest types are the number and string types,
which are used to hold a single value, either a number (always a double-precision floating-point
number) or a string. Vectors of scalar numbers and vectors of strings are also available, together
with a set of functions operating directly on vectors. The waveform type is used to represent
waveforms and communicate with Eldo. Finally, a file type is available for ASCII file
manipulations.
All variables have an identifier starting with a letter, or an “_” character, followed by a sequence
of letters, digits, “_” and/or “#”. All variables, without exception, must be given an explicit
initial value. There is no such thing as an uninitialized variable by construction.
All types of variables can be passed as arguments (either input or output) to testbenches and
tasks.
All variables are local to the task in which they are declared.
In this topic:
Variable Declaration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 821
Variable Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 822
Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 823
Complex Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 823
Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 824
Vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825
Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 831
Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 833
Predefined Constants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 834
Variable Declaration
Variables are defined at the beginning of a task, before any other statement. It is not permitted to
declare variables inside a for or while loop, or anywhere but at the very beginning of a task
(except if .option restrict_eldo_cl_declarations=0 is specified in the netlist).
Scalar variables containing numbers are similar to (local) .PARAM in regular simulation
syntax.
A scalar variable can hold either a numeric value, a string of characters, a vector of such
numbers or strings, or a file (logical) name. An initial value is mandatory. For example:
set a=1.3 b=2
set s="hello"
Eldo® User's Manual, 15.3 821

Eldo Control Language
Statement Overview
Variables a and b are scalar numbers. Variable s is a character string.
The type of a variable is determined by the value assigned to it.
Tip
See “.OPTION RESTRICT_ELDO_CL_DECLARATIONS” in the Eldo Reference
Manual.
Note About Numbers
Variables declared with an integer value are stored and handled as integer values to save
memory space. For example the b variable in the example above is an integer variable.
However, the type is automatically changed to floating point representation (always in double
precision) when required. For example:
set a=5 b=2 c=0
c = a/b
Expression a/b evaluates to 2.5 (not 2) and assigns 2.5 to c (although c was initially an integer).
Also, floating point expressions are changed to integer when used as vector indices.
Related Topics
Variables
Variable Assignment
Variables take an initial value using the set command. The type of the variable is inherited from
this initial assignment. Variables are changed through assignments using the = operator; they
may also change value when they are passed as task output arguments. Variables can change
type if they are assigned a value of a type different to their current type.
Examples
set a = 2
set b = 3
set s = "hello"
set c = sin(2*3.14159*1e6*100e-9)
set i = a + 1
Several initial assignments can occur within a single set command, so:
set a = 2
set b = 3
is equivalent to:
set a = 2 b = 3
822
Eldo® User's Manual, 15.3

Once assigned an initial value, variables can be reassigned with the = operator:
set a = 2.0
set b = 3.0
a = a + b/2
Eldo Control Language
Statement Overview
Note
+=, -=, *=, /=, … operators are also available (a = a + b/2 is equivalent to writing a += b/2).
Related Topics
Variables
Numbers
Generally, numerical variables are double-precision floating point numbers. If a number is used
as an index to address a vector, it is automatically truncated to a signed 32-bit integer.
Scalar variables holding numbers are similar to (local) .PARAM in regular simulation syntax.
The usual mathematical operators (+, -, *, /, %, **, ++, --, ==, !=, =, &&, ||, !) are
available to form expressions using numbers. A library of mathematical functions is also
available (sin(), cos(), abs(), and so on).
The sensitive functions such as sqrt(), exp(), or log() are protected against floating-point
overflows and so on. If for some reason it is still necessary to use the native exp() function, then
the set of such native functions is available, prefixed with “unsafe_”. For example
“unsafe_exp(1e300)” will blow up.
exp() is calculated accurately until exp(80), beyond which, the function is extrapolated linearly.
Related Topics
Variables
Library of Functions for Tasks
Complex Numbers
Complex numbers are also supported. Operators that work on complex numbers are: “+”, “-”,
“*”, “/”, “++”, “--”, “==”, “!=”.
Complex numbers can be created using the functions ritocomplex or mptocomplex or can be
complex results of a simulation.
Eldo® User's Manual, 15.3 823

Eldo Control Language
Statement Overview
Example
.define_testbench tb_top
v1 1 0 ac 1
r1 1 2 10k
c1 2 0 100u ic=0
*Extract gain and phase at 1Hz as a complex number.
.extract ac label=gp_1 yval(v(2,0),1)
.ac dec 19 1e-9 1e9
.end_define_testbench
.define_task t_simu
set gp = 0
/* Run simulation and get the complex result gp_1. */
if (simulation(tb_top(), gp=@gp_1).simu_status == 0)
fprint(stdout, "Simulation succeeded\n")
fprint(stdout, "1Hz: gain = %.2f dB phase = %.2f rad\n", db(gp),\
phase(gp))
else
fprint(stdout, "Simulation failed\n")
endif
.end_define_task
.t_simu
See “Variables” on page 821, “Flow Control Statements” on page 835, “Defining and Running
Simulations” on page 841, and the fprint function for more information on the concepts used in
the example.
Related Topics
Variables
Library of Functions for Tasks
Strings
Case-sensitivity of strings (for comparison operators) is set through a global option (.option
set_eldo_cl_string_comparison_case_sensitive=1). Strings are case-insensitive by default, and
it is recommended that this is left unchanged to ensure compatibility.
Tip
See “.OPTION SET_ELDO_CL_STRING_COMPARISON_CASE_SENSITIVE” in the
Eldo Reference Manual.
String variables are manipulated with simple operators. The == and != operators can be used to
test equality or inequality of two strings. The < and > operators are used to test the lexical
ordering of two strings, based on the alphabetical order. For example:
set s_ok = "success" s_fail = "failed" s_code1 = "" s_code2 = "whatever"
824
Eldo® User's Manual, 15.3

Eldo Control Language
Statement Overview
if ((s_code1 == s_failed) || (s_code2 != s_ok))
endif
fprint (stdout, "Cannot complete task.\n")
Note
To have string comparison working accordingly to the intuitive alphanumerical order, you
must ensure that numerical parts inside the strings to compare have the same number of
digits (for example “string12” < “string3” but “string12” > “string03”).
Strings can be concatenated using the + operator. For example:
set s_ok = "success" s_fail = "failed" s_code1 = "" s_code2 = "whatever"
set s_task_name = "task_sim1"
s_result = s_task_name + " : " + s_fail
fprint (stdout, s_result)
See Library of Functions for Tasks for the complete list of functions operating on strings.
Related Topics
Variables
Library of Functions for Tasks
Vectors
All vectors are dynamic; their dimensions are handled dynamically, as they are addressed
(except if the .option set_eldo_cl_array_auto_expand is set to 0, in which case their sizes must
be explicitly managed using the resize function).
Tip
See “.OPTION SET_ELDO_CL_ARRAY_AUTO_EXPAND” in the Eldo Reference
Manual.
One-dimensional and two-dimensional vectors are available for numbers and strings. A onedimensional
vector is a contiguous array of numbers indexed with an integer number. The size
of vectors is dynamic, and there is an automatic reallocation mechanism. The indexes are
always signed 32-bit integer numbers; in other words, the maximum range is from −2×10 31 to
2×10 31 −1.
The declaration of a vector defines what it contains (numbers or strings) and, optionally, its
initial dimension. The initial fill value is mandatory. The [] indicates that this variable is a
vector, not a scalar.
Eldo® User's Manual, 15.3 825

Eldo Control Language
Statement Overview
A vector element can be addressed using the usual notation a[i], where a is the vector name and
i is the index. i must have an integer value, otherwise it is rounded to a signed 32-bit integer
number. Any attempt to address a vector outside of its allocated index range is trapped and
causes an error (in the case that the .option set_eldo_cl_array_auto_expand is set to 0).
One-dimensional Vectors
Example:
set a[] = 2001
This command simply declares the vector a, and explicitly sets the initial value of any of its
elements to 2001. This initialization is mandatory. The actual range will be assigned
dynamically with further references and/or assignations.
set b[0,99]=0
This command declares the vector b, and explicitly sets the initial value of any of its element
to 0. In this example, reading the vector from index 0 to index 99 will return 0. Reading outside
of this range will extend the vector to the necessary size to make the reference “legal”, fill all
uninitialized cells with the default value, and return the initial value. For example:
set b[0, 99] = 0.1234 a = 1
a = b[150]
The reference to b[150] causes the b[] vector to be automatically extended. All cells from index
100 to 150 are filled with the value 0.1234, and the a variable is assigned the value of b[150]:
0.1234.
Assigning an element whose index is outside the current range of the vector automatically
extends its range. For example:
set a[0,99]=3.14
a[500]=17
In this example, the first statement creates a vector a[] of 100 elements, from a[0] to a[99]. All
elements are initialized to 3.14. The second assignment extends the range of a[] from 99 to 500,
and fills a[500] with the value 17. The elements a[100] to a[499] are filled with the initial value
of the vector, which is 3.14.
If a vector has no explicit initial range, as in:
set a[]=0
then a subsequent assignment of an element with index will create the element i. For
example:
826
Eldo® User's Manual, 15.3

Eldo Control Language
Statement Overview
set b[]=0.1
b[10]=1.0e-6
In this example, the first statement creates an empty vector, b. The second assignment extends
the range of b to [10,10]. The elements b[10] is set to 1.0×10 −6 .
Filling Vector Sub-range
It is possible to fill a sub-range of a vector with a value using the assignment operator. For
example:
set b[-5,5]=1.414
set i = 0
step (param=i, start=0, stop=5, step=1)
b[i] = 1.732
endstep
is a very complicated way to accomplish the same as:
set b[-5,5]=1.414
b[0,5] = 1.732
Filling can simultaneously extend the range if needed:
set b[-5,5]=1.414
b[-10,10] = 1.732
It is possible to use negative indexes such as in:
set a[-50,50] = 10
which would declare a vector containing 101 values, addressable from a[-50] to a[50]. The
entire vector is initially filled with the value 10.0. Explicitly specifying an initial fill-in value is
mandatory.
Although negative indices are allowed, the addressing is always in ascending order; in other
words, imax must be greater than or equal to imin.
To explicitly define a one-dimensional array with different values specify them inside {}. If
used inside a declaration, the default value of the array is the first of the set; if not specified, the
first index of the array is 1. The ranges, when explicitly specified, must correspond otherwise an
error will occur at run-time. Examples:
Eldo® User's Manual, 15.3 827

Eldo Control Language
Statement Overview
set a[] = {1, 2, 4}
set b[-3,3] = {-1, 0, 0, 1, 0, 0, -1}
a[5] = 8 /* a[4] will be 1 because it is the default value. */
b[1, 2] = {0.5, -0.5}
The memory corresponding to a vector is automatically freed upon exit of the task in which it
was allocated.
Multi-dimensional Vectors
Multi-dimensional vectors are created using the ; separator (or alternatively separate brackets)
for the dimensions. The example below creates a 10×10 matrix:
set a[0,9;0,9] = 0
Elements of multi-dimensional vectors are referred to using the notation a[i;j] or a[i][j].
Both notations are equivalent, and a matrix is implemented in ECL as a vector of vectors. mat[i]
yields line i of the matrix (a vector). mat[i][j] yields the matrix element on line i and column j.
A matrix can be declared and initialized using the following equivalent syntaxes:
set a[0,9;0,9] = 0
set b[0,9][0,9] = 0
To declare an empty matrix:
set c[][] = 0
Matrix Attributes
The number of lines of a matrix is the number of elements of vector (of vectors):
mat.size
The number of columns of a matrix is the number of elements of any line, for example the first
line, which is vector mat[mat.imin]:
mat[mat.imin].size
Refer to the example $MGC_AMS_HOME/examples/ecl/12-rc_compounds/rc_compounds.cir
that shows how to loop on all the matrix elements.
Beware, there is no mechanism that forces the lines of the matrix to remain the same size, that
is, line vectors grow independently using the auto-expanding mechanism of ECL. For example,
the following code:
828
Eldo® User's Manual, 15.3

Eldo Control Language
Statement Overview
* Looping on all element of a matrix
.define_task all_elements_of_a_matrix
set mat[0,2][0,2]=0 l=0 c=0
mat[0][0] = 1.0
mat[3][7] = 2.0
mat[7][5] = 3.0
fprint(stdout, " ")
for(c=mat[0].imin; c

Eldo Control Language
Statement Overview
To explicitly free (almost) the entirety of the memory used by a vector that is no longer needed,
in the case that it is needed to do so before the task or function terminates, use:
free (b)
The free command frees the entire vector, whatever the number of dimensions.
Vector Attributes
A set of useful attributes is available on vectors:
• imin to get the minimum index of the vector
• imax to get the maximum index of the vector
• size to get the size of the vector
Example:
set a[0,10] = 1
fprint(stdout, "a.imin = %d\n", a.imin)
fprint(stdout, "a.imax = %d\n", a.imax)
fprint(stdout, "a.size = %d\n", a.size)
Passing Vectors as Task Arguments
Example using a vector as an input argument:
.define_task my_vector_average (a[]=0, @avg=0)
set tmp=0 i=0
step (type=linear, param=i, start=a.imin, stop=a.imax, step=1)
tmp = tmp + a[i]
endstep
avg = tmp / a.size
.end_define_task
The corresponding call from another task would be:
set tprop[0,99]=0 tprop_avg=0
my_vector_average (a=tprop, tprop_avg=@avg)
Example using a vector as an output argument:
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Eldo® User's Manual, 15.3

Eldo Control Language
Statement Overview
.define_task my_vector_sum (a[]=0, b[]=0, @sum[]=0)
set tmp=0 i=0
if ((a.imin != b.imin)) || (a.imax != b.imax))
printf (stdout, "error")
return
endif
step (type=linear, param=i, start=a.imin, stop=a.imax, step=1)
sum[i] = a[i] + b[i]
endstep
.end_define_task
The corresponding call from another task would be:
set tprop1[0,99]=0.1 tprop2[0,99]=10.7 total[0,99]=0
my_vector_sum (a=tprop1, b=tprop2, total=@sum)
Related Topics
Variables
Library of Functions for Tasks
Waveforms
Waveforms are represented using a specific type of variable. They enable easy communication
with the simulator, which creates this type of object through .PLOT commands for example.
The normal usage of waveforms is to retrieve a waveform from a simulation, and possibly use it
within some calculations as part of a task.
Tip
See “.PLOT” in the Eldo Reference Manual.
The waveform object is created and filled by the simulator, under normal usage. A library of
functions operating directly on waveforms is available. It is possible to read the size of the
waveforms (its number of points, its full name, and so on, from within a task or function.
Complex and compound waveforms are also supported.
The following operators are supported on waveforms: +, -, *, /, %, ==, !=, >=, ?, >,

Eldo Control Language
Statement Overview
set w1 = 0
set w2 = 0
set w3 = 0
set w4 = 0
simulation(tb(), w1=@wave1, w2=@wave2)
w3 = w1 + 1
w4 = w1 + w2
Examples
Example One
.define_testbench follower
.connect inn out
.ac dec 10 1 1g
* need to give a name to the waveform like this to be able to get it back
from the simulation command:
.plot ac voutdb_wave=vdb(out)
.end_define_testbench
.define_task opamp_gain_max_from_wave
/* This example shows how to retrieve a simple AC waveform,
and use it to extract its maximum value (a very complicated way).
*/
set vout=0
set i=0 max_gain=-1000 imax=0 x=0.0 y=0.0 iter=0
simulation(
+ powersupply(pvdd = 2.0),
+ follower(),
+ vout = @voutdb_wave)
iter = beginval(vout, x, y)
while (iter != 0)
if (y > max_gain)
max_gain = y
imax = x
endif
iter = nextval(vout, x, y)
endwhile
fprint (stdout, "Maximum gain : %.5g at frequency = %.5g.\n",\
max_gain, vout.x[imax])
.end_define_task
.opamp_gain_max_from_wave()
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, “Defining and Running Simulations” on page 841, and the fprint,
beginval, and nextval functions for more information on the concepts used in the example.
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Eldo® User's Manual, 15.3

Eldo Control Language
Statement Overview
Example Two
.define_testbench overshoot (tmax=1000n)
.connect inn out
.tran 0 tmax
Vinp inp 0 pulse ...
.plot tran vout_wave=v(out)
.end_define_testbench
.define_task opamp_max_overshoot
/*
* This example shows how to retrieve a simple TRAN waveform,
* and use it to extract its maximum value
* (a simple way using the predefined waveform function library).
*/
set vout=0
set max_v=-1000 fmax=0
simulation(
+ powersupply(pvdd = 2.0),
+ overshoot(tmax=100e-9),
+ vout = @vout_wave)
max_v = max(vout)
t_max = xval(vout, max_v)[1]
fprint (stdout, "Maximum overshoot : %.5g at time = %.5g.\n", max_v,
t_max)
.end_define_task
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, “Defining and Running Simulations” on page 841, and the fprint
function for more information on the concepts used in the example.
See Library of Functions for Tasks for the complete list of functions operating on waveforms.
Related Topics
Variables
Defining and Running Simulations
Library of Functions for Tasks
Files
File type variables are used to hold the logical names of files.
For example:
Eldo® User's Manual, 15.3 833

Eldo Control Language
Statement Overview
.define_task hello_world_2
set myfile = NULL
myfile = fopen ("./hello.txt", "w", \
"cannot open hello.txt for writing")
fprint (myfile, "Hello world.\n")
fclose (myfile)
.end_define_task
See “Task Definition” on page 814 and “Variables” on page 821 for more information on the
concepts used in the example.
File type variables are used by the fopen, fprint and fclose commands. The fopen command in
the example above attempts to open the file hello.txt for writing. If this is successful, the logical
name myfile can be used in further commands to reference the file. If for some reason this is not
possible (for example the disk full, access is denied, and so on) the die optional message is
printed to the standard output, and the program aborts. If the file can be opened, then the myfile
name becomes non-NULL, and it can be used in subsequent fprint commands to designate this
particular file. To close the file, the fclose command must be used. The myfile variable is then
automatically set to NULL, and any further attempt to use it in an fprint command will result in
an error.
The stdout logical name can be used to write to the standard output of the calling process
(usually the console). Standard error (stderr) is not supported.
See Library of Functions for Tasks for the complete list of functions operating on file type
variables.
Related Topics
Variables
Library of Functions for Tasks
Predefined Constants
A number of physical constants are available. This is a list of reserved symbols, such as pi,
boltz, and so on. Using these symbols for any purpose (a variable or task for example) is
forbidden.
• epso = 8.854214871×10 −12
• boltz = 1.3806226×10 −23
• charge = 1.6021918×10 −19
• pi = 3.141592654
• twopi = 6.283185308
834
Eldo® User's Manual, 15.3

Eldo Control Language
Statement Overview
Flow Control Statements
One of the main objectives of the Eldo Control Language is to offer a level of flow control
within the simulation plan, instead of letting the simulator do everything automatically.
To achieve this goal some simple constructs are available:
• if/else/endif Construct
• Step Loops
• While Loops
• For Loops
These constructs are similar to those available in any language for flow control (except for
SPICE, if SPICE can be considered a language). However, the step loop proposed here has
some specificities originating from its similarity with the .STEP command in a simulation
context (see .STEP in the Eldo Reference Manual). The linear, logarithmic, and list-driven
loops are heavily used in existing netlists, and the step loop enables the implementation of these
special kinds of loops easily, in addition to classical for i=1 to n loops.
if/else/endif Construct
The if construct enables the testing of a boolean condition, the triggering a sequence of
statements if the condition is true and, optionally, another sequence if the condition is false.
For example:
if (passfail != 1)
endif
fprint (stdout, "Cannot complete measure_tprop() task for\
cload=%.5g\n", cload[i])
The binary logical operator to test equality or inequality inside a condition are the ones used in
C: == and !=.
The else clause enables the specification of an alternate command sequence:
if (passfail != 1)
fprint (stdout, "Cannot complete measure_tprop() task for\
cload=%.5g\n", cload[i])
else
fprint (stdout, "measure_tprop() task successfully completed.\n")
endif
Eldo® User's Manual, 15.3 835

Eldo Control Language
Statement Overview
Related Topics
Flow Control Statements
Step Loops
The step loop implements a loop with different stepping mechanisms, specified with the type
argument. The step loop syntax is taken from the Eldo/SPICE .STEP command syntax.
Note
The type argument is optional, as the type of step loop to execute is actually defined by
another parameter, but it may be used to increase readability.
There are a number of variant forms of this loop:
• Incremental Loop
• Linear Type Loop
• Log Type Loop
• List Type Loop
Incremental Loop
The simplest variant is the incremental loop:
set i = 0
set tmp = 0
step (type=step, param=i, start=i1, stop=i2, step=1)
tmp = tmp + a[i]
endstep
The parameter being swept is specified with param. The start, stop, and step (or the equivalent
incr or decr) define the loop structure. With this type of loop, the step is explicitly stated. The
loop ends with the endstep command.
Linear Type Loop
This variant on the incremental loop uses the lin or linear type. In this case, the progression is
still linear, but the total number of iterations is provided as an integer. The step is computed
from the start, stop, and n parameters. If the n number is negative or null, or if stop is lower than
or equal to start, no iteration is performed, and execution resumes after the endstep command.
836
Eldo® User's Manual, 15.3

Eldo Control Language
Statement Overview
set cload = 0
step (type=linear, param=cload, start=1.56p, stop=7.28p, n=100)
simulation
// ...
endstep
Log Type Loop
This variant on the incremental loop uses the log type. In this case, the progression is
logarithmic, and the number of iterations per decade of the swept parameter is provided as a
strictly positive integer. The step is computed from the start, stop, and dec parameters.
set fmin = 0
step (type=log, param=fmin, start=1e3, stop=2e7, dec=5)
simulation
// ...
endstep
List Type Loop
This variant uses the list type, which enables looping on sets of parameters. The lengths of the
lists must match.
set cload = 0 ptemp = 0 pvdd = 0
step (type=list, param=(cload,ptemp,pvdd), list=((1p,27,1.8),\
(2p,27,1.9), (3p,55,1.9)))
simulation
// ...
endstep
For one-dimensional list-type loops, no parentheses are required. In other words, the following
syntax may be used:
set pvdd = 0
step (type=list, param=pvdd, list=(1.8,1.85,1.9))
simulation
// ...
endstep
These step/endstep loops are very similar to the .STEP command available in most SPICE
simulators. However, they differ in that they allow the implementation of a specific sequence of
actions/simulations/evaluations, and so on, whereas a .STEP in a netlist always has a global
scope—in other words, it will re-run basically every analysis in the netlist. In many cases, rerunning
everything is neither efficient nor required.
Eldo® User's Manual, 15.3 837

Eldo Control Language
Statement Overview
Tip
See “.STEP” in the Eldo Reference Manual.
Related Topics
Flow Control Statements
While Loops
The while construct is very simple; the sequence of statements between while and endwhile is
repeatedly executed as long as the condition specified on the while command is true. If the
condition is false from the beginning (when the while command is first encountered) no
iteration is performed at all.
The break and continue keywords can be used inside these loops.
set i = 0
set wstr = ""
while (i != n && passfail == 1)
endif
cload[i] = cloadstart + i*(cloadstop-cloadstart)/(n-1)
simulation(\
tran_options( ),\
measure_trop(cload=cload[i], trise=1n,\
signal="v(out)"), tprop[i]=@tp , passfail = @passfail)
if (passfail != 1)
sprint (wstr, "Cannot complete measure_tprop() task for\
cload=%.5g\n",\cload[i])
fprint (stdout, wstr)
i = i + 1
endwhile
See “Variables” on page 821, “Flow Control Statements” on page 835, “Defining and Running
Simulations” on page 841, and the fprint and sprint functions for more information on the
concepts used in the example.
Related Topics
Flow Control Statements
838
Eldo® User's Manual, 15.3

Eldo Control Language
Functions
For Loops
This construct is comparable to the C for loop:
set i = 0
set wstr = ""
for (; i != n; i++)
endif
endfor
cload[i] = cloadstart + i*(cloadstop-cloadstart)/(n-1)
simulation(\
tran_options( ),\
measure_trop(cload=cload[i], trise=1n,\
signal="v(out)"), tprop[i]=@tp , passfail = @passfail)
if (passfail != 1)
sprint (wstr, "Cannot complete measure_tprop() task for\
cload=%.5g\n",\cload[i])
fprint (stdout, wstr)
See “Variables” on page 821, “Flow Control Statements” on page 835, “Defining and Running
Simulations” on page 841, and the fprint and sprint functions for more information on the
concepts used in the example.
Related Topics
Flow Control Statements
Functions
A function is similar to a task, except that it returns a value. The return type can be a number, a
string, or a vector. The keywords .define_function and .end_define_function tell the compiler
that an object must be returned.
The following example rewrites the second example in the topic “Passing Vectors as Task
Arguments” on page 830 using a function rather than a task:
Eldo® User's Manual, 15.3 839

Eldo Control Language
Functions
.define_function f_avg (a[]=0, i1=1, i2=1)
set tmp=0 i=0
step (type=linear, param=i, start=i1, stop=i2, step=1)
tmp = tmp + a[i]
endstep
tmp = tmp / (i2 - i1 + 1)
return tmp
.end_define_function
Once a function is defined, it can be used wherever its return type can be used. For example:
set tprop[0,99]=0 n=100 avg=0
avg = f_avg(a=tprop, i1=0, i2=n-1)
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Defining and Running Simulations
Eldo Control Language
Defining and Running Simulations
The simulation command is used to launch a simulation. It is used to assemble the different
pieces of netlist and testbench necessary to create the desired simulation, and to run it. Upon
completion of the simulation, any .EXTRACT, .MEAS, or waveform results having a label are
available for further processing, except if the simulation failed (they can be assigned to task
variables as if they were output arguments of the simulation command).
There are essentially two use models.
• Create a simulation from the local netlist (the netlist from where the task is launched)
and parameterized testbenches.
• Create a simulation from external files and parameterized testbenches.
Each testbench used in the simulation optionally receives parameters, which override the
default values. All parameters are optional; if a parameter is not passed to a testbench, it takes
its default value. If a testbench has no parameter, the action of listing the testbench in the
simulation is similar to including the content of the testbench, as-is, in the assembled netlist.
Simulations launched in this way can only be “child” simulations—in other words, they cannot
include task executions. They must be plain, simple, classical simulations. Specifically, any task
execution statements present in the submitted assembled netlist are ignored.
The simulation command takes three different types of optional argument:
• Arguments related to the launch of the simulation; name and log to specify the name of
the generated netlist and of the log file of the simulation (it may be beneficial to specify
the name of a directory so that all generated temporary files can be easily removed) and
args to set specific Eldo command-line options. To change the default behavior of
passing arguments, see the option in the Arguments section in “Simulation” on
page 1114.
• Testbench instantiations (testbench names but not prefixed with a “.” here).
• Expressions to get return simulation results.
Below shows an example of a simulation command:
Eldo® User's Manual, 15.3 841

Eldo Control Language
Defining and Running Simulations
set tprop=0 powercons=0 res=0
res = simulation
+ (name="sim_dir/tprop.cir", log="sim_dir/tprop.log", args="-silent -
nowdb",
+ tran_options(),
+ measure_trop(cload_val=1.5p, signal="dff_out"),
+ tprop=@tp, powercons=@avgivdd))
if (res.simu_status == 0)
fprint(stdout, "tprop: %.5g power_cons: %.5g\n", tprop, powercons)
else
fprint(stdout, "Simulation failed\n")
endif
In the example above, the simulation is built by instantiating two testbenches, namely
tran_options and measure_tprop, which were previously shown as examples (see “Testbenches”
on page 809). The tran_options testbench has no parameters. The measure_tprop testbench is
passed several arguments, which override the default values provided in its definition. The
cload_val parameter takes the value 0.5p (0.5×10 −12 ), and the signal parameter is set to dff_out.
The trise parameter is not passed, thus it will take its default value, 10n.
The tprop and powercons scalar variables (explained in “Variables” on page 821) are used to
store the values of the tp and avgivdd quantities computed as results of the simulation (they are
labels of the extract commands contained in the measure_tprop testbench).
Normally, the order of appearance of commands or element descriptions in the final netlist is
not important. Note, however, that the testbenches defined within the simulation command are
appended in the same order as they appear in the simulation command.
Based on the example above, the fprint function generates the resulting netlist, tprop.cir, as
follows:
*tran_options testbench :
.option eps=1e-8 hmax=10p reltol=1e-7 gear
*measure_tprop testbench :
.tran 0 10n
cload dff_out gnd 1.5p
VD D gnd PULSE 0V 1.8V 0n 10n 10n 50n 100n
.extract tran label=tp xup(V(dff_out))-xup(V(D))
.extract tran label=avgivdd avg(i(vdd))
And the process would be launched as follows:
eldo -silent -nowdb -i sim_dir/tprop.cir > sim_dir/tprop.log &
This previous example illustrates the first use model: indeed, the local netlist must not be empty
for the simulation to succeed; it must contain dff_out and gnd nodes, a D input, and a VDD
power supply.
842
Eldo® User's Manual, 15.3

Eldo Control Language
Defining and Running Simulations
In this topic:
Result Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 843
Generated Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 844
Collecting Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 846
Vector Simulation Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 848
Result Structure
The result returned by the call to the simulation command is a structure with many fields:
Example 1:
set res = simulation(tb())
set err_code = res.simu_status
if (err_code == 0)
fprint(stdout, "Simulation succeeded.\n")
else
fprint(stdout, "Simulation failed!\n")
endif
Example 2:
Table 18-2. ECL Result Structure Fields
Field
Description
avg_newton Average number of Newton iterations
newton_iter Number of Newton iterations
tot_elements Total number of elements
simu_status Return code of the simulation (0 is OK)
simu_time Simulation elapsed time, in seconds
nb_steps Number of accepted time steps
nb_rej_steps Number of rejected time steps
nb_lte_rej_steps Number of rejected time steps due to LTE
nb_nodes Number of nodes
nb_proc_used Number of processors used
set res = simulation(tb())
set elapsed = res.simu_time
fprint(stdout, "Elapsed time: %.1f s.\n", elapsed)
See “Variables” on page 821, “Flow Control Statements” on page 835, and the fprint function
for more information on the concepts used in these examples.
Eldo® User's Manual, 15.3 843

Eldo Control Language
Defining and Running Simulations
Related Topics
Defining and Running Simulations
Generated Files
When simulations are run, a number of files have to be generated on disk. By default, when the
name and log parameters of the simulation command are not set, these files are generated in a
temporary directory located in the Eldo outpath directory, named eldo_cl_simu_, with an
automatically generated number appended, for example: eldo_cl_simu_12345.
In this directory, you can find the generated netlist named by default, eldo_cl_simu.cir, and the
simulation output log file named eldo_cl_simu.log. If the simulation failed, it is necessary to
view this log file to understand why an error occurred. Any error listed in this log file will refer
to the generated netlist eldo_cl_simu.cir.
The generated netlist will be overwritten if many simulations are run successively (default
behavior) which is contrary to the simulation output log file which is not overwritten
(simulation log files of each simulation are appended). Therefore, backup files of the generated
netlists are created in case it is necessary to find out which netlist was simulated. The first
backup file is named eldo_cl_simu__1.cir, the second eldo_cl_simu__2.cir, and so on.
For example, if a task defined in the file netlist.cir runs many simulations:
.define_task many_simu
set n = 0
for (n=1; n

Eldo Control Language
Defining and Running Simulations
***** Running simulation ...
***** Generated simulation file:
/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.cir
***** (backup file:
/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu__1.cir)
***** Log file: /home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.log
***** Simulation succeeded
***** Running simulation ...
***** Generated simulation file:
/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.cir
***** (backup file:
/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu__2.cir)
***** Log file: /home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.log
***** Simulation succeeded
***** Running simulation ...
***** Generated simulation file:
/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.cir
***** (backup file:
/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu__3.cir)
***** Log file: /home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.log
Warning 1803: In file "/home/jdoe/eldo/netlist.cir" line 5:
+ Control Language warning: failed to complete the simulation (please
check '/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.log' for more
details).
***** Running simulation ...
***** Generated simulation file:
/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.cir
***** (backup file:
/home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu__4.cir)
***** Log file: /home/jdoe/eldo/eldo_cl_simu_20287/eldo_cl_simu.log
***** Simulation succeeded
The warning 1803 indicates that the third simulation failed. It gives the line number where the
simulation failed in the main netlist netlist.cir (line 5 corresponds to the statement
simulation(add_c(node=n))) and this can provide a first indication to understand the error. Most
of the time it is easier to look at the output log file of the simulation: eldo_cl_simu_20287/
eldo_cl_simu.log. The error in this output log file references the netlist run by the third
simulation. Because the file eldo_cl_simu_20287/eldo_cl_simu.cir was overwritten by the
fourth simulation (at the end of the global simulation of netlist.cir, the file eldo_cl_simu_20287/
eldo_cl_simu.cir is identical to the last backup file eldo_cl_simu_20287/eldo_cl_simu__4.cir),
the line error has to be searched for in the backup file of the third simulation
eldo_cl_simu_20287/eldo_cl_simu__3.cir.
The default behavior can be changed. It is possible to generate different files for successive
simulations. For example:
.define_task many_simu
set n = 0
for (n=1; n

Eldo Control Language
Defining and Running Simulations
This task will generate the simulation files in different directories (simu1, simu2, simu3, and
simu4).
All these generated files are extremely useful to debug simulations. Once the debug phase has
been completed and the simulations behave as expected, it is possible to force Eldo to
automatically remove these generated files. Refer to the section “Temporary Files” in
“Simulation” on page 1114 for more information.
Related Topics
Defining and Running Simulations
Collecting Simulation Results
Once a simulation has successfully completed, the following simulation data can be saved into
task local variables, from where it will be available for post-processing:
• Values of parameters.
• .EXTRACT and .MEAS results if they have been given a label (for example:
.EXTRACT tran label=thresh4 xthresh(v(2,0), 4)).
• Waveforms if they have been given a name (for example: .PLOT tran u20_tran=v(2,0)).
These data are managed as output arguments of the simulation command, and their values can
be obtained by requesting them using their names or labels prefixed with a “@” character.
Example
The following testbench, tb_rc, instantiates an RC circuit, plots the voltage across the capacitor
and also extracts the time value when this voltage reaches 4V. The task t_simu runs the
simulation of this circuit and prints the time value when the voltage across the capacitor reaches
4V, calculated using two different methods.
846
Eldo® User's Manual, 15.3

Eldo Control Language
Defining and Running Simulations
.define_testbench tb_rc(v_extract=4)
.param param_v = 5
.param param_r = 10k
.param param_c = 1m
v1 1 0 param_v
r1 1 2 param_r
c1 2 0 param_c ic=0
.tran 1 20 uic
* Give a name to the waveform to be able to retrieve it from the task.
.plot tran uc=v(2,0)
* Give a label to the extract to be able to retrieve it from the task.
.extract tran label=x_extract xthres(v(2,0), v_extract)
.end_define_testbench
.define_task t_simu
set pv = 0
set pr = 0
set pc = 0
set ptemp = 0
set extract_res = 0
set xval_res_vect = 0
set xval_res = 0
set uc_wave = 0
/* Run the simulation and get some results (parameter values,
extract value and waveform) inside local variables.*/
if (simulation( \
name="simu_rc/simu_rc.cir", \
tb_rc(), \
pv=@param_v, \
pr=@param_r, \
pc=@param_c, \
ptemp=@temp, /* temp is indeed an implicitly defined parameter. */ \
extract_res=@x_extract, \
uc_wave=@uc \
).simu_status == 0)
/* Call xval on the waveform to see if we get the same result as
the extract result. */
xval_res_vect = xval(uc_wave, 4)
/* xval_res_vect is a vector because there could be many values.
Take the first one here. */
xval_res = xval_res_vect[xval_res_vect.imin]
fprint(stdout, "Simulation succeeded:\n")
fprint(stdout, "with v=%.4eV, r=%.4eOhm, c=%.4eF, temp=%.4fC\n", pv,
pr, pc, ptemp)
fprint(stdout, "uc reaches 4V at %.4fs (.extract)\n", extract_res)
fprint(stdout, "uc reaches 4V at %.4fs (.plot + xval)\n", xval_res)
else
fprint(stdout, "Simulation failed\n")
endif
.end_define_task
.t_simu
Eldo® User's Manual, 15.3 847

Eldo Control Language
Defining and Running Simulations
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, “Defining and Running Simulations” on page 841, and the fprint
function for more information on the concepts used in the example.
The output is:
Simulation succeeded:
With v=5.0000e+00V, r=1.0000e+04Ohm, c=1.0000e-03F, temp=27.0000C
uc reaches 4V at 16.0921s (.extract)
uc reaches 4V at 16.0921s (.plot + xval)
Related Topics
Defining and Running Simulations
Vector Simulation Results
Simulation data results can be returned as vectors; there are two primary cases when this can
happen:
• When the keywords vect or catvect have been specified on an .EXTRACT or a .MEAS
command.
• When the netlist to simulate contains an .ALTER command.
The first case is obvious: when the result of an .EXTRACT or a .MEAS command is an array of
values, and this result is assigned to a task local variable, then this variable is a vector.
Examples
Example 1 (.MEAS vect)
This example is similar to the previous one except that the input voltage is a rectangular pulse
and that the task prints all time values when the voltage across the capacitor reaches 4V,
calculated using a .MEAS vect command.
848
Eldo® User's Manual, 15.3

Eldo Control Language
Defining and Running Simulations
.define_testbench tb_rc(v_extract=4)
v1 1 0 pulse (0 5 0 10n 10n 5 10)
r1 1 2 10k
c1 2 0 100u ic=0
.tran 1 20 uic
.plot tran v(1,0)
.plot tran v(2,0)
.meas tran vect label=cross_meas trig at 0 targ v(2,0) val=v_extract
.end_define_testbench
.define_task t_simu
set meas_res [] = 0
set i = 0
/* Run the simulation and get the vector result. */
if (simulation( \
name="simu_rc/simu_rc.cir", \
tb_rc(), \
meas_res=@cross_meas).simu_status == 0)
fprint(stdout, "Simulation succeeded:\n")
fprint(stdout, "uv crosses 4V at: [ ")
for (i=meas_res.imin; i

Eldo Control Language
Defining and Running Simulations
.define_testbench tb_rc(v_extract=4)
.param param_r = 10k
.step param param_r 10k 50k 10k
v1 1 0 5
r1 1 2 param_r
c1 2 0 100u ic=0
.tran 1 20 uic
.plot tran v(1,0)
.plot tran v(2,0)
.extract tran catvect label=x_extract xthres(v(2,0), v_extract)
* Need to do this extract to be able to get all the values of param_v
* otherwise only the last one would be available if getting the value
* of param_r instead of r_vect in the task..
.extract tran catvect label=r_vect param_r
.end_define_testbench
.define_task t_simu
set extract_res [] = 0
set r_res [] = 0
set i = 0
/* Run the simulation and get the vector results. */
if (simulation( \
name="simu_rc/simu_rc.cir", \
tb_rc(), \
extract_res=@x_extract, r_res=@r_vect).simu_status == 0)
fprint(stdout, "Simulation succeeded:\n")
fprint(stdout, "uv crosses 4V at:\n")
for (i=extract_res.imin; i

Eldo Control Language
Defining and Running Simulations
result in the netlist being simulated again, the different results of the .EXTRACT or .MEAS
commands have to be saved inside a vector to be able to retrieve all the results. So if the netlist
has two .ALTER commands then the size of the result vectors will be 3. The first value will be
the result corresponding to the simulation of the netlist without any .ALTER, and the two other
values will be the results corresponding to the simulation of the netlist with the two .ALTER
commands.
Note
.PLOT and .PLOT commands combined with .ALTER commands will produce compound
waveforms, not arrays of waveforms. Note also that if the simulation has succeeded but the
.EXTRACT or .MEAS command failed because no value could be calculated, then the UNDEF
value is stored inside the vector.
Example 3 (.ALTER)
This example is similar to the previous one except that a .ALTER command is used to modify
the value of the resistance.
Eldo® User's Manual, 15.3 851

Eldo Control Language
Defining and Running Simulations
.define_testbench tb_rc(v_extract=4)
.param param_r = 10k
v1 1 0 5
r1 1 2 param_r
c1 2 0 100u ic=0
.tran 1 20 uic
.plot tran v(1,0)
.plot tran v(2,0)
* x_extract will be a vector because of the .alter commands at the end of
the netlist.
.extract tran label=x_extract xthres(v(2,0), v_extract)
.end_define_testbench
.define_task t_simu
set extract_res [] = 0
set r_res [] = 0
set i = 0
/* Run the simulation and get the vector results. */
if (simulation( \
name="simu_rc/simu_rc.cir", \
tb_rc(), \
extract_res=@x_extract, r_res=@param_r).simu_status == 0)
fprint(stdout, "Simulation succeeded:\n")
fprint(stdout, "uv crosses 4V at:\n")
for (i=extract_res.imin; i

Eldo Control Language
Defining and Running Simulations
Simulation succeeded:
uv crosses 4V at:
1.6121s when r=1.0000e+04Ohm
8.0378s when r=5.0000e+04Ohm
16.0921s when r=1.0000e+05Ohm
UNDEF when r=1.5000e+05Ohm
Related Topics
Defining and Running Simulations
Eldo® User's Manual, 15.3 853

Eldo Control Language
Library of Functions for Tasks
Library of Functions for Tasks
Describes functions to be used inside a task.
Command
abs
acos
acosh
acot
acoth
append
asin
asinh
atan
atan2
atanh
atof
atoi
avg
beginval
Table 18-3. Library of Functions for Tasks
Description
Returns the absolute value.
Arc cosine function.
Inverse hyperbolic cosine function.
Arc cotangent function.
Inverse hyperbolic cotangent function.
Appends the content of the array array2 at the end of array
array1. This function does not return any value: the array1
argument is modified.
Arc sine function.
Inverse hyperbolic sine function.
Arc tangent function.
Returns the principal value of the arctangent of y/x,
expressed in radians. To compute the value, the function
uses the signs of both arguments to determine the quadrant.
Inverse hyperbolic tangent function.
Converts the string value VAL into a real.
Converts the string value VAL into an integer.
Returns the average value.
Returns the first point of a waveform. Returns 0 if the
waveform is empty, otherwise x_res and y_res are set with
the coordinates of the first point of the waveform. If wf is a
complex waveform, then y_res must be a complex number.
bitof Returns 1 if bit b of the integer value of parameter a is 1.
Returns 0 if bit b of the integer value of parameter a is 0.
cat
ceil
Concatenates the content of the arrays given as arguments
and returns the resulting array. This function does not
modify the array arguments, it allocates and returns a new
array. When possible, use append instead of cat for better
performance.
Ceiling rounding function.
854
Eldo® User's Manual, 15.3

Command
compoundcontent
conj
cos
cosh
cot
coth
db
derive
drv
exp
fclose
fft
fgetc
fgets
floor
fopen
fprint
Table 18-3. Library of Functions for Tasks (cont.)
Description
Eldo Control Language
Library of Functions for Tasks
Returns an array containing the waveforms that are part of
the compound waveform wf.
Returns the complex conjugate of the input complex number
c.
Cosine function.
Hyperbolic cosine function.
Cotangent function.
Hyperbolic cotangent function.
Returns value in decibels.
Returns the derivative of a waveform at a single point.
Computes the derivative of the input waveform (the result is
a waveform).
Exponent function.
Closes the file represented by the file variable FILE.
The Discrete Fourier Transform (DFT) is used to determine
the frequency content of analog signals encountered in
circuit simulation, which deals with sequences of time
values. The fft() function uses the Fast Fourier Transform
(FFT) method for calculating the DFT.
Returns the next character from the file represented by the
file variable FILE, or EOF if the end of the file has been
reached.
Returns the next characters from the file represented by the
file variable FILE, or EOF if the end of the file has been
reached. It has the same behavior as the C fgets function: the
function stops reading when NB_CHARS characters have
been read or if a \n character is read (in which case, \n is the
last character of the returned string).
Floor rounding function.
Returns a file variable if the file whose path is FILE_PATH
has been successfully opened; otherwise, the program exits
printing the optional message DIE_MESSAGE.
Prints a formatted string in the file represented by the file
variable FILE; this is the same behavior as the C fprintf
function.
Eldo® User's Manual, 15.3 855

Eldo Control Language
Library of Functions for Tasks
Command
frexp
fscan
hypot
ifft
imag
imax
imin
int
integ
integral
intersect
isarray
iscompound
kurt
ldexp
limit
log
Table 18-3. Library of Functions for Tasks (cont.)
Description
Breaks a floating-point number into a normalized fraction
and an integral power of 2. Returns an array of 2 elements,
the first element being the normalized fraction and the
second element being the integral power of 2.
Returns the number of elements that have been parsed. It has
the same behavior as the C fscanf function.
Computes the length of the hypotenuse of a right angle
triangle.
Calculates the inverse Fast Fourier Transform of the input
waveform.
Imaginary part function.
Returns the index of the maximum value of the elements of
the array array. If istart and istop are specified, this function
applies to the part of array beginning at index istart and
ending at index istop.
Returns the index of the minimum value of the elements of
the array array. If istart and istop are specified, this function
applies to the part of array beginning at index istart and
ending at index istop.
Integer value of VAL.
Returns the definite integral value with upper and lower
limits of a waveform.
Computes the indefinite integral (also known as antiderivative)
of the input waveform (the result is a waveform).
Returns a vector containing all of the intersection points of
two waveforms. If the slopes are supplied, the result will be
collected only when the waveforms have the specified
slopes.
Returns 1 if var is an array, 0 otherwise.
Returns 1 if wf is a compound waveform, 0 otherwise.
Returns the fourth standardized moment also known as
sample kurtosis (unbiased value if bias is 0, biased value
otherwise) of the elements of the array array.
Returns the value x multiplied by 2 raised to the power y
(computes the quantity: x × 2y).
Returns b if a < b, returns c if a > c, returns a otherwise.
Natural logarithm function.
856
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
Command
log10
magnitude
max
mcconv
mcnbench
min
mod
modf
mptpcomplex
nextval
ongrid
phase
pow
pow_10
pwr
real
Table 18-3. Library of Functions for Tasks (cont.)
Description
Decimal (base 10) logarithm function.
Returns the absolute magnitude.
Returns the maximum value.
Returns 1 or 0 to indicate convergence of the Monte Carlo
process for the elements of the array array.
Returns the number of non-UNDEF values among the
elements of the array array. If istart and istop are specified,
this function applies to the part of array beginning at index
istart and ending at index istop.
Returns the minimum value.
Modulo operator. Floating-point remainder value function
of dividing x by y. Returns the value x − i×y, where i is the
quotient of x/y, rounded towards zero to an integer. mod
will exit properly if y is equal to 0.
Breaks the argument x into integral and fractional parts,
each of which has the same sign as the argument. Returns an
array of two elements, the first element being the fractional
part and the second element being the integral part.
Constructs a complex number from its magnitude m and its
phase in radians p.
Returns the next point of a waveform. Returns 0 if there are
no more points in the waveform, otherwise x_res and y_res
are set with the coordinates of the next point of the
waveform.
Returns 1 if value=offset + (k×step) where k is an integer
value. Otherwise it returns 0. The default value of offset is
0.0.
Returns the phase.
Returns the value of VAL1 to the power of the integer part
of VAL2. pow will exit properly if VAL1 is a equal to 0 and
VAL2 is negative.
Computes the value of 10 raised to the power of wf: 10wf
(the result is a waveform).
Returns the absolute value of VAL1, raised to the power of
VAL2, with the sign of VAL1. pwr will exit properly if
VAL1 is a equal to 0 and VAL2 is negative.
Real part function.
Eldo® User's Manual, 15.3 857

Eldo Control Language
Library of Functions for Tasks
Command
relation
ritocomplex
rms
rms_ac
rms_noise
rms_tran
round
sgn
sign
sin
sinh
size
skew
sprint
sqr
sqrt
sscan
std
strtok
sum
Table 18-3. Library of Functions for Tasks (cont.)
Description
Generates a waveform from a point-by-point relational
expression.
Constructs a complex number from its real part r and its
imaginary part i.
Returns the root mean square value of a waveform.
Returns the root mean square value of a waveform for AC
analysis.
Returns the root mean square value of a waveform for noise
analysis.
Returns the root mean square value of a waveform for
transient analysis.
Returns value of VAL rounded to the nearest integer.
Returns the signum of VAL: +1 if VAL>0, 0 if VAL=0, -1 if
VAL=0, -1 if
VAL1

Command
system
tan
tanh
trunc
var
wadd_data_enum_value
wadd_scale
wclose
wcreate_data_type
wcreate_scale_table
wcreate_wave
wget
wftoascii
wftodata
wmkfolder
wopen
Table 18-3. Library of Functions for Tasks (cont.)
Description
Eldo Control Language
Library of Functions for Tasks
Executes the STR_CMD shell command. If no other
argument is passed, the result of the command is displayed
on the standard output, otherwise the result is stored in the
string STR_RES, which can be parsed to get the result.
Tangent function.
Hyperbolic tangent function.
Truncated value of VAL (integer part of real value).
Returns the variance (unbiased value) of the elements of the
array array.
This function must be used to define enumeration values for
an enumerated data type created with wcreate_data_type.
This function is used to add sub-units to a scale table created
with wcreate_scale_table.
Saves (if the .wdb file was opened in write mode) and closes
the .wdb file whose identifier is wdbId.
If the appropriate data type does not exist, it is possible to
create it using this function.
If the appropriate scale table does not exist, then it can be
created with this function.
Creates a new waveform inside the specified .wdb file, and
returns a waveform variable to, for example, call postprocessing
functions on it.
Reads the waveform named wave1 located at the folder
folder inside the .wdb file whose identifier is wdbId.
Dumps a waveform in a text file.
Returns the datapoints of a waveform in a matrix. Its first
line is a vector containing the X values and its second line is
a vector containing the Y values.
This function creates a folder folder in the .wdb file whose
identifier is wdbId.
This function can be used to open .wdb files. The .wdb file
must already exist to be opened in read mode. In write
mode, it will be created if it does not exist, or overwritten if
it already existed. This function returns a file identifier used
in the next function to identify the .wdb file.
Eldo® User's Manual, 15.3 859

Eldo Control Language
Library of Functions for Tasks
Command
wsave
wset_values
xdown
xmax
xmin
xofmax
xofmin
xup
xval
xwave
yval
Table 18-3. Library of Functions for Tasks (cont.)
Description
This function saves the waveform which the variable wave
points to inside the folder folder in the .wdb file whose
identifier is wdbId.
This function can be used to set points to a waveform
created with the wcreate_wave function if the x and y
vectors were not given at that time. It can also be used to
add new points to the waveform.
Returns a vector containing all the X values where a
waveform falls below the given Y level with a negative
slope.
Returns the maximum X value where a waveform is
defined.
Returns the minimum X value where a waveform is defined.
Returns a vector containing all the X values at the maximum
(or maxima) of a waveform.
Returns a vector containing all of the X values at the
minimum (or minima) of a waveform.
Returns a vector containing all the X values where a
waveform rises above the given Y level with a positive
slope.
Returns in a vector all the X values at the given Y level of
the waveform wf. If the slope is supplied, the result will be
collected only when the waveform has the specified slope.
Interpolation is applied.
Creates a new waveform with Y values identical to X values
(the result is a waveform).
Returns the Y value at a given X coordinate of a waveform.
Interpolation is applied. If wf is a complex waveform, the
result is a complex number.
860
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
abs
Task function category: Mathematical Functions, Functions Operating on Waveforms
Returns the absolute value.
Usage
Mathematical Function
abs(VAL)
Waveform Function
abs(wf)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
Return Values
Mathematical Function
Returns the absolute value of VAL.
Waveform Function
Returns the absolute value of the waveform input argument (the result is a waveform).
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 861

Eldo Control Language
Library of Functions for Tasks
acos
Task function category: Mathematical Functions, Functions Operating on Waveforms
Arc cosine function.
Usage
Mathematical Function
acos(VAL)
unsafe_acos(VAL)
Waveform Function
acos(wf)
acos(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Arc cosine of VAL. acos will exit properly if VAL is not included in [-1;1].
Waveform Function
Computes the principal value of the arc cosine of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
862
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
acosh
Task function category: Mathematical Functions, Functions Operating on Waveforms
Inverse hyperbolic cosine function.
Usage
Mathematical Function
acosh(VAL)
unsafe_acosh(VAL)
Waveform Function
acosh(wf)
acosh(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Inverse hyperbolic cosine of VAL. acosh will exit properly if VAL is less than 1.
Waveform Function
Inverse hyperbolic cosine of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
Eldo® User's Manual, 15.3 863

Eldo Control Language
Library of Functions for Tasks
acot
Task function category: Mathematical Functions, Functions Operating on Waveforms
Arc cotangent function.
Usage
Mathematical Function
acot(VAL)
unsafe_acot(VAL)
Waveform Function
acot(wf)
acot(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Arc cotangent of VAL.
Waveform Function
Arc cotangent of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
864
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
acoth
Task function category: Mathematical Functions, Functions Operating on Waveforms
Inverse hyperbolic cotangent function.
Usage
Mathematical Function
acoth(VAL)
unsafe_acoth(VAL)
Waveform Function
acoth(wf)
acoth(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Inverse hyperbolic cotangent of VAL. acoth will exit properly if VAL is included in [-1;1].
Waveform Function
Inverse hyperbolic cotangent of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
Eldo® User's Manual, 15.3 865

Eldo Control Language
Library of Functions for Tasks
append
Task function category: Functions Operating on Arrays
Appends the content of the array array2 at the end of array array1. This function does not return
any value: the array1 argument is modified.
Usage
append(array1 {, arrayn}*)
Arguments
• array1
First array.
• arrayn
N th array.
Examples
set a[]={1,2}
set b[]={3,4,5,6}
set i=0
append(a,b)
for (i=a.imin; i

Eldo Control Language
Library of Functions for Tasks
asin
Task function category: Mathematical Functions, Functions Operating on Waveforms
Arc sine function.
Usage
Mathematical Function
asin(VAL)
unsafe_asin(VAL)
Waveform Function
asin(wf)
asin(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Arc sine of VAL. asin will exit properly if VAL is not included in [-1;1].
Waveform Function
Computes the principal value of the arc sine of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
Eldo® User's Manual, 15.3 867

Eldo Control Language
Library of Functions for Tasks
asinh
Task function category: Mathematical Functions, Functions Operating on Waveforms
Inverse hyperbolic sine function.
Usage
Mathematical Function
asinh(VAL)
unsafe_asinh(VAL)
Waveform Function
asinh(wf)
asinh(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Inverse hyperbolic sine of VAL.
Waveform Function
Inverse hyperbolic sine of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
868
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
atan
Task function category: Mathematical Functions, Functions Operating on Waveforms
Arc tangent function.
Usage
Mathematical Function
atan(VAL)
Waveform Function
atan(wf)
atan(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Arc tangent of VAL.
Waveform Function
The principal value of the arc tangent of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 869

Eldo Control Language
Library of Functions for Tasks
atan2
Task function category: Mathematical Functions
Returns the principal value of the arctangent of y/x, expressed in radians. To compute the value,
the function uses the signs of both arguments to determine the quadrant.
Usage
atan2(y, x)
Arguments
• y
y value.
• x
x value.
Related Topics
Library of Functions for Tasks
870
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
atanh
Task function category: Mathematical Functions, Functions Operating on Waveforms
Inverse hyperbolic tangent function.
Usage
Mathematical Function
atanh(VAL)
Waveform Function
atanh(wf)
atanh(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Inverse hyperbolic tangent of VAL. atanh will exit properly if VAL is not included in [-1;1].
Waveform Function
The inverse hyperbolic tangent of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 871

Eldo Control Language
Library of Functions for Tasks
atof
Task function category: Functions Operating on Strings
Converts the string value VAL into a real.
Usage
atof(VAL)
Arguments
• VAL
String value.
Related Topics
Library of Functions for Tasks
atoi
872
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
atoi
Task function category: Functions Operating on Strings
Converts the string value VAL into an integer.
Usage
atoi(VAL)
Arguments
• VAL
String value.
Related Topics
Library of Functions for Tasks
atof
Eldo® User's Manual, 15.3 873

Eldo Control Language
Library of Functions for Tasks
avg
Task function category: Functions Operating on Arrays, Functions Operating on Waveforms
Returns the average value.
Usage
Array Function
avg(array [, istart, istop])
Waveform Function
avg(wf)
avg(wf, x_start, x_end)
Arguments
Array Function
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Array Function
Returns the average value of the elements of the array array. If istart and istop are specified, this
function applies to the part of array beginning at index istart and ending at index istop.
Waveform Function
Returns the average value of a waveform which is computed as:
874
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 875

Eldo Control Language
Library of Functions for Tasks
beginval
Task function category: Functions Operating on Waveforms
Returns the first point of a waveform. Returns 0 if the waveform is empty, otherwise x_res and
y_res are set with the coordinates of the first point of the waveform. If wf is a complex
waveform, then y_res must be a complex number.
Usage
beginval(wf, x_res, y_res)
Arguments
• wf
Waveform identifier.
• x_res
Variable name for X coordinate of first point in waveform. Must be a double-precision
floating-point variable otherwise an error is generated.
• y_res
Variable name for Y coordinate of first point in waveform. Must be a double-precision
floating-point variable otherwise an error is generated.
Related Topics
Library of Functions for Tasks
nextval
876
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
bitof
Task function category: Mathematical Functions
Returns 1 if bit b of the integer value of parameter a is 1. Returns 0 if bit b of the integer value
of parameter a is 0.
Usage
bitof(a, b)
Arguments
• a
a value.
• b
b value.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 877

Eldo Control Language
Library of Functions for Tasks
cat
Task function category: Functions Operating on Arrays
Concatenates the content of the arrays given as arguments and returns the resulting array. This
function does not modify the array arguments, it allocates and returns a new array. When
possible, use append instead of cat for better performance.
Usage
cat(array1 {, arrayn}*)
Arguments
• array1
First array.
• arrayn
n τη array.
Examples
set a[]={1,2}
set b[]={3,4,5,6}
set c[]={7}
set d = cat(a,b,c)
set i = 0
for (i=d.imin; i

Eldo Control Language
Library of Functions for Tasks
ceil
Task function category: Mathematical Functions, Functions Operating on Waveforms
Ceiling rounding function.
Usage
Mathematical Function
ceil(VAL)
Waveform Function
ceil(wf)
ceil(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Returns the smallest integer value not less than VAL. This is known as rounding up. For
example ceil(1.25) returns 2.0 and ceil(-1.25) returns -1.0.
Waveform Function
Computes the smallest integral value not less than each data point of a waveform wf (the result
is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
floor
Eldo® User's Manual, 15.3 879

Eldo Control Language
Library of Functions for Tasks
compoundcontent
Task function category: Functions Operating on Compound Waveforms
Returns an array containing the waveforms that are part of the compound waveform wf.
Usage
compoundcontent(wf)
Arguments
• wf
Waveform identifier.
Examples
Example:
set w_array[] = 0
set w_compound = 0
set i = 0
set w = 0
if (simulation(tb_step(),
+ w_compound=@w_tran).simu_status == 0)
w_array = compoundcontent(w_compound)
for (i=w_array.imin; i

Eldo Control Language
Library of Functions for Tasks
.option set_eldo_cl_verbose=0
.define_testbench tb_rc
.param period=10
.param pw=1
.step param pw 1 period 1
v1 1 0 pulse (0 5 0 10n 10n 'pw' 'period')
r1 1 2 1k
c1 2 0 1m ic=0
.tran 1 20 uic
.plot tran uc=v(2,0)
.extract tran catvect label=pw_vect pw
.end_define_testbench
* First task using directly the waveform functions on the compound
waveform (more complicated)
.define_task t_simu_rc_compound_arg
set compound_uc = 0
set pw [] = 0
set i = 0
set j = 0
set res_xup4 [] = 0
if (simulation(name="simu_rc/simu_rc.cir", tb_rc(), \
compound_uc=@uc, pw=@pw_vect).simu_status == 0)
/* compound_uc is a compound waveform and pw is the array containing
the different values of the 'pw' parameter. */
res_xup4 = xup(compound_uc, 4)
/* res_xup4 is indeed a matrix. res_xup4[i] is the array containing the
time values where 'uc' rises above 4V when the 'pw' parameter has
the value pw[i]. */
fprint(stdout, "\nExample with compound argument\nuc rises above 4V
at:\n")
/* In the loops below, i is the index of the waveform in the compound
and j iterates through the result values of xup applied to the
waveform with index i of compound_uc. */
for (i=res_xup4.imin; i

Eldo Control Language
Library of Functions for Tasks
if (simulation(name="simu_rc/simu_rc.cir", tb_rc(), \
compound_uc=@uc, pw=@pw_vect).simu_status == 0)
/* Get the waveforms contained in the compound: uc_arr will be an array
of waveforms. */
uc_arr = compoundcontent(compound_uc)
fprint(stdout, "\nExample with compoundcontent\nuc rises above 4V
at:\n")
for (i=uc_arr.imin; i

Eldo Control Language
Library of Functions for Tasks
The only exceptions are the functions xmin and xmax. Indeed, in most of the cases, all
waveforms composing a compound waveform are defined on the same time/frequency interval,
so xmin and xmax will almost always return a single real value instead of an array of identical
values (xmin and xmax will return an array only if the values are not the same).
Example:
Adding the following lines in the task t_simu_rc_compound_arg above:
fprint(stdout, "xmin(compound_uc)=%.4f\n", xmin(compound_uc))
fprint(stdout, "xmax(compound_uc)=%.4f\n", xmax(compound_uc))
is valid and will produce the output:
xmin(compound_uc)=0.0000
xmax(compound_uc)=20.000
Related Topics
Library of Functions for Tasks
iscompound
Testbenches
Tasks
Variables
Flow Control Statements
Defining and Running Simulations
fprint
Eldo® User's Manual, 15.3 883

Eldo Control Language
Library of Functions for Tasks
conj
Task function category: Mathematical Functions Operating on Complex Numbers
Returns the complex conjugate of the input complex number c.
Usage
conj(c)
Arguments
• c
Input complex number.
Related Topics
Library of Functions for Tasks
884
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
cos
Task function category: Mathematical Functions, Functions Operating on Waveforms
Cosine function.
Usage
Mathematical Function
cos(VAL)
Waveform Function
cos(wf)
cos(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Cosine of VAL.
Waveform Function
Cosine of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 885

Eldo Control Language
Library of Functions for Tasks
cosh
Task function category: Mathematical Functions, Functions Operating on Waveforms
Hyperbolic cosine function.
Usage
Mathematical Function
cosh(VAL)
Waveform Function
cosh(wf)
cosh(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Hyperbolic cosine of VAL.
Waveform Function
The principal value of the arc cosine of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
886
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
cot
Task function category: Mathematical Functions, Functions Operating on Waveforms
Cotangent function.
Usage
Mathematical Function
cot(VAL)
unsafe_cot(VAL)
Waveform Function
cot(wf)
cot(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Cotangent of VAL. cot will exit properly if VAL is a multiple of pi.
Waveform Function
Cotangent of wf (the result is a waveform). Cotangent is defined as the reciprocal of the tangent,
that is:
Related Topics
Library of Functions for Tasks
Numbers
Eldo® User's Manual, 15.3 887

Eldo Control Language
Library of Functions for Tasks
coth
Task function category: Mathematical Functions, Functions Operating on Waveforms
Hyperbolic cotangent function.
Usage
Mathematical Function
coth(VAL)
unsafe_coth(VAL)
Waveform Function
coth(wf)
coth(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Hyperbolic cotangent of VAL. coth will exit properly if VAL is equal to 0.
Waveform Function
The hyperbolic cotangent of wf (the result is a waveform). Hyperbolic cotangent is defined as
the reciprocal of the hyperbolic tangent, that is:
Related Topics
Library of Functions for Tasks
Numbers
888
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
db
Task function category: Mathematical Functions, Mathematical Functions Operating on
Complex Numbers, Functions Operating on Waveforms
Returns value in decibels.
Usage
Mathematical Function
db(VAL)
unsafe_db(VAL)
Complex Number Function
db(c)
unsafe_db(c)
Waveform Function
db(wf)
db(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Complex Number Function
• c
Input complex number.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Decibel of VAL (20×log10(VAL)). db will exit properly if VAL is negative or null.
Converts the magnitude of the complex number c to decibels. db will exit properly if c is (0, 0).
Eldo® User's Manual, 15.3 889

Eldo Control Language
Library of Functions for Tasks
Complex Number Function
Converts the magnitude of the complex number c to decibels. db will exit properly if c is (0, 0).
Waveform Function
Converts the magnitude data of the input complex waveform wf to decibels (the result is a
waveform).
Related Topics
Library of Functions for Tasks
Numbers
890
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
derive
Task function category: Functions Operating on Waveforms
Returns the derivative of a waveform at a single point.
Usage
derive(wf, at_x)
Arguments
• wf
Waveform identifier.
• at_x
X coordinate.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
Related Topics
Library of Functions for Tasks
integ
drv
integral
Eldo® User's Manual, 15.3 891

Eldo Control Language
Library of Functions for Tasks
drv
Task function category: Functions Operating on Waveforms
Computes the derivative of the input waveform (the result is a waveform).
Usage
drv(wf)
drv(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Related Topics
Library of Functions for Tasks
integral
892
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
exp
Task function category: Mathematical Functions, Mathematical Functions Operating on
Complex Numbers, Functions Operating on Waveforms
Exponent function.
Usage
Mathematical Function
exp(VAL)
unsafe_exp(VAL)
Complex Number Function
exp(c)
unsafe_exp(c)
Waveform Function
exp(wf)
exp(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Complex Number Function
• c
Input complex number.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Computes the value of e raised to the power of VAL: e VAL . exp will output a linear
extrapolation of the result if VAL is more than 80.
Eldo® User's Manual, 15.3 893

Eldo Control Language
Library of Functions for Tasks
Complex Number Function
Computes the value of e raised to the power of complex number c: e c . exp will output a linear
extrapolation of the result if real(c) is more than 80.
Waveform Function
Computes the value of e raised to the power of waveform wf: e wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
pow_10
Numbers
894
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
fclose
Task function category: Functions Operating on Files
Closes the file represented by the file variable FILE.
Usage
fclose(FILE)
Arguments
• FILE
File variable.
Related Topics
Library of Functions for Tasks
fopen
Eldo® User's Manual, 15.3 895

Eldo Control Language
Library of Functions for Tasks
fft
Task function category: Functions Operating on Waveforms
The Discrete Fourier Transform (DFT) is used to determine the frequency content of analog
signals encountered in circuit simulation, which deals with sequences of time values. The fft()
function uses the Fast Fourier Transform (FFT) method for calculating the DFT.
Usage
fft(wf)
fft(wf, time_start)
fft(wf, time_start, time_stop)
fft(wf, time_start, time_stop, sampling_frequency)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points,
sampling)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points,
sampling, padding)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points,
sampling, padding, averaging)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points,
sampling, padding, averaging, windowing)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points,
sampling, padding, averaging, windowing, windowing_arg)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points,
sampling, padding, averaging, windowing, windowing_arg,
reference_frequency)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points,
sampling, padding, averaging, windowing, windowing_arg,
reference_frequency, minimum_frequency)
fft(wf, time_start, time_stop, sampling_frequency, number_of_points,
sampling, padding, averaging, windowing, windowing_arg,
reference_frequency, minimum_frequency, maximum_frequency)
Arguments
• wf
Specifies the input waveform name.
• time_start
Specifies the start time of the input waveform.
• time_stop
Specifies the stop time of the input waveform.
• sampling_frequency
Specifies the sampling frequency of the signal.
• number_of_points
Specifies the number of sampling points.
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Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
• sampling
Specifies the method of computing the sampled data. Valid values are “No Sampling” or
“Interpolation”.
• padding
Activates data padding to pad the input data with zeros, before or after the input data set.
Valid values are: “No Padding”, “Padding Right”, “Padding Left” or “Padding Left and
Right”. The input parameter will be verified by the algorithm and changed if necessary.
• averaging
Specifies whether you want to take an average on the raw data to reduce noise and smooth
the frequency domain waveform. Specify 1 to turn this on, or 0 to not modify the raw data
from calculation.
• windowing
Applies a windowing function from a selection of windows. Valid values are:
“Rectangular”, “Hamming”, “Hanning”, “Parzen”, “Welch”, “Blackman”, “Blackman-
Harris”, “Bartlett”, “Kaiser”, “Klein” or “Dolph Chebyshev”.
• windowing_arg
Specifies the alpha or beta value that is required by “Hanning”, “Kaiser”, and “Dolph
Chebyshev” windows.
• reference_frequency
Adjusts the results around the y-axis so that the point for the specified frequency is 0.0.
• minimum_frequency
Specifies the starting frequency used inside the Fast Fourier Transform result window.
• maximum_frequency
Specifies the last frequency used inside the Fast Fourier Transform result window.
Description
For symmetric windows, the parameters above satisfy the following equation:
((number_of_points) / sampling_frequency) = time_stop - time_start.
For periodic windows, the parameters above satisfy the following equation:
((number_of_points-1) / sampling_frequency) = time_stop - time_start.
For “Hanning”, symmetric window shapes are preferred when using a Hanning window in FIR
filter design. Periodic window shapes are preferred when using a Hanning window in spectral
analysis. This is because the Discrete Fourier Transform assumes periodic extension of the
input vector. A periodic Hanning window is obtained by constructing a symmetric window and
removing the last sample.
Eldo® User's Manual, 15.3 897

Eldo Control Language
Library of Functions for Tasks
Related Topics
Library of Functions for Tasks
ifft
898
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
fgetc
Task function category: Functions Operating on Files
Returns the next character from the file represented by the file variable FILE, or EOF if the end
of the file has been reached.
Usage
fgetc(FILE)
Arguments
• FILE
File variable.
Related Topics
Library of Functions for Tasks
fgets
Eldo® User's Manual, 15.3 899

Eldo Control Language
Library of Functions for Tasks
fgets
Task function category: Functions Operating on Files
Returns the next characters from the file represented by the file variable FILE, or EOF if the end
of the file has been reached. It has the same behavior as the C fgets function: the function stops
reading when NB_CHARS characters have been read or if a \n character is read (in which case,
\n is the last character of the returned string).
Usage
fgets(FILE, NB_CHARS)
Arguments
• FILE
File variable.
• NB_CHARS
Number of characters.
Examples
Example 1:
.define_task read_file
set myfile = NULL
set s = ""
myfile = fopen ("./hello.txt", "r")
while(1)
s = fgets(myfile, 200)
if (s == EOF)
break
else
printf(stdout, "%s", s)
endif
endwhile
fclose (myfile)
.end_define_task
Example 2:
900
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
.define_task parse_file
/* This example shows how to parse a file 'corners.txt' formatted
this way:
vdd=1.0, temp=25, corner=tt
vdd=1.1, temp=75, corner=ss
vdd=1.2, temp=100, corner=ff
*/
set line = ""
set tokens [] = ""
set vdd = 0
set temp = 0
set corner = ""
set myfile = fopen("./corners.txt", "r")
while(1)
line = fgets(myfile, 1000)
if (line == EOF)
break
else
/* Itemize the line into the "tokens[]" vector of strings. Don't
forget to add '\n' into the list of separators; indeed fgets doesn't
remove it from the line it returns. */
tokens = strtok(line, "=, \t\n");
vdd = atof(tokens[tokens.imin + 1])
temp = atoi (tokens[tokens.imin + 3])
corner = tokens[tokens.imin + 5]
fprint(stdout, "Parsed line: vdd=%.4e, temp=%d, corner=%s\n", vdd,
temp, corner)
endif
endwhile
fclose(myfile)
.end_define_task
Related Topics
Library of Functions for Tasks
fgetc
fprint
fclose
Tasks
Variables
Flow Control Statements
Eldo® User's Manual, 15.3 901

Eldo Control Language
Library of Functions for Tasks
floor
Task function category: Mathematical Functions, Functions Operating on Waveforms
Floor rounding function.
Usage
Mathematical Function
floor(VAL)
Waveform Function
floor(wf)
floor(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Returns the largest integer value not greater than VAL. This is known as rounding down. For
example floor(1.25) returns 1.0 and floor(-1.25) returns -2.0.
Waveform Function
Computes the largest integral value not greater than each data point of a waveform wf (the result
is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
ceil
902
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
fopen
Task function category: Functions Operating on Files
Returns a file variable if the file whose path is FILE_PATH has been successfully opened;
otherwise, the program exits printing the optional message DIE_MESSAGE.
Usage
fopen(FILE_PATH, MODE [, DIE_MESSAGE])
Arguments
• FILE_PATH
Path to file.
• MODE
MODE selects the open mode: "w" for write, "r" for read, or "a" for append (note that it is a
string). The file must already exist to be opened in read mode. In write mode, it will be
created if it does not exist, or overwritten if it already existed. In append mode, if the file
already exists it will be appended to.
• DIE_MESSAGE
Optional. Function exit message text.
Examples
If you want to append the same file multiple times during the execution of many tasks, instead
of using multiple fopen/fclose functions it is more efficient to keep the file always open and to
pass the file variable as a task parameter. To do so, it is necessary to define a main task that will
open the file and then call the subtasks with the file variable as a parameter, for example:
Eldo® User's Manual, 15.3 903

Eldo Control Language
Library of Functions for Tasks
.define_task main_task
set myfile = NULL
// Open the "jitter.results" file here:
myfile = fopen("jitter.results", "w", \
"cannot open jitter.results.\n")
period_jitter(corner="tt", myfile=myfile)
period_jitter(corner="ss", myfile=myfile)
period_jitter(corner="ff", myfile=myfile)
// Close the "jitter.results" file :
fclose(myfile)
.end_define_task
.define_task period_jitter(corner="tt", myfile=stdout)
/* Instead of calling here fopen("jitter.results", "w") during the
* first call to this task to overwrite the file and then
* fopen("jitter.results", "a") to append it,
* it is much more efficient to move the call to fopen into the
* main task and to use here the file variable myfile to print
* some data in this file. */
...
simulation(...)
fprint(myfile, "...")
..
.end_define_task
Related Topics
Library of Functions for Tasks
fclose
904
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
fprint
Task function category: Functions Operating on Files
Prints a formatted string in the file represented by the file variable FILE; this is the same
behavior as the C fprintf function.
Usage
fprint(FILE, FORMAT [,ARG]*)
Arguments
• FILE
File variable.
• FORMAT
FORMAT is a string that contains the text to be formatted. This string can contain format
tags. A format tag must follow this specification:
%[flags][width][.precision]specifier
where:
specifier is:
c for a character
d or i or u for an integer number
e or E for a double precision floating point number in scientific notation
f for a double-precision floating-point number; the default precision is 6 digits
g or G to use the shorter of %f or %e or %E
s for a string
x or X for an hexadecimal integer number
% to print the % character
flags is:
- to force left justification within the given width
+ to force the sign to be always written
“ ” to insert a space before a number for which no sign is written
# to specify if 0x or 0X must be written before a not null hexadecimal number or to
specify if “.” must be always written for a double-precision floating-point number
0 to insert zeroes instead of spaces before a number
width is the minimum number of characters to be displayed (spaces are added if
necessary)
precision is the minimum number of digits to be written for integers (zeroes are added if
necessary).
Eldo® User's Manual, 15.3 905

Eldo Control Language
Library of Functions for Tasks
or is the minimum number of digits to be written after the “.” for e, E and f specifiers.
or is the maximum number of significant digits for g or G specifiers.
or is the maximum number of characters to be written for string.
• ARG
Optional. An argument of the corresponding type must be specified for each format tag
present in the FORMAT argument.
Related Topics
Library of Functions for Tasks
sprint
906
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
frexp
Task function category: Mathematical Functions
Breaks a floating-point number into a normalized fraction and an integral power of 2. Returns
an array of 2 elements, the first element being the normalized fraction and the second element
being the integral power of 2.
Usage
frexp(x)
Arguments
• x
Floating point number.
Examples
set res = frexp(2.5)
set frac = res[res.imin]
set int_pow = res[res.imin + 1]
fprint(stdout, "frexp(2.5) = [%.4f, %.4f]\n", frac, int_pow)
/* Display: frexp(2.5) = [0.6250, 2.0000] */
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 907

Eldo Control Language
Library of Functions for Tasks
fscan
Task function category: Functions Operating on Files
Returns the number of elements that have been parsed. It has the same behavior as the C fscanf
function.
Usage
fscan(FILE, FORMAT, [,ARG]*)
Arguments
• FILE
File variable.
• FORMAT
FORMAT is a string that contains:
whitespace characters (space, newline and tab characters); they are read and ignored.
non-whitespace characters: sscan will read one character from STR_TO_PARSE and if
it does not match then sscan will return, otherwise the processing of the FORMAT
string continues.
format tags that must follow this specification:
%[*][width]specifier
where:
specifier is:
c for a character
d or i or u for an integer number
e, E, f, g, or G for a double-precision floating-point number
s for a string
x or X for an hexadecimal integer number
% to read the % character
* specifies that the corresponding data must be read but ignored; no argument must
be added for it.
width specifies the maximum number of characters to read.
An argument of the corresponding type must be specified for each format tag present in the
FORMAT argument (except for a format tag preceded with *).
• ARG
Optional. An argument of the corresponding type must be specified for each format tag
present in the FORMAT argument.
908
Eldo® User's Manual, 15.3

Examples
Eldo Control Language
Library of Functions for Tasks
.define_task parse_file
/* Same example but using fscan instead of fgets and strtok. */
set vdd = 0.0 /* Be careful to declare vdd as a floating point number
(required for '%f'). */
set temp = 0 /* Be careful to declare temp as an integer(required for
'%d'). */
set corner = "" /* Be careful to declare corner as a string(required for
'%s'). */
set myfile = fopen("./corners.txt", "r")
while(fscan(myfile, "vdd=%f, temp=%d, corner=%s\n", vdd, temp, corner)
== 3)
fprint(stdout, "Parsed line: vdd=%.4e, temp=%d, corner=%s\n", vdd,
temp, corner)
endwhile
fclose(myfile)
.end_define_task
Related Topics
Library of Functions for Tasks
sscan
fprint
fclose
Tasks
Variables
Flow Control Statements
Eldo® User's Manual, 15.3 909

Eldo Control Language
Library of Functions for Tasks
hypot
Task function category: Mathematical Functions
Computes the length of the hypotenuse of a right angle triangle.
Usage
hypot(x, y)
Arguments
• x
Length of side.
• y
Length of side.
Description
Computes the length of the hypotenuse of a right triangle: .
Related Topics
Library of Functions for Tasks
910
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
ifft
Task function category: Functions Operating on Waveforms
Calculates the inverse Fast Fourier Transform of the input waveform.
Usage
ifft(wf)
ifft(wf, start_frequency)
ifft(wf, start_frequency, stop_frequency)
ifft(wf, start_frequency, stop_frequency, sampling_time)
ifft(wf, start_frequency, stop_frequency, sampling_time,
number_of_points)
ifft(wf, start_frequency, stop_frequency, sampling_time,
number_of_points, sampling)
ifft(wf, start_frequency, stop_frequency, sampling_time,
number_of_points, sampling, padding)
ifft(wf, start_frequency, stop_frequency, sampling_time,
number_of_points, sampling, padding, normalized)
Arguments
• wf
Specifies the input waveform name.
• start_frequency
Specifies the start frequency of the signal.
• stop_frequency
Specifies the stop frequency of the signal.
• sampling_time
Specifies the sampling time of the signal.
• number_of_points
Specifies the number of sampling points.
• sampling
Specifies the method of computing the sampled data. Valid values are “No Sampling” or
“Interpolation”.
• padding
Activates data padding to pad the input data with zeros, before or after the input data set.
Valid values are: “No Padding”, “Padding Right”, “Padding Left”, and “Padding Left and
Right”. The input parameter will be verified by the algorithm and changed if necessary.
• normalized
Specifies whether to normalize the data. Specify 0 to use the raw data from the calculation
unmodified. Specify 1 to normalize the raw data.
Eldo® User's Manual, 15.3 911

Eldo Control Language
Library of Functions for Tasks
Description
For symmetric windows, the parameters above satisfy the following equation:
((number_of_points) / sampling_frequency) = stop_frequency - start_frequency.
For periodic windows, the parameters above satisfy the following equation:
((number_of_points-1) / sampling_frequency) = stop_frequency - start_frequency.
Related Topics
Library of Functions for Tasks
fft
912
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
imag
Task function category: Mathematical Functions Operating on Complex Numbers, Functions
Operating on Waveforms
Imaginary part function.
Usage
Complex Number Function
imag(c)
Waveform Function
imag(wf)
imag(wf, x_start, x_end)
Arguments
Complex Number Function
• c
Input complex number.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Complex Number Function
Returns the imaginary part of the input complex number c.
Waveform Function
Returns the imaginary part of the input complex waveform wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
real
Eldo® User's Manual, 15.3 913

Eldo Control Language
Library of Functions for Tasks
imax
Task function category: Functions Operating on Arrays
Returns the index of the maximum value of the elements of the array array. If istart and istop are
specified, this function applies to the part of array beginning at index istart and ending at index
istop.
Usage
imax(array [, istart, istop])
Arguments
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
Related Topics
Library of Functions for Tasks
imin
skew
914
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
imin
Task function category: Functions Operating on Arrays
Returns the index of the minimum value of the elements of the array array. If istart and istop are
specified, this function applies to the part of array beginning at index istart and ending at index
istop.
Usage
imax(array [, istart, istop])
Arguments
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
Related Topics
Library of Functions for Tasks
skew
Eldo® User's Manual, 15.3 915

Eldo Control Language
Library of Functions for Tasks
int
Task function category: Mathematical Functions
Integer value of VAL.
Usage
int(VAL)
Arguments
• VAL
Value.
Description
Equivalent to trunc.
Related Topics
Library of Functions for Tasks
trunc
916
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
integ
Task function category: Functions Operating on Waveforms
Returns the definite integral value with upper and lower limits of a waveform.
Usage
integ(wf)
integ(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Related Topics
Library of Functions for Tasks
derive
drv
integral
Eldo® User's Manual, 15.3 917

Eldo Control Language
Library of Functions for Tasks
integral
Task function category: Functions Operating on Waveforms
Computes the indefinite integral (also known as anti-derivative) of the input waveform (the
result is a waveform).
Usage
integral(wf)
integral(wf, y0)
integral(wf, y0, x_start, x_end)
Arguments
• wf
Waveform identifier.
• y0
Integration constant.
• x_start
Waveform start point.
• x_end
Waveform end point.
Related Topics
Library of Functions for Tasks
drv
918
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
intersect
Task function category: Functions Operating on Waveforms
Returns a vector containing all of the intersection points of two waveforms. If the slopes are
supplied, the result will be collected only when the waveforms have the specified slopes.
Note
Does not support complex waveforms (but it is possible to call it separately on the real part
and the complex part or on the magnitude and phase of a complex waveform).
Usage
intersect(wf1, wf2)
intersect(wf1, wf2, with_y)
intersect(wf1, wf2, x_start, x_end)
intersect(wf1, wf2, x_start, x_end, with_y)
intersect(wf1, wf2, slope_wf1, slope_wf2)
intersect(wf1, wf2, slope_wf1, slope_wf2x_start, x_end)
intersect(wf1, wf2, slope_wf1, slope_wf2x_start, x_end, with_y)
Arguments
• wf1
First waveform identifier.
• wf2
Second waveform identifier.
• with_y
Valid values for with_y are 0 and 1. If with_y==0 (default), then the function returns a
vector. If with_y==1, then the function returns a matrix; its first line is a vector containing
the X values of the intersection points and the second line is a vector containing the
corresponding Y values.
• x_start
Waveform start point.
• x_end
Waveform end point.
• slope_wf1, slope_wf2
Valid values for slope_wf1 and slope_wf2 are: pos, neg, or either.
• slope_wf2x_start
Slope of second waveform at start point. Valid values are: pos, neg, or either.
Eldo® User's Manual, 15.3 919

Eldo Control Language
Library of Functions for Tasks
Examples
set v_intersect[]=0
set mat_intersect[]=0
set i = 0
mat_intersect = intersect(wave1, wave2, 1)
fprint(stdout, "Intersection points are:\n")
for (i=mat_intersect[1].imin; i

Eldo Control Language
Library of Functions for Tasks
isarray
Task function category: Functions Operating on Arrays
Returns 1 if var is an array, 0 otherwise.
Usage
isarray(var)
Arguments
• var
Variable name.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 921

Eldo Control Language
Library of Functions for Tasks
iscompound
Task function category: Functions Operating on Compound Waveforms
Returns 1 if wf is a compound waveform, 0 otherwise.
Usage
iscompound(wf)
Arguments
• wf
Waveform identifier.
Related Topics
Library of Functions for Tasks
compoundcontent
922
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
kurt
Task function category: Functions Operating on Arrays
Returns the fourth standardized moment also known as sample kurtosis (unbiased value if bias
is 0, biased value otherwise) of the elements of the array array.
Usage
kurt(array [, istart, istop], bias)
Arguments
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
• bias
Bias value. Set to 0 for unbiased value.
Description
If istart and istop are specified, this function applies to the part of array beginning at index istart
and ending at index istop.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 923

Eldo Control Language
Library of Functions for Tasks
ldexp
Task function category: Mathematical Functions
Returns the value x multiplied by 2 raised to the power y (computes the quantity: x × 2y).
Usage
ldexp(x, y)
Arguments
• x
x value.
• y
y value.
Related Topics
Library of Functions for Tasks
924
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
limit
Task function category: Mathematical Functions
Returns b if a < b, returns c if a > c, returns a otherwise.
Usage
limit(a, b, c)
Arguments
• a
a value.
• b
b value.
• c
c value.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 925

Eldo Control Language
Library of Functions for Tasks
log
Task function category: Mathematical Functions, Mathematical Functions Operating on
Complex Numbers, Functions Operating on Waveforms
Natural logarithm function.
Usage
Mathematical Function
log(VAL)
unsafe_log(VAL)
Complex Number Function
log(c)
unsafe_log(c)
Waveform Function
log(wf)
log(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Complex Number Function
• c
Input complex number.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Natural logarithm of VAL. log will exit properly if VAL is negative or null.
926
Eldo® User's Manual, 15.3

Complex Number Function
Natural logarithm of complex number c. log will exit properly if c is (0, 0).
Waveform Function
Natural logarithm of the input waveform (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
log10
Eldo Control Language
Library of Functions for Tasks
Eldo® User's Manual, 15.3 927

Eldo Control Language
Library of Functions for Tasks
log10
Task function category: Mathematical Functions, Mathematical Functions Operating on
Complex Numbers, Functions Operating on Waveforms
Decimal (base 10) logarithm function.
Usage
Mathematical Function
log10(VAL)
unsafe_log10(VAL)
Complex Number Function
log10(c)
unsafe_log10(c)
Waveform Function
log10(wf)
log10(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Complex Number Function
• c
Input complex number.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Decimal logarithm of VAL. log10 will exit properly if VAL is negative or null.
928
Eldo® User's Manual, 15.3

Complex Number Function
Decimal logarithm of complex number c. log10 will exit properly if c is (0, 0).
Waveform Function
Decimal logarithm of the input waveform (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
log
Eldo Control Language
Library of Functions for Tasks
Eldo® User's Manual, 15.3 929

Eldo Control Language
Library of Functions for Tasks
magnitude
Task function category: Mathematical Functions Operating on Complex Numbers, Functions
Operating on Waveforms
Returns the absolute magnitude.
Usage
Complex Number Function
magnitude(c)
Waveform Function
magnitude(wf)
magnitude(wf, x_start, x_end)
Arguments
Complex Number Function
• c
Input complex number.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Complex Number Function
Returns the absolute magnitude of the input complex number c.
Waveform Function
Returns the absolute magnitude of the input complex waveform wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
930
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
max
Task function category: Mathematical Functions, Functions Operating on Arrays, Functions
Operating on Waveforms
Returns the maximum value.
Usage
Mathematical Function
max(VAL1,..., VALn)
dmax(VAL1,...,VALn)
Array Function
max(array [, istart, istop])
Waveform Function
max(wf)
max(wf, x_start, x_end)
max(wf, x_start, x_end, with_x_at_max)
Arguments
Mathematical Function
• VAL1
First value.
• VALn
n th value. There is no limit to the number of values that can be specified.
Array Function
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
Eldo® User's Manual, 15.3 931

Eldo Control Language
Library of Functions for Tasks
• x_end
Waveform end point.
• with_x_at_max
Valid values for with_x_at_max are 0 and 1. If with_x_at_max==0 (default), then the
function returns a double-precision floating-point value. If with_x_at_min==1, then the
function returns a vector of two elements. The first element is the X value at the maximum
and the second element is the Y maximum value.
Return Values
Mathematical Function
Returns the maximum of VAL1 to VALn.
Array Function
Returns the maximum value off the elements of the array array. If istart and istop are specified,
this function applies to the part of array beginning at index istart and ending at index istop.
Waveform Function
Returns the maximum value of a waveform. If the input waveform is complex, it returns the
largest magnitude of its elements.
Examples
Waveform function example:
set fmax = 0
set vxymax[] = 0
fmax = max(wave1)
fprint(stdout, "the maximum Y value is: %.4e\n", fmax)
vxymax = max(wave1, 10, 40, 1)
fprint(stdout, "the maximum Y value between 10 and 40 is: %.4e and is
reached at %.4e\n",
+ vxymax[2], vxymax[1])
Related Topics
imin
min
Library of Functions for Tasks
skew
932
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
mcconv
Task function category: Functions Operating on Arrays
Returns 1 or 0 to indicate convergence of the Monte Carlo process for the elements of the array
array.
Usage
mcconv(array, "AVG"|"STD", "CONFIDENCE" [,nrun_pilot [, confidence_level
[, abstol [, reltol]]]])
Arguments
• array
Array.
• AVG | STD
The Monte Carlo analysis has converged when the confidence interval is small. This
algorithm is defined for AVG and STD; not for SKEW, or KURT.
• CONFIDENCE
When the CONFIDENCE algorithm is specified, the default values are NRUN_PILOT=20,
CONFIDENCE_LEVEL=0.95, ABSTOL=0.01, and RELTOL=0.01. For example, a 99%
confidence interval will correspond to CONFIDENCE_LEVEL=0.99.
Related Topics
Library of Functions for Tasks
_simu_get_mcsens
Eldo® User's Manual, 15.3 933

Eldo Control Language
Library of Functions for Tasks
mcnbench
Task function category: Functions Operating on Arrays
Returns the number of non-UNDEF values among the elements of the array array. If istart and
istop are specified, this function applies to the part of array beginning at index istart and ending
at index istop.
Usage
mcnbench(array [, istart, istop])
Arguments
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
Related Topics
Library of Functions for Tasks
934
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
min
Task function category: Mathematical Functions, Functions Operating on Arrays, Functions
Operating on Waveforms
Returns the minimum value.
Usage
Mathematical Function
min(VAL1,..., VALn)
dmin(VAL1,...,VALn)
Array Function
min(array [, istart, istop])
Waveform Function
min(wf)
min(wf, x_start, x_end)
min(wf, x_start, x_end, with_x_at_min)
Arguments
Mathematical Function
• VAL1
First value.
• VALn
n τη value. There is no limit to the number of values that can be specified.
Array Function
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
Eldo® User's Manual, 15.3 935

Eldo Control Language
Library of Functions for Tasks
• x_end
Waveform end point.
• with_x_at_min
Valid values for with_x_at_min are 0 and 1. If with_x_at_min==0, then the function returns
a double-precision floating-point value. If with_x_at_min==1, then the function returns a
vector of two elements. The first element is the X value at the minimum and the second
element is the Y minimum value.
Return Values
Mathematical Function
Returns the minimum of VAL1 to VALn.
Array Function
Returns the minimum value off the elements of the array array. If istart and istop are specified,
this function applies to the part of array beginning at index istart and ending at index istop.
Waveform Function
Returns the minimum value of a waveform. If the input waveform is complex, it returns the
smallest magnitude of its elements.
Related Topics
Library of Functions for Tasks
max
936
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
mod
Task function category: Mathematical Functions
Modulo operator. Floating-point remainder value function of dividing x by y. Returns the value
x − i×y, where i is the quotient of x/y, rounded towards zero to an integer. mod will exit properly
if y is equal to 0.
Usage
mod(x, y)
unsafe_mod(x, y)
Arguments
• x
x value.
• y
y value.
Related Topics
Library of Functions for Tasks
Numbers
Eldo® User's Manual, 15.3 937

Eldo Control Language
Library of Functions for Tasks
modf
Task function category: Mathematical Functions
Breaks the argument x into integral and fractional parts, each of which has the same sign as the
argument. Returns an array of two elements, the first element being the fractional part and the
second element being the integral part.
Usage
modf(x)
Arguments
• x
x value.
Examples
set res = modf(2.5)
set frac = res[res.imin]
set int = res[res.imin + 1]
fprint(stdout, "modf(2.5) = [%.4f, %.4f]\n", frac, int)
/* Display: modf(2.5) = [0.5000, 2.0000] */
Related Topics
Library of Functions for Tasks
938
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
mptpcomplex
Task function category: Mathematical Functions Operating on Complex Numbers
Constructs a complex number from its magnitude m and its phase in radians p.
Usage
mptocomplex(m, p)
Arguments
• m
Magnitude.
• p
Phase in radians.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 939

Eldo Control Language
Library of Functions for Tasks
nextval
Task function category: Functions Operating on Waveforms
Returns the next point of a waveform. Returns 0 if there are no more points in the waveform,
otherwise x_res and y_res are set with the coordinates of the next point of the waveform.
Usage
nextval(wf, x_res, y_res)
Arguments
• wf
Waveform identifier.
• x_res
Variable name for X coordinate of next point in waveform. Must be a double-precision
floating-point variable otherwise an error is generated.
• y_res
Variable name for Y coordinate of next point in waveform. Must be a double-precision
floating-point variable otherwise an error is generated. If wf is a complex waveform, then
y_res must be a complex number.
Description
Must be called after beginval.
Examples
Example 1:
/* here, the float value 0.0 and not the integer 0 must be assigned to x
and y otherwise there will be an error when calling beginval and nextval.
*/
set x = 0.0
set y = 0.0
set iter = 0
iter = beginval(wave1, x, y)
while (iter != 0)
fprint(stdout, "(%12.4e;%12.4e)\n", x, y)
iter = nextval(wave1, x, y)
endwhile
Example 2:
940
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
set x = 0.0
/* here, a complex value must be assigned to y otherwise there will be an
error when calling beginval and nextval. */
set y = ritocomplex(0.0, 0.0)
set iter = 0
iter = beginval(complex_wave1, x, y)
while (iter != 0)
fprint(stdout, "(%12.4e;(%12.4e, %12.4e))\n", x, real(y), imag(y))
iter = nextval(wave1, x, y)
endwhile
Related Topics
Library of Functions for Tasks
beginval
Variables
Flow Control Statements
fprint
Eldo® User's Manual, 15.3 941

Eldo Control Language
Library of Functions for Tasks
ongrid
Task function category: Mathematical Functions
Returns 1 if value=offset + (k×step) where k is an integer value. Otherwise it returns 0. The
default value of offset is 0.0.
Usage
ongrid([offset], step, value)
Arguments
• offset
Optional. Offset value.
• step
Step value.
• value
Value.
Related Topics
Library of Functions for Tasks
942
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
phase
Task function category: Mathematical Functions Operating on Complex Numbers, Functions
Operating on Waveforms
Returns the phase.
Usage
Complex Number Function
phase(c)
Waveform Function
phase(wf)
phase(wf, x_start, x_end)
Arguments
Complex Number Function
• c
Input complex number.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Complex Number Function
Returns the phase (or argument) of the input complex number c in radians, limited to [-pi, pi].
Waveform Function
Returns the phase of the input complex waveform wf in radians, limited to [-pi, pi] (the result is
a waveform).
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 943

Eldo Control Language
Library of Functions for Tasks
pow
Task function category: Mathematical Functions
Returns the value of VAL1 to the power of the integer part of VAL2. pow will exit properly if
VAL1 is a equal to 0 and VAL2 is negative.
Usage
pow(VAL1, VAL2)
unsafe_pow(VAL1, VAL2)
Arguments
• VAL1
Value 1.
• VAL2
Value 2.
Related Topics
Library of Functions for Tasks
pow_10
Numbers
944
Eldo® User's Manual, 15.3

pow_10
Task function category: Functions Operating on Waveforms
Eldo Control Language
Library of Functions for Tasks
Computes the value of 10 raised to the power of wf: 10 wf (the result is a waveform).
Usage
pow_10(wf)
Arguments
• wf
Waveform identifier.
Related Topics
Library of Functions for Tasks
exp
Eldo® User's Manual, 15.3 945

Eldo Control Language
Library of Functions for Tasks
pwr
Task function category: Mathematical Functions
Returns the absolute value of VAL1, raised to the power of VAL2, with the sign of VAL1. pwr
will exit properly if VAL1 is a equal to 0 and VAL2 is negative.
Usage
pwr(VAL1, VAL2)
unsafe_pwr(VAL1, VAL2)
Arguments
• VAL1
Value 1.
• VAL2
Value 2.
Related Topics
Library of Functions for Tasks
pow
Numbers
946
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
real
Task function category: Mathematical Functions Operating on Complex Numbers, Functions
Operating on Waveforms
Real part function.
Usage
Complex Number Function
real(c)
Waveform Function
real(wf)
real(wf, x_start, x_end)
Arguments
Complex Number Function
• c
Input complex number.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Complex Number Function
Returns the real part of the input complex number c.
Waveform Function
Returns the real part of the input complex waveform wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
imag
Eldo® User's Manual, 15.3 947

Eldo Control Language
Library of Functions for Tasks
relation
Task function category: Functions Operating on Waveforms
Generates a waveform from a point-by-point relational expression.
Usage
relation(wf1, wf2, op)
Arguments
• wf1
First waveform identifier.
• wf2
Second waveform identifier.
• op
Valid values for op are 1, 0, and -1 where 1 stands for “greater than”, 0 for “equals” and -1
for “less than”.
Return Values
It returns 1 corresponding to the scalar value op:
if op = 1 and wf1 > wf2,
or if op = 0 and wf1 = wf2,
or if op = -1 and wf1 < wf2;
otherwise 0 is returned.
Related Topics
Library of Functions for Tasks
948
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
ritocomplex
Task function category: Mathematical Functions Operating on Complex Numbers
Constructs a complex number from its real part r and its imaginary part i.
Usage
ritocomplex(r, i)
Arguments
• r
Real part of complex number.
• i
Imaginary part of complex number.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 949

Eldo Control Language
Library of Functions for Tasks
rms
Task function category: Functions Operating on Waveforms
Returns the root mean square value of a waveform.
Usage
rms(wf)
rms(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
The root mean square value of a waveform is computed as:
if X domain is Frequency or
otherwise.
Related Topics
Library of Functions for Tasks
rms_ac
rms_noise
rms_tran
950
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
rms_ac
Task function category: Functions Operating on Waveforms
Returns the root mean square value of a waveform for AC analysis.
Usage
rms_ac(wf)
rms_ac(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
The root mean square value is computed as:
Related Topics
Library of Functions for Tasks
rms
rms_noise
rms_tran
Eldo® User's Manual, 15.3 951

Eldo Control Language
Library of Functions for Tasks
rms_noise
Task function category: Functions Operating on Waveforms
Returns the root mean square value of a waveform for noise analysis.
Usage
rms_noise(wf)
rms_noise(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
The root mean square value is computed as:
Related Topics
Library of Functions for Tasks
rms
rms_ac
rms_tran
952
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
rms_tran
Task function category: Functions Operating on Waveforms
Returns the root mean square value of a waveform for transient analysis.
Usage
rms_ac(wf)
rms_ac(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
The root mean square value of a waveform for transient analysis is computed as:
Related Topics
Library of Functions for Tasks
rms
rms_ac
rms_noise
Eldo® User's Manual, 15.3 953

Eldo Control Language
Library of Functions for Tasks
round
Task function category: Mathematical Functions
Returns value of VAL rounded to the nearest integer.
Usage
round(VAL)
Arguments
• VAL
Value.
Related Topics
Library of Functions for Tasks
954
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
sgn
Task function category: Mathematical Functions
Returns the signum of VAL: +1 if VAL>0, 0 if VAL=0, -1 if VAL

Eldo Control Language
Library of Functions for Tasks
sign
Task function category: Mathematical Functions
Returns the signum of VAL1: +1 if VAL1>=0, -1 if VAL1

Eldo Control Language
Library of Functions for Tasks
sin
Task function category: Mathematical Functions, Functions Operating on Waveforms
Sine function.
Usage
Mathematical Function
sin(VAL)
Waveform Function
sin(wf)
sin(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Sine of VAL.
Waveform Function
Sine of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 957

Eldo Control Language
Library of Functions for Tasks
sinh
Task function category: Mathematical Functions, Functions Operating on Waveforms
Hyperbolic sine function.
Usage
Mathematical Function
sinh(VAL)
Waveform Function
sinh(wf)
sinh(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Return Values
Mathematical Function
Hyperbolic sine of VAL.
Waveform Function
The hyperbolic sine of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
958
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
size
Task function category: Functions Operating on Waveforms
Returns the number of points of a waveform.
Usage
size(wf)
size(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 959

Eldo Control Language
Library of Functions for Tasks
skew
Task function category: Functions Operating on Arrays
Returns the third standardized moment also known as sample skewness (unbiased value if bias
is 0, biased value otherwise) of the elements of the array array.
Usage
skew(array [, istart, istop], bias)
Arguments
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
• bias
Bias value. Set to 0 for unbiased value.
Description
If istart and istop are specified, this function applies to the part of array beginning at index istart
and ending at index istop.
Related Topics
Library of Functions for Tasks
960
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
sprint
Task function category: Functions Operating on Strings
Returns a formatted string; same behavior as the C sprintf function.
Usage
sprint(FORMAT [,ARG]*)
Arguments
• FORMAT
FORMAT is a string that contains the text to be formatted. This string can contain format
tags. A format tag must follow this specification:
%[flags][width][.precision]specifier
where:
specifier is:
c for a character
d or i or u for an integer number
e or E for a double precision floating point number in scientific notation
f for a double-precision floating-point number; the default precision is 6 digits
g or G to use the shorter of %f or %e or %E
s for a string
x or X for an hexadecimal integer number
% to print the % character
flags is:
- to force left justification within the given width
+ to force the sign to be always written
“ ” to insert a space before a number for which no sign is written
# to specify if 0x or 0X must be written before a not null hexadecimal number or to
specify if “.” must be always written for a double-precision floating-point number
0 to insert zeroes instead of spaces before a number
width is the minimum number of characters to be displayed (spaces are added if
necessary)
precision is the minimum number of digits to be written for integers (zeroes are added if
necessary).
or is the minimum number of digits to be written after the “.” for e, E and f specifiers.
or is the maximum number of significant digits for g or G specifiers.
or is the maximum number of characters to be written for string.
Eldo® User's Manual, 15.3 961

Eldo Control Language
Library of Functions for Tasks
• ARG
Optional. An argument of the corresponding type must be specified for each format tag
present in the FORMAT argument.
Examples
Example:
set t[] = 0
set y[] = 0
set s = ""
set i = 0
t[0] = -1
y[0] = 0
t[1] = 0
y[1] = 1.578
t[2] = 1
y[2] = 15.71
t[3] = 10
y[3] = 203.8
s = sprint("(% 3d;%12.4e)\n\
(% 3d;%12.4e)\n\
(% 3d;%12.4e)\n\
(% 3d;%12.4e)\n",\
t[0], y[0], t[1], y[1], t[2], y[2], t[3], y[3])
fprint(stdout, "%s", s)
The output of the previous example is:
( -1; 0.000e+00)
( 0; 1.578e+00)
( 1; 1.571e+01)
( 10; 2.038e+02)
Ensure you provide adequate precision for the %f output format, or use the %e, %E, %g, or %G
format. For example, if the variable to be printed is smaller than 1e-6, it cannot be represented
with the %f format without changing the precision:
set myvar=1n
fprint(stdout, "Result %s: %f\n", "%f", myvar)
fprint(stdout, "Result %s: %.9f\n", "%.9f", myvar)
fprint(stdout, "Result %s: %e\n", "%e", myvar)
will output:
Result %f: 0.000000
Result %.9f: 0.000000001
Result %e: 1.000000e-09
Related Topics
Library of Functions for Tasks
fprint
962
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
sqr
Task function category: Mathematical Functions, Functions Operating on Waveforms
Square function.
Usage
Mathematical Function
sqr(VAL)
Waveform Function
sqr(wf)
sqr(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Mathematical Function
Computes the square of VAL: val 2 .
Waveform Function
Computes the square of the input argument: wf 2 (the result is a waveform).
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 963

Eldo Control Language
Library of Functions for Tasks
sqrt
Task function category: Mathematical Functions, Functions Operating on Waveforms
Square root function.
Usage
Mathematical Function
sqrt(VAL)
unsafe_sqrt(VAL)
Waveform Function
sqrt(wf)
sqrt(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Mathematical Function
Square root of VAL. sqrt will exit properly if VAL is negative.
Waveform Function
Square root of the input waveform (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
964
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
sscan
Task function category: Functions Operating on Strings
Returns the number of elements that have been parsed. Same behavior as the C sscanf function.
Usage
sscan(STR_TO_PARSE, FORMAT [,ARG]*)
Arguments
• STR_TO_PARSE
String to be parsed.
• FORMAT
FORMAT is a string that contains:
whitespace characters (space, newline and tab characters); they are read and ignored.
non-whitespace characters: sscan will read one character from STR_TO_PARSE and if
it does not match then sscan will return, otherwise the processing of the FORMAT
string continues.
format tags that must follow this specification:
%[*][width]specifier
where:
specifier is:
c for a character
d or i or u for an integer number
e, E, f, g, or G for a double-precision floating-point number
s for a string
x or X for an hexadecimal integer number
% to read the % character
* specifies that the corresponding data must be read but ignored; no argument must
be added for it.
width specifies the maximum number of characters to read.
An argument of the corresponding type must be specified for each format tag present in the
FORMAT argument (except for a format tag preceded with *).
• ARG
Optional. An argument of the corresponding type must be specified for each format tag
present in the FORMAT argument.
Eldo® User's Manual, 15.3 965

Eldo Control Language
Library of Functions for Tasks
Examples
set s1 = "str1 12 25.3"
set s2 = "1 2 3 4 5 6 7 8 9 10"
set sRes = ""
set iRes =0
set vRes[] = 0
set fRes = 0.0 /*f must be declared as a real otherwise error. */
sscan(s1, "%s %d %f", sRes, iRes, fRes)
sscan(s2, "%d %d %d %d %d %d %d %d %d %d",
+vRes[1] , vRes[2] , vRes[3] , vRes[4] , vRes[5] ,
+vRes[6] , vRes[7] , vRes[8] , vRes[9] , vRes[10])
Related Topics
Library of Functions for Tasks
system
966
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
std
Task function category: Functions Operating on Arrays
Returns the standard deviation (unbiased value) of the elements of the array array.
Usage
std(array [, istart, istop])
Arguments
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
Description
If istart and istop are specified, this function applies to the part of array beginning at index istart
and ending at index istop.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 967

Eldo Control Language
Library of Functions for Tasks
strtok
Task function category: Functions Operating on Strings
Returns a vector containing the parsed tokens.
Usage
strtok(STR_TO_PARSE, STR_SEPARATORS)
Arguments
• STR_TO_PARSE
String to parse.
• STR_SEPARATORS
Separators present in string.
Examples
set s = "tok1;tok2\ntok3;tok4"
set v = strtok(s, ";\n")
set i = 0
for (i=v.imin; i

Eldo Control Language
Library of Functions for Tasks
sum
Task function category: Functions Operating on Waveforms
Returns the sum of all the Y values of a waveform. If the input waveform is complex, then the
sum function is applied on its real part.
Usage
sum(wf)
sum(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Related Topics
Library of Functions for Tasks
Eldo® User's Manual, 15.3 969

Eldo Control Language
Library of Functions for Tasks
system
Task function category: Functions Operating on Files
Executes the STR_CMD shell command. If no other argument is passed, the result of the
command is displayed on the standard output, otherwise the result is stored in the string
STR_RES, which can be parsed to get the result.
Usage
system(STR_CMD [,STR_RES])
Arguments
• STR_CMD
Shell command.
• STR_RES
String containing the result.
Examples
.define_testbench tb_simu_file (file="")
.include file
.end_define_testbench
.define_task simu_files
set files = ""
set i = 0
set v [] = ""
set res = system("cd ~/testcase;ls *.cir", files)
v = strtok(files, "\n")
for (i=v.imin; i

Eldo Control Language
Library of Functions for Tasks
tan
Task function category: Mathematical Functions, Functions Operating on Waveforms
Tangent function.
Usage
Mathematical Function
tan(VAL)
unsafe_tan(VAL)
Waveform Function
tan(wf)
tan(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Mathematical Function
Tangent of VAL. tan will exit properly if VAL is a multiple of pi/2.
Waveform Function
Tangent of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
Numbers
Eldo® User's Manual, 15.3 971

Eldo Control Language
Library of Functions for Tasks
tanh
Task function category: Mathematical Functions, Functions Operating on Waveforms
Hyperbolic tangent function.
Usage
Mathematical Function
tanh(VAL)
Waveform Function
tanh(wf)
tanh(wf, x_start, x_end)
Arguments
Mathematical Function
• VAL
Value.
Waveform Function
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Mathematical Function
Hyperbolic tangent of VAL.
Waveform Function
Hyperbolic tangent of wf (the result is a waveform).
Related Topics
Library of Functions for Tasks
972
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
trunc
Task function category: Mathematical Functions
Truncated value of VAL (integer part of real value).
Usage
trunc(VAL)
Arguments
• VAL
Value.
Description
Equivalent to int.
Related Topics
Library of Functions for Tasks
int
Eldo® User's Manual, 15.3 973

Eldo Control Language
Library of Functions for Tasks
var
Task function category: Functions Operating on Arrays
Returns the variance (unbiased value) of the elements of the array array.
Usage
std(array [, istart, istop])
Arguments
• array
Array.
• istart
Optional. Array start index.
• istop
Optional. Array stop index.
Description
If istart and istop are specified, this function applies to the part of array beginning at index istart
and ending at index istop.
Related Topics
Library of Functions for Tasks
974
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
wadd_data_enum_value
Task function category: Functions Creating New Waveforms
This function must be used to define enumeration values for an enumerated data type created
with wcreate_data_type.
Usage
wadd_data_enum_value("data_type", "label", value)
Arguments
• "data_type"
Name of the data type. It must have been created with wcreate_data_type with a "-Enum"
type.
• "label"
Label displayed for this value.
• value
Value to add. It must be a positive integer.
Examples
For an example, see “wadd_data_enum_value” on page 975.The following example shows how
to display graphically the bandwidth of a RLC circuit.
Eldo® User's Manual, 15.3 975

Eldo Control Language
Library of Functions for Tasks
* Parallel RLC circuit.
vin 1 0 ac 10
r2 1 2 50
r3 2 3 50k
r5 3 0 50
l1 2 3 100u
c4 2 3 10n
.ac dec 10 1 1g
.option eps = 1.0e-6
.plot w2=v(2) w1=v(1)
.define_task plot_bandwidth
set w1 = 0
set w2 = 0
set w_db_gain = 0
set w_bandwidth = 0
set fcut[] = 0
/* Run the simulation and calculate gain. */
simulation(w1 = @w1, w2 = @w2)
/* Compute the gain and save the waveform. */
w_db_gain = db(w2 / w1)
wsave(wstdout, w_db_gain, "results")
/* Compute the -3dB bandwidth. */
fcut = xval(w_db_gain, -3)
if (fcut.size != 2)
fprint(stdout, "Failed to compute the -3dB bandwidth.\n")
return -1
else
fprint(stdout, "\n\t-3dB bandwidth = (%.2eHz, %.2eHz)\n",
fcut[fcut.imin], fcut[fcut.imin + 1])
endif
/* Create enum data type: 0: cut, 1: pass. */
wcreate_data_type("cut_pass", "-Enum")
wadd_data_enum_value("cut_pass", "cut", 0)
wadd_data_enum_value("cut_pass", "pass", 1)
/* Create the waveform showing graphically the -3dB bandwidth. */
w_bandwidth = wcreate_wave(wstdout, "bandwidth", "results",
"double_frequency", "cut_pass", "-LOG_X")
/* It is usually more efficient to create 2 vectors for x and y values
and call wset_values only once. But here since there are few values, it is
not a real problem to do this: */
wset_values(w_bandwidth, 1, 0)
wset_values(w_bandwidth, fcut[fcut.imin], 1)
wset_values(w_bandwidth, fcut[fcut.imin + 1], 0)
wset_values(w_bandwidth, 1G, 0)
fprint(stdout, "\n\tPlot of bandwidth succeeded.\n")
.end_define_task
976
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
.plot_bandwidth
.option set_eldo_cl_verbose=0
.option remove_eldo_cl_temp_files=3
.option keep_eldo_cl_temp_waves=0
Related Topics
Library of Functions for Tasks
wadd_scale
wcreate_data_type
wcreate_scale_table
wcreate_wave
wset_values
Testbenches
Tasks
Variables
Flow Control Statements
Defining and Running Simulations
fprint
Eldo® User's Manual, 15.3 977

Eldo Control Language
Library of Functions for Tasks
wadd_scale
Task function category: Functions Creating New Waveforms
This function is used to add sub-units to a scale table created with wcreate_scale_table.
Usage
wadd_scale("scale_table", "unit", unit_value)
Arguments
• "scale_table"
Name of a scale table created with wcreate_scale_table (for example "size").
• "unit"
Name of the sub-unit (for example: "m").
• unit_value
Multiple of the smallest sub-unit of the scale table corresponding to the sub-unit to add to
the scale table (for example: 1e15 for m if the smallest sub-unit of the scale table is fm).
Examples
For an example, see “wcreate_data_type” on page 980.
Related Topics
Library of Functions for Tasks
wadd_data_enum_value
wcreate_data_type
wcreate_scale_table
wcreate_wave
wset_values
978
Eldo® User's Manual, 15.3

Eldo Control Language
Library of Functions for Tasks
wclose
Task function category: Functions Operating on wdb Files
Saves (if the .wdb file was opened in write mode) and closes the .wdb file whose identifier is
wdbId.
Usage
wclose(wdbId)
Arguments
• wdbId
.wdb file identifier.
wstdout Variable
The main .wdb file (if the netlist run by the main Eldo process, containing the Control Language
task, is named netlist1.cir, then the main .wdb file will be by default netlist1.wdb) must not be
opened or closed using the functions wopen and wclose (otherwise the behavior will be
completely undefined). Instead, the predefined wstdout variable has to be used as the identifier
for this .wdb file. It is especially useful if the netlist is run with the option .option
keep_eldo_cl_temp_waves=0 to completely control how waveforms are saved in this file. See
“wdb File” in “Simulation” on page 1114.
Description
wdbId cannot be used anymore in any of the wdb management functions after the .wdb file has
been closed.
Related Topics
Library of Functions for Tasks
wget
wmkfolder
wopen
wsave
Eldo® User's Manual, 15.3 979

Eldo Control Language
Library of Functions for Tasks
wcreate_data_type
Task function category: Functions Creating New Waveforms
If the appropriate data type does not exist, it is possible to create it using this function.
Usage
wcreate_data_type("name", "base_type")
wcreate_data_type("name", "base_type", "scale_table")
Arguments
• "name"
Name of the new data type (it must be different from existing data types).
• "base_type"
Basic type of the values that will be allowed for this data type. It can be one of the following
strings:
"-Double" for double precision floating point values.
"-Long" for integer values.
"-Complex" for complex values.
"-Enum" to define an enumerated type (need to use wadd_data_enum_value then to
define the allowed values).
• "scale_table"
Name of the associated scale table (where units for this data type are defined). It can be one
of the following:
"Current" for a current scale table (sub-units: fA, pA, nA, …, A, …).
"Frequency" for a frequency scale table (sub-units: fHz, pHz, nHz, …, Hz, …).
"Magnitude" for a magnitude scale table (unit: dB).
"noise" for a noise scale table (unit: dBc).
"Phase" for a phase scale table (unit: radians).
"phased" for a phase scale table (unit: degrees).
"phaseg" for a phase scale table (unit: gradians).
"temperatureC" for a temperature scale table (unit: Celsius).
"temperatureK" for a temperature scale table (unit: Kelvin).
"Time" for a time scale table (sub-units: fs, ps, ns, …, s, …).
"Voltage" for a voltage scale table (sub-units: fV, pV, nV, …, V, …).
Any scale table created with wcreate_scale_table and wadd_scale.
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Examples
The following example shows how to create a “Size” data type and how to use it to plot the
evolution of the saturation drain current versus the gate width and the gate length.
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.define_testbench mos (vgs_val=1, vds_val=1, w_val=1u, l_val=1u)
m1 d g s s n w=w_val l=l_val
vgs g s vgs_val
vds d s vds_val
.connect d 0
.dc
.extract dc label=m1_ids '-i(vds)'
.extract dc label=m1_mode opmode(m1)
.end_define_testbench
.define_task plot_ids_sat_w_l
set w_res [] = 0
set l_res [] = 0
set ids_sat_w_res [] = 0
set ids_sat_l_res [] = 0
set w_ids_sat_w = 0
set w_ids_sat_l = 0
set w = 0
set l = 0
set vds = 0
set vds_min = 0
set vds_max = 5
set m1_ids = 0
set m1_mode = ""
set i = 0
set iter = 0
/**
* Compute ids_sat by dichotomy for many values of w.
*/
step (type = lin, param = w, start = 1u, stop = 5u, n = 20)
i++
w_res[i] = w
/* Check bounds. */
vds_min = 0
vds_max = 5
simulation(mos(w_val = w, vds_val=vds_min), m1_mode = @m1_mode, m1_ids
= @m1_ids)
if (m1_mode != "linear")
fprint(stdout, "Failed to find ids_sat for w=%em because with
vds=%eV, opmode(m1)=%s\n", w, vds_min, m1_mode)
return -1
endif
simulation(mos(w_val = w, vds_val=vds_max), m1_mode = @m1_mode, m1_ids
= @m1_ids)
if (m1_mode != "saturation")
fprint(stdout, "Failed to find ids_sat for w=%em because with
vds=%eV, opmode(m1)=%s\n", w, vds_max, m1_mode)
return -1
endif
/* Dichotomy. */
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iter = 0
while (abs(vds_max - vds_min) > 0.001 && iter < 50)
iter++
vds = vds_min + (abs(vds_max - vds_min) / 2)
simulation(mos(w_val = w, vds_val=vds), m1_mode = @m1_mode, m1_ids =
@m1_ids)
if (m1_mode == "linear")
vds_min = vds
else
vds_max = vds
endif
endwhile
if (iter >= 50)
fprint(stdout, "Failed to find ids_sat in less than 50 iterations for
w=%em.\n", w)
return -1
else
ids_sat_w_res[i] = m1_ids
endif
endstep
/**
* Compute ids_sat by dichotomy for many values of l.
*/
i = 0
step (type = lin, param = l, start = 1u, stop = 5u, n = 20)
i++
l_res[i] = l
/* Check bounds. */
vds_min = 0
vds_max = 5
simulation(mos(l_val = l, vds_val=vds_min), m1_mode = @m1_mode, m1_ids
= @m1_ids)
if (m1_mode != "linear")
fprint(stdout, "Failed to find ids_sat for l=%em because with
vds=%eV, opmode(m1)=%s\n", l, vds_min, m1_mode)
return -1
endif
simulation(mos(l_val = l, vds_val=vds_max), m1_mode = @m1_mode, m1_ids
= @m1_ids)
if (m1_mode != "saturation")
fprint(stdout, "Failed to find ids_sat for l=%em because with
vds=%eV, opmode(m1)=%s\n", l, vds_max, m1_mode)
return -1
endif
/* Dichotomy. */
iter = 0
while (abs(vds_max - vds_min) > 0.001 && iter < 50)
iter++
vds = vds_min + (abs(vds_max - vds_min) / 2)
simulation(mos(l_val = l, vds_val=vds), m1_mode = @m1_mode, m1_ids =
@m1_ids)
if (m1_mode == "linear")
vds_min = vds
else
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vds_max = vds
endif
endwhile
if (iter >= 50)
fprint(stdout, "Failed to find ids_sat in less than 50 iterations for
l=%em.\n", l)
return -1
else
ids_sat_l_res[i] = m1_ids
endif
endstep
/**
* Plot the waveforms.
*/
/* Create the scale table. */
wcreate_scale_table("Size", "Sizes", "fm", 1e-15)
wadd_scale("Size", "pm", 1e3)
wadd_scale("Size", "nm", 1e6)
wadd_scale("Size", "um", 1e9)
wadd_scale("Size", "mm", 1e12)
wadd_scale("Size", "m", 1e15)
wadd_scale("Size", "km", 1e18)
/* Create the data type. */
wcreate_data_type("double_size", "-Double", "Size")
/* Create the waveforms. */
w_ids_sat_w = wcreate_wave(wstdout, "ids_sat(w)", "results",
w_res,ids_sat_w_res, "double_size", "double_current")
w_ids_sat_l = wcreate_wave(wstdout, "ids_sat(l)", "results", l_res,
ids_sat_l_res, "double_size", "double_current")
fprint(stdout, "\n\tPlot ids_sat(w) and ids_sat(l) succeeded.\n")
end_define_task
.plot_ids_sat_w_l
.option set_eldo_cl_verbose=0
.option remove_eldo_cl_temp_files=3
.model n nmos
+ level = 53 U0 = 0.041
+ Lmin = 5E-7 Lmax = 0.01
+ Wmin = 6E-7 Wmax = 0.01
*
…
Related Topics
Library of Functions for Tasks
wadd_data_enum_value
wadd_scale
wcreate_scale_table
wcreate_wave
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Library of Functions for Tasks
wset_values
Testbenches
Tasks
Variables
Defining and Running Simulations
fprint
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wcreate_scale_table
Task function category: Functions Creating New Waveforms
If the appropriate scale table does not exist, then it can be created with this function.
Usage
wcreate_scale_table("singular_name", "plural_name", "smalles_ unit",
smallest_unit_value)
Arguments
• "singular_name"
Singular name of the scale table (for example: "size").
• "pural_name"
Plural name of the scale table (for example: "sizes").
• "smallest_unit"
Smallest sub-unit of the scale table (for example: "fm").
• smallest_unit_value
Corresponding value of the smallest sub-unit (for example: 1e-15 if the smallest sub-unit is
fm).
Description
Then wadd_scale must be called to define all sub-units.
Examples
For an example, see “wcreate_data_type” on page 980.
Related Topics
Library of Functions for Tasks
wadd_data_enum_value
wadd_scale
wcreate_data_type
wcreate_wave
wset_values
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wcreate_wave
Task function category: Functions Creating New Waveforms
Creates a new waveform inside the specified .wdb file, and returns a waveform variable to, for
example, call post-processing functions on it.
Usage
wcreate_wave(wdbId, "wave_name", "folder", [[x_values], y_values])
wcreate_wave(wdbId, "wave_name", "folder", [[x_values], y_values],
"x_data_type")
wcreate_wave(wdbId, "wave_name", "folder", [[x_values], y_values],
"x_data_type", "y_data_type")
wcreate_wave(wdbId, "wave_name", "folder", [[x_values], y_values],
"x_data_type", "y_data_type", "options")
wcreate_wave(wdbId, "wave_name", "folder", [[x_values], y_values],
"x_data_type", "y_data_type", "options", x_scale)
wcreate_wave(wdbId, "wave_name", "folder", [[x_values], y_values],
"x_data_type", "y_data_type", "options", x_scale, y_scale)
Arguments
• wdbId
Identifier of the .wdb file where to create the waveform. It can be wstdout to create the
waveform inside the main .wdb file, or any identifier of a .wdb file created with wopen in
write mode.
• "wave_name"
Name to assign to the new waveform (no waveform with the same name must already exist
in the folder where the wave will be created).
• "folder"
Path to the folder where the waveform will be created. If it does not exist, it will be created.
The path may be hierarchical.
• x_values
Vector containing the x-values of the points to plot. If this argument is omitted and y_values
are specified, then the indexes of the y-values in the vector y_values are taken as x-values.
The values of x_values have to be ordered.
• y_values
Vector containing the y-values of the points to plot. If this argument and x_values are
omitted then the waveform will be created empty and its content can be specified later using
the wset_values function.
This vector can contain complex values if the data type of the y-axis is set to "complex".
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• x_data_type
Data type of the x-axis. By default, it is set to "double". Possible values are as follows:
"double" for double precision floating point values with no specific unit.
"double_current" for double precision floating point current values (in A).
"double_frequency" for double precision floating point frequency values (in Hz).
"double_mag_db" for double precision floating point magnitude values (in dB).
"double_phase" for double precision floating point phase values (in radians).
"double_phased" for double precision floating point phase values (in degrees)
"double_phaseg" for double precision floating point phase values (in gradians).
"double_temperatureC" for double precision floating point temperature values
(in Celsius).
"double_temperatureK" for double precision floating point temperature values
(in Kelvin).
"double_time" for double precision floating point time values (in s).
"double_voltage" for double precision floating point voltage values (in V).
"long" for integer values with no specific unit.
"long_index" for integer values representing an index.
"noise" for double precision floating point noise values (in dBc).
Any data type created with wcreate_data_type with the restriction than its type has to be -
Long or -Double.
Note
Creating a waveform with "double_phase" as x_data_type only means that the
values passed in x_values (or in a further call to wset_values) are given in radians; it
won’t modify your EZwave display preferences. When displaying the waveform in
EZwave, the x-axis may still be scaled in degrees if it is your preferential unit for phase
data.
• y_data_type
Data type of the y-axis. By default, it is set to "double". Possible values are as follows:
"boolean" for Boolean values.
"complex" for complex values with no specific unit.
"complex_current" for complex current values.
"complex_voltage" for complex voltage values.
"double" for double precision floating point values with no specific unit.
"double_current" for double precision floating point current values (in A).
"double_frequency" for double precision floating point frequency values (in Hz).
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"double_mag_db" for double precision floating point magnitude values (in dB).
"double_phase" for double precision floating point phase values (in radians).
"double_phased" for double precision floating point phase values (in degrees)
"double_phaseg" for double precision floating point phase values (in gradians).
"double_temperatureC" for double precision floating point temperature values
(in Celsius).
"double_temperatureK" for double precision floating point temperature values
(in Kelvin).
"double_time" for double precision floating point time values (in s).
"double_voltage" for double precision floating point voltage values (in V).
"long" for integer values with no specific unit.
"long_index" for integer values representing an index.
"noise" for double precision floating point noise values (in dBc).
"std_logic" for std_logic values with the following mapping: {0 "'U'"} {1 "'X'"} {2
"'0'"} {3 "'1'"} {4 "'Z'"} {5 "'W'"} {6 "'L'"} {7 "'H'"} {8 "'-'"}).
Any data type created with wcreate_data_type.
Note
Creating a waveform with "double_phase" as y_data_type only means that the
values passed in y_values (or in a further call to wset_values) are given in radians; it
won’t modify your EZwave display preferences. When displaying the waveform in
EZwave, the y-axis may still be scaled in degrees if it is your preferential unit for phase
data.
• "options"
Is a list of options (can be empty) among the following ones:
"-Type analog" to specify a continuous drawing mode.
"-Type step" to specify a sampled drawing mode.
"-Type histogram" to specify a histogram drawing mode.
"-Type scatter" to specify a scattered drawing mode.
"-Type spectral" to specify a spectral drawing mode.
"-Type railroad" to specify a one-dimension drawing mode.
"-LINEAR_X" to specify a linear scale for the x-axis.
"-LOG_X" to specify a logarithmic scale for the x-axis.
"-LOG2_X" to specify a logarithmic scale (base 2) for the x-axis.
"-LINEAR_Y" to specify a linear scale for the y-axis.
"-LOG_Y" to specify a logarithmic scale for the y-axis.
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"-LOG2_Y" to specify a logarithmic scale (base 2) for the y-axis.
• x_scale
Is the scale of the x-axis. Default value is 1. For example, if the x_data_type is
"double_voltage" and the x_scale is 1e-6, then it means the values of x_values are given in
mV.
• y_scale
Is the scale of the y-axis. Default value is 1. For example, if the y_data_type is
"double_voltage" and the y_scale is 1e-6, then it means the values of y_values are given in
mV.
Description
You can use EZwave to display graphically the evolution of one measurement versus another
(which is not always directly possible using a .PLOT command in the netlist) when setting up a
complex corner case simulation plan.
Examples
The following example shows how to create two waveforms displaying the evolution of the
saturation drain current versus the drain-to-source voltage, and the limit between linear and
saturation regions depending on gate-to-source and drain-to-source voltages.
The creation of the waveforms is obtained through the two calls to wcreate_wave at the end of
the task. Everything that is done before is to compute the values to plot: first, the threshold gateto-source
voltage is computed; then, the gate-to-source voltage is increased logarithmically
from this threshold voltage and for each value, the saturation current and the saturation drain-tosource
voltages are computed.
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.define_testbench mos (vgs_val = 1, vds_val = 1)
m1 d g s s n w=3.2u l=1.2u
vgs g s vgs_val
vds d s vds_val
.connect d 0
.dc
.extract dc label=m1_ids '-i(vds)'
.extract dc label=m1_mode opmode(m1)
.end_define_testbench
.define_task plot_ids_sat_and_lim_lin_sat
set vgs_res [] = 0
set vds_sat_res [] = 0
set ids_sat_res [] = 0
set w_ids_sat_vds = 0
set w_lim_lin_sat = 0
set vgs = 0
set vth = 0
set vth_min = 0
set vth_max = 5
set vds = 0
set vds_min = 0
set vds_max = 5
set m1_ids = 0
set m1_mode = ""
set i = 0
set iter = 0
/**
* Find vth by dichotomy.
*/
/* Check bounds. */
simulation(mos(vgs_val = vth_min), m1_mode = @m1_mode)
if (m1_mode != "subthreshold")
fprint(stdout, "Failed to find vth because with vgs=%eV,
opmode(m1)=%s\n",
vth_min, m1_mode)
return -1
endif
simulation(mos(vgs_val = vth_max), m1_mode = @m1_mode)
if (m1_mode == "subthreshold")
fprint(stdout, "Failed to find vth because with vgs=%eV,
opmode(m1)=%s\n",
vth_max, m1_mode)
return -1
endif
/* Dichotomy. */
while (abs(vth_max - vth_min) > 0.001 && iter < 50)
iter++
vth = vth_min + (abs(vth_max - vth_min) / 2)
simulation(mos(vgs_val = vth), m1_mode = @m1_mode)
if (m1_mode == "subthreshold")
vth_min = vth
else
vth_max = vth
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endif
endwhile
if (iter >= 50)
fprint(stdout, "Failed to find vth in less than 50 iterations.\n")
return -1
else
fprint(stdout, "\n\tvth=%.2eV\n", vth)
endif
/**
* Compute ids_sat by dichotomy for many values of vgs > vth.
*/
step (type=log, param=vgs, start = vth + 0.01, stop=10, dec=20)
i++
vgs_res[i] = vgs
/* Check bounds. */
vds_min = 0
vds_max = 5
simulation(mos(vgs_val = vgs, vds_val = vds_min), m1_mode = @m1_mode,
m1_ids =
@m1_ids)
if (m1_mode != "linear")
fprint(stdout, "Failed to find ids_sat for vgs=%eV because with vds=%eV,
opmode(m1)=%s\n", vgs, vds_min, m1_mode)
return -1
endif
simulation(mos(vgs_val = vgs, vds_val = vds_max), m1_mode = @m1_mode,
m1_ids =
@m1_ids)
if (m1_mode != "saturation")
fprint(stdout, "Failed to find ids_sat for vgs=%eV because with vds=%eV,
opmode(m1)=%s\n", vgs, vds_max, m1_mode)
return -1
endif
/* Dichotomy. */
iter = 0
while (abs(vds_max - vds_min) > 0.001 && iter < 50)
iter++
vds = vds_min + (abs(vds_max - vds_min) / 2)
simulation(mos(vgs_val = vgs, vds_val = vds), m1_mode = @m1_mode, m1_ids
=
@m1_ids)
if (m1_mode == "linear")
vds_min = vds
else
vds_max = vds
endif
endwhile
if (iter >= 50)
fprint(stdout, "Failed to find ids_sat in less than 50 iterations for
vgs=%eV.\n", vgs)
return -1
else
vds_sat_res[i] = vds
ids_sat_res[i] = m1_ids
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endif
endstep
/**
* Create the waveforms.
*/
w_ids_sat_vds = wcreate_wave(wstdout, "ids_sat(vds)", "results",
vds_sat_res,
ids_sat_res, "double_voltage", "double_current")
w_lim_lin_sat = wcreate_wave(wstdout, "vds_sat(vgs)", "results", vgs_res,
vds_sat_res, "double_voltage", "double_voltage")
fprint(stdout, "\n\tPlot ids_sat(vds) and vds_sat(vgs) succeeded.\n")
.end_define_task
.plot_ids_sat_and_lim_lin_sat
.option set_eldo_cl_verbose=0
.option remove_eldo_cl_temp_files=3
.model n nmos
+ level = 53 U0 = 0.041
+ Lmin = 5E-7 Lmax = 0.01
+ Wmin = 6E-7 Wmax = 0.01
*
+ Tnom = 25.0 Tox = 1.923E-08
+ Xj = 2.385E-07 Nch = 1.568E+17
+ lln = 1 lwn = 1
+ wln = 1 wwn = 1
+ lint = 1.651E-08 ll = 0
+ wint = 2.914E-08 ww = 0
+ Mobmod = 1 binunit = 1
+ Dwg = 0 Dwb = 8.378E-09
*
+ Vth0 = 0.3248 K1 = 0.9641 K2 = -0.03744
+ K3 = 25.64 lK3 = 0
+ Dvt0 = 6.014 Dvt1 = 0.5389 Dvt2 = -0.06328
+ Dvt0w = 9.103E-07 Dvt1w = 2E+06 Dvt2w = -9.733E-06
+ Nlx = 1.74E-07 W0 = 2.039E-06 lW0 = 0
+ K3b = -6.173 lK3b = 0
*
+ Vsat = 1.115E+05 lVsat = -2.364E+03 wVsat = 0
+ Ua = -8.629E-10 Ub = 3.009E-18 Uc = 4.655E-11
+ Rdsw = 1406 Prwb = -4.441E-19 Prwg = -2.662E-02
+ Wr = 1.004
+ A0 = 0.3287 lA0 = -0.07189 wA0 = -0.07049
+ Keta = -0.02931 lKeta = 0 wKeta = 0
+ A1 = 0.00 A2 = 0.9900000
+ Ags = 4.441E-15 lAgs = -0.1 wAgs = 0
+ B0 = 2.868E-06 B1 = 6.971E-06
*
+ Voff = -0.2 NFactor = 0.8724 Cit = -5.284E-04
+ Cdsc = -1E-05 Cdscb = 6.172E-06 Cdscd = -1E-04
+ Eta0 = 0.02484 Etab = -0.06802 Dsub = 0.6624
*
+ Pclm = 2.683
+ Pdiblc1= 0.1875 Pdiblc2 = 1E-05 Pdiblcb = -0.001
+ Drout = 0.6357 Pscbe1 = 4.597E+08 Pscbe2 = 31.79E-06
+ Pvag = 3.828 Delta = 0.01
+ Alpha0 = 4.183E-06 Beta0 = 36.27
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*
+ Kt1 = -0.3454 Kt2 = -2.952E-02
+ At = 1.833E+04 Ute = -0.7011274
+ Ua1 = 7.804E-09 Ub1 = -1.227E-17 Uc1 = 2.121E-10
+ Kt1l = 0.00 Prt = 645.5
*
+ Cj = 4.54E-4 Mj = 0.115 Pb = 1
+ Cjsw = 2.70E-10 Mjsw = 0.05 Php = 1
+ Cta = 0 Ctp = 0 Pta = 0
+ Ptp = 0
+ Dlc = 1.29E-7 Cgbo = 1.154E-10
*+ Js = 1.22E-7 N = 1.054 Xti = 1.346
+ JS = 0.0 IS = 0.0 JSW = 0.0
+ Capmod = 1 NQSMOD = 0 Elm = 5
+ Xpart = 1
+ Cgsl = 0 Cgdl = 0 Ckappa = 0.6
+ Cf = 0 Clc = 1E-7 Cle = 0.6
.end
Related Topics
Library of Functions for Tasks
wadd_data_enum_value
wadd_scale
wcreate_data_type
wcreate_scale_table
wset_values
Testbenches
Tasks
Variables
Flow Control Statements
Defining and Running Simulations
fprint
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Library of Functions for Tasks
wget
Task function category: Functions Operating on wdb Files
Reads the waveform named wave1 located at the folder folder inside the .wdb file whose
identifier is wdbId.
Usage
wget(wdbId, "folder/wave1")
Arguments
• wdbId
.wdb file identifier.
• "folder/wave1"
Waveform wave1 located in the folder folder in the .wdb file whose identifier is wdbId.
Description
The .wdb file must have been opened in read mode. The result of this function must be assigned
to a task variable to be able to perform any post processing for example on this waveform.
Related Topics
Library of Functions for Tasks
wclose
wmkfolder
wopen
wsave
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Library of Functions for Tasks
wftoascii
Task function category: Functions Operating on Waveforms
Dumps a waveform in a text file.
Usage
wftoascii(path, wf)
wftoascii(path, wf, x_start, x_end)
Arguments
• path
Path for text file.
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Related Topics
Library of Functions for Tasks
wftodata
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Library of Functions for Tasks
wftodata
Task function category: Functions Operating on Waveforms
Returns the datapoints of a waveform in a matrix. Its first line is a vector containing the X
values and its second line is a vector containing the Y values.
Note
This function may be highly memory-intensive if the waveform has many points.
Usage
wftodata(wf)
wftodata(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Examples
set i = 0
set mat_wf = wftodata(w1, 10, 40)
for(i= mat_wf[1].imin; i

Eldo Control Language
Library of Functions for Tasks
wmkfolder
Task function category: Functions Operating on wdb Files
This function creates a folder folder in the .wdb file whose identifier is wdbId.
Usage
wmkfolder(wdbId, "folder")
Arguments
• wdbId
.wdb file identifier.
• "folder"
Folder in the .wdb file whose identifier is wdbId.
Description
The .wdb file must have been opened in write mode. To create hierarchical folders, for example
a folder folder_sub inside a folder folder_top (located at the root of the .wdb file), then the
second argument has just to be set to folder_top/folder_sub, or /folder_top/folder_sub.
Related Topics
Library of Functions for Tasks
wclose
wget
wopen
wsave
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Eldo Control Language
Library of Functions for Tasks
wopen
Task function category: Functions Operating on wdb Files
This function can be used to open .wdb files. The .wdb file must already exist to be opened in
read mode. In write mode, it will be created if it does not exist, or overwritten if it already
existed. This function returns a file identifier used in the next function to identify the .wdb file.
Usage
wopen("path/wdb1.wdb", "r" | "w")
Arguments
• "path/wdb1.wdb"
Path to the .wdb file.
• "r" | "w"
Open mode. r for read or w for write (note that it is a string).
Description
wstdout Variable
The main .wdb file (if the netlist run by the main Eldo process, containing the Control Language
task, is named netlist1.cir, then the main .wdb file will be by default netlist1.wdb) must not be
opened or closed using the functions wopen and wclose (otherwise the behavior will be
completely undefined). Instead, the predefined wstdout variable has to be used as the identifier
for this .wdb file. It is especially useful if the netlist is run with the option .option
keep_eldo_cl_temp_waves=0 to completely control how waveforms are saved in this file. See
“wdb File” in “Simulation” on page 1114.
Related Topics
Library of Functions for Tasks
wclose
wget
wmkfolder
wsave
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Eldo Control Language
Library of Functions for Tasks
wsave
Task function category: Functions Operating on wdb Files
This function saves the waveform which the variable wave points to inside the folder folder in
the .wdb file whose identifier is wdbId.
Usage
wsave(wdbId, wave, "folder")
Arguments
• wdbId
.wdb file identifier.
• wave
Variable pointing to the waveform.
• "folder"
Folder in the .wdb file whose identifier is wdbId.
Description
The .wdb file must have been opened in write mode. If the folder does not exist, it is
automatically created. The folder can be hierarchical.
Examples
The following example shows how to save two waveforms of the first simulation in the file
wdb1.wdb and two waveforms of the second simulation in the main .wdb file using the wstdout
variable. It demonstrates also how to open the first .wdb file (wdb1.wdb) to read the waveforms
saved in it and make some post-processing operations on them.
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.option keep_eldo_cl_temp_waves=0
.option remove_eldo_cl_temp_files=3
.define_task t_save1 (file="")
set w1 = 0
set w2 = 0
/* Create a wdb file to save the waveforms. */
set wdb1 = wopen(file, "w")
set res = simulation(w1=@w1, w2=@w2)
if (res.simu_status == 0)
/* Copy the waveforms. */
wsave(wdb1, w1, "simu1")
wsave(wdb1, w2, "simu1")
fprint(stdout, "\nSimulation 1 succeeded.\n")
else fprint(stdout, "\nSimulation 1 failed.\n")
endif
/* Save and close. */
wclose(wdb1)
.end_define_task
.define_task t_save2
set w1 = 0
set w2 = 0
set res = simulation(w1=@w1, w2=@w2)
if (res.simu_status == 0)
/* Copy the waveforms in the main wdb file. */
wsave(wstdout, w1, "simu2")
wsave(wstdout, w2, "simu2")
fprint(stdout, "\nSimulation 2 succeeded.\n")
else
fprint(stdout, "\nSimulation 2 failed.\n")
endif
.end_define_task
.define_task t_read (file="", folder="")
set w1 = 0
set w2 = 0
set v = 0
set wdbId = wstdout
if (file != "")
/* Open the file in read mode. */
wdbId = wopen(file, "r")
fprint(stdout, "\nUsing " + file + " file to read.\n")
else
fprint(stdout, "\nUsing main wdb file to read.\n")
endif
w1 = wget(wdbId, folder + "/w1")
w2 = wget(wdbId, folder + "/w2")
v = yval(w1, 1)
fprint(stdout, "\tyval(w1, 1) = %.1f\n", v)
v = yval(w2, 1)
fprint(stdout, "\tyval(w2, 1) = %.1f\n", v)
if (file != "")
/* Close the file. */
wclose(wdbId)
endif
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Eldo Control Language
Library of Functions for Tasks
.end_define_task
* Call the tasks to save the waveforms in the specified file.t_save1
file="wdb_save.wdb"
.t_read file="wdb_save.wdb" folder="simu1"
* Save the waveforms in the main wdb file
.t_save2
Related Topics
Library of Functions for Tasks
wclose
wget
wmkfolder
wopen
Testbenches
Tasks
Variables
Flow Control Statements
Defining and Running Simulations
fprint
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Eldo Control Language
Library of Functions for Tasks
wset_values
Task function category: Functions Creating New Waveforms
This function can be used to set points to a waveform created with the wcreate_wave function if
the x and y vectors were not given at that time. It can also be used to add new points to the
waveform.
Usage
set_values(wave, y_values)
wset_values(wave, x_values, y_values)
Arguments
• wave
Waveform created with wcreate_wave.
• x_values
Vector containing the x-values of the points to plot. If this argument is omitted, then the
indexes of the y-values in the vector y_values are taken as x-values. The values of x_values
have to be ordered.
• y_values
Vector containing the y-values of the points to plot. This vector can contain complex values
if the data type of the y-axis is set to "complex".
Description
The only restriction is that all the x-values must be ordered: it is not possible to add a point (x,y)
to the waveform if its current last point (xl, yl) is such that xl > x. The function returns the
number of values that have been successfully saved.
Examples
In the example given for wcreate_wave, it would have been possible to write the following in
the task definition:
Eldo® User's Manual, 15.3 1003

Eldo Control Language
Library of Functions for Tasks
…
.define_task plot_ids_sat_and_lim_lin_sat
set vgs_res [] = 0
set vds_sat_res [] = 0
set ids_sat_res [] = 0
/**
* Create empty waveforms.
*/
set w_ids_sat_vds = wcreate_wave(wstdout, "ids_sat(vds)", "results",
"double_voltage", "double_current")
set w_lim_lin_sat = wcreate_wave(wstdout, "vds_sat(vgs)", "results",
"double_voltage", "double_voltage")
…
/**
* Set the values of the waveforms.
*/
wset_values(w_ids_sat_vds, vds_sat_res, ids_sat_res)
wset_values(w_lim_lin_sat, vgs_res, vds_sat_res)
fprint(stdout, "\n\tPlot ids_sat(vds) and vds_sat(vgs) succeeded.\n")
.end_define_task
…
Related Topics
Library of Functions for Tasks
wadd_data_enum_value
wadd_scale
wcreate_data_type
wcreate_scale_table
wcreate_wave
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Eldo Control Language
Library of Functions for Tasks
xdown
Task function category: Functions Operating on Waveforms
Returns a vector containing all the X values where a waveform falls below the given Y level
with a negative slope.
Usage
xdown(wf, at_y)
xdown(wf, at_y, x_start, x_end)
Arguments
• wf
Waveform identifier.
• at_y
Y value.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
Related Topics
Library of Functions for Tasks
xup
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Eldo Control Language
Library of Functions for Tasks
xmax
Task function category: Functions Operating on Waveforms
Returns the maximum X value where a waveform is defined.
Usage
xmax(wf)
Arguments
• wf
Waveform identifier.
Related Topics
Library of Functions for Tasks
xmin
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Eldo Control Language
Library of Functions for Tasks
xmin
Task function category: Functions Operating on Waveforms
Returns the minimum X value where a waveform is defined.
Usage
xmin(wf)
Arguments
• wf
Waveform identifier.
Related Topics
Library of Functions for Tasks
xmax
Eldo® User's Manual, 15.3 1007

Eldo Control Language
Library of Functions for Tasks
xofmax
Task function category: Functions Operating on Waveforms
Returns a vector containing all the X values at the maximum (or maxima) of a waveform.
Usage
xofmin(wf)
xofmin(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
Examples
set i = 0
set xres = xofmax(w1, 10, 40)
fprint(stdout, "X values where w1 is maximum between 10 and 40 are:")
for(i=xres.imin; i

Eldo Control Language
Library of Functions for Tasks
xofmin
Task function category: Functions Operating on Waveforms
Returns a vector containing all of the X values at the minimum (or minima) of a waveform.
Usage
xofmin(wf)
xofmin(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
Related Topics
Library of Functions for Tasks
xofmax
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Eldo Control Language
Library of Functions for Tasks
xup
Task function category: Functions Operating on Waveforms
Returns a vector containing all the X values where a waveform rises above the given Y level
with a positive slope.
Usage
xup(wf, at_y)
xup(wf, at_y, x_start, x_end)
Arguments
• wf
Waveform identifier.
• at_y
Y value.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
Related Topics
Library of Functions for Tasks
xdown
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Eldo Control Language
Library of Functions for Tasks
xval
Task function category: Functions Operating on Waveforms
Returns in a vector all the X values at the given Y level of the waveform wf. If the slope is
supplied, the result will be collected only when the waveform has the specified slope.
Interpolation is applied.
Usage
xval(wf, at_y)
xval(wf, at_y, slope)
xval(wf, at_y, x_start, x_end)
xval(wf, at_y, slope, x_start, x_end)
Arguments
• wf
Waveform identifier.
• at_y
Y level in waveform.
• slope
Slope. Valid values are: pos, neg, or either.
• x_start
Waveform start point.
• x_end
Waveform end point.
Description
Does not support complex waveforms (but it is possible to call it separately on the real part and
the complex part or on the magnitude and phase of a complex waveform).
Examples
set i = 0
set xres = xval(w1, 10.5)
fprint(stdout, "X values where w1 is 10.5 are:")
for(i=xres.imin; i

Eldo Control Language
Library of Functions for Tasks
xwave
Task function category: Functions Operating on Waveforms
Creates a new waveform with Y values identical to X values (the result is a waveform).
Usage
xwave(wf)
xwave(wf, x_start, x_end)
Arguments
• wf
Waveform identifier.
• x_start
Waveform start point.
• x_end
Waveform end point.
Related Topics
Library of Functions for Tasks
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Eldo Control Language
Library of Functions for Tasks
yval
Task function category: Functions Operating on Waveforms
Returns the Y value at a given X coordinate of a waveform. Interpolation is applied. If wf is a
complex waveform, the result is a complex number.
Usage
yval(wf, at_x)
Arguments
• wf
Waveform identifier.
• at_x
X coordinate in waveform.
Examples
set yres = yval(w1, 1.5)
fprint(stdout, "The value of w1 at 1.5 is: %.4e", yres)
Related Topics
Library of Functions for Tasks
xval
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Eldo Control Language
Simulation Dynamic Control
Simulation Dynamic Control
A callback mechanism is provided to temporarily stop the simulation at specific times to let the
user execute some ECL commands to monitor the simulation. The way to get simulation results
inside this callback is different to the simulation function method: you must explicitly use some
predefined functions to obtain the results you want to access.
Callback functions can use and modify variables of the calling task but the syntax may be quite
heavy, especially if there are many variables to manage. This is why some simulation control
functions are also provided to replace the simulation function and work directly in the main
task.
Limitations:
• Dynamic control is only allowed over one simulation at a time.
• Eldo Premier is not compatible with the functionality inside this Simulation Dynamic
Control section. An error message will be output if callbacks or flow-control functions
are used with Eldo Premier.
• Callback functions are restricted to transient analyses.
This section is divided into the following:
• Callback Functions
• Extended Simulation Functions
Callback Functions
A callback function can be defined and associated to a simulation function so that it is executed
at predefined time intervals during a transient analysis.
The callback function is an ECL user-defined function (or task). It can be assigned to a
“simulation” function using the “callback” argument or the simulation function. When setting
this argument, another argument is required which defines the condition when this callback will
be called. This argument must be chosen from among the following five arguments:
• progress_period
Its value must be a number and stands for the percentage of simulation that has to be
reached before calling the callback. For example, setting progress_period=20 means to
execute the callback function when 20%, 40%, 60%, 80% and 100% of the simulation
have been computed.
• elapsed_s_period
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Eldo Control Language
Simulation Dynamic Control
Its value must be a number and stands for the time interval (in seconds) at which the
callback will be executed. For example, setting elapsed_s_period=60 means to execute
the callback function every 60 seconds of real time.
• elapsed_m_period
Same as elapsed_s_period but the number value stands for minutes.
• elapsed_h_period
Same as elapsed_s_period but the number value stands for hours.
• condition
Example:
Contrary to the previous arguments, this argument does not define a periodic condition.
Its value must be a string, standing for the condition that has to be met before executing
the callback. Refer to the function _simu_set_cond to know which syntax is supported to
specify this condition.
Here is a simple example for displaying a simulation progress on the standard output every time
10% of the simulation has been computed.
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, “Defining and Running Simulations” on page 841, and the fprint
function for more information on the concepts used in the example.
Eldo® User's Manual, 15.3 1015

Eldo Control Language
Simulation Dynamic Control
.define_task main_simu
set ov = 0
set max_g = 0
set f_max_g = 0
set res = simulation(
/* netlist to simulate. */
+ tb_filter(),
/* The callback defined below will be called each time
* 10% of the simulation has been computed.
*/
+ callback=f_callback(), progress_period=10,
/* Results to get at the end. */
+ ov=@overshoot, max_g=@max_gain, f_max_g=@f_max_gain)
/* Output. */
if (res.simu_status == 0)
fprint(stdout, "\n\nSimulation succeeded.\n\n")
fprint(stdout, "\tovershoot=%.1e V.\n", ov)
fprint(stdout, "\tmax_gain=%.1e dB at %.1e Hz.\n", max_g, f_max_g)
else
fprint(stdout, "Simulation failed.\n")
endif
.end_define_task
.define_function f_callback ()
/* It is the callback function that will be called
* regularly during the simulation.
*/
/* Use the functions '_simu_get' to access the current
* simulation time and the progress.
*/
set curtime = _simu_get("time")
set progress = _simu_get("progress")
/* Output. */
fprint(stdout, "Progress=%d%% (current simulation time=%.1e)\n",
progress, curtime)
/* Return 0: mandatory for the simulation to go on. */
return 0
.end_define_function
* Call the task
.main_simu
* Remove temporary simulation files
.option remove_eldo_cl_temp_files=3
* Netlist
.define_testbench tb_filter
*4th Order Butterworth Filter
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Eldo Control Language
Simulation Dynamic Control
c1 4 0 1.5307n
c2 3 0 1.0824n
l1 3 4 1.5772u
l2 2 3 .38268u
r1 1 2 1
v1 1 0 ac 1 pwl (0 0 1u 0 2u 1 20u 1 20.1u 0)
.tran .2u 40u
.plot tran v(4) (-1,1.5)
.plot tran v(1) (0,1.5)
.extract tran label=overshoot max(v(4)) - max(v(1))
.ac dec 20 10000 100meg
.option eps=1.0e-6 be
.plot ac vdb(4) (-120,40)
.plot ac vp(4) (-200,200)
.extract ac label=max_gain max(vdb(4))
.extract ac label=f_max_gain xmax(vdb(4))
.end_define_testbench
The output is:
***** Running simulation ...
***** Arguments:
***** Simulation succeeded
Progress=10% (current simulation time=4.0e-06)
***** Simulation succeeded
Progress=22% (current simulation time=8.8e-06)
***** Simulation succeeded
Progress=34% (current simulation time=1.4e-05)
***** Simulation succeeded
Progress=50% (current simulation time=2.0e-05)
***** Simulation succeeded
Progress=50% (current simulation time=2.0e-05)
***** Simulation succeeded
Progress=60% (current simulation time=2.4e-05)
***** Simulation succeeded
Progress=70% (current simulation time=2.8e-05)
***** Simulation succeeded
Progress=80% (current simulation time=3.2e-05)
***** Simulation succeeded
Progress=90% (current simulation time=3.6e-05)
***** Simulation succeeded
Progress=100% (current simulation time=4.0e-05)
***** Simulation succeeded
Simulation succeeded.
overshoot=5.0e-02 V.
max_gain=2.8e+01 dB at 2.8e+06 Hz.
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Eldo Control Language
Simulation Dynamic Control
Return Value
The result returned by the callback function indicates if the simulation can go on after the
callback has been executed. It must be 0 to continue the simulation. Any other number will stop
the simulation.
Note
Tasks can be used as callback functions. If a task does not explicitly end with a 'return'
statement, then 0 is returned by default.
Example:
Here is an example of how to stop the simulation once a condition has been met (when the
specific frequency of an oscillator has been reached).
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, “Defining and Running Simulations” on page 841, and the fprint
function for more information on the concepts used in the example.
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Eldo Control Language
Simulation Dynamic Control
.define_task t_osc
set w = 0
set res = simulation(
/* netlist to simulate. */
+ tb_osc(),
/* The callback defined below will be called when the
* frequency is stabilized at 7 MHz.
* 'period_osc' is a vector so need to specify '[LAST]'
* to get the last calculated period.
* Need to add a condition on time because the frequency
* is erratic at the beginning before falling progressively
* to 7 MHz.
*/
+ callback=f_callback_osc(),
+ condition="(meas(period_osc[LAST]) > (1/7Meg)) && (time>1u)",
/* To save the wave in the wdb file. */
+ w=@w_osc)
if (res.simu_status == 0)
fprint(stdout, "Simulation succeeded.\n")
else
fprint(stdout, "Simulation failed.\n")
endif
.end_define_task
.define_function f_callback_osc()
/* It is the callback function that will be called
* when the condition is met.
*/
set i = 0
/* Get the time where the simulation was stopped. */
set curtime = _simu_get("time")
/* Get some extract values using '_simu_get_extract'. */
set max_v = _simu_get_extract("max_v_osc")
/* v_period i a vector. */
set v_period = _simu_get_extract("period_osc")
/* Get the last frequency. */
set freq = 1 / v_period[v_period.imax]
fprint(stdout, "Evolution of the frequency of the waveform from 0 s to
%.2e s:\n", curtime) for (i = v_period.imin; i

Eldo Control Language
Simulation Dynamic Control
.t_osc
* Remove temporary simulation files
.option remove_eldo_cl_temp_files=3
* Netlist
.define_testbench tb_osc
.model ts2 npn
+ bf=10 br=1 xtb=3 is=10f eg=1.11 rb=100
+ rc=10 vaf=50 tr=6n mjc=0.75 mje=0.33 vje=0.75
*Colpitts Oscillator
l1 1 3 5u
c1 1 2 2n
c2 2 3 100p
r3 2 4 2200
q1 3 0 2 ts2
v1 1 0 5
v2 4 0 -5
i1 2 4 pulse(0 10u 0 5n 5n 25n 50n)
.option eps=1.0e-6
.tran 1u 12u
.plot tran w_osc=v(1,3) (10,-10)
.extract tran label=max_v_osc max(v(1,3))
/* The extract to calculate the period of the waveform.
* 'vect' must be specified so that all periods are
* computed, and not only the first one.
*/
.extract tran vect label=period_osc tperiod(v(1,3), vth=0)
.end_define_testbench
The output is:
Evolution of the frequency of the waveform from 0 s to 2.32e-06 s:
frequency[ 1] = 6.964e+06 Hz
frequency[ 2] = 7.563e+06 Hz
frequency[ 3] = 7.677e+06 Hz
frequency[ 4] = 7.676e+06 Hz
frequency[ 5] = 7.689e+06 Hz
frequency[ 6] = 7.702e+06 Hz
frequency[ 7] = 7.687e+06 Hz
frequency[ 8] = 7.624e+06 Hz
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Eldo Control Language
Simulation Dynamic Control
frequency[ 9] = 7.538e+06 Hz
frequency[10] = 7.428e+06 Hz
frequency[11] = 7.107e+06 Hz
frequency[12] = 7.046e+06 Hz
frequency[13] = 7.021e+06 Hz
frequency[14] = 7.010e+06 Hz
frequency[15] = 7.004e+06 Hz
frequency[16] = 7.001e+06 Hz
frequency[17] = 7.000e+06 Hz
Frequency stabilized at 7.000e+06 Hz at t=2.32e-06 s.
***** Simulation succeeded
Callback Arguments
The callback function can have input and output arguments. The way to set them is quite
natural: the expression assigned to the “callback” argument of the simulation function is the
expression evaluated when the callback function will be automatically executed.
Example 1
The values of some variables are passed from the main task to the callback:
Eldo® User's Manual, 15.3 1021

Eldo Control Language
Simulation Dynamic Control
...
.define_task t_rc
set v = 10
set r = 20
set c = 0.1
set res = simulation(tb_rc(p_v=v, p_r=r, p_c=c),
/* Pass the testbench arguments to the callback. */
+ callback=f_callback_rc(p_v=v, p_r=r, p_c=c),
+ condition="v(2) > " + (0.632 * v))
if (res.simu_status == 0)
fprint(stdout, "Simulation succeeded.\n")
else
fprint(stdout, "Simulation failed.\n")
endif
.end_define_task
.define_function f_callback_rc (p_v=1, p_c=1, p_r=1)
fprint(stdout, "The simulation of 'tb_rc p_v=%.1f p_c=%.1f p_r=%.1f' has
been stopped " +
+ "at t = %.1f s " +
+ "because the expected condition has been met.\n",
+ _simu_get("time"),
+ p_v, p_r, p_c)
return 1
.end_define_function
.t_rc
It is possible to do the same if the callback needs to have output arguments.
If a periodic callback needs to save some values so that it can retrieve them the next time it is
called, then it has to define one input and one output variable for each of them, to be able to
store and get the result from a local variable defined in the main task.
See “Tasks” on page 814, “Variables” on page 821, “Flow Control Statements” on page 835,
“Defining and Running Simulations” on page 841, and the fprint function for more information
on the concepts used in the example.
Example 2
This example shows how to sample a signal using a periodic callback and store the values in an
array defined in the main task. The current index in the array also needs to be saved.
1022
Eldo® User's Manual, 15.3

Eldo Control Language
Simulation Dynamic Control
.define_function f_callback (in_sampling[] = 0, @out_sampling[] = 0,
+ in_cur_index = 0, @out_cur_index = 0)
/* Get the voltage value. */
set v2 = _simu_get("v(2)")
/* Save previous results into working variables
* (that will be returned).
*/
out_sampling = in_sampling
out_cur_index = in_cur_index
/* Save voltage. */
out_sampling[out_cur_index] = v2
out_cur_index++
return 0
.end_define_function
.define_task main_simu
set arr_sampling[] = 0
set cur_index = 0
set i = 0
set res = simulation(callback=f_callback(in_sampling = arr_sampling,
+ in_cur_index = cur_index,
+ arr_sampling = @out_sampling,
+ cur_index = @out_cur_index),
+ elapsed_s_period=1)
if (res.simu_status == 0)
fprint(stdout, "Simulation succeeded.\n\n")
fprint(stdout, "Sampling values for v(2):\n")
for (i=0; i

Eldo Control Language
Extended Simulation Functions
Extended Simulation Functions
Simulation results can be monitored inside a callback function. But some specific functions
have to be used depending on the type of the data to get. It is also possible to modify some
netlist parameters during the simulation or also to use flow-control functions to avoid using
callbacks which may sometimes be necessary. All these functions begin with the prefix
“_simu”.
Table 18-4. Extended Simulation Functions
Command
Description
Netlist Monitoring These functions are used to monitor the simulation.
Functions
Simulation Flow-Control
Functions
Netlist Modification
Functions
_simu_end
_simu_get
_simu_get_extract
_simu_load
_simu_reload
_simu_run
Using callback functions is not the only mechanism to have
a tight control over simulations. To have a more linear
control over simulations, the simulation function has been
split into some more specific functions.
When using the simulation flow-control functions, it is
possible to modify some netlist parameters between runs
with the _simu_set function.
Exits the current simulation and evaluates the output
expressions.
Returns the current value of the specified voltage or current
at the current simulation time.
Returns the value of the extract having the label label.
This function has similar syntax to the current simulation
function and its purpose is to setup the simulation
environment. It will create the simulation file dir/file.cir and
return a result structure (as the simulation command): as
usual, its simu_status attribute is set to 0 if no syntax error
was found during the netlist processing. This is the first
command to be executed before any other advanced
simulation function. No other flow-control function can be
run if this function has not successfully executed.
Reloads the file generated by the last call to _simu_load. If
the netlist was modified using the simu_set function, then
these changes are erased.
Runs the current simulation once the simulation
environment has been set. Its result is the same as the
simulation function.
1024
Eldo® User's Manual, 15.3

Command
_simu_set
_simu_set_cond
_simu_get_wave
Table 18-4. Extended Simulation Functions (cont.)
Description
Eldo Control Language
Extended Simulation Functions
When using the simulation flow-control functions, it is
possible to modify some netlist parameters between runs
with the _simu_set function.
Sets a stop condition.
Returns the wave having the name wave to be able to make
some post-processing on it.
Netlist Monitoring Functions
These functions are used to monitor the simulation.
Refer to “Extended Simulation Functions” on page 1024.
Simulation Flow-Control Functions
Using callback functions is not the only mechanism to have a tight control over simulations. To
have a more linear control over simulations, the simulation function has been split into some
more specific functions.
The three functions _simul_load, _simu_run, and_simu_end are equivalent to the usual
simulation function:
Refer to “Extended Simulation Functions” on page 1024.
Netlist Modification Functions
When using the simulation flow-control functions, it is possible to modify some netlist
parameters between runs with the _simu_set function.
Refer to “Extended Simulation Functions” on page 1024.
Eldo® User's Manual, 15.3 1025

Eldo Control Language
Extended Simulation Functions
_simu_end
Task function category: Simulation Flow-Control Functions
Exits the current simulation and evaluates the output expressions.
Usage
_simu_end(loc_var1=@extract1, loc_var2=@wave2, ...)
Arguments
• loc_var1=@extract1
Extract data.
• loc_var2=@wave2
Waveform data.
Description
All simulation data used in these output expressions must have been pre-declared in the
_simu_load function (out_vars argument).
Related Topics
_simu_set_cond
_simu_load
_simu_reload
_simu_run
Extended Simulation Functions
1026
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Eldo Control Language
Extended Simulation Functions
_simu_get
Task function category: Netlist Monitoring Functions
Returns the current value of the specified voltage or current at the current simulation time.
Usage
_simu_get("voltage")
_simu_get("current")
_simu_get("expression")
Arguments
• "voltage"
Return the voltage.
• "current"
Returns the current.
• "expression"
Evaluates an expression.
Description
Expressions of the general-purpose extraction language can also be evaluated if the necessary
.PLOT commands have been specified in the netlist. The expression cannot be the label of an
extract; the function _simu_get_extract may be used in this case.
Examples
_simu_get("v(2)")
_simu_get("i(2)")
_simu_get("max(v(2))") /* '.plot tran v(2)' is necessary in the
netlist. */
Related Topics
_simu_get_extract
_simu_get_wave
Extended Simulation Functions
Eldo® User's Manual, 15.3 1027

Eldo Control Language
Extended Simulation Functions
_simu_get_extract
Task function category: Netlist Monitoring Functions
Returns the value of the extract having the label label.
Usage
_simu_get_extract("label")
Arguments
• "label"
Return the label.
Description
If this command is executed during the simulation, then only expressions of the transient
extraction language can be used with this command. If the extract has not yet been computed at
the time the simulation was stopped, then the function returns UNDEF.
Extract expressions using the general-purpose language are only computed at the end of the
simulation so are not available using this specific function (taking the label of the extract as
argument) inside a callback for example.
The _simu_get function may be used instead (but passing the entire expression as argument).
Examples
/* '.extract tran label=cross_v2 tcross(v(2), vth=1.5)' is necessary in
the netlist. */
_simu_get_extract("cross_v2")
Related Topics
_simu_get
_simu_get_wave
Extended Simulation Functions
1028
Eldo® User's Manual, 15.3

Eldo Control Language
Extended Simulation Functions
_simu_load
Task function category: Simulation Flow-Control Functions
This function has similar syntax to the current simulation function and its purpose is to setup the
simulation environment. It will create the simulation file dir/file.cir and return a result structure
(as the simulation command): as usual, its simu_status attribute is set to 0 if no syntax error was
found during the netlist processing. This is the first command to be executed before any other
advanced simulation function. No other flow-control function can be run if this function has not
successfully executed.
Usage
_simu_load([name="dir/file.cir"], [log="dir/file.log"],
+ [args="-eldo_arg"], [testbench1(arg1=val1)], [testbench2(arg2=val2)],
...
+ [out_vars="@extract1 @wave2"])
Arguments
• name="dir/file.cir"
Simulation file to be created.
• log="dir/file.log"
Log file.
• args="-eldo_arg"
List of Eldo arguments.
• testbench1(arg1=val1)
Testench 1
• testbench2(arg2=val2)
Testbench 2.
• out_vars="@extract1 @wave2"
Specifies which data will be requested at the end of the simulation (in _simu_end).
Related Topics
_simu_end
_simu_set_cond
_simu_reload
_simu_run
Extended Simulation Functions
Eldo® User's Manual, 15.3 1029

Eldo Control Language
Extended Simulation Functions
_simu_reload
Task function category: Simulation Flow-Control Functions
Reloads the file generated by the last call to _simu_load. If the netlist was modified using the
simu_set function, then these changes are erased.
Usage
_simu_reload()
Arguments
None.
Related Topics
_simu_end
_simu_load
_simu_run
_simu_set_cond
Extended Simulation Functions
1030
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Eldo Control Language
Extended Simulation Functions
_simu_run
Task function category: Simulation Flow-Control Functions
Runs the current simulation once the simulation environment has been set. Its result is the same
as the simulation function.
Usage
_simu_run(mode="after va1")
_simu_run(mode="until val1")
_simu_run(mode="for val1")
_simu_run(mode="next")
_simu_run(mode="skip")
Arguments
• mode
The mode argument may be set to partially run the simulation: its value is a string specifying
a simulation period or a specific simulation time to reach.
Description
The simu_status field of the result will be set to 0 if no error occurred during the simulation.
Without any parameter, a call to this command will run the simulation completely.
Examples
S/* Asks to go on simulating during 2ns (simulation time). */
_simu_run(mode="for 2n")
/* Asks to go on simulating until the simulation has been computed until
exactly 10ns (simulation time). */
_simu_run(mode="until 10n")
/* Asks to go on simulating until the simulation has been computed until
about 10ns (simulation time). */
_simu_run(mode="after 10n")
If the netlist contains a .STEP command, then one call to _simu_run(mode="next") will run
only one simulation. If the simulation was stopped (for example if a stop condition is met, see
_simu_set_cond), _simu_run(mode="skip") requests the simulator to stop the simulation. It is
then possible to run it again from the beginning (after modifying some parameters for example,
see _simu_set.
Related Topics
_simu_end
_simu_load
_simu_reload
_simu_set_cond
Extended Simulation Functions
Eldo® User's Manual, 15.3 1031

Eldo Control Language
Extended Simulation Functions
_simu_set
1032
Eldo® User's Manual, 15.3

Eldo Control Language
Extended Simulation Functions
_simu_set
Task function category: Netlist Modification Functions
When using the simulation flow-control functions, it is possible to modify some netlist
parameters between runs with the _simu_set function.
Usage
_simu_set("e", "device", ["W/L/AD/AS/PD/PS/NRD/NRS/AREA",] va1)
_simu_set("m", "model", "parameter", val1)
_simu_set("p", "parameter", val1)
Arguments
• _simu_set("e", "device", ["W/L/AD/AS/PD/PS/NRD/NRS/AREA",] va1)
This function can be used to modify the value of the device device. If necessary, the
parameter name must be specified.
• _simu_set("m", "model", "parameter", val1)
This function can be used to change the value of the parameter parameter of the model
model to val1.
• _simu_set("p", "parameter", val1)
This function can be used to change the value of the parameter parameter to the value val1.
Description
The value of its first argument must be either e, m, or p, and specifies the type of data to modify:
device, model, or parameter. Compared to the simulation function, the advantage of this flow is
that the simulator does not need to elaborate the netlist again, which would be costly if the
netlist is large.
Examples
Example 1:
w = _simu_set("e", "m16", "w", 4.8u)
Example 2:
Here is an example of finding the value of a parameter that will make the voltage of node 2
reach 1.5V before 10ns.
Eldo® User's Manual, 15.3 1033

Eldo Control Language
Extended Simulation Functions
set v2 = 0
set param1 = 0
set res_load = 0
set res_run = 0
set irun = 0
set w = 0
res_load = _simu_load(tb_netlist(), out_vars="@w2")
if (res_load.simu_status == 0)
param1 = _simu_get("pval(param1)")
/* First run. */
irun++
res_run = _simu_run(mode="until 10n")
if (res_run.simu_status == 0)
/* Get voltage. */
v2 = _simu_get("v(2)")
while (v2 < 1.5)
/* Skip end of simulation. */
_simu_run(mode="skip")
/* Set new value of 'param1'. */
param1 += 0.1
_simu_set("p", "param1", param1)
/* Run again. */
irun++
res_run = _simu_run(mode="until 10n")
if (res_run.simu_status != 0)
fprint(stdout, "Simulation failed (run %d).\n", irun)
break
endif
/* Get new voltage. */
v2 = _simu_get("v(2)")
endwhile
fprint(stdout, "Param1 must be set to: %.4e.\n", param1)
/* Complete the simulation. */
_simu_run()
else
fprint(stdout, "Simulation failed (run %d).\n", irun)
endif
else
fprint(stdout, "Simulation failed (load).\n")
endif
_simu_end(w=@w2) /* Save the wave in the wdb file. */
Related Topics
Simulation Dynamic Control
Extended Simulation Functions
Variables
Flow Control Statements
1034
Eldo® User's Manual, 15.3

Eldo Control Language
Extended Simulation Functions
Defining and Running Simulations
fprint
Eldo® User's Manual, 15.3 1035

Eldo Control Language
Extended Simulation Functions
_simu_set_cond
Task function category: Simulation Flow-Control Functions
Sets a stop condition.
Usage
_simu_set_cond("condition")
Arguments
• "condition"
Stop condition.
Description
The condition can refer to the simulation time value (time), the real time (elapsed_s, elapsed_n,
elapsed_h), the simulation progress (progress), voltages or currents and labels of extracts using
the transient extraction language (but the corresponding .PLOT commands must have been
specified in the netlist and the extract label must be enclosed inside the meas function).
Examples
Notes:
_simu_set_cond("v(2) > 1.5")
_simu_set_cond("(time > 500n) || (elapsed_m >= 20)")
/* If a '.extract tran label=cross1 tcross(v(2),vth=1)' is contained in
the netlist:*/
_simu_set_cond("meas(cross1) > 0")
• Only one condition can be active at a time. A call to _simu_set_cond will delete the
previous conditions. However, multiple conditions can be combined into one condition
using the boolean operators || and &&.
• If you want to use more complex expressions, it is advised to add parentheses around the
different parts composing the expressions. Most of the time, it will help prevent syntax
errors.
The result structure returned by the _simu_run function has a field named simu_stop. It can be
used to know if the simulation has stopped because the condition set with the _simu_set_cond
function has been met or if it has stopped because the simulation has ended without reaching the
condition. If the condition is met, then the _simu_stop attribute will be set to 1. If the simulation
has ended, it is set to -1. If the simulation stopped because of the mode attribute of the
_simu_run function (for example if mode="for 2n" and that the simulator completed the
simulation of this time period), then it is set to 0.
Example:
1036
Eldo® User's Manual, 15.3

Eldo Control Language
Extended Simulation Functions
set thresh = 2
set max_time = 10
set v2 = 0
set res_load = 0
set res_run = 0
/* Init simu. */
res_load = _simu_load()
if (res_load.simu_status == 0)
/* Set stop condition. */
_simu_set_cond("(v(2) > " + thresh + ") || (time > " + max_time + ")")
/* Run until condition is met. */
res_run = _simu_run()
if (res_run.simu_status == 0)
if (res_run.simu_stop == 1)
fprint(stdout, "The condition has been reached: v(2)=%.1f and
time=%.1f.\n",
+ _simu_get("v(2)"), _simu_get("time"))
else
fprint(stdout, "The condition has not been reached.\n")
endif
else
fprint(stdout, "Simulation failed (run).\n")
endif
else
fprint(stdout, "Simulation failed (load).\n")
endif
Related Topics
_simu_end
_simu_reload
_simu_load
_simu_run
Extended Simulation Functions
Variables
Flow Control Statements
Defining and Running Simulations
fprint
Eldo® User's Manual, 15.3 1037

Eldo Control Language
Extended Simulation Functions
_simu_get_wave
Task function category: Netlist Monitoring Functions
Returns the wave having the name wave to be able to make some post-processing on it.
Note
If executed during the simulation, this function may be very costly. Specifically, it will have
to save the .wdb file of the simulation into an auxiliary file to be able to extract wave data.
Usage
_simu_get_wave("wave")
Arguments
• "wave"
Wave name.
Examples
w = _simu_get_wave("w_c2") /* '.plot tran w_c2=v(2)' is necessary in the
netlist. */
Related Topics
_simu_get
_simu_get_extract
Extended Simulation Functions
1038
Eldo® User's Manual, 15.3

Eldo Control Language
Parallel Operation
Parallel Operation
This section is divided into the following:
• General Settings for Parallelism in ECL
• Parallel Construct
• Parallel Loops
• Extended Simulation Functions
• Launching ECL Simulations on Different Machines
General Settings for Parallelism in ECL
Parallelism in ECL means that ECL code will be executed inside different execution threads at
the same time. These threads belong to the main Eldo process, so they will always be run on the
computer that executes the ECL netlist.
The parallelizable ECL code specified by the user is split by ECL into jobs. The threads will
execute these jobs in parallel. There can be more jobs than threads; in that case a thread will
execute another job when it has finished its first job. When there is no parallelism, there is only
one thread, the main thread, which executes all these jobs sequentially.
It is usually interesting to run simulations inside these jobs so that they are executed in parallel.
Simulations are launched by ECL on other Eldo processes (they can be even launched on
different machines when using the .ELDO_CL_MPRUN command). It is important to
understand that parallelism is done at the level of the threads executing ECL jobs, not at the
level of the Eldo processes running simulations; the Eldo processes will be run in parallel only if
the jobs executing the simulation commands are executed by different threads.
The maximum number of threads used for parallelism can be set using the option
set_eldo_cl_max_para=val. The default value corresponds to the number of processors of the
computer. If threads are used to run simulations on the same computer, it is not advised to
increase this number (having more threads than processors to execute heavy jobs is not
efficient).
Concurrency Issues
ECL is very strict about what can be parallelized to avoid concurrency issues (variables having
different values depending on the order of execution of the jobs) and will output errors if the
code is not thread safe. The best way to write correct parallel code is to store any result inside
arrays indexed by the index of the current job and to perform any post-processing inside
sequential code.
Eldo® User's Manual, 15.3 1039

Eldo Control Language
Parallel Operation
Difference Between Sequential and Parallel Execution
The same task run with parallelism activated or deactivated should have exactly the same effect
except for the following two points:
• If outputs are printed by tasks run in parallel, then the order of the outputs is undefined.
If the order is important then you must not use fprint inside tasks run in parallel but
outside, for example in a loop run sequentially.
• A break used inside a loop run in parallel may cause differences between sequential and
parallel execution; see the section “Continue, Break and Return Parallel Behavior” on
page 1050.
Generated Netlists
For simulations run in parallel, if you specify the same netlist name for each simulation, ECL
changes it automatically to suffix it with the index of the job.
Waveforms
Inside the main wdb file, the names of waveforms generated by simulations run will be suffixed
by a unique index to avoid concurrency issues.
Debug Mode
When in debug mode (setenv ELDO_CL_DEBUG) when jobs are executed in parallel, their
debug outputs are mixed but they are prefixed with the index of the corresponding job to enable
better understanding.
Related Topics
Parallel Construct
Parallel Construct
The first parallel construct enables you to define tasks or functions (jobs) to be run in parallel.
The results of the tasks or functions are stored inside an array.
Para Function to Parallelize Tasks
See function “Identifying the Index of the Current Job” on page 1040.
Identifying the Index of the Current Job
For ease of use, it is possible to call the function ijob() to obtain the index of the current job.
Example: basic use of ijob():
1040
Eldo® User's Manual, 15.3

Eldo Control Language
Parallel Operation
.define_task t_print_index(index=0)
fprint(stdout, "Index: %d\n", index)
.end_define_task
.define_task t_main_para
para(t_print_index(index=ijob()) /* ijob() returns 1. */,
+ t_print_index(index=ijob()) /* ijob() returns 2. */)
.end_define_task
.t_main_para
The output of the execution of the previous example can be:
Index: 1
Index: 2or:Index: 2
Index: 1
Example: storing results inside arrays:
Eldo® User's Manual, 15.3 1041

Eldo Control Language
Parallel Operation
.define_testbench tb_netlist(pr_value=100k, pc_value=10u)
.param pr=pr_value
.param pc=pc_value
v1 1 0 PWL 0 0 0.1 3
r1 1 2 pr
c1 2 0 pc
.tran 1 10
.extract label=t2 xthres(v(2), 2)
.end_define_testbench
.define_task t_main_para
set i = 0
set r_val[] = {10k, 20k, 30k, 40k, 50k}
set t2[] = 0
/* Run 5 different simulations in parallel for each value of r1
* and get the extract results inside the array named t2.
*/
set res = para(simulation(tb_netlist(pr_value=r_val[ijob()]),
+ t2[ijob()]=@t2),
+ simulation(tb_netlist(pr_value=r_val[ijob()]),
+ t2[ijob()]=@t2),
+ simulation(tb_netlist(pr_value=r_val[ijob()]),
+ t2[ijob()]=@t2),
+ simulation(tb_netlist(pr_value=r_val[ijob()]),
+ t2[ijob()]=@t2),
+ simulation(tb_netlist(pr_value=r_val[ijob()]),
+ t2[ijob()]=@t2))
for (i=res.imin; i

Concurrency Issues
Eldo Control Language
Parallel Operation
When using the function para(), concurrency issues can emerge if some output results are stored
inside the same variable. If this happens, then ECL will generate an error. Therefore it is
strongly recommended to store results inside arrays indexed by the index of the current job.
Example: ECL issues an error because the variable res is accessed in write mode by two
different jobs:
.define_task t_assign_value (in=0, @out=0)
out=in
.end_define_task
.define_task t_main_para
set res = 0
para(t_assign_value(in=1, res=@out),
+ t_assign_value(in=2, res=@out))
fprint(stdout, "res: %d\n", res)
.end_define_task
.t_main_para
Example: fix the concurrency issue using an array.
.define_task t_assign_value (in=0, @out=0)
out=in.end_define_task
.define_task t_main_para
set res[] = 0
set i = 0
para(t_assign_value(in=1, res[ijob()]=@out),
+ t_assign_value(in=2, res[ijob()]=@out))
for (i=res.imin; i

Eldo Control Language
Parallel Operation
.define_testbench tb_netlist(pr_value=100k, pc_value=10u)
.param pr=pr_value
.param pc=pc_value
v1 1 0 PWL 0 0 0.1 3
r1 1 2 pr
c1 2 0 pc
.tran 1 10
.extract label=t2 xthres(v(2), 2)
.end_define_testbench
.define_task t_main_para
para(t_inner_para(r_val=50k),
+ t_inner_para(r_val=100k))
.end_define_task
.define_task t_inner_para(r_val=100k)
set t2[] = 0
set res[] = 0
set c_val[] = {5u, 10u}
set i = 0
res = para(simulation(tb_netlist(pr_value=r_val,
+ pc_value=c_val[ijob()]),
+ t2[ijob()]=@t2),
+ simulation(tb_netlist(pr_value=r_val,
+ pc_value=c_val[ijob()]),
+ t2[ijob()]=@t2))
for (i=res.imin; i

Eldo Control Language
Parallel Operation
para
Task function category: Parallelize Functions
The function para() is used to run in parallel the tasks and functions specified as parameters.
The first parallel construct enables you to define tasks or functions (jobs) to be run in parallel.
The results of the tasks or functions are stored inside an array.
Usage
para()
para(task1(), task2())
Arguments
• task 1
First task to be run in parallel.
• task 2
Second task to be run in parallel.
Examples
Example: task1 and task2 run in parallel:
para(task1(), task2())
The result returned by the function para() is an array containing the results of the execution of
the arguments.
Example: obtaining the results of two simulations:
set i =0
set res[] = 0
res = para(simulation(tb1()),
+ simulation(tb2()))
for (i=res.imin; i

Eldo Control Language
Parallel Operation
Parallel Loops
step and for loops can be parallelized by using the keywords para_step and para_for. The body
of the loop defines jobs that can be executed in parallel (one job for each run of the loop).
Note
It is not possible to parallelize while loops because the loop variable is managed inside the
body of the loop itself and therefore it cannot be parallelized.
para_for/para_step to Parallelize Loops
Adding para_ in front of a loop requests ECL to parallelize the loop if the content of the loop
does not contain concurrency errors. When the loop is executed, it creates a job for each
iteration. Then these jobs are executed in parallel.
Example: ten iterations of the loop are parallelized:
.define_task t_for_para
set i = 0
para_for (i = 10k;
+ i

Eldo Control Language
Parallel Operation
Example: use of ijob() inside a step parallel loop:
.define_task t_step_para
set i = 0
para_step (type=step,
+ param=i,
+ start=100k,
+ stop=10k,
+ step=-10k)
fprint(stdout,
+ "Beginning run %d with i=%.2g.\n",
+ ijob(),
+ i)
end_para_step
.end_define_task
.t_step_para
The output of this example may be:
Beginning run 1 with i=1e+05.
Beginning run 3 with i=8e+04.
Beginning run 2 with i=9e+04.
Beginning run 4 with i=7e+04.
Beginning run 6 with i=5e+04.
Beginning run 5 with i=6e+04.
Beginning run 7 with i=4e+04.
Beginning run 9 with i=2e+04.
Beginning run 8 with i=3e+04.
Beginning run 10 with i=1e+04.
Concurrency Issues
To prevent concurrency issues from occurring, ECL is very strict about code that is allowed to
be parallelized inside loops. By default, no scalar variable can be assigned inside a parallel loop
(otherwise a syntax error is generated). It is only possible to store values inside arrays. During
execution, ECL checks that no value of an array is accessed by more than one job in write mode.
If more than one job accesses the same value (inside an array) in write mode, then an error
occurs at run time. It is strongly recommended to store results inside arrays indexed by the
index of the current job.
Example: a step parallel loop running simulations:
Eldo® User's Manual, 15.3 1047

Eldo Control Language
Parallel Operation
.define_testbench tb_netlist(pr_value=100k, pc_value=10u)
.param pr=pr_value
.param pc=pc_value
v1 1 0 PWL 0 0 0.1 3
r1 1 2 pr
c1 2 0 pc
.tran 1 10
.extract label=t2 xthres(v(2), 2)
.end_define_testbench
.define_task t_step_para
set i = 0
set cumul = 0
set nb_errors = 0
/* Use arrays to prevent concurrency errors. */
set r_val[] = 0
set res[] = 0
set t2[] = 0
/* Parallel loop for simulations. */
para_step (type=step,
+ param=i,
+ start=10k,
+ stop=100k,
+ step=10k)
r_val[ijob()] = i
res[ijob()] = simulation(tb_netlist(pr_value=r_val[ijob()]),
+ t2[ijob()]=@t2)
/* Forbidden to compute cumul here (concurrency issue). */
/* cumul += t2[ijob()] */
end_para_step
/* Sequential loop to analyze results;
* cumul can be computed only here.
*/
for (i = res.imin;
+ i

Eldo Control Language
Parallel Operation
+ cumul / (res.size - nb_errors))
endif
.end_define_task
.t_step_para
Local Declarations for Temporary Results
To avoid using arrays for temporary results, you can declare some local variables inside a
parallel loop even if .option restrict_eldo_cl_declarations=1. In this case, each run of the loop
has its own internal copy of the variable and then it is allowed to modify its value inside the
loop body. When .option restrict_eldo_cl_declarations=1, it is not allowed to define local
variables having the same name as other task variables.
Tip
See “.OPTION RESTRICT_ELDO_CL_DECLARATIONS” in the Eldo Reference
Manual.
Example: alternative to the previous example; if not computing the average and if the order of
the outputs does not matter, it is possible to avoid using arrays by using private variables:
Eldo® User's Manual, 15.3 1049

Eldo Control Language
Parallel Operation
.define_testbench tb_netlist(pr_value=100k, pc_value=10u)
.param pr=pr_value
.param pc=pc_value
v1 1 0 PWL 0 0 0.1 3
r1 1 2 pr
c1 2 0 pc
.tran 1 10
.extract label=t2 xthres(v(2), 2)
.end_define_testbench
.define_task t_step_para
set i = 0
/* Parallel loop for simulations. */
para_step (type=step,
+ param=i,
+ start=10k,
+ stop=100k,
+ step=10k)
/* Use local variables for local results inside the loop. */
set res = 0
set t2 = 0
res = simulation(tb_netlist(pr_value=i),
+ t2=@t2)
if (res.simu_status == 0)
fprint(stdout,
+ "t2=%.2g for R=%.2g\n",
+ t2, i)
else
fprint(stdout,
+ "Run %d failed.\n",
+ ijob())
endif
end_para_step
.end_define_task
.t_step_para
Continue, Break and Return Parallel Behavior
The continue keyword has the same meaning and the same effect inside a parallel loop as inside
a sequential loop: the current run is stopped. The break and return keywords have a different
semantic: break and return only prevent the execution of runs (jobs) that have not begun
(because of .option set_eldo_cl_max_para); all runs that have begun won’t be stopped.
Example: because of parallelism, using a break on the 5th run will not always prevent the 6th
from being executed:
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Eldo Control Language
Parallel Operation
.define_task t_step_para
set i = 0
para_step (type=step,
+ param=i,
+ start=100k,
+ stop=10k,
+ step=-10k)
set j = ijob()
fprint(stdout,
+ "Beginning run %d with i=%.2g.\n",
+ j,
+ i)
system("sleep 10")
if (j == 5)
fprint(stdout, "Break on run 5!\n")
break
endif
fprint(stdout,
+ "End of run %d.\n",
+ j)
end_para_step
.end_define_task
.t_step_para
The output of this example may be:
Beginning run 1 with i=1e+05.
Beginning run 3 with i=8e+04.
Beginning run 2 with i=9e+04.
Beginning run 4 with i=7e+04.
End of run 2.
End of run 1.
Beginning run 6 with i=5e+04.
Beginning run 5 with i=6e+04.
End of run 3.
End of run 4.
Beginning run 7 with i=4e+04.
Break on run 5!
End of run 6.
End of run 7.
Multiple Levels of Parallelism
It is possible to have nested loops executed in parallel.
Example: use of a matrix to store extract results of nested loops:
Eldo® User's Manual, 15.3 1051

Eldo Control Language
Parallel Operation
.define_testbench tb_netlist(pr_value=100k, pc_value=10u)
.param pr=pr_value
.param pc=pc_value
v1 1 0 PWL 0 0 0.1 3
r1 1 2 pr
c1 2 0 pc
.tran 1 10
.extract label=t2 xthres(v(2), 2)
.end_define_testbench
.define_task t_step_para
set j1 = 0
set j2 = 0
set r_val = 0
set c_val = 0
set r_values[] = 0
set c_values[] = 0
set mat[][] = 0
para_step (type=step,
+ param=r_val,
+ start=10k,
+ stop=100k,
+ step=10k)
set job1 = ijob()
r_values[job1] = r_val
para_step (type=step,
+ param=c_val,
+ start=1u,
+ stop=10u,
+ step=1u)
set job2 = ijob()
set t2 = 0
set res = 0
/* Store c_val only once otherwise error! */
if (job1 == 1)
c_values[job2] = c_val
endif
res = simulation(tb_netlist(pr_value=r_val, pc_value=c_val),
+ t2=@t2)
if (res.simu_status != 0)
t2 = -1
fprint(stdout,
+ "Simulation#%d#%d failed!",
+ job1, job2)
endif
mat[job1][job2] = t2
end_para_step
end_para_step
for (j1=r_values.imin; j1

Eldo Control Language
Parallel Operation
fprint(stdout,
+ "t2=%.2f for R=%.2g and C=%.2g\n",
+ mat[j1][j2], r_values[j1], c_values[j2])
endfor
endfor
.end_define_task
.t_step_para
Related Topics
Extended Simulation Functions
Extended Simulation Functions
Simulations run inside different jobs are independent from each other. It is not possible to load
the netlist with _simu_load inside one job and to execute _simu_run functions inside other jobs.
The only way to use extended simulation functions in parallel is to do _simu_load and then
_simu_run inside each job.
Example: tasks containing extended simulation functions can be run in parallel:
Eldo® User's Manual, 15.3 1053

Eldo Control Language
Parallel Operation
.define_testbench tb_netlist()
.param pr=100k
.param pc=10u
v1 1 0 PWL 0 0 0.1 3
r1 1 2 pr
c1 2 0 pc
.tran 1 10
.extract label=t2 xthres(v(2), 2)
.end_define_testbench
.define_task t_run(pr_value=10k, index=0)
set res = 0
set t2 = 0
/* Load the netlist. */
res = _simu_load(tb_netlist())
if (res.simu_status == 0)
/* Modify the parameter. */
_simu_set("p", "pr", pr_value)
/* Run the simulation. */
res = _simu_run()
if (res.simu_status == 0)
t2 = _simu_get_extract("t2")
fprint(stdout,
+ "t2=%.2g for R=%.2g\n",
+ t2, pr_value)
else
fprint(stdout, "Running simulation %d failed!\n", index)
endif
else
fprint(stdout, "Loading simulation %d failed!\n", index)
endif
_simu_end()
.end_define_task
.define_task t_main_para
para(t_run(pr_value=10k, index=ijob()),
+ t_run(pr_value=20k, index=ijob()),
+ t_run(pr_value=30k, index=ijob()),
+ t_run(pr_value=40k, index=ijob()),
+ t_run(pr_value=50k, index=ijob()))
.end_define_task
.t_main_para
Related Topics
Launching ECL Simulations on Different Machines
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Launching ECL Simulations on Different Machines
Eldo Control Language
Parallel Operation
The .ELDO_CL_MPRUN command is the equivalent of the .MPRUN command but at the ECL
level. The .ELDO_CL_MPRUN command is used to dispatch the simulations executed from
ECL tasks on one multi-processor machine, or on many machines.
The .ELDO_CL_MPRUN command has the same syntax as the .MPRUN command except for
some restrictions (see the .ELDO_CL_MPRUN command in the Eldo Reference Manual).
Options set_eldo_cl_max_para and remove_eldo_cl_temp_files can be used to overcome some
of these limitations. The two commands .ELDO_CL_MPRUN and .MPRUN can be combined
since they operate at different levels.
Example: how to dispatch parallel ECL simulations on many machines:
Eldo® User's Manual, 15.3 1055

Eldo Control Language
Parallel Operation
.define_testbench tb_netlist(pr_value=100k)
.param pr=pr_value
v1 1 0 PWL 0 0 0.1 3
r1 1 2 pr
c1 2 0 10u
.tran 1 10
.extract label=t2 xthres(v(2), 2)
.end_define_testbench
.define_task t_step_para
set i = 0
set r_val_step = 0
set t2[] = 0
set r_val[] = 0
para_step (type=step,
+ param=r_val_step,
+ start=10k,
+ stop=100k,
+ step=10k)
set job = ijob()
set res = 0
r_val[job] = r_val_step
res = simulation(name="simu_para/step_" +
+ job +
+ ".cir",
+ tb_netlist(pr_value=r_val_step),
+ t2[job]=@t2)
if (res.simu_status == 0)
fprint(stdout, "Simulation #" + job + " succeeded.\n")
else
fprint(stdout, "Simulation #" + job + " failed!\n")
endif
end_para_step
for (i=r_val.imin; i

Eldo Control Language
Parallel Operation
.define_testbench tb_netlist(pr_value=100k)
.param pr=pr_value
v1 1 0 PWL 0 0 0.1 3
r1 1 2 pr
c1 2 0 10u
.tran 1 10
.extract label=t2 xthres(v(2), 2)
.end_define_testbench
.define_task t_sim
set res = 0
set t2_res = 0
res = simulation(name="simu/simu.cir",
+ tb_netlist(),
+ t2_res=@t2)
if (res.simu_status == 0)
fprint(stdout, "t2=%.2f\n", t2_res)
else
fprint(stdout, "Simulation failed!\n")
endif
.end_define_task
.t_sim
.eldo_cl_mprun dispatcher=lsf
+ dispatcher_options=(-q myqueue -m "host1 host2 host3")
Related Topics
Parallel Operation
Eldo® User's Manual, 15.3 1057

Eldo Control Language
Statistical Processing
Statistical Processing
Controlling a Monte Carlo simulation with ECL relies on the ECL extended simulation flow.
The Monte Carlo flow is dedicated to advanced users, with a strong knowledge of statistics.
This is not supported by Eldo Premier.
The flow to control a Monte Carlo simulation is as follows:
• Activate the extended simulation flow
The first function to call to activate the ECL Monte Carlo flow is the _simu_load
function to load the netlist in the extended simulation flow.
Tip
See also Simulation Dynamic Control.
• Activating the Monte Carlo Flow
The ECL Monte Carlo flow is activated using the function:
_simu_set_mc_flow([max_nb_runs])
• Accessing Statistical Parameters
After the netlist is loaded and the ECL Monte Carlo flow activated, you can access
statistical parameters, managed internally by ECL and identified by an index.
The first index is 1 and the number of statistical parameters is given by a call to the
following function:
_simu_get_nb_stat_params
Use the following functions to access data related to statistical parameters:
_simu_get_stat_param_name
_simu_get_stat_param_distrib
For uniform and normal distributions, you can call the following functions:
_simu_get_stat_param_nom
_simu_get_stat_param_ref_param
_simu_is_stat_param_dev
_simu_is_stat_param_locked
_simu_get_stat_param_dev
_simu_get_stat_param_nb_draw
_simu_is_stat_param_devx
Use the following functions to parse their names:
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Eldo® User's Manual, 15.3

Eldo Control Language
Statistical Processing
_simu_get_stat_param_netlist_param
_simu_get_stat_param_netlist_dev
_simu_get_stat_param_netlist_dev_pa
ram
_simu_get_stat_param_netlist_mod
_simu_get_stat_param_netlist_mod_p
aram
Use the following functions to modify statistical parameters:
_simu_lock_stat_param
_simu_set_mc_flow
• Modifying the Sampling
You can modify the sampling values of the statistical parameters with the following
functions:
_simu_get_stat_param_sampling_val
_simu_get_raw_sampling
_simu_erase_last_run
_simu_get_sampling
_simu_set_stat_param_sampling_val
_simu_get_random
Use the following functions to generate random values:
_simu_get_random
_simu_reset_random_generators
• Running the Nominal Simulation
After the netlist is loaded and the ECL Monte Carlo flow activated, you run the nominal
simulation using the function:
Running Monte Carlo Runs in Parallel(mode="nom")
• Controlling the Monte Carlo Runs
The _simu_run function also enables you to execute a specified number of Monte Carlo
runs:
Running Monte Carlo Runs in Parallel
• Monitoring Monte Carlo Results
After the requested number of Monte Carlo simulations has been executed, results are
accessible through the use of post-processing functions.
See functions operating on arrays in “Library of Functions for Tasks” on page 854.
Eldo® User's Manual, 15.3 1059

Eldo Control Language
Statistical Processing
In addition, you can use the following function (requires a simulation to be loaded with
_simu_load):
_simu_get_mcsens.
• Running Monte Carlo Runs in Parallel
You can run ECL Monte Carlo simulations in parallel, the simulations will be performed
by different simulators.
See “Running Monte Carlo Runs in Parallel” on page 1105.
The default sampling values generated by ECL when no parallel structures are used in the ECL
tasks are the same as the sampling values generated by Eldo when dataflow=1 is specified on
the .MC command. To compare results obtained with ECL Monte Carlo flow to Eldo Monte
Carlo results, dataflow=1 must be specified on the .MC command when running the netlist with
Eldo.
When Monte Carlo simulations are run inside parallel loops by ECL, sampling values will be
different because ECL will create one random number generator by job to ensure the
reproducibility of the results.
Table 18-5. Statistical Processing Functions
Command
Description
_simu_erase_all_runs Erases all sampling data from all the previous Monte Carlo
runs so that they are not taken into account if
_simu_get_sampling() or _simu_get_raw_sampling() is
called.
_simu_erase_last_run Erases all sampling data from the previous Monte Carlo run
so that it is not taken into account if _simu_get_sampling()
or _simu_get_raw_sampling() is called.
_simu_get_mcsens Returns the sensitivity list of the elements of the array array
for a given sampling.
_simu_get_nb_stat_param Returns the number of statistical parameters inside a netlist.
s
_simu_get_random Returns a random value corresponding to the requested
distribution.
_simu_get_raw_sampling Returns a matrix containing all the sampling values
computed during the Monte Carlo simulation.
_simu_get_sampling Returns a matrix containing all the sampling values
computed during the Monte Carlo simulation.
1060
Eldo® User's Manual, 15.3

Command
_simu_get_stat_param_de
v
_simu_get_stat_param_dis
trib
_simu_get_stat_param_na
me
_simu_get_stat_param_nb
_draw
_simu_get_stat_param_net
list_dev
_simu_get_stat_param_net
list_dev_param
_simu_get_stat_param_net
list_mod
_simu_get_stat_param_net
list_mod_param
_simu_get_stat_param_net
list_param
_simu_get_stat_param_no
m
_simu_get_stat_param_ref
_param
_simu_get_stat_param_sa
mpling_val
_simu_is_stat_param_dev
_simu_is_stat_param_dev
x
_simu_is_stat_param_lock
ed
_simu_is_stat_param_lot
Table 18-5. Statistical Processing Functions (cont.)
Description
Eldo Control Language
Statistical Processing
Returns the deviation (for Gaussian distributions) or halfrange
(for uniform distributions) value of the parameter
identified by the index stat_param_index.
Returns the name of the distribution identified by the index
stat_param_index.
Returns the name of the parameter identified by the index
stat_param_index.
Returns a positive integer value that acts as a multiplier to
set how many times the value of the parameter identified by
the index stat_param_index is to be calculated (only the
random value having the greatest deviation is selected).
Returns the name of the corresponding device in the netlist
(device_name), or "" if not relevant.
Returns the name of the corresponding device parameter in
the netlist (device_parameter_name), or "" if not relevant.
Returns the name of the corresponding model in the netlist
(model_name), or "" if not relevant.
Returns the name of the corresponding model parameter in
the netlist (model_parameter_name), or "" if not relevant.
Returns the name of the corresponding parameter in the
netlist (parameter_name).
Returns the nominal (mean) value of the parameter
identified by the index stat_param_index.
Returns the index of the parameter on which the parameter
stat_param_index depends (0 if none).
Returns the current sampling value of the parameter
identified by the index stat_param. It is the value used for
the next Monte Carlo run.
Returns 1 if the statistical parameter comes from a DEV
variation.
Returns 1 if the statistical parameter comes from a DEVX
variation.
Returns 1 if the parameter identified by the index
stat_param_index has been locked, that is to say it will not
vary and remain to its nominal value.
Returns 1 if the statistical parameter comes from a LOT
variation.
Eldo® User's Manual, 15.3 1061

Eldo Control Language
Statistical Processing
Command
_simu_lock_stat_param
_simu_reset_random_gene
rators
_simu_run
_simu_set_mc_flow
_simu_set_stat_param_sa
mpling_val
_simu_unlock_stat_param
Running Monte Carlo
Runs in Parallel
Table 18-5. Statistical Processing Functions (cont.)
Description
Specifies that the value of the parameter identified by the
index stat_param_index must not vary during the Monte
Carlo simulation and remain equal to its nominal value.
Resets the random number generators. This can be useful to
reset the random number generators between two Monte
Carlo simulations if you want them to use the same random
numbers.
_simu_run(mode="nom") runs the nominal Monte Carlo
simulation and returns a result structure (as the simulation
function).
Activates the ECL Monte Carlo flow. The netlist may or
may not contain a .MC command; it is entirely ignored if the
ECL Monte Carlo flow is activated.
Sets the current sampling value of the parameter identified
by the index stat_param to the value val. It will be the value
used for the next Monte Carlo run.
Specifies that the value of the parameter identified by the
index stat_param_index must vary during the Monte Carlo
simulation according to its distribution.
Running ECL Monte Carlo simulations in parallel requires
to call _simu_load, _simu_set_mc_flow, simu_run and
_simu_end inside the para_for loop. This means the Monte
Carlo simulations will be performed by different simulators.
1062
Eldo® User's Manual, 15.3

Eldo Control Language
Statistical Processing
_simu_erase_all_runs
Task function category: Statistical Processing Functions
Erases all sampling data from all the previous Monte Carlo runs so that they are not taken into
account if _simu_get_sampling() or _simu_get_raw_sampling() is called.
Note
This function can only be called in ECL Monte Carlo flow.
Usage
_simu_erase_all_runs()
Arguments
None.
Related Topics
Statistical Processing
_simu_erase_last_run
_simu_get_sampling
_simu_get_raw_sampling
Eldo® User's Manual, 15.3 1063

Eldo Control Language
Statistical Processing
_simu_erase_last_run
Task function category: Statistical Processing Functions
Erases all sampling data from the previous Monte Carlo run so that it is not taken into account if
_simu_get_sampling() or _simu_get_raw_sampling() is called.
Note
This function can only be called in ECL Monte Carlo flow.
Usage
_simu_erase_last_run()
Arguments
None.
Related Topics
Statistical Processing
_simu_get_random
_simu_get_sampling
_simu_get_raw_sampling
1064
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Eldo Control Language
Statistical Processing
_simu_get_mcsens
Task function category: Statistical Processing Functions
Returns the sensitivity list of the elements of the array array for a given sampling.
Usage
_simu_get_mcsens(array, "GLOB"|"GLOB_ACCURATE"|"LSS" [,
matrix_raw_sampling])
Arguments
• array
The array of values (typically the values of a given extract for each run) to compute the
sensitivity.
• "GLOB" | "GLOB_ACCURATE" | "LSS"
Specifies the sensitivity methodology:
"GLOB"
Eldo computes global sensitivities extracted from the results of the random sampling.
This is faster than "GLOB_ACCURATE" but results may be less accurate.
"GLOB_ACCURATE"
Eldo computes global sensitivities extracted from the results of the random sampling.
This is more accurate than "GLOB" and can have a large CPU cost depending on the
circuit. The CPU cost is related to the number of sensitivities, number of Monte Carlo
runs, number of parameters with Monte Carlo variation, and number of extracts.
"LSS"
Specifies the large scale screening algorithm to identify the principal parameters
during a Monte Carlo analysis. This is useful when the number of variables is much
larger than the number of runs allowed. A class of Least Squares solvers based on the
principle of homotopy methods is used.
• matrix_raw_sampling
The matrix storing all the raw sampling values computed during the Monte Carlo
simulation. If n runs were performed and there are p statistical parameters, then
matrix_raw_sampling[i;j] must be the raw sampling value of the j-th parameter for the i-th
run. The user can call _simu_get_raw_sampling() to easily get this matrix (this is what is
done by default). Be careful not to use _simu_get_sampling() otherwise sensitivities may be
wrong.
Description
The result is a matrix: the first line contains the index of the important parameters (the first
being the most important parameter). The second line contains their importance percentage (1.0
for 100%). Will return an empty array if not enough Monte Carlo simulations have been run.
Eldo® User's Manual, 15.3 1065

Eldo Control Language
Statistical Processing
Examples
Example: how to monitor the evolution of the average, deviation and sensitivities of an extract:
1066
Eldo® User's Manual, 15.3

Eldo Control Language
Statistical Processing
.define_testbench tb_mc()
.model modres res lot=10% dev=5%
v1 1 0 pwl 0 0 1n 0 2n 3
r1 1 2 modres 1k
c1 2 0 1p
.tran 0 10u
.mc 100
.extract catvect label=rise_time xthres(v(2), 1.5)
.end_define_testbench
.define_task t()
set extract_name = "rise_time"
set extract_res[] = 0
set nbmc = 0
set res = 0
set conv = 0
/* Load the netlist. */
res = _simu_load(name = "tmp/tmp.cir", tb_mc())
if (res.simu_status == 0)
_simu_set_mc_flow()
/* Run nominal. */
res = _simu_run(mode="nom")
if (res.simu_status == 0)
/* Begin Monte-Carlo simulation. */
res = _simu_run(mode="mc 5")
nbmc += 5
while (res.simu_status == 0)
/* Get the results. */
extract_res = _simu_get_extract(extract_name);
/* Display results (+1 to exclude nominal extract). */
print_res(p_nbmc=nbmc,
+ p_extract_res=extract_res[extract_res.imin + 1,
+ extract_res.imax])
/* Stop when it has converged. */
if (mcconv(extract_res,
+ "AVG",
+ "CONFIDENCE") == 1)
break;
endif
/* Prevent infinite loop. */
if (nbmc > 10000)
fprint(stdout, "Failed to converge!\n")
break;
endif
/* Continue Monte-Carlo simulation. */
res = _simu_run(mode="mc 5")
nbmc += 5
endwhile
endif
endif
.end_define_task
.define_task print_res(p_nbmc=10, p_extract_res[] = 0)
set avg_val = avg(p_extract_res)
set std_val = std(p_extract_res)
Eldo® User's Manual, 15.3 1067

Eldo Control Language
Statistical Processing
set sens_list = _simu_get_mcsens(p_extract_res, "GLOB")
fprint(stdout, "\nRise time after " + p_nbmc + " runs:\n")
fprint(stdout, "Average: %.2e\n", avg_val)
fprint(stdout, "Standard deviation: %.2e\n", std_val)
fprint(stdout, "Most important parameter:\n")
if (sens_list[1].imin

Eldo Control Language
Statistical Processing
.define_task t_main()
set important_params[]=""
set i = 0
set width[] = 0
set device[] = ""
set res = 0
/* Load the netlist. */
res = _simu_load(name = "mc/mc.cir")
if (res.simu_status == 0)
_simu_set_mc_flow()
/* Run nominal. */
if (run_nominal() != 0)
/* Run Monte-Carlo to find important parameters. */
if (find_important_params(p_extract_name = "OPFREQ",
+ important_params=@p_important_params)
!= 0)
for (i = important_params.imin;
+ i

Eldo Control Language
Statistical Processing
.define_function run_nominal()
set res = 0
set delay1 = 0
set delay2 = 0
fprint(stdout, "Running nominal...\n")
res = _simu_run(mode="nom")
if (res.simu_status == 0)
delay1 = _simu_get_extract("DELAY1")
delay2 = _simu_get_extract("DELAY2")
fprint(stdout, "DELAY1 = %.3g Sec\nDELAY2 = %.3g Sec\n", delay1,
delay2)
else
fprint(stdout, "Nominal failed!\n")
return 0
endif
return 1
.end_define_function
.define_function find_important_params(p_extract_name = "",
+ @p_important_params[] = 0)
set res = 0
set conv = 0
set sens_list[] = 0
set i = 0
set nb_important_params = 0
set extract_res[] = 0
set nbmc = 0
while (conv == 0)
/* Execute 20 more Monte-Carlo runs. */
fprint(stdout, "Running 20 Monte-Carlo...\n")
res = _simu_run(mode="mc 20")
nbmc += 20
if (res.simu_status != 0)
fprint(stdout, "Simulation failed!\n")
return 0;
endif
/* Get the result. */
extract_res = _simu_get_extract(p_extract_name);
/* See if it has converged. */
conv = mcconv(extract_res,
+ "AVG",
+ "CONFIDENCE",
+ 50,
+ 0.99,
+ 0.00,
+ 5.0e-3)
/* Prevent infinite loop. */
if (nbmc > 10000)
fprint(stdout, "Failed to converge!\n")
return 0;
endif
endwhile
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Eldo Control Language
Statistical Processing
/* Get sensitivities; need to remove the extract value
computed for the nominal. */
sens_list = _simu_get_mcsens(extract_res[extract_res.imin + 1,
+ extract_res.imax],
+ "LSS")
/* Extract parameters having importance >= 10%. */
if (sens_list.size > 0)
for (i = sens_list[1].imin;
+ i = 0.1)
nb_important_params++
/* Get its index. */
p_important_params[nb_important_params] = sens_list[1][i]
endif
endfor
endif
return 1
.end_define_function
.t_main
.option set_eldo_cl_verbose=0
* Netlist for CMOS RIPPLE CARRY ADDER
* This example centers around an 1-bit CMOS ripple carry adder
.PARAM WIN_GLOB =40U
.PARAM WOUT_GLOB=40U
* INCLUDE NMOS AND PMOS MODELS
.SUBCKT ONEBITADDER VDD VSS A B C SUM CO PARAM: WIN=40U WOUT=40U
XMP1 VDD A 1 VDD P W={2*WIN} L=1U AD=400P AS=400P
XMP2 VDD B 1 VDD P W={2*WIN} L=1U AD=400P AS=400P
XMP3 VDD A 2 VDD P W=20U L=1U AD=400P AS=400P
XMP4 VDD A 3 VDD P W=20U L=1U AD=400P AS=400P
XMP5 VDD B 3 VDD P W=20U L=1U AD=400P AS=400P
XMP6 VDD C 3 VDD P W=20U L=1U AD=400P AS=400P
MP7 1 C NC VDD P W={2*WIN} L=1U AD=400P AS=400P
XMP8 2 B NC VDD P W=20U L=1U AD=400P AS=400P
XMP9 3 NC NS VDD P W=20U L=1U AD=400P AS=400P
XMP10 VDD A 7 VDD P W=20U L=1U AD=400P AS=400P
XMP11 7 B 8 VDD P W=20U L=1U AD=400P AS=400P
XMP12 8 C NS VDD P W=20U L=1U AD=400P AS=400P
XMN13 NC C 4 VSS N W=WIN L=1U AD=400P AS=400P
XMN14 NC B 5 VSS N W=20U L=1U AD=400P AS=400P
XMN15 NS NC 6 VSS N W=20U L=1U AD=400P AS=400P
XMN16 4 A VSS VSS N W=WIN L=1U AD=400P AS=400P
Eldo® User's Manual, 15.3 1071

Eldo Control Language
Statistical Processing
XMN17 4 B VSS VSS N W=WIN L=1U AD=400P AS=400P
XMN18 5 A VSS VSS N W=20U L=1U AD=400P AS=400P
XMN19 6 A VSS VSS N W=20U L=1U AD=400P AS=400P
XMN20 6 B VSS VSS N W=20U L=1U AD=400P AS=400P
XMN21 6 C VSS VSS N W=20U L=1U AD=400P AS=400P
XMN22 NS C 9 VSS N W=20U L=1U AD=400P AS=400P
XMN23 9 B 10 VSS N W=20U L=1U AD=400P AS=400P
XMN24 10 A VSS VSS N W=20U L=1U AD=400P AS=400P
* SUM AND CARRY OUTPUT BUFFERS
XMP25 VDD NS SUM VDD P W=20U L=1U AD=400P AS=400P
XMN26 SUM NS VSS VSS N W=20U L=1U AD=400P AS=400P
XMP27 VDD NC CO VDD P W={2*WOUT} L=1U AD=400P AS=400P
XMN28 CO NC VSS VSS N W=WOUT L=1U AD=400P AS=400P
* LAYOUT CAPACITANCES
C1 1 VSS 0.05P
C2 2 VSS 0.05P
C3 3 VSS 0.05P
C4 4 VSS 0.05P
C5 5 VSS 0.05P
C6 6 VSS 0.05P
CA A VSS 0.1P
CB B VSS 0.1P
CC C VSS 0.1P
CSM SUM VSS 0.15P
CCO CO VSS 0.15P
.ENDS ONEBITADDER
VDD VDD 0 5
X0 VDD 0 A0 B0 0 SUM0 CO0 ONEBITADDER WIN=WIN_GLOB WOUT=WOUT_GLOB
VA0 A0 0 5
VB0 B0 0 PULSE 0 5 .2N .2N .2N 9.8N 20N
* TRANSIENT ANALYSIS
.TRAN 0.1N 6N
.PLOT TRAN V(SUM0) V(B0)
* EXTRACT SECTION
.EXTRACT TRAN LABEL=DELAY1 TPD(V(B0),V(SUM0),VTHIN=2.5,VTHOUT=0.5)
.EXTRACT TRAN LABEL=DELAY2 TPD(V(B0),V(CO0),VTHIN=2.5,VTHOUT=4.5)
.EXTRACT TRAN LABEL=OPFREQ CATVECT (1/MAX(EXTRACT(DELAY1),
EXTRACT(DELAY2)))
+ LBOUND=280Meg
* MONTE CARLO ANALYSIS
.OPTION AEX DUMP_MCINFO
.MC 100
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Eldo Control Language
Statistical Processing
+ DATAFLOW=1
.EXTRACT MC LABEL=MINFREQ MCMIN(OPFREQ)
.EXTRACT MC LABEL=MAXFREQ MCMAX(OPFREQ)
* A global factor that artificially scales the sigma of all variables:
.param g_mm_factor=10
* The sigtail option is used to allow wider spread (up to +/- 4 sigmas) for
the input variables:
.option sigtail=4
* The device models (some of the .model parameters have statistical
variations):
.subckt n d g s b param: w=1u l=1u ad=400p as=400p
m1 d g s b modn w=w l=l ad=ad as=as
.param Tox=19E-09 a_mm_Tox=0.4543u b_mm_Tox=0.1435 dev_mm_Tox
='a_mm_Tox/sqrt(w*l)+b_mm_Tox'
.param Vth0=.3322 a_mm_Vth0=0.40654u b_mm_Vth0=0.11654 dev_mm_Vth0
='a_mm_Vth0/sqrt(w*l)+b_mm_Vth0'
.param U0=388.3203 a_mm_U0=0.565745u b_mm_U0=0.264563 dev_mm_U0
='a_mm_U0/sqrt(w*l)+b_mm_U0'
.model modn NMOS
+Level=53
+Tox =Tox dev/gauss={g_mm_factor*dev_mm_Tox}%
+Vth0 =Vth0 dev/gauss={g_mm_factor*dev_mm_Vth0}%
+U0 =U0 dev/gauss={g_mm_factor*dev_mm_U0}%
+kf=1e-27 af=2
+Tnom=27.0
+Nch= 2.498E+17 Xj=1.00000E-07+Lint=9.36e-8 Wint=1.47e-7
+K1= .756 K2= -3.83e-2 K3= -2.612+Dvt0= 2.812 Dvt1= 0.462 Dvt2=-9.17e-
2
+Nlx= 3.52291E-08 W0= 1.163e-6+K3b= 2.233
+Vsat= 86301.58 Ua= 6.47e-9 Ub= 4.23e-18 Uc=-4.706281E-11
+Rdsw= 650 wr=1
+A0= .3496967 Ags=.1 B0=0.546 B1= 1
+ Dwg = -6.0E-09 Dwb = -3.56E-09 Prwb = -.213
+Keta=-3.605872E-02 A1= 2.778747E-02 A2= .9
+Voff=-6.735529E-02 NFactor= 1.139926 Cit= 1.622527E-04
+Cdsc=-2.147181E-05
+Cdscb= 0 Dvt0w = 0 Dvt1w = 0 Dvt2w = 0
+ Cdscd = 0 Prwg = 0
+Eta0= 1.0281729E-02 Etab=-5.042203E-03
+Dsub= .31871233
+Pclm= 1.114846 Pdiblc1= 2.45357E-03 Pdiblc2= 6.406289E-03
+Drout= .31871233 Pscbe1= 5000000 Pscbe2= 5E-09 Pdiblcb = -.234
+Pvag= 0 delta=0.01
+ Wl = 0 Ww = -1.420242E-09 Wwl = 0
+ Wln = 0 Wwn = .2613948 Ll = 1.300902E-10
+ Lw = 0 Lwl = 0 Lln = .316394
Eldo® User's Manual, 15.3 1073

Eldo Control Language
Statistical Processing
+ Lwn = 0
+kt1=-.3 kt2=-.051
+At= 22400
+Ute=-1.48
+Ua1= 3.31E-10 Ub1= 2.61E-19 Uc1= -3.42e-10
+Kt1l=0 Prt=764.3
.ends
.subckt p d g s b param: w=1u l=1u ad=400p as=400p
m1 d g s b modp w=w l=l ad=ad as=as
.param Tox=19E-09 a_mm_Tox=0.365543u b_mm_Tox=0.001435 dev_mm_Tox
='a_mm_Tox/sqrt(w*l)+b_mm_Tox'
.param Vth0=-.3732829 a_mm_Vth0=0.30654u b_mm_Vth0=0.1452
dev_mm_Vth0 ='a_mm_Vth0/sqrt(w*l)+b_mm_Vth0'
.param U0=138.7609 a_mm_U0=0.565745u b_mm_U0=0.366454 dev_mm_U0
='a_mm_U0/sqrt(w*l)+b_mm_U0'
.model modp PMOS
+Level=53
+Tox =Tox dev/gauss={g_mm_factor*dev_mm_tox}%
+Vth0 =Vth0 dev/gauss={abs(g_mm_factor*dev_mm_Vth0)}%‘
+U0 =U0 dev/gauss={g_mm_factor*dev_mm_U0}%
+kf=1e-27 af=2
+Tnom=27.0
+Nch= 3.533024E+17 Xj=1.00000E-07
+Lint=6.23e-8 Wint=1.22e-7
+ K1= .8362093 K2=-8.606622E-02 K3= 1.82
+Dvt0= 1.903801 Dvt1= .5333922 Dvt2=-.1862677
+Nlx= 1.28e-8 W0= 2.1e-6
+K3b= -0.24 Prwg=-0.001 Prwb=-0.323
+Vsat= 103503.2 Ua= 1.39995E-09 Ub= 1.e-19 Uc=-2.73e-11
+ Rdsw= 460
+A0= .4716551 Ags=0.12
+Keta=-1.871516E-03 A1= .3417965 A2= 0.83
+Voff=-.074182 NFactor= 1.54389 Cit=-1.015667E-03
+Cdsc= 8.937517E-04
+Cdscb= 1.45e-4 Cdscd=1.04e-4
+ Dvt0w=0.232 Dvt1w=4.5e6 Dvt2w=-0.0023
+Eta0= 6.024776E-02 Etab=-4.64593E-03
+Dsub= .23222404
+Pclm= .989 Pdiblc1= 2.07418E-02 Pdiblc2= 1.33813E-3
+Drout= .3222404 Pscbe1= 118000 Pscbe2= 1E-09
+Pvag= 0
+kt1= -0.25 kt2= -0.032 prt=64.5
+At= 33000
+Ute= -1.5
+Ua1= 4.312e-9 Ub1= 6.65e-19 Uc1= 0
+Kt1l=0
.ends
The output of the previous example will be:
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Eldo Control Language
Statistical Processing
Running nominal...
DELAY1 = 4.67e-09 Sec
DELAY2 = 2.41e-09 Sec
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Increase width of X0.XMN14.M1 to 4e-05
Increase width of X0.XMN18.M1 to 4e-05
Increase width of X0.XMP9.M1 to 4e-05
Running nominal...
DELAY1 = 2.93e-09 Sec
DELAY2 = 1.39e-09 Sec
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1075

Eldo Control Language
Statistical Processing
_simu_get_nb_stat_params
Task function category: Statistical Processing Functions
Returns the number of statistical parameters inside a netlist.
Usage
_simu_get_nb_stat_params()
Arguments
None.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_get_random
Task function category: Statistical Processing Functions
Returns a random value corresponding to the requested distribution.
Usage
_simu_get_random("UNIFORM" | "GAUSS", nom, dev [, sigtail])
Arguments
• "UNIFORM" | "GAUSS"
Distribution type.
• nom
Nominal value
• dev
Deviation.
• sigtail
Optional. The sigtail argument is only valid for Gaussian distributions. Its default value is 4.
Related Topics
Statistical Processing
_simu_reset_random_generators
Eldo® User's Manual, 15.3 1077

Eldo Control Language
Statistical Processing
_simu_get_raw_sampling
Task function category: Statistical Processing Functions
Returns a matrix containing all the sampling values computed during the Monte Carlo
simulation.
Usage
_simu_get_raw_sampling()
Arguments
None.
Description
If n runs were performed and there are p statistical parameters, then the element [i;j] of the
result matrix is the sampling value of the j-th parameter for the i-th run.
The difference between _simu_get_sampling() and _simu_get_raw_sampling() is related to
parameters dependent on other parameters (for them _simu_get_stat_param_ref_param()
returns a non-null value). _simu_get_raw_sampling() returns a matrix containing the raw values
given by the random number generator whereas _simu_get_sampling() returns a matrix
containing the values that will be applied to the statistical parameters, that is to say after the
dependencies between parameters have been taken into account.
Related Topics
Statistical Processing
_simu_get_sampling
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Eldo Control Language
Statistical Processing
_simu_get_sampling
Task function category: Statistical Processing Functions
Returns a matrix containing all the sampling values computed during the Monte Carlo
simulation.
Usage
_simu_get_sampling()
Arguments
None.
Description
If n runs were performed and there are p statistical parameters, then the element [i;j] of the
result matrix is the sampling value of the j-th parameter for the i-th run.
The difference between _simu_get_sampling() and _simu_get_raw_sampling() is related to
parameters dependent on other parameters (for them _simu_get_stat_param_ref_param()
returns a non-null value). _simu_get_raw_sampling() returns a matrix containing the raw values
given by the random number generator whereas _simu_get_sampling() returns a matrix
containing the values that will be applied to the statistical parameters, that is to say after the
dependencies between parameters have been taken into account.
Related Topics
Statistical Processing
_simu_get_raw_sampling
Eldo® User's Manual, 15.3 1079

Eldo Control Language
Statistical Processing
_simu_get_stat_param_dev
Task function category: Statistical Processing Functions
Returns the deviation (for Gaussian distributions) or half-range (for uniform distributions) value
of the parameter identified by the index stat_param_index.
Usage
_simu_get_stat_param_dev(stat_param_index, is_relative)
Arguments
• stat_param_index
Index of statistical parameter.
• is_relative
If is_relative is set to 1, then the result is a percentage value (1.0 for 100%) relatively to the
nominal value, otherwise it is an absolute value.
Description
The result may be -1 if it cannot be computed when is_relative is 1 (especially in the case of a
parameter defined in the netlist with .PARAM p=0 LOT=0.1: it would require to divide by 0 to
get the percentage result). If is_relative is 0, then the result can always be computed.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_get_stat_param_distrib
Task function category: Statistical Processing Functions
Returns the name of the distribution identified by the index stat_param_index.
Usage
simu_get_stat_param_name(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Return Values
Returns the name of the distribution of the parameter identified by the index stat_param_index.
Possible results are:
"UNIFORM" for uniform distribution.
"GAUSS" for normal distribution.
"UNSUPPORTED" for "LIMIT" distributions, user-defined distributions or distributions
defined with Accusim syntax (lot/dev=(dtype, -3sig, +3sig [, bi, -dz, +dz [, off, sv] [,
scale]])).
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1081

Eldo Control Language
Statistical Processing
_simu_get_stat_param_name
Task function category: Statistical Processing Functions
Returns the name of the parameter identified by the index stat_param_index.
Usage
simu_get_stat_param_name(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_get_stat_param_nb_draw
Task function category: Statistical Processing Functions
Returns a positive integer value that acts as a multiplier to set how many times the value of the
parameter identified by the index stat_param_index is to be calculated (only the random value
having the greatest deviation is selected).
Usage
_simu_get_stat_param_nb_draw(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1083

Eldo Control Language
Statistical Processing
_simu_get_stat_param_netlist_dev
Task function category: Statistical Processing Functions
Returns the name of the corresponding device in the netlist (device_name), or "" if not relevant.
Usage
_simu_get_stat_param_netlist_dev(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_get_stat_param_netlist_dev_param
Task function category: Statistical Processing Functions
Returns the name of the corresponding device parameter in the netlist
(device_parameter_name), or "" if not relevant.
Usage
_simu_get_stat_param_netlist_dev_param(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1085

Eldo Control Language
Statistical Processing
_simu_get_stat_param_netlist_mod
Task function category: Statistical Processing Functions
Returns the name of the corresponding model in the netlist (model_name), or "" if not relevant.
Usage
_simu_get_stat_param_netlist_mod(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_get_stat_param_netlist_mod_param
Task function category: Statistical Processing Functions
Returns the name of the corresponding model parameter in the netlist
(model_parameter_name), or "" if not relevant.
Usage
_simu_get_stat_param_netlist_mod_param(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1087

Eldo Control Language
Statistical Processing
_simu_get_stat_param_netlist_param
Task function category: Statistical Processing Functions
Returns the name of the corresponding parameter in the netlist (parameter_name).
Note
For ease of use, if there is no corresponding parameter but a corresponding model
parameter, then the model parameter is returned (model_parameter_name).
Usage
_simu_get_stat_param_netlist_param(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_get_stat_param_nom
Task function category: Statistical Processing Functions
Returns the nominal (mean) value of the parameter identified by the index stat_param_index.
Usage
simu_get_stat_param_name(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1089

Eldo Control Language
Statistical Processing
_simu_get_stat_param_ref_param
Task function category: Statistical Processing Functions
Returns the index of the parameter on which the parameter stat_param_index depends (0 if
none).
Note
In the case of a parameter having LOT and DEV variations, the DEV parameters will
depend on the LOT parameter.
Usage
_simu_get_stat_param_ref_param(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_get_stat_param_sampling_val
Task function category: Statistical Processing Functions
Returns the current sampling value of the parameter identified by the index stat_param. It is the
value used for the next Monte Carlo run.
Usage
_simu_get_stat_param_sampling_val(stat_param)
Arguments
• stat_param
Statistical parameter index.
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1091

Eldo Control Language
Statistical Processing
_simu_is_stat_param_dev
Task function category: Statistical Processing Functions
Returns 1 if the statistical parameter comes from a DEV variation.
Usage
_simu_is_stat_param_dev(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_is_stat_param_devx
Task function category: Statistical Processing Functions
Returns 1 if the statistical parameter comes from a DEVX variation.
Usage
_simu_is_stat_param_devx(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1093

Eldo Control Language
Statistical Processing
_simu_is_stat_param_locked
Task function category: Statistical Processing Functions
Returns 1 if the parameter identified by the index stat_param_index has been locked, that is to
say it will not vary and remain to its nominal value.
Note
By default, parameters are all unlocked.
Usage
_simu_is_stat_param_devx(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Examples
Example: how to access statistical parameters:
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Eldo Control Language
Statistical Processing
.define_testbench tb_mc()
.param pv=2 lot/uni=2.5%
.subckt s
.model resistor r level=3 w=3u l=3u rsh=100 dw=0u lot=0.05u dlr=0u
dev=0.05u
.param pr=agauss(1000, 20, 1, 2)
v1 1 0 pv
r1 1 2 resistor
r2 2 0 pr
.ends
x1 s
x2 s
.dc
.extract v(x1.2) v(x2.2)
.mc 100
.end_define_testbench
.define_task t_display_stat_params()
set iparam = 0
set nbparams = 0
set res = 0
res = _simu_load(name = "tmp/tmp.cir", tb_mc())
if (res.simu_status == 0)
_simu_set_mc_flow()
nbparams = _simu_get_nb_stat_params()
fprint(stdout, "List of statistical parameters:\n")
fprint(stdout, "Name Distribution Nominal Deviation Nb
draw\n")
for (iparam = 1; iparam

Eldo Control Language
Statistical Processing
• PE(parameter_name, device_name, instance_parameter_name)
• PP(parameter1_name, parameter2_name)
• PM(parameter_name, model_name, model_parameter_name)
• P(parameter_name)
• PEM(parameter_name, device_name, instance_parameter_name)
• M(model_name, model_parameter_name)
• EM(device_name, model_parameter_name)
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_is_stat_param_lot
Task function category: Statistical Processing Functions
Returns 1 if the statistical parameter comes from a LOT variation.
Usage
_simu_is_stat_param_lot(stat_param_index)
Arguments
• stat_param_index
Index of statistical parameter.
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1097

Eldo Control Language
Statistical Processing
_simu_lock_stat_param
Task function category: Statistical Processing Functions
Specifies that the value of the parameter identified by the index stat_param_index must not vary
during the Monte Carlo simulation and remain equal to its nominal value.
Note
Except in the case the parameter is dependent on another one, then the value of the
parameter is equal to the value of the parameter it depends on (so _simu_lock_stat_param
only removes the own variation of a parameter).
Usage
_simu_lock_stat_param(stat_param_index)
_simu_lock_stat_param("LOT" | "DEV")
Arguments
• stat_param_index
Index of statistical parameter.
• "LOT" | "DEV"
Calls _simu_lock_stat_param on all parameters having LOT or DEV and DEVX variation.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_reset_random_generators
Task function category: Statistical Processing Functions
Resets the random number generators. This can be useful to reset the random number generators
between two Monte Carlo simulations if you want them to use the same random numbers.
Usage
_simu_reset_random_generators()
Arguments
None.
Examples
Example: how to modify the distribution of a parameter to simulate only extreme values:
Eldo® User's Manual, 15.3 1099

Eldo Control Language
Statistical Processing
.define_testbench tb_mc()
.param pv=2 lot/uni=2.5%
.subckt s
.model resistor r level=3 w=3u l=3u rsh=100 dw=0u lot=0.05u dlr=0u
dev=0.05u
.param pr=agauss(1000, 20, 1)
v1 1 0 pv
r1 1 2 resistor
r2 2 0 pr
.ends
x1 s
x2 s
.dc
.plot w1=v(x1.2)
.mc 100 all
* To enlarge the Gaussian distributions.
.option sigtail=8
.end_define_testbench
.define_task t_simu(extreme=1)
set iparam = 0
set iparam_x1_r2 = 0
set nbparams = 0
set nbruns = 0
set res = 0
set w = 0
res = _simu_load(name = "tmp/tmp.cir", tb_mc())
if (res.simu_status == 0)
_simu_set_mc_flow()
nbparams = _simu_get_nb_stat_params()
/* Find the parameter we want to modify the distribution of.
*/
for (iparam = 1; iparam

Eldo Control Language
Statistical Processing
break
endif
endif
/* Execute 1 run. */
res = _simu_run()
if (res.simu_status != 0)
fprint(stdout, "Simulation #" + nbruns + " failed!\n")
break
endif
endwhile
w = _simu_get_wave("w1")
else
fprint(stdout, "Failed to find the parameter!\n")
endif
endif
.end_define_task
.define_function modify_distrib(index=0)
set distrib = _simu_get_stat_param_distrib(index)
set nom = _simu_get_stat_param_nom(index)
set dev = _simu_get_stat_param_dev(index, 0)
set val = _simu_get_stat_param_sampling_val(index)
if (distrib != "GAUSS")
fprint(stdout, "Error: distribution must be GAUSS!\n")
return 1
endif
while (abs(val - nom) < 2 * dev)
/* Get a more extreme value. */
val = _simu_get_random(distrib, nom, dev, 8)
endwhile
/* Force the value. */
_simu_set_stat_param_sampling_val(index, val)
return 0
.end_define_function
.t_simu extreme=0
.t_simu extreme=1
Related Topics
Statistical Processing
_simu_get_random
Eldo® User's Manual, 15.3 1101

Eldo Control Language
Statistical Processing
_simu_run
Task function category: Statistical Processing Functions
_simu_run(mode="nom") runs the nominal Monte Carlo simulation and returns a result
structure (as the simulation function).
Usage
_simu_run(mode="nom")
_simu_run(mode="mc n")
Arguments
• mode="nom"
Normal mode.
• mode="mc n"
Runs n Monte Carlo simulations.
Description
The _simu_run function also enables you to execute a specified number of Monte Carlo runs.
_simu_run(mode="mc n") runs n Monte Carlo simulations and returns a result structure (as the
simulation function).
• .MPRUN is not supported.
• Calling _simu_run() is equivalent to calling _simu_run(mode="mc 1") in ECL Monte
Carlo flow.
• Other modes than mode="nom" or mode="mc n" are not supported in ECL Monte Carlo
flow (error). Inversely, an error occurs if these modes are used outside the ECL Monte
Carlo flow.
• _simu_set_cond() is not supported in ECL Monte Carlo flow.
Related Topics
Statistical Processing
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Eldo® User's Manual, 15.3

Eldo Control Language
Statistical Processing
_simu_set_mc_flow
Task function category: Statistical Processing Functions
Activates the ECL Monte Carlo flow. The netlist may or may not contain a .MC command; it is
entirely ignored if the ECL Monte Carlo flow is activated.
Usage
_simu_set_mc_flow([max_nb_runs])
Arguments
• max_nb_runs
The maximum number of runs for the Monte Carlo simulation. Default value is 100000.
Description
The netlist needs to be reloaded to deactivate the ECL Monte Carlo flow.
The function will generate a warning if statistical parameters with unsupported distributions
(see after) are in the netlist
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1103

Eldo Control Language
Statistical Processing
_simu_set_stat_param_sampling_val
Task function category: Statistical Processing Functions
Sets the current sampling value of the parameter identified by the index stat_param to the value
val. It will be the value used for the next Monte Carlo run.
Usage
_simu_set_stat_param_sampling_val(stat_param, val)
Arguments
• stat_param
Index of statistical parameter.
Related Topics
Statistical Processing
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Eldo Control Language
Statistical Processing
_simu_unlock_stat_param
Task function category: Statistical Processing Functions
Specifies that the value of the parameter identified by the index stat_param_index must vary
during the Monte Carlo simulation according to its distribution.
Usage
_simu_unlock_stat_param(stat_param_index)
_simu_unlock_stat_param("LOT" | "DEV")
Arguments
• stat_param_index
Index of statistical parameter.
• "LOT" | "DEV"
Calls _simu_unlock_stat_param on all parameters having LOT or DEV and DEVX
variation.
Related Topics
Statistical Processing
Running Monte Carlo Runs in Parallel
Running ECL Monte Carlo simulations in parallel requires to call _simu_load,
_simu_set_mc_flow, simu_run and _simu_end inside the para_for loop. This means the Monte
Carlo simulations will be performed by different simulators.
To ensure reproducibility of results, only one-level of para_for loops is allowed (nested parallel
loops are not allowed to run simulations using the ECL Monte Carlo flow) and each job uses a
different random number generator (they are initialized with different seeds); the reproducibility
of results is ensured between different runs of the same ECL netlist, but not if the para_loop is
changed into a sequential for loop (because simulations run inside a sequential for loop use the
same random number generator).
Monte Carlo results from each job must be saved and aggregated to be able to call Monte Carlo
post-processing functions. If sensibilities have to be computed, then each sampling must also be
saved since _simu_get_mcsens needs it.
Example: (same example as before but using parallelism) first a parallel Monte Carlo simulation
is run to find the most important parameters acting on the propagation delay; then from the
name of these parameters, the width of the corresponding MOS is increased to see how it
impacts the delay.
Eldo® User's Manual, 15.3 1105

Eldo Control Language
Statistical Processing
.define_task t_main()
set important_params[]=""
set i = 0
set width[] = 0
set device[] = ""
set res = 0
/* Load the netlist. */
res = _simu_load(name = "mc/mc.cir")
if (res.simu_status == 0)
_simu_set_mc_flow()
/* Run nominal. */
run_nominal()
/* Call _simu_end now because when running the parallel loop
* in the function find_important_params, each job will have
* to do _simu_load, _simu_set_mc_flow, _simu_run and _simu_end.
_simu_end()
else
fprint(stdout, "Parsing failed!\n")
endif
/* Run parallel Monte-Carlo to find important parameters. */
if (find_important_params(p_extract_name = "OPFREQ",
+ important_params=@p_important_params) != 0)
/* Reload the netlist to be able to find the names and the widths of
* the important parameters.
*/
res = _simu_load(name = "mc_get_res/mc_get_res.cir")
if (res.simu_status == 0)
_simu_set_mc_flow()
for (i = important_params.imin;
+ i

Eldo Control Language
Statistical Processing
/* Increase its width to reduce the delay
* (this must be done before _simu_set_mc_flow).
*/
fprint(stdout,
+ "Increase width of %s to %.2g\n",
+ device[i],
+ width[i]*2)
_simu_set("E", device[i], "W", width[i]*2)
endfor
_simu_set_mc_flow()
/* Re-run nominal. */
run_nominal()
endif
_simu_end()
endif
.end_define_task
.define_function run_nominal()
set res = 0
set delay1 = 0
set delay2 = 0
fprint(stdout, "Running nominal...\n")
res = _simu_run(mode="nom")
if (res.simu_status == 0)
delay1 = _simu_get_extract("DELAY1")
delay2 = _simu_get_extract("DELAY2")
fprint(stdout, "DELAY1 = %.3g Sec\nDELAY2 = %.3g Sec\n",
delay1, delay2)
else
fprint(stdout, "Nominal failed!\n")
return 0
endif
return 1
.end_define_function
.define_function find_important_params(p_extract_name = "",
+ @p_important_params[] = 0)
set res = 0
set conv = 0
set sens_list[] = 0
set i = 0
set nb_para_runs = 20
set nb_important_params = 0
set extract_res[] = 0
set nbmc = 0
set sampling_saved[] = 0
set global_sampling[] = 0
while (conv == 0)
/* Execute in parallel 20 more Monte-Carlo runs. */
fprint(stdout, "Running 20 Monte-Carlo...\n")
para_for(i = 1; i

Eldo Control Language
Statistical Processing
if (local_res.simu_status != 0)
fprint(stdout, "Simulation %d failed!\n", nbmc + i)
return 0;
endif
/* Get the result; use 'nbmc + i' to build the array
containing
* all results.
*/
extract_res[nbmc + i] = _simu_get_extract(p_extract_name)
/* Save the sampling (necessary to call _simu_get_mcsens); use
* 'i' because the samplings saved during this 20 new runs will
* be appended to the global sampling outside this loop.
*/
sampling_saved[i] = _simu_get_raw_sampling()
_simu_end()
end_para_for
/* sampling_saved is an array containing many samplings. To
* build the global sampling, we must append each sampling
* to each other.
*/
for (i = 1; i 10000)
fprint(stdout, "Failed to converge!\n")
return 0;
endif
endwhile
/* Get sensitivities. */
sens_list = _simu_get_mcsens(extract_res,
+ "LSS",
+ global_sampling)
/* Extract parameters having importance >= 10%. */
if (sens_list.size > 0)
for (i = sens_list[1].imin;
+ i = 0.1)
nb_important_params++
/* Get its index. */
p_important_params[nb_important_params] =
sens_list[1][i]
endif
endfor
endif
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Eldo Control Language
Statistical Processing
return 1
.end_define_function
.t_main
.option set_eldo_cl_verbose=0
* Netlist for CMOS RIPPLE CARRY ADDER
* This example centers around an 1-bit CMOS ripple carry adder
.PARAM WIN_GLOB =40U
.PARAM WOUT_GLOB=40U
* INCLUDE NMOS AND PMOS MODELS
.SUBCKT ONEBITADDER VDD VSS A B C SUM CO PARAM: WIN=40U WOUT=40U
XMP1 VDD A 1 VDD P W={2*WIN} L=1U AD=400P AS=400P
XMP2 VDD B 1 VDD P W={2*WIN} L=1U AD=400P AS=400P
XMP3 VDD A 2 VDD P W=20U L=1U AD=400P AS=400P
XMP4 VDD A 3 VDD P W=20U L=1U AD=400P AS=400P
XMP5 VDD B 3 VDD P W=20U L=1U AD=400P AS=400P
XMP6 VDD C 3 VDD P W=20U L=1U AD=400P AS=400P
XMP7 1 C NC VDD P W={2*WIN} L=1U AD=400P AS=400P
XMP8 2 B NC VDD P W=20U L=1U AD=400P AS=400P
XMP9 3 NC NS VDD P W=20U L=1U AD=400P AS=400P
XMP10 VDD A 7 VDD P W=20U L=1U AD=400P AS=400P
XMP11 7 B 8 VDD P W=20U L=1U AD=400P AS=400P
XMP12 8 C NS VDD P W=20U L=1U AD=400P AS=400P
XMN13 NC C 4 VSS N W=WIN L=1U AD=400P AS=400P
XMN14 NC B 5 VSS N W=20U L=1U AD=400P AS=400P
XMN15 NS NC 6 VSS N W=20U L=1U AD=400P AS=400P
XMN16 4 A VSS VSS N W=WIN L=1U AD=400P AS=400P
XMN17 4 B VSS VSS N W=WIN L=1U AD=400P AS=400P
XMN18 5 A VSS VSS N W=20U L=1U AD=400P AS=400P
XMN19 6 A VSS VSS N W=20U L=1U AD=400P AS=400P
XMN20 6 B VSS VSS N W=20U L=1U AD=400P AS=400P
XMN21 6 C VSS VSS N W=20U L=1U AD=400P AS=400P
XMN22 NS C 9 VSS N W=20U L=1U AD=400P AS=400P
XMN23 9 B 10 VSS N W=20U L=1U AD=400P AS=400P
XMN24 10 A VSS VSS N W=20U L=1U AD=400P AS=400P
* SUM AND CARRY OUTPUT BUFFERS
XMP25 VDD NS SUM VDD P W=20U L=1U AD=400P AS=400P
XMN26 SUM NS VSS VSS N W=20U L=1U AD=400P AS=400P
XMP27 VDD NC CO VDD P W={2*WOUT} L=1U AD=400P AS=400P
XMN28 CO NC VSS VSS N W=WOUT L=1U AD=400P AS=400P
* LAYOUT CAPACITANCES
C1 1 VSS 0.05P
C2 2 VSS 0.05P
C3 3 VSS 0.05P
C4 4 VSS 0.05P
C5 5 VSS 0.05P
C6 6 VSS 0.05P
CA A VSS 0.1P
CB B VSS 0.1P
CC C VSS 0.1P
CSM SUM VSS 0.15P
Eldo® User's Manual, 15.3 1109

Eldo Control Language
Statistical Processing
CCO CO VSS 0.15P
.ENDS ONEBITADDER
VDD VDD 0 5
X0 VDD 0 A0 B0 0 SUM0 CO0 ONEBITADDER WIN=WIN_GLOB WOUT=WOUT_GLOB
VA0 A0 0 5
VB0 B0 0 PULSE 0 5 .2N .2N .2N 9.8N 20N
* TRANSIENT ANALYSIS
.TRAN 0.1N 6N
.PLOT TRAN V(SUM0) V(B0)
* EXTRACT SECTION
.EXTRACT TRAN LABEL=DELAY1
TPD(V(B0),V(SUM0),VTHIN=2.5,VTHOUT=0.5)
.EXTRACT TRAN LABEL=DELAY2
TPD(V(B0),V(CO0),VTHIN=2.5,VTHOUT=4.5)
.EXTRACT TRAN LABEL=OPFREQ (1/MAX(EXTRACT(DELAY1),
EXTRACT(DELAY2)))
+ LBOUND=280Meg
* MONTE CARLO ANALYSIS
.OPTION AEX DUMP_MCINFO
.MC 100
+ DATAFLOW=1
.EXTRACT MC LABEL=MINFREQ MCMIN(OPFREQ)
.EXTRACT MC LABEL=MAXFREQ MCMAX(OPFREQ)
* A global factor that artificially scales the sigma of all
variables:
.param g_mm_factor=10
* The sigtail option is used to allow wider spread (up to +/- 4
sigmas) for the input variables:
.option sigtail=4
* The device models (some of the .model parameters have
statistical variations):
.subckt n d g s b param: w=1u l=1u ad=400p as=400p
m1 d g s b modn w=w l=l ad=ad as=as
.param Tox=19E-09 a_mm_Tox=0.4543u b_mm_Tox=0.1435 dev_mm_Tox
='a_mm_Tox/sqrt(w*l)+b_mm_Tox'
.param Vth0=.3322 a_mm_Vth0=0.40654u b_mm_Vth0=0.11654
dev_mm_Vth0
='a_mm_Vth0/sqrt(w*l)+b_mm_Vth0'
.param U0=388.3203 a_mm_U0=0.565745u b_mm_U0=0.264563 dev_mm_U0
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Eldo Control Language
Statistical Processing
='a_mm_U0/sqrt(w*l)+b_mm_U0'
.model modn NMOS
+Level=53
+Tox =Tox dev/gauss={g_mm_factor*dev_mm_Tox}%
+Vth0 =Vth0 dev/gauss={g_mm_factor*dev_mm_Vth0}%
+U0 =U0 dev/gauss={g_mm_factor*dev_mm_U0}%
+kf=1e-27 af=2
+Tnom=27.0
+Nch= 2.498E+17 Xj=1.00000E-07
+Lint=9.36e-8 Wint=1.47e-7
+K1= .756 K2= -3.83e-2 K3= -2.612
+Dvt0= 2.812 Dvt1= 0.462 Dvt2=-9.17e-2
+Nlx= 3.52291E-08 W0= 1.163e-6
+K3b= 2.233
+Vsat= 86301.58 Ua= 6.47e-9 Ub= 4.23e-18 Uc=-4.706281E-11
+Rdsw= 650 wr=1
+A0= .3496967 Ags=.1 B0=0.546 B1= 1
+ Dwg = -6.0E-09 Dwb = -3.56E-09 Prwb = -.213
+Keta=-3.605872E-02 A1= 2.778747E-02 A2= .9
+Voff=-6.735529E-02 NFactor= 1.139926 Cit= 1.622527E-04
+Cdsc=-2.147181E-05
+Cdscb= 0 Dvt0w = 0 Dvt1w = 0 Dvt2w = 0
+ Cdscd = 0 Prwg = 0
+Eta0= 1.0281729E-02 Etab=-5.042203E-03
+Dsub= .31871233
+Pclm= 1.114846 Pdiblc1= 2.45357E-03 Pdiblc2= 6.406289E-03
+Drout= .31871233 Pscbe1= 5000000 Pscbe2= 5E-09 Pdiblcb = -.234
+Pvag= 0 delta=0.01
+ Wl = 0 Ww = -1.420242E-09 Wwl = 0
+ Wln = 0 Wwn = .2613948 Ll = 1.300902E-10
+ Lw = 0 Lwl = 0 Lln = .316394
+ Lwn = 0
+kt1=-.3 kt2=-.051
+At= 22400
+Ute=-1.48
+Ua1= 3.31E-10 Ub1= 2.61E-19 Uc1= -3.42e-10
+Kt1l=0 Prt=764.3
.ends
.subckt p d g s b param: w=1u l=1u ad=400p as=400p
m1 d g s b modp w=w l=l ad=ad as=as
.param Tox=19E-09 a_mm_Tox=0.365543u b_mm_Tox=0.001435
dev_mm_Tox
='a_mm_Tox/sqrt(w*l)+b_mm_Tox'
.param Vth0=-.3732829 a_mm_Vth0=0.30654u b_mm_Vth0=0.1452
dev_mm_Vth0
='a_mm_Vth0/sqrt(w*l)+b_mm_Vth0'
.param U0=138.7609 a_mm_U0=0.565745u b_mm_U0=0.366454 dev_mm_U0
='a_mm_U0/sqrt(w*l)+b_mm_U0'
.model modp PMOS
+Level=53
Eldo® User's Manual, 15.3 1111

Eldo Control Language
Statistical Processing
+Tox =Tox dev/gauss={g_mm_factor*dev_mm_tox}%
+Vth0 =Vth0 dev/gauss={abs(g_mm_factor*dev_mm_Vth0)}%
+U0 =U0 dev/gauss={g_mm_factor*dev_mm_U0}%
+kf=1e-27 af=2
+Tnom=27.0
+Nch= 3.533024E+17 Xj=1.00000E-07
+Lint=6.23e-8 Wint=1.22e-7
+ K1= .8362093 K2=-8.606622E-02 K3= 1.82
+Dvt0= 1.903801 Dvt1= .5333922 Dvt2=-.1862677
+Nlx= 1.28e-8 W0= 2.1e-6
+K3b= -0.24 Prwg=-0.001 Prwb=-0.323
+Vsat= 103503.2 Ua= 1.39995E-09 Ub= 1.e-19 Uc=-2.73e-11
+ Rdsw= 460
+A0= .4716551 Ags=0.12
+Keta=-1.871516E-03 A1= .3417965 A2= 0.83
+Voff=-.074182 NFactor= 1.54389 Cit=-1.015667E-03
+Cdsc= 8.937517E-04
+Cdscb= 1.45e-4 Cdscd=1.04e-4
+ Dvt0w=0.232 Dvt1w=4.5e6 Dvt2w=-0.0023
+Eta0= 6.024776E-02 Etab=-4.64593E-03
+Dsub= .23222404
+Pclm= .989 Pdiblc1= 2.07418E-02 Pdiblc2= 1.33813E-3
+Drout= .3222404 Pscbe1= 118000 Pscbe2= 1E-09
+Pvag= 0
+kt1= -0.25 kt2= -0.032 prt=64.5
+At= 33000
+Ute= -1.5
+Ua1= 4.312e-9 Ub1= 6.65e-19 Uc1= 0
+Kt1l=0
.ends
The output of the previous example will be:
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Increase width of X0.XMN14.M1 to 4e-05
Increase width of X0.XMN18.M1 to 4e-05
Increase width of X0.XMP9.M1 to 4e-05
Running nominal...
DELAY1 = 2.93e-09 Sec
DELAY2 = 1.39e-09 Sec
Running nominal...
DELAY1 = 4.67e-09 Sec
DELAY2 = 2.41e-09 Sec
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
Running 20 Monte-Carlo...
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Eldo Control Language
Statistical Processing
Related Topics
Statistical Processing
Eldo® User's Manual, 15.3 1113

Eldo Control Language
Advanced Simulation Options
Advanced Simulation Options
This section describes advanced simulation options, how to activate the debug mode, and the
complete grammar of the Eldo Control Language:
• Simulation
• Debug Mode
• ECL Grammar Description
Simulation
This section describes advanced simulation options.
Verbosity
By default, when a simulation is run, information is displayed on the standard output:
***** Running simulation...
*****Generated simulation file: simu_1.cir
***** (backup file: simu_1__1.cir)
*****Log file: simu_1.log
***** Simulation succeeded
This information display can be disabled by setting:
.option set_eldo_cl_verbose=0
warn2err
If a simulation command fails for any reason, then the warning 1803 will be generated on the
standard output. To generate an error instead, add the following command to the netlist:
Log File
.option warn2err=1803
The name of the log file can be specified through the log parameter of the simulation command.
By default, if many simulations are performed and they use the same log file, each log file will
be appended. To change this behavior, set the following option:
.option set_eldo_cl_sim_log_append=0
Then, if many simulations use the same log file, at the end of the simulation the log file is the
log file of the last simulation.
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Temporary Files
Eldo Control Language
Advanced Simulation Options
To perform simulations, a number of temporary files have to be generated on-disk. By default,
when the name and log parameters of the simulation command are not set, these files are
generated in a temporary directory located in the Eldo outpath directory, named
“eldo_cl_simu_” with an automatically generated number appended, for example:
eldo_cl_simu_12345.
To ensure that these files are automatically removed after the simulation has ended, specify one
of the following options:
• .option remove_eldo_cl_temp_files=3
All temporary files are removed (even if the child simulation has failed, so this option
should only be used when confidence that the simulation will complete successfully is
high, otherwise it may be difficult to debug).
• .option remove_eldo_cl_temp_files=2
All temporary files are removed except for the log file (in this case, the log file is
generated outside the temporary directory and has the same name as the temporary
directory: eldo_cl_simu_xxxxx.log) and also backup files of the generated simulation
file.
• .option remove_eldo_cl_temp_files=1
This is the default; only files that are not useful for debugging are removed (typically the
ecl_cmd script file used to launch the child simulation).
• .option remove_eldo_cl_temp_files=0
No temporary files are removed.
These options have an effect only if the name and log parameters of the simulation command
are not set; otherwise:
chi File
• If the name parameter is set and the value of the remove_eldo_cl_temp_files option is
more than 2, it is automatically set to 1.
• If the log parameter is set and the value of the remove_eldo_cl_temp_files option is
equal to 3, it is automatically set to 2.
The name of the netlist file can be specified through the name parameter of the simulation
function. By default, if many simulations are performed (in the same task) and they use the
same netlist file, each .chi file will be appended to the previous one. To change this behavior, set
the following option:
.option set_eldo_cl_sim_chi_append=0
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Eldo Control Language
Advanced Simulation Options
Then, if many simulations use the same netlist file, at the end of the simulation the .chi file is the
.chi file of the last simulation.
Backup cir File
By default, the Control Language makes a copy of the netlist simulated inside tasks to provide a
trace in case debug is needed. To change this behavior, set the following option:
wdb File
.option backup_eldo_cl_netlists=0
By default, when waveform results are assigned to task local variables to be able to perform
some post-processing after a simulation, the waveforms are copied from the .wdb file generated
during the simulation to the main .wdb file. If many simulations are run and many waveform
results are used, the main .wdb can become very large and slow further simulations. To avoid
this problem, set the following option:
.option keep_eldo_cl_temp_waves=0
Then, waveforms results will be automatically deleted from the main .wdb file when they are
not used anymore (the waveform is deleted when all variables depending on this waveform
become out of scope). See functions operating on wdb files in “Library of Functions for Tasks”
on page 854 to know how to explicitly save waveforms in a .wdb file in this case.
Arguments
By default, arguments passed to Eldo on the command line will also be passed to Eldo processes
performing the Control Language simulations. If arguments are set with the args argument of
the simulation function, these new arguments will be appended to those passed to the main Eldo
process. For example, if you run Eldo with the arguments -compat or -premier, Eldo processes
performing the simulation will also be run using these arguments. To deactivate this behavior,
set the following option:
.option propagate_eldo_cl_main_args=0
Then, arguments set to the args parameter of the simulation function will be the only ones
passed to the Eldo processes performing the simulations.
Related Topics
Defining and Running Simulations
Generated Files
Tasks
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Debug Mode
Eldo Control Language
Advanced Simulation Options
A specific mode is available to provide a trace of what happened during the execution of a
sequence of Control Language code. Using this mode is much more efficient than inserting
multiple fprint commands into your code.
The trace can either be written to a file or to the standard output:
• To write the trace to a file, set the environment variable ELDO_CL_DEBUG to the path
to the target file:
setenv ELDO_CL_DEBUG /path/file.txt
• To send the trace to the standard output, set the environment variable to stdout:
setenv ELDO_CL_DEBUG stdout
Example of generated trace:
*** In file '/home/jdoe/eldo/testcase/debug.cir'
25 ** call to t_simu:
16 u12

Eldo Control Language
Advanced Simulation Options
** end of call to simulation
17 simu_res

Eldo Control Language
Advanced Simulation Options
/* Lexemes. */
ID ::= ID_FRAG;
OUT_ID ::= '@' ID_FRAG;
ENV_ID ::= '$' ID_FRAG;
SIM_CMD_ID ::= '.' ID_FRAG;
ID_FRAG ::= LETTER_FRAG (DIGIT_FRAG | LETTER_FRAG | '#')*;
LETTER_FRAG := 'a'..'z' | 'A'..'Z' | '_';
NUM ::= (DIGIT_FRAG+ ('.' DIGIT_FRAG*)? NUM_EXP_FRAG? UNIT_FRAG?)|
('.' DIGIT_FRAG+ NUM_EXP_FRAG? UNIT_FRAG?)|
('0' ('x' |'X') HEX_DIGIT_FRAG+);
DIGIT_FRAG ::= '0'..'9';
NUM_EXP_FRAG ::= ('E' | 'e') ('+' | '-')? DIGIT_FRAG+;
HEX_DIGIT_FRAG ::= '0'..'9' | 'a'..'f' | 'A'..'F';
UNIT_FRAG ::= ('A'|'a') |
('F'|'f') |
('P'|'p') |
('N'|'n') |
('U'|'u') |
('M'|'m') |
('K'|'k') |
('MEG'|'meg') |
('G'|'g') |
('T'|'t');
STRING_LITERAL ::= '"' (ESCAPE_SEQUENCE_FRAG | ~( '\\' | '"'))* '"';
ESCAPE_SEQUENCE_FRAG::= '\\' ('b'|
't'|
'n'|
'f'|
'r'|
'\"'|
'\\'|
'\n');
WS ::= WS_FRAG;
WS_FRAG ::= ' ' | '\t';
NEWLINE ::= NEWLINE_FRAG;
NEWLINE_FRAG ::= '\r'? '\n';
CUTLINE_OR_COMMENT ::=
(NEWLINE_FRAG
(NEWLINE_FRAG | WS_FRAG | COMMENT_FRAG)*
('+' | '*' (~('\n'))*)) |
('\\' NEWLINE_FRAG) |
COMMENT_FRAG;
COMMENT_FRAG ::= '//' (~('\n'))* |
'/*' .* '*/';
/* Testbench grammar rules. */
testbench ::=
'.define_testbench' ID (argument_def)? NEWLINE+
testbench_block?
'.end_define_testbench'
testbench_block ::=
Eldo® User's Manual, 15.3 1119

Eldo Control Language
Advanced Simulation Options
(simulation_command NEWLINE+)+;
simulation_command ::= ? SPICE simulation command ?
/* Task and function grammar rules. */
task ::=
NEWLINE*
'.define_task'
ID (argument_def)? NEWLINE+
block?
'.end_define_task' NEWLINE*
function ::=
'.define_function' ID (argument_def)? NEWLINE+
block?
'.end_define_function'
block ::=
(declaration_or_statement ';'? NEWLINE+)+;
declaration_or_statement ::= declaration | statement;
declaration ::= 'set' ( (left_value | ID '[' ']') '=' expression)+;
statement::= assignment |
return_statement |
if_statement |
while_statement |
step_statement |
for_statement |
function_call |
'break' |
'continue';
return_statement ::= 'return' expression;
if_statement ::= 'if' '(' expression ')' NEWLINE+
block?
('else' NEWLINE+
block?)?
'endif';
while_statement ::= 'while' '(' expression ')' NEWLINE+
block?
'endwhile';
step_statement ::=
'step' '('
('type' '=' ('step' | 'incr' | 'decr' |
'lin' | 'linear' | 'log' |
'list') ',')?
'param' '=' id_list ','
(('list' '=' expression_list_list) |
('start' '=' expression ','
'stop' '=' expression ','
('step' | 'incr' | 'decr' | 'n' | 'dec') '=' expression))
')' NEWLINE+
block?
'endstep';
for_statement ::= 'for' '(' assignment? ';'
expression? ';'
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Eldo Control Language
Advanced Simulation Options
assignment? ')' NEWLINE+
block?
'endfor';
id_list ::= (ID | '(' ID (',' ID)* ')');
expression_list_list ::=
expression_list |
('(' expression_list (',' expression_list)* ')');
expression_list ::= expression |
'(' expression (',' expression)* ')';
/* Common grammar rules. */
argument_def ::= '(' argument_list? ')';
argument_list ::= argument (',' argument)*;
multi_index_range ::= index_range (';' index_range )*;
index_range ::= expression (',' expression)? ;
left_value ::= ID | array_access;
assignment ::= left_value
(('++' | '--') |
('=' | '+=' | '-=' | '*=' | '/=' | '%=' |
'&=' | '|=' | '^=' | '=') expression);
argument ::= expression | assignment
expression ::= conditional_expression;
conditional_expression ::= logical_or_expression
('?' expression
':' expression)?;
logical_or_expression ::= logical_and_expression
('||' logical_and_expression)*;
logical_and_expression ::= inclusive_or_expression
('&&' inclusive_or_expression)*;
inclusive_or_expression ::= exclusive_or_expression
('|' exclusive_or_expression)*;
exclusive_or_expression ::= and_expression
('^' and_expression)*;
and_expression ::= equality_expression
('&' equality_expression)*;
equality_expression ::= relational_expression
(('==' | '!=') relational_expression)*;
relational_expression ::= shift_expression
(('' | '=') shift_expression)*;
shift_expression ::= additive_expression
(('') additive_expression)*;
additive_expression ::= multiplicative_expression
(('+' | '-') multiplicative_expression)*;
multiplicative_expression ::= power_expression
(('*' | '/' | '%') power_expression)*;
power_expression ::= unary_expression
('**' power_expression)?;
unary_expression ::= postfix_expression |
unary_operator unary_expression;
postfix_expression ::= primary_expression |
function_call |
Eldo® User's Manual, 15.3 1121

Eldo Control Language
Advanced Simulation Options
array_access attribute? |
id_expression attribute;
attribute ::= array_attribute | sim_res_attribute;
array_attribute ::= '.imin' | '.imax' | '.size';
sim_res_attribute ::= '.simu_status' |
'.simu_time' |
'.nb_tot_elements' |
'.nb_nodes' |
'.avg_newton' |
'.nb_newton_iter' |
'.nb_steps' |
'.nb_rej_steps' |
'.nb_newt_rej_steps' |
'.nb_lte_rej_steps' |
'.nb_proc_used';
function_call ::= ID '(' argument_list? ')';
array_access ::= id_expression ('[' multi_index_range ']')+;
unary_operator ::= '+' | '-' | '~' | '!';
primary_expression ::= id_expression |
ENV_ID |
constant |
'(' expression ')';
id_expression ::= ID | OUT_ID;
constant ::= NUM | STRING_LITERAL;
/* Testbench instantiation or task/function call from the SPICE netlist.
*/
command_call ::= SIM_CMD_ID spice_argument_list?;
spice_argument_list ::= assignement+;
Related Topics
Advanced Simulation Options
Tasks
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Eldo® User's Manual, 15.3

Eldo Control Language
Examples Using ECL as an Alternative to Standard Eldo Commands
Examples Using ECL as an Alternative to
Standard Eldo Commands
The Eldo Control Language can be used as a powerful custom alternative to standard Eldo
commands. The examples here show the steps required to create ECL alternatives.
• .STEP Alternative
• .EXTRACT Alternative
• .PRINTFILE Alternative #1
• .PRINTFILE Alternative #2
• .OPTIMIZE Alternative
.STEP Alternative
Netlist directory: 25-step_alternative
The following example shows how the step loops available inside ECL can be used as an
alternative to the regular .STEP command in Eldo.
It uses an ECL step loop inside a testbench instead of a .STEP param statement. The testbench
instantiates an RC circuit and steps the resistor value from 1 to 10 with increments of 1. This is
only a simple example, highlighting the mechanism used, and can be extended to more complex
simulation sequences possible only with ECL.
Original Netlist
* ECL .STEP alternative
v1 1 0 3
r1 1 2 p
c1 2 0 1u ic=0
* name needed for ECL
.plot tran res_wave = v(2)
.tran 0.1 1 uic
.param p = 1
.step param p 1k 200k 1k
.end
Steps to Create an ECL Alternative
Follow the steps below to replace the regular .STEP by an ECL step loop:
1. Parametrize the netlist by creating a testbench:
Eldo® User's Manual, 15.3 1123

Eldo Control Language
.STEP Alternative
.define_testbench tb_netlist (param_tb_value = 1 )
2. Modify the original netlist to exclude the .STEP and modify the .PARAM command to
use the testbench argument:
.param p = param_tb_value
.end_define_testbench
3. Define an ECL task with a step loop to run the simulations. This is an incremental loop;
the parameter being swept, loop_param, is specified with param. The start, stop, and
step define the loop structure. The loop ends with the endstep command.
.define_task t1
/* parameter for the step loop. */
set loop_param = 1
set wave_res[] = 0
/* step loop similar to the .step command. */
step (type=step, param=loop_param, start=1k, stop=200k, step=1k)
/* run the simulation. */
simulation(tb_netlist(param_tb_value=loop_param),
+ name="res/simu" + loop_param + ".cir",
+ wave_res[loop_param/1k]=@res_wave)
endstep
.end_define_task
.t1
The full example is located in $MGC_AMS_HOME/examples/ecl/25-step_alternative.
The simulation command runs the simulation of the testbench and obtains results. The
simulation files and waveforms for each step will be generated in different files in the output
directory res. The name of each file is made up of the simu prefix followed by the step index
(simu1, simu2, simu3, and so on). These generated files can be useful to debug simulations. A
directory has been specified so that all generated temporary files can be easily removed. The
testbench is instantiated with the .t1 statement.
An important difference to note compared with a regular .STEP is:
With the original netlist, compound waveforms are generated; but with ECL, since there are 200
simulations, by default 200 wdb files will be generated; if the same wdb is used, it will be
overwritten. To avoid this, there are two solutions:
• Specify a specific name for each wdb file (using the “name” argument).
Avoid this solution, because you will have 200 wdb files generated.
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Eldo Control Language
.EXTRACT Alternative
• (Used in the example.) Specify explicitly the waveforms you want in the main wdb file
(by using the “@out” argument). Do this by giving a name to waveforms (res_wave
above) and then acquire them for each simulation.
As a result, inside the main wdb file, there will be 200 waveforms.
Parallel Version
The step loop in the previous example is sequential: simulations are performed one after the
other. It is possible to run these simulations in parallel when using the parallel version of the
step loop by replacing the keywords “step” and “endstep” with “para_step” and
“end_para_step” accordingly. The parallel loops are also more restrictive than the sequential
loops (ECL will output errors to make sure the parallel code does not cause any concurrency
issues). It is advised to only run simulations in parallel and store their results inside arrays, and
to perform any post-processing computation outside the parallel loop, in a sequential loop.
The full example is located in $MGC_AMS_HOME/examples/ecl/25-step_alternative/
step_alternative_para.cir.
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, and “Defining and Running Simulations” on page 841 for more
information on the concepts used in the example.
Tip
See “.STEP” in the Eldo Reference Manual.
Related Topics
.EXTRACT Alternative
Examples Using ECL as an Alternative to Standard Eldo Commands
.EXTRACT Alternative
Netlist directory: 26-extract_alternative
The following example shows how the ECL can be used as an alternative to the regular
.EXTRACT commands in Eldo to print results in a custom format.
This example uses the same original netlist as used in the .STEP Alternative. Add a .EXTRACT
command to the previous netlist (inside the testbench) as follows:
* name needed for ECL
.extract tran label=res_extract xthres(v(2), 1.5)
The default display without any additional ECL custom formatting is:
Eldo® User's Manual, 15.3 1125

Eldo Control Language
.EXTRACT Alternative
RES_EXTRACT[1] = 6.9296E-01
RES_EXTRACT[2] = 1.3859E+00
RES_EXTRACT[3] = 2.0937E+00
RES_EXTRACT[4] = 2.7718E+00
RES_EXTRACT[5] = 3.4785E+00
RES_EXTRACT[6] = 4.1633E+00
RES_EXTRACT[7] = 4.8633E+00
RES_EXTRACT[8] = 5.5480E+00
RES_EXTRACT[9] = 6.2396E+00
RES_EXTRACT[10] = 6.9389E+00
Update the netlist with the following ECL task to add ECL custom formatting (see section
below the “display results in a custom way” comment):
.define_task t1
/* parameter for the step loop. */
set loop_param = 1
set param_value[] = 0
set extract_res[] = 0
/* step loop similar to the .step command. */
step (type=step, param=loop_param, start=1, stop=10, step=1)
/* run the simulation. */
param_value[loop_param] = loop_param
simulation(tb_netlist(param_tb_value=loop_param),
+ name="res/simu" + loop_param + ".cir",
+ extract_res[loop_param]=@res_extract)
endstep
/* display results in a custom way. */
fprint(stdout, "Parameter value | Extract result\n")
for (loop_param = extract_res.imin; loop_param

Eldo Control Language
.PRINTFILE Alternative #1
The full example is located in $MGC_AMS_HOME/examples/ecl/26-extract_alternative.
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, “Defining and Running Simulations” on page 841, and the fprint
function for more information on the concepts used in the example.
Tip
See “.EXTRACT” in the Eldo Reference Manual.
Related Topics
.PRINTFILE Alternative #1
Examples Using ECL as an Alternative to Standard Eldo Commands
.PRINTFILE Alternative #1
Netlist directory: 27-printfile_alternative
The following example shows how the ECL can be used as an alternative to the regular
.PRINTFILE command in Eldo to print results inside a file.
This example expands on the example used in the .EXTRACT Alternative. In addition, it uses
the ECL fopen and fprint functions to print results inside a user-defined file, results.txt.
Eldo® User's Manual, 15.3 1127

Eldo Control Language
.PRINTFILE Alternative #1
* ECL .PRINTFILE alternative
.define_testbench tb_netlist (param_tb_value = 1 )
v1 1 0 3
r1 1 2 p
c1 2 0 1 ic=0
.plot tran res_wave = v(2)
.tran 1 10 uic
.param p = param_tb_value
* name needed for ECL
.extract tran label=res_extract xthres(v(2), 1.5)
.end_define_testbench
.define_task t1
/* parameter for the step loop. */
set loop_param = 1
set param_value[] = 0
set extract_res[] = 0
set file1 = fopen("results.txt", "w")
/* step loop similar to the .step command. */
step (type=step, param=loop_param, start=1, stop=10, step=1)
/* run the simulation. */
param_value[loop_param] = loop_param
simulation(tb_netlist(param_tb_value=loop_param),
+ name="res/simu" + loop_param + ".cir",
+ extract_res[loop_param]=@res_extract)
endstep
/* display results in a custom way. */
fprint(file1, "Parameter value | Extract result\n")
for (loop_param = extract_res.imin; loop_param

Eldo Control Language
.PRINTFILE Alternative #2
Related Topics
.PRINTFILE Alternative #2
Examples Using ECL as an Alternative to Standard Eldo Commands
.PRINTFILE Alternative #2
The following example shows how the ECL can be used as an alternative to the regular
.PRINTFILE command in Eldo to print CSV results inside a file.
In this example, the DC offset of an operational amplifier is computed for different values of
vdd and then printed into a .csv file (that can be loaded in EZwave for example).
Eldo® User's Manual, 15.3 1129

Eldo Control Language
.PRINTFILE Alternative #2
* Generate a .csv file.
.define_testbench netlist (pvdd=1.5)
* op amp
m16 vdd bias m17d vdd p w=4.8u l=1.2u
m17 m17d m17d vss vss n w=3.2u l=1.2u
m15 m15d m17d vss vss n w=3.2u l=1.2u
m13 m13d m17d vss vss n w=3.2u l=1.2u
m14 vdd m15d m15d vdd p w=1u l=1.2u
m12 vdd m13d m13d vdd p w=4.8u l=1.2u
m3 vdd m13d m1d vdd p w=4.8u l=1.2u
m4 vdd m13d m2d vdd p w=4.8u l=1.2u
m11 vdd m13d out vdd p w=16u l=1.2u
m1 m1d inp com com n w=0.8u l=0.6u
m2 m2d inn com com n w=0.8u l=0.6u
m9 com m17d vss vss n w=3.2u l=1.2u
m5 m2d m15d m7d vdd p w=2.4u l=1.2u
m6 m1d m15d m8d vdd p w=2.4u l=1.2u
m7 m7d m7d vss vss n w=1.6u l=1.2u
m8 m8d m7d vss vss n w=1.6u l=1.2u
cx m8d out 0.2p ! lousy compensation cap.
cl out 0 1p ! load cap.
m10 out m8d vss vss n w=13u l=1.2u
vb bias 0 0.95V
**************************
.option tuning=vhigh
**************************
* powersupply
vdd vdd 0 pvdd
vss vss 0 -pvdd
.connect out inn ! follower connection
vinp inp 0 DC 0
.dc
.extract dc label=vout_follower V(out)
.extract dc label=dc_offset V(inp)-V(out)
.end_define_testbench
*========================================================================
.define_task print_dc_offset (n=40)
set loop_param=0
set vdd[]=1.65
set dc_offset[]=0
// create the .csv file
set csv_file = fopen("results.csv", "w")
// for each value of VDD from 1.5V to 1.8V, find out the DC offset
step (type=step, param=loop_param, start=1, stop=n, step=1)
vdd[loop_param] = 1.5 + (loop_param-1) * (1.8-1.5) / (n-1)
simulation(
+ name = "simu_dc_offset/simu.cir",
+ netlist(pvdd = vdd[loop_param]),
+ dc_offset[loop_param] = @vout_follower)
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Eldo Control Language
.OPTIMIZE Alternative
endstep
// print a header
fprint(csv_file, ".HEADER\n")
fprint(csv_file, "..NAMES\n")
fprint(csv_file, "Vdd,DC Offset\n")
fprint(csv_file, "..UNITS\n")
fprint(csv_file, "Voltage,Voltage\n")
fprint(csv_file, ".DATA\n")
// print values
for (loop_param = vdd.imin; loop_param

Eldo Control Language
.OPTIMIZE Alternative
* ECL .OPTIMIZE alternative
.define_testbench optimize_this()
.paramopt res_value=(5,1,10)
v1 1 0 dc 2
r1 1 0 res_value
.dc
.plot dc v(1) i(v1) i2(v1)
.option aex
.extract dc label=v1_current i2(v1) goal=0.35
.optimize
.option opseldo_netlist
.end_define_testbench
.define_testbench final_run(res_value=0)
v1 1 0 dc 2
r1 1 0 res_value
.dc
.plot dc v(1) i(v1) i2(v1)
.option aex
.extract dc label=v1_current i2(v1)
.end_define_testbench
.define_task run()
set current=0
set return_value=0
set final_resistance=0
return_value = simulation(name="optimization_file",
+ log="optimization_run.log", optimize_this(),
+ final_resistance=@res_value)
if (return_value.simu_status == 0)
fprint(stdout, "\nfinal_resistance = %g\n", final_resistance)
else
fprint(stdout, "\nBad optimization run. return status = %g.\n",
+ return_value.simu_status)
endif
return_value = simulation(name="final_results_file",
+ log="final_rerun.log", final_run(res_value=final_resistance))
if (return_value.simu_status == 0)
fprint(stdout, "\nFinal run made from file %s\n",
+ "final_results_file.cir")
else
fprint(stdout, "\nBad final run. return status = %g\n",
+ return_value.simu_status)
endif
.end_define_task
.run
.end
The full example is located in $MGC_AMS_HOME/examples/ecl/28-optimize_alternative.
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Eldo Control Language
.MPRUN with Monte Carlo Analysis Example
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, “Defining and Running Simulations” on page 841, and the fprint
function for more information on the concepts used in the example.
Tip
See “.OPTIMIZE” in the Eldo Reference Manual.
Related Topics
Examples Using ECL as an Alternative to Standard Eldo Commands
.MPRUN with Monte Carlo Analysis Example
This example shows how the .MPRUN command works at the testbench level. For a given
simulation (run from an ECL task), if the netlist to simulate contains a .MPRUN command and
a .MC command for example, then the Monte Carlo runs of this simulation will be distributed as
usual.
.define_testbench tb_netlist (param_tb_value = 1 )
[netlist]
* parameter for the ECL step loop
.param p = param_tb_value
* parameter for the .mc
.param pv=3 lot=0.01
.mc 100
.mprun host=myhost1, myhost2, myhost3
.end_define_testbench
.define_task t1
set loop_param = 1
set wave_res[] = 0
set res = 0
/* step loop similar to the .step command. */
step (type=step, param=loop_param, start=1, stop=10, step=1)
/* run the simulation. */
res = simulation(tb_netlist(param_tb_value=loop_param),
+ name="res/simu" + loop_param + ".cir",
+ wave_res[loop_param]=@res_wave)
if (res.simu_status != 0)
fprint(stdout, "Error: simulation failed!\n")
return -1
endif
endstep
.end_define_task
.t1
Eldo® User's Manual, 15.3 1133

Eldo Control Language
.MPRUN with Monte Carlo Analysis Example
The ten ECL simulations are run sequentially (even if the .MPRUN command is written out of
the testbench). For each of these ten simulations, the 100 Monte Carlo runs are distributed on
the specified hosts.
See “Testbenches” on page 809, “Tasks” on page 814, “Variables” on page 821, “Flow Control
Statements” on page 835, “Defining and Running Simulations” on page 841, and the fprint
function for more information on the concepts used in the example.
Tip
See “.MPRUN” in the Eldo Reference Manual.
Related Topics
Examples Using ECL as an Alternative to Standard Eldo Commands
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Chapter 19
Post-Processing Library
The Post-Processing Library (PPL) is a tool that enables interfacing between Eldo and a set of
predefined, user defined DSP or mathematical functions. User Defined Functions (UDF) are
written using the scripting language Tcl. For Post-Processing capability you can use Eldo
commands to call a PPL function and the Tcl language extensions.
Post-Processing Library Example Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1137
General Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1139
Registering User Defined Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1139
Making Specific Calls to User Defined Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1139
Waveform Definition With User Defined Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1140
Macro-Like Usage of User Defined Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1141
Keyword Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1142
Working with Waveforms Inside User Defined Functions . . . . . . . . . . . . . . . . . . . . . . . . 1142
evalExpr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1144
defineVec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1146
EZwave Waveform Calculator Functions Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1149
Built-In Waveform Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1150
ABS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1151
ACOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1152
ACOSH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1153
ACOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1154
ACOTH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1155
ASIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1156
ASINH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1157
ATAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1158
ATANH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1159
AVG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1160
COMPRESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1161
COS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1162
COSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1163
COT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1164
COTH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1165
DB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1166
DEG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1167
DELAY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1168
DERIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1169
DRV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1170
EXP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1171
FALLTIME. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1172
Eldo® User's Manual, 15.3 1135

Post-Processing Library
GMARGIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1173
HISTOGRAM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1174
IMAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1175
INTEG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1176
INTEGRAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1177
INTERSECT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1178
INVDB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1179
LOG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1180
LOG10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1181
MAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1182
MAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1183
MIN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1184
PHASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1185
PHMARGIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1186
RAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1187
REAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1188
RELATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1189
RISETIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1190
RMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1191
SAMPLE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1192
SETTLINGTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1193
SIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1194
SINH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1195
SQR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1196
SQRT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1197
SUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1198
TAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1199
TANH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1200
TPD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201
TPDDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1202
TPDDU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1203
TPDUD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204
TPDUU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1205
VMAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1206
VMIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1207
WINDOW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1208
XCOMPRESS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1209
XVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1210
XWAVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1211
YVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1212
IIPX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1213
OIPX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1214
Built-In DSP Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1215
AUTOCOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1216
CONV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1217
1136
Eldo® User's Manual, 15.3

Post-Processing Library
Post-Processing Library Example Files
CORRELO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1218
CT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1220
FFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1222
HARMONICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1224
HDIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1225
IFFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1226
PERIODO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1227
PSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1229
SAMPLER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1230
SNR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1232
Accessing Waves Inside an External Database Functions . . . . . . . . . . . . . . . . . . . . . . . . 1233
LOAD_FILE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1234
DISP_FILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1235
UNLOAD_FILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1236
Additional PPL Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1237
DISPLAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1238
GETSIZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1239
GETPOINT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1240
SETPOINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1241
CREATEVECTOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1242
Post-Processing Library Example Files
A number of example files are provided to illustrate different configurations. The example files
are provided in your installed directory: $MGC_AMS_HOME/examples/ppl.
Table 19-1 lists the example filenames and descriptions.
asciigen.cir and
asciigen.tcl
expressions.cir and
expressions.tcl
realvalue.cir and
realvalue.tcl
samphold.cir and
samphold.tcl
tcl_wave.cir and
expressions.tcl
Table 19-1. PPL Example Files
Demonstrates how to use several .CALL_TCL commands to dump
waves in an ASCII output file.
Demonstrates how to use .CALL_TCL commands and how to work
with expressions inside the UDF. In this example the input and the
output are a waveform (set return $ commands are used).
Demonstrates how to use UDF in a macro-like way to define a resistor
value.
Demonstrates how to use UDF in a macro-like way to define
defwaves, and namespace in Tcl.
Demonstrates how to use the .TCL_WAVE command.
Eldo® User's Manual, 15.3 1137

Post-Processing Library
Post-Processing Library Example Files
wave_info.cir and
wave_info.tcl
wave_meas.cir and
wave_meas.tcl
Table 19-1. PPL Example Files (cont.)
Demonstrates how to use wave information commands and loops
in Tcl.
Demonstrates how to use measurement functions in UDF. In this
example the input is a waveform and the output is a number (set/puts/
display commands are used).
Related Topics
General Usage
Built-In Waveform Functions
Built-In DSP Functions
Accessing Waves Inside an External Database Functions
Additional PPL Functions
1138
Eldo® User's Manual, 15.3

Post-Processing Library
General Usage
General Usage
This section lists the general usage topics together with any associated command.
Table 19-2. General Usage Topics
Topic
Registering User Defined Functions
Making Specific Calls to User Defined Functions
Waveform Definition With User Defined Functions
Macro-Like Usage of User Defined Functions
Keyword Parameters
Working with Waveforms Inside User Defined Functions
Associated Command
.USE_TCL
.CALL_TCL
.TCL_WAVE
Registering User Defined Functions
The .USE_TCL command loads the Tcl file, filename, into the Eldo Tcl interpreter, enabling all
declared functions to be recognized inside Eldo.
.USE_TCL filename
After loading the Tcl file, Eldo can use all the functions written inside this file as if they were
macros. This means these functions can accept any argument, are defined for the whole netlist,
and can return both numbers and/or waves.
EZwave also supports Tcl scripting, enabling you to create batch files to execute Tcl commands
from within EZwave. When .USE_TCL is used in EZwave mode, then the Tcl script must
adhere to the EZwave Tcl command syntax rules.
Tip
See “.USE_TCL” in the Eldo Reference Manual and “Tcl Scripting Support” in the EZwave
User’s and Reference Manual.
Making Specific Calls to User Defined Functions
The .CALL_TCL command is used to perform a single call to a Tcl function. The example files
expressions.cir and expressions.tcl demonstrate how .CALL_TCL can be used in the netlist,
creating waveforms for EZwave to plot using PPL Built-in functions.
Tip
See “.CALL_TCL” in the Eldo Reference Manual.
Eldo® User's Manual, 15.3 1139

Post-Processing Library
Waveform Definition With User Defined Functions
Related Topics
Post-Processing Library Example Files
Keyword Parameters
Waveform Definition With User Defined Functions
The .TCL_WAVE command defines a new waveform using a Tcl function. The example files
tcl_wave.cir and expressions.tcl demonstrate how .TCL_WAVE can be used in the netlist to
create waveforms for EZwave to plot using PPL Built-in functions. The waveform expression
must be a single Tcl function.
This enables you to dynamically manage User Defined Functions (UDF) written in Tcl
language. The functions of the post-processor library and other commands are available through
the Tcl interface.
Tip
See “.TCL_WAVE” and “.DEFWAVE” in the Eldo Reference Manual.
Notes
• Built-in PPL functions that act on a waveform cannot be used in Tcl procs that are called
from .DEFWAVE statements. This is because .DEFWAVE expressions represent a
numerical value, and not a waveform.
• The name of the Tcl function inside a .CALL_TCL command is case sensitive. It must
exactly match the name in the .tcl file.
• Tcl function names can be either lowercase or uppercase inside a netlist. However when
they are used outside of a .CALL_TCL command, for example in a resistor expression,
they are converted to uppercase. They must be uppercase inside the Tcl source file.
• .USE_TCL commands must always be placed before the first call to a Tcl function.
Otherwise, Eldo will not be able to parse the expressions using these functions.
Related Topics
Post-Processing Library Example Files
Registering User Defined Functions
Making Specific Calls to User Defined Functions
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Macro-Like Usage of User Defined Functions
Macro-Like Usage of User Defined Functions
An example is provided to demonstrate how two resistors obtain their values directly from a
UDF function or through a parameter (the files are realvalue.cir and realvalue.tcl). This
example demonstrates the use of a simple Tcl function returning a real value.
File realvalue.tcl listing:
proc GETVALUE { rname rval } {
# Use native Tcl syntax for expression calculation
set newvalue [expr 2*$rval + log($rval)]
}
puts "The value of resistor $rname is $newvalue"
return $newvalue
Note
The name of the function must be in uppercase in this example otherwise Eldo will not be
able to identify it, because it is not called from a .CALL_TCL command.
File realvalue.cir listing:
* Simple Tcl function returning a real value
.use_tcl realvalue.tcl
.param p1={GETVALUE("R1",TEMPER)}
.param p2=1
v1 1 0 sin(0 2 1g)
r1 1 2 p1
r2 2 0 {GETVALUE("R2",p2)}
.tran 1n 10n
.plot tran i(r1)
.end
Except for the dump of the value, the Tcl function GETVALUE is equivalent to:
.defmac GETVALUE(val) = 2*val+log(val)
UDF parameters can be real values, strings, waves, macros, UDF or keywords (see “Keyword
Parameters” on page 1142). It is important to note that for this kind of use, the UDF may be
called for each timestep. Thus wave parameters are not passed to the UDF as objects but as real
values.
The example files samphold.cir and samphold.tcl contain another example of UDF. The
function uses a Tcl namespace to keep the previous value of a wave, and is called inside a
.DEFWAVE to create a sampled representation of the input wave.
Eldo® User's Manual, 15.3 1141

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Keyword Parameters
Related Topics
Post-Processing Library Example Files
Registering User Defined Functions
Making Specific Calls to User Defined Functions
Keyword Parameters
Keyword parameters can be used in any calls to UDF.
These are:
XAXIS / TIME / FREQ - specifies the current timestamp or frequency
TEMPER - specifies the current temperature
The following keywords can only be used in .CALL_TCL commands:
ICARLO - specifies the current index of Monte-Carlo run
IRUN - specifies the current step index
IALTER - specifies the current alter index
NBCARLO - specifies the number of Monte-Carlo run
NBRUN - specifies the number of steps
NBALTER - specifies the number of .ALTER statements
Related Topics
Making Specific Calls to User Defined Functions
Working with Waveforms Inside User Defined
Functions
You can work with waveforms in arguments and expressions.
Waveforms in Arguments
In the context of .CALL_TCL commands, waves are not real values but vectors, or, in a more
general way, objects are generated by Eldo and given to the PPL. The argument that UDF
receives is only a reference to an object. Thus it is impossible to directly use these references in
mathematical expressions such as:
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Working with Waveforms Inside User Defined Functions
proc WAVE_PLUS { wv_in } {set wv_out [expr $wv_in + $wv_in]
+ return $wv_out}
Waveforms in Expressions
To enable operations on waveforms, a set of commands has been registered inside the PPL
environment. Table 19-3 lists common operators’ syntax and the equivalent syntax used inside
the PPL.
These commands accept real, complex and/or wave arguments. For example, it is possible to
add two waveforms, a waveform and a real, or two reals.
Two commands are available to simplify the syntax: evalExpr and defineVec.
Looking more closely at the Tcl syntax, complex expressions can be very difficult to read. For
example, in common language:
a = ((b+c)*(d+e))/(f+g)
becomes, in Tcl:
set a [div [mult [add $b $c] [add $d $e]] [add $f $g]]
The example files, expressions.cir and expressions.tcl, show the usage of the evalExpr and
defineVec commands with the two different syntaxes.
Related Topics
Table 19-3. C and PPL Syntax
C Syntax C Example PPL Syntax PPL Example
+ a = b + c add set a [add $b $c]
- a = b - c sub set a [sub $b $c]
* a = b * c mult set a [mult $b $c]
/ a = b / c div set a [div $b $c]
^ a = b ^ c pow set a [pow $b $c]
fmod a = fmod(b,c) mod set a [mod $b $c]
Post-Processing Library Example Files
evalExpr
defineVec
Making Specific Calls to User Defined Functions
Eldo® User's Manual, 15.3 1143

Post-Processing Library
evalExpr
evalExpr
Evaluates an expression in C-like syntax. The evalExpr command enables evaluation of an
expression written using C-like syntax. It can contain both numbers and/or waves. Quotes are
mandatory. If the expression is purely numerical a single value is returned. Otherwise the result
is a vector and is printed using the display command format (display command and output will
be described later). The PPL is able to handle complex arguments, and display them correctly.
Tip
This command is more likely to be used with numerical expressions whereas the defineVec
command is for wave calculations.
Syntax
evalExpr expression
Arguments
• expression
Expression to be evaluated.
Examples
This example demonstrates the evalExpr command. If the .tcl file contains:
proc EVAL_EXPR { wv_in } {
# evalExpr using numbers
set a 3
set numerical [evalExpr "2*$a + 4"]
puts "numerical = $numerical"
# evalExpr using waves
set vector [evalExpr "2*$wv_in + 4"]
puts "vector = $vector"
}
The following simple call to this function from the Eldo command in the .cir file:
.call_tcl tran when=END_OF_RUN EVAL_EXPR(v(1))
produces the following output:
numerical = 10.00000000000000
vector = { 0 0.00000000000000 4.00000000000000 + 0.00000000000000j }
{ 1 0.00000000002000 4.50133293425722 }
{ 2 0.00000000003900 4.97030313987119 }
{ 3 0.00000000007699 5.86034757905359 }
{ 4 0.00000000015297 7.27942102760290 }
{ 5 0.00000000022966 7.96738275669581 }
{ 6 0.00000000025000 8.00000000000000 }
{ 7 0.00000000029068 7.87006296906364 }
{ 8 0.00000000035325 7.18743864881722 }
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evalExpr
Related Topics
defineVec
Making Specific Calls to User Defined Functions
Eldo® User's Manual, 15.3 1145

Post-Processing Library
defineVec
defineVec
Defines a PPL object using C-like syntax. Similar to the evalExpr command, defineVec enables
evaluation of an expression written using C-like syntax but the result is stored in a PPL object
named output_object rather than displayed. An error occurs if an object using the same name
already exists in the PPL.
Tip
This command is more likely to be used with wave calculations, whereas the evalExpr
command is for numerical expressions.
Syntax
defineVec expression
Arguments
• output_object
Name of the object which contains the result of the expression.
• expression
Expression to be evaluated.
Examples
Example 1
This function demonstrates the defineVec command. It produces the same results as the
evalExpr function example and returns to Eldo a reference to the PPL object “vector” to plot it.
proc DEFINE_VEC { wv_in } {
# evalExpr using numbers
set a 3
defineVec numerical "2*$a+4"
puts "numerical = [display numerical]"
# evalExpr using waves (use display command to print vector values)
defineVec vector "$wv_in+4"
puts "vector = [display vector]"
return vector
}
A call to this function from the Eldo command:
.call_tcl tran when=END_OF_RUN PLOT=YES LABEL=Absv1 DEFINE_VEC(v(1))
produces the same output as evalExpr but the object vector can be reused in any expression or
returned to Eldo to be dumped in the output file.
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defineVec
Note
The return value of this function is not a Tcl variable but directly a vector.
Example 2
This function demonstrates the difference between Tcl variables and PPL references. It uses
Mathematical functions with both C-like and Tcl syntaxes and returns to Eldo a reference to the
PPL object “wv_final” to plot it.
proc WAVE_REFERENCE { wv_in } {
# Define a PPL object named wv_out
defineVec wv_out "2*abs($wv_in)"
# Store a PPL refence inside a Tcl variable wv_out
set wv_out [exp $wv_in]
# Define a PPL object named wv_final using both PPL object
# wv_out and the value of Tcl variable wv_out
defineVec wv_final "wv_out + $wv_out"
# Return the final object to Eldo
return wv_final
}
A call to this function from the Eldo command:
.call_tcl tran when=END_OF_RUN PLOT=YES LABEL=Refv1 WAVE_REFERENCE(v(1))
produces a waveform named Refv1 in the .wdb output file; this waveform being the return of
the Tcl function.
Example 3
The following examples show the name of the Tcl function inside a .CALL_TCL command is
case sensitive. It must exactly match the name in the .tcl file.
If the my_func.tcl file contains:
Eldo® User's Manual, 15.3 1147

Post-Processing Library
defineVec
proc MY_EXPRESSION { wv_in } {
# puts "hello 1"
defineVec vector "2*$wv_in"
# puts "hello 2"
return vector
}
proc my_xwave { wv_in } {
# puts "hello 3"
defineVec vector [xwave $wv_in]
# puts "hello 4"
return vector
}
proc MY_INTEG { wv_in } {
puts "hello 5"
defineVec vector [integ $wv_in]
puts "hello 6"
return vector
}
proc my_exp { wv_in } {
puts "hello 7"
defineVec vector [exp $wv_in]
puts "hello 8"
return vector
}
Then calls to these from an Eldo netlist must match in case, as shown below:
v1 1 0 sin(1 2 1e9)
r1 1 2 1k
r2 2 0 1k
.tran 1p 1n
.option eps=1e-8
.use_tcl my_func.tcl mode=ppl
.call_tcl tran where=end_of_run plot=yes label=f1 MY_INTEG(v(1))
.call_tcl tran where=end_of_run plot=yes label=f2 MY_EXPRESSION(v(1))
.call_tcl tran where=end_of_run plot=yes label=f3 my_xwave(v(1))
.call_tcl tran where=end_of_run plot=yes label=f4 my_exp(v(1))
.probe tran v(1) v(2)
.end
Related Topics
evalExpr
Making Specific Calls to User Defined Functions
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Post-Processing Library
EZwave Waveform Calculator Functions Usage
EZwave Waveform Calculator Functions Usage
The EZwave Waveform Calculator library can be used from Eldo through Tcl scripts. The wfc
function enables full access to all the calculation operations of the EZwave Waveform
Calculator.
Tip
See “Waveform Calculator” and the “wfc command” in the EZwave User’s and Reference
Manual.
Syntax
wfc expression
Arguments
• expression
Waveform Calculator expression.
Examples
This example shows how to pass parameters from the Eldo Tcl procedure to an EZwave wfc
expression.
* Passing Tcl proc parameters to a wfc expression
r1 net50 0 1
v1 net50 0 am(1 1 100meg 1G)
.tran 20n 20n
.option eps=1e-8
.probe tran all
.extract tran label=initial_rise tcross(v(net50), vth=1.25, occur=1)
.use_tcl eldo_syntax_ko.tcl mode=ezwave
.call_tcl tran where=end_of_run
+ ezwave_p2p_ex(v(net50), meas(initial_rise))
.end
proc ezwave_p2p_ex {wave xstart} {
set pk_to_pk \
[wfc "peaktopeak($wave, x_start=$xstart, x_end=\"20e-9\")"]
puts "The proc computed value is... $pk_to_pk"
}
The expression passed to wfc needs to be enclosed in double quotes if it contains Tcl variables,
otherwise parentheses { } can be used. If arguments of wfc functions are strings, they need to be
enclosed in single quotes (‘) or escaped double quotes (\”).
Related Topics
General Usage
Eldo® User's Manual, 15.3 1149

Post-Processing Library
Built-In Waveform Functions
Built-In Waveform Functions
Lists the built-in waveform functions.
Table 19-4. Built-In Waveform Functions
Eldo Functions
ABS ACOS ACOSH ACOT ACOTH
ASIN ASINH ATAN ATANH AVG
COMPRESS COS COSH COT COTH
DB DEG DELAY DERIVE DRV
EXP FALLTIME GMARGIN HISTOGRAM IMAG
INTEG INTEGRAL INTERSECT INVDB LOG
LOG10 MAG MAX MIN PHASE
PHMARGIN RAD REAL RELATION RISETIME
RMS SAMPLE SETTLINGTIM SIN
SINH
E
SQR SQRT SUM TAN TANH
TPD TPDDD TPDDU TPDUD TPDUU
VMAX VMIN WINDOW XCOMPRESS XVAL
XWAVE YVAL
Eldo RF Functions
IIPX
OIPX
See also:
• Built-In DSP Functions
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ABS
ABS
Eldo built-in waveform function
Absolute wave.
Usage
set wv_out [abs $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
ACOS
ACOS
Eldo built-in waveform function
Inverse trigonometric wave function.
Usage
set wv_out [acos $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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ACOSH
ACOSH
Eldo built-in waveform function
Inverse hyperbolic wave function.
Usage
set wv_out [acosh $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1153

Post-Processing Library
ACOT
ACOT
Eldo built-in waveform function
Inverse trigonometric wave function.
Usage
set wv_out [acot $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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ACOTH
ACOTH
Eldo built-in waveform function
Inverse hyperbolic wave function.
Usage
set wv_out [acoth $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1155

Post-Processing Library
ASIN
ASIN
Eldo built-in waveform function
Inverse trigonometric wave function.
Usage
set wv_out [asin $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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ASINH
ASINH
Eldo built-in waveform function
Inverse hyperbolic wave function.
Usage
set wv_out [asinh $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1157

Post-Processing Library
ATAN
ATAN
Eldo built-in waveform function
Inverse trigonometric wave function.
Usage
set wv_out [atan $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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ATANH
ATANH
Eldo built-in waveform function
Inverse hyperbolic wave function.
Usage
set wv_out [atanh $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1159

Post-Processing Library
AVG
AVG
Eldo built-in waveform function
Average value of a wave.
Usage
set out_value [avg $wv_in]
set out_value [avg $wv_in $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
out_value is the resulting average value of the wave.
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COMPRESS
COMPRESS
Eldo built-in waveform function
Extracts the Y-axis value of the wave at the point where the difference between the actual value
of the wave and the linear extrapolation of the wave based on the computed slope value
becomes greater than val. The slope is computed using the first two points of the waveform.
Usage
set out_value [compress $wv_in $val]
Arguments
• wv_in
The input waveform the function is acting upon.
• val
The threshold value.
Return Values
out_value is the resulting Y-axis value.
Eldo® User's Manual, 15.3 1161

Post-Processing Library
COS
COS
Eldo built-in waveform function
Trigonometric wave function.
Usage
set wv_out [cos $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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COSH
COSH
Eldo built-in waveform function
Hyperbolic wave function.
Usage
set wv_out [cosh $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1163

Post-Processing Library
COT
COT
Eldo built-in waveform function
Trigonometric wave function.
Usage
set wv_out [cot $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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COTH
COTH
Eldo built-in waveform function
Hyperbolic wave function.
Usage
set wv_out [coth $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1165

Post-Processing Library
DB
DB
Eldo built-in waveform function
Conversion dB magnitude. Works only for real waveforms representing magnitude.
Usage
set wv_out [db $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Related Topics
INVDB
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DEG
DEG
Eldo built-in waveform function
Conversion degrees.
Usage
set wv_out [deg $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Related Topics
RAD
Eldo® User's Manual, 15.3 1167

Post-Processing Library
DELAY
DELAY
Eldo built-in waveform function
Creates a delayed wave.
Usage
set wv_out [delay $wv_in $delay_value]
Arguments
• wv_in
The input waveform the function is acting upon.
• delay_value
The required delay value.
Return Values
wv_out is the resulting output waveform.
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DERIVE
DERIVE
Eldo built-in waveform function
Derivative of a wave at an x value.
Usage
set out_value [derive $wv_in $xvalue]
Arguments
• wv_in
The input waveform the function is acting upon.
• xvalue
The required x value.
Return Values
out_value is the resulting value for the derivative of a wave at an x value.
Eldo® User's Manual, 15.3 1169

Post-Processing Library
DRV
DRV
Eldo built-in waveform function
Derivative of a wave with respect to the x (or scale) variable.
Usage
set wv_out [drv $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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EXP
EXP
Eldo built-in waveform function
Wave exponential.
Usage
set wv_out [exp $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1171

Post-Processing Library
FALLTIME
FALLTIME
Eldo built-in waveform function
Fall time of a wave, the result is of unit {x_unit}.
Usage
set out_value [falltime $wv_in $lower_thr $upper_thr]
set out_value [falltime $wv_in $lower_thr $upper_thr $after]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_thr
Lower threshold.
• upper_thr
Upper threshold.
• after
First transition between lower and upper thresholds is treated after this x value.
Return Values
out_value is the fall time of a wave.
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GMARGIN
GMARGIN
Eldo built-in waveform function
Gain margin is the linear gain distance to 1.0.
Tip
See gain margin extraction example.
Usage
set out_value [gmargin $wv_in1 $wv_in2]
Arguments
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
Return Values
out_value is the gain margin.
Eldo® User's Manual, 15.3 1173

Post-Processing Library
HISTOGRAM
HISTOGRAM
Eldo built-in waveform function
Generates a histogram of the input wave showing the waves magnitude probability density
distribution. The input wave is first sampled to equidistant points if the optional argument
$sample is set.
Usage
set wv_out [histogram $wv_in $intervals]
set wv_out [histogram $wv_in $intervals $sample]
set wv_out [histogram $wv_in $intervals $lower_bound $upper_bound]
set wv_out [histogram $wv_in $intervals $lower_bound $upper_bound $sample]
Arguments
• wv_in
The input waveform the function is acting upon.
• intervals
The number of histogram intervals.
• sample
If 0 or not specified: don’t sample.
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
wv_out is the resulting output waveform.
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IMAG
IMAG
Eldo built-in waveform function
Imaginary part of a complex number/wave.
Usage
set wv_out [imag $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Related Topics
REAL
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INTEG
INTEG
Eldo built-in waveform function
Definite integral of the input wave with respect to the x (or scale) variable, global integral or
interval integral the result has the unit {wave_unit}*{x_unit}.
Usage
set out_value [integ $wv_in]
set out_value [integ $wv_in $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
out_value is the definite integral of the input wave.
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INTEGRAL
INTEGRAL
Eldo built-in waveform function
Indefinite integral of the input wave with respect to the x-axis variable. The result is a
waveform.
Usage
set wv_out [integral $wv_in $first_y_value]
Arguments
• wv_in
The input waveform the function is acting upon.
• first_y_value
Integration constant.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
INTERSECT
INTERSECT
Eldo built-in waveform function
Get the intersection point (s) of two waves.
Usage
set out_vector [intersect $wv_in1 $wv_in2]
set out_vector [intersect $wv_in1 $wv_in2 $lower_bound $upper_bound]
Arguments
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
• lower_bound
x value after which measurement starts
• upper_bound
x value after which measurement stops
Return Values
out_vector is the intersection of two waves.
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INVDB
INVDB
Eldo built-in waveform function
Conversion linear magnitude. Works only for real waveforms representing magnitude.
Usage
set wv_out [invdb $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Related Topics
DB
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LOG
LOG
Eldo built-in waveform function
Wave logarithm.
Usage
set wv_out [log $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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LOG10
LOG10
Eldo built-in waveform function
Wave logarithm.
Usage
set wv_out [log10 $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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MAG
MAG
Eldo built-in waveform function
Linear magnitude from real and imaginary part.
Usage
set wv_out [mag $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
MAX
MAX
Eldo built-in waveform function
Maximum wave of two waves (max is evaluated point-by-point).
Usage
set wv_out [max $wv_in1 $wv_in2]
Arguments
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1183

Post-Processing Library
MIN
MIN
Eldo built-in waveform function
Minimum wave of two waves (min is evaluated point-by-point).
Usage
set wv_out [min $wv_in1 $wv_in2]
Arguments
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
PHASE
PHASE
Eldo built-in waveform function
Phase (in degrees) from real and imaginary part.
Usage
set wv_out [phase $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1185

Post-Processing Library
PHMARGIN
PHMARGIN
Eldo built-in waveform function
Phase margin is the phase distance to -180 degrees.
Tip
See phase margin extraction example.
Usage
set out_value [phmargin $wv_in1 $wv_in2]
Arguments
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
Return Values
out_value is the phase margin.
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Post-Processing Library
RAD
RAD
Eldo built-in waveform function
Conversion radians.
Usage
set wv_out [rad $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Related Topics
DEG
Eldo® User's Manual, 15.3 1187

Post-Processing Library
REAL
REAL
Eldo built-in waveform function
Real part of a complex number/wave.
Usage
set wv_out [real $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Related Topics
IMAG
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Post-Processing Library
RELATION
RELATION
Eldo built-in waveform function
Generates a wave from the point-by-point comparison of two waves.
Usage
set wv_out [relation $wv_in1 $wv_in2 $operator]
Arguments
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
• operator
The operator affects how the return values are calculated (allowed values 1, 0, or -1).
Return Values
Function returns 1 whenever operator is 1 and wv_in1 > wv_in2, or operator is 0 and wv_in1 ==
wv_in2, or operator is -1 and wv_in1 < wv_in2. Otherwise it returns 0.
Eldo® User's Manual, 15.3 1189

Post-Processing Library
RISETIME
RISETIME
Eldo built-in waveform function
Rise time of a wave, the result is of unit {x_unit}.
Usage
set out_value [risetime $wv_in $lower_thr $upper_thr]
set out_value [risetime $wv_in $lower_thr $upper_thr $after]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_thr
Lower threshold.
• upper_thr
Upper threshold.
• after
First transition between lower and upper thresholds is treated after this x value.
Return Values
out_value is the rise time of a wave.
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Post-Processing Library
RMS
RMS
Eldo built-in waveform function
Root mean square value of a wave.
Usage
rms=sqrt ((1/ (x_max-x_min))*integ(wave^2)).
set out_value [rms $wv_in]
set out_value [rms $wv_in $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
out_value is the rms value of a wave.
Eldo® User's Manual, 15.3 1191

Post-Processing Library
SAMPLE
SAMPLE
Eldo built-in waveform function
Creates a sampled wave. Points are linearly interpolated.
Usage
set wv_out [sample $wv_in $sample_time]
set wv_out [sample $wv_in $sample_time $lower_bound $upper_bound $sample]
Arguments
• wv_in
The input waveform the function is acting upon.
• sample_time
Sampling period.
• lower_bound
x value after which sampling starts.
• upper_bound
x value after which sampling stops.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
SETTLINGTIME
SETTLINGTIME
Eldo built-in waveform function
Time required for the input wave to settle within a certain limit around the final value.
Usage
set out_value [settlingtime $wv_in $yvalue $eps]
set out_value [settlingtime $wv_in $yvalue $eps $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• yvalue
Value to reach.
• eps
Tolerance value (yvalue +/- eps/2).
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
out_value is the time required for the input wave to settle within a certain limit around the final
value.
Eldo® User's Manual, 15.3 1193

Post-Processing Library
SIN
SIN
Eldo built-in waveform function
Trigonometric wave function.
Usage
set wv_out [sin $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
SINH
SINH
Eldo built-in waveform function
Hyperbolic wave function.
Usage
set wv_out [sinh $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1195

Post-Processing Library
SQR
SQR
Eldo built-in waveform function
Wave square function.
Usage
set wv_out [sqr $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
SQRT
SQRT
Eldo built-in waveform function
Wave square root function.
Usage
set wv_out [sqrt $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1197

Post-Processing Library
SUM
SUM
Eldo built-in waveform function
Sums up the real part of a vector.
Usage
set out_value [sum $wv_in]
set out_value [sum $wv_in $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
out_value is the sum of the real part of a vector.
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Post-Processing Library
TAN
TAN
Eldo built-in waveform function
Trigonometric wave function.
Usage
set wv_out [tan $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1199

Post-Processing Library
TANH
TANH
Eldo built-in waveform function
Hyperbolic wave function.
Usage
set wv_out [tanh $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
TPD
TPD
Eldo built-in waveform function
Returns the propagation delay between wv_in1 and wv_in2.
Usage
set out_value [tpd $wv_in1 $wv_in2]
set out_value [tpd $wv_in1 $wv_in2 $vth]
set out_value [tpd $wv_in1 $wv_in2 $vthin $vthout]
set out_value [tpd $wv_in1 $wv_in2 $vthin $vthout $before $after]
set out_value [tpd $wv_in1 $wv_in2 $vthin $vthout $before $after $occur]
Arguments
Note
For a complete description of TPD and its parameters, see the .EXTRACT command in the
Eldo Reference Manual.
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
• vth
Voltage defining a threshold or starting point.
• vthin
Voltage defining a threshold or starting point.
• vthout
Voltage defining a threshold or starting point.
• before
Causes the function to be performed only if TIME < val.
• after
Causes the function to be performed only if TIME < val.
• occur
Computes the function for the VALth occurrence of the event.
Return Values
out_value is the propagation delay.
Eldo® User's Manual, 15.3 1201

Post-Processing Library
TPDDD
TPDDD
Eldo built-in waveform function
Returns the propagation delay with wv_in1 and wv_in2 both falling.
Usage
set out_value [tpddd $wv_in1 $wv_in2]
set out_value [tpddd $wv_in1 $wv_in2 $vth]
set out_value [tpddd $wv_in1 $wv_in2 $vthin $vthout]
set out_value [tpddd $wv_in1 $wv_in2 $vthin $vthout $before $after]
set out_value [tpddd $wv_in1 $wv_in2 $vthin $vthout $before $after $occur]
Arguments
Note
For a complete description of TPDDD and its parameters, see the .EXTRACT command in
the Eldo Reference Manual.
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
• vth
Voltage defining a threshold or starting point.
• vthin
Voltage defining a threshold or starting point.
• vthout
Voltage defining a threshold or starting point.
• before
Causes the function to be performed only if TIME < val.
• after
Causes the function to be performed only if TIME < val.
• occur
Computes the function for the VALth occurrence of the event.
Return Values
out_value is the propagation delay.
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Post-Processing Library
TPDDU
TPDDU
Eldo built-in waveform function
Returns the propagation delay with wv_in1 falling, wv_in2 rising.
Usage
set out_value [tpddu $wv_in1 $wv_in2]
set out_value [tpddu $wv_in1 $wv_in2 $vth]
set out_value [tpddu $wv_in1 $wv_in2 $vthin $vthout]
set out_value [tpddu $wv_in1 $wv_in2 $vthin $vthout $before $after]
set out_value [tpddu $wv_in1 $wv_in2 $vthin $vthout $before $after $occur]
Arguments
Note
For a complete description of TPDDU and its parameters, see the .EXTRACT command in
the Eldo Reference Manual.
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
• vth
Voltage defining a threshold or starting point.
• vthin
Voltage defining a threshold or starting point.
• vthout
Voltage defining a threshold or starting point.
• before
Causes the function to be performed only if TIME < val.
• after
Causes the function to be performed only if TIME < val.
• occur
Computes the function for the VALth occurrence of the event.
Return Values
out_value is the propagation delay.
Eldo® User's Manual, 15.3 1203

Post-Processing Library
TPDUD
TPDUD
Eldo built-in waveform function
Returns the propagation delay with wv_in1 rising, wv_in2 falling.
Usage
set out_value [tpdud $wv_in1 $wv_in2]
set out_value [tpdud $wv_in1 $wv_in2 $vth]
set out_value [tpdud $wv_in1 $wv_in2 $vthin $vthout]
set out_value [tpdud $wv_in1 $wv_in2 $vthin $vthout $before $after]
set out_value [tpdud $wv_in1 $wv_in2 $vthin $vthout $before $after $occur]
Arguments
Note
For a complete description of TPDUD and its parameters, see the .EXTRACT command in
the Eldo Reference Manual.
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
• vth
Voltage defining a threshold or starting point.
• vthin
Voltage defining a threshold or starting point.
• vthout
Voltage defining a threshold or starting point.
• before
Causes the function to be performed only if TIME < val.
• after
Causes the function to be performed only if TIME < val.
• occur
Computes the function for the VALth occurrence of the event.
Return Values
out_value is the propagation delay.
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Post-Processing Library
TPDUU
TPDUU
Eldo built-in waveform function
Returns the propagation delay with wv_in1 and wv_in2 both rising.
Usage
set out_value [tpduu $wv_in1 $wv_in2]
set out_value [tpduu $wv_in1 $wv_in2 $vth]
set out_value [tpduu $wv_in1 $wv_in2 $vthin $vthout]
set out_value [tpduu $wv_in1 $wv_in2 $vthin $vthout $before $after]
set out_value [tpduu $wv_in1 $wv_in2 $vthin $vthout $before $after $occur]
Arguments
Note
For a complete description of TPDUU and its parameters, see the .EXTRACT command in
the Eldo Reference Manual.
• wv_in1
The first input waveform the function is acting upon.
• wv_in2
The second input waveform the function is acting upon.
• vth
Voltage defining a threshold or starting point.
• vthin
Voltage defining a threshold or starting point.
• vthout
Voltage defining a threshold or starting point.
• before
Causes the function to be performed only if TIME < val.
• after
Causes the function to be performed only if TIME < val.
• occur
Computes the function for the VALth occurrence of the event.
Return Values
out_value is the propagation delay.
Eldo® User's Manual, 15.3 1205

Post-Processing Library
VMAX
VMAX
Eldo built-in waveform function
Maximum value of a wave.
Usage
set out_value [vmax $wv_in]
set out_value [vamx $wv_in $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
out_value is the maximum value of a wave.
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Post-Processing Library
VMIN
VMIN
Eldo built-in waveform function
Minimum value of a wave.
Usage
set out_value [vmin $wv_in]
set out_value [vmin $wv_in $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
out_value is the minimum value of a wave.
Eldo® User's Manual, 15.3 1207

Post-Processing Library
WINDOW
WINDOW
Eldo built-in waveform function
Selects a window (a, b) out of a wave, the points at the interval bounds are interpolated.
Usage
set wv_out [window $wv_in $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• lower_bound
Start of the wave window to select.
• upper_bound
End of the wave window to select.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
XCOMPRESS
XCOMPRESS
Eldo built-in waveform function
Extracts the x-axis value of the wave at the point where the difference between the actual value
of the wave and the linear extrapolation of the wave based on the computed slope value
becomes greater than val.
Usage
set out_value [xcompress $wv_in $val]
Arguments
• wv_in
The input waveform the function is acting upon.
• val
Threshold value.
Return Values
out_value is the x-axis value.
Eldo® User's Manual, 15.3 1209

Post-Processing Library
XVAL
XVAL
Eldo built-in waveform function
All x (or scale) values for one wave (or y) value.
Usage
set out_vector [xval $wv_in $yvalue]
set out_vector [xval $wv_in $yvalue $slope]
set out_vector [xval $wv_in $yvalue $slope $lower_bound $upper_bound]
Arguments
• wv_in
The input waveform the function is acting upon.
• slope
Find only x values, where wave crosses y with slope:
slope > 0 Positive slope
slope < 0 Negative slope
slope = 0 Positive and negative slope.
• lower_bound
x value after which measurement starts.
• upper_bound
x value after which measurement stops.
Return Values
out_vector is all x (or scale) values for one wave (or y) value.
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Post-Processing Library
XWAVE
XWAVE
Eldo built-in waveform function
Creates a wave with y = x values.
Usage
set wv_out [xwave $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1211

Post-Processing Library
YVAL
YVAL
Eldo built-in waveform function
Wave value at x (or scale) value (linear interpolation to get the exact value).
Usage
set out_value [yval $wv_in $xvalue]
Arguments
• wv_in
The input waveform the function is acting upon.
• xvalue
The x value.
Return Values
out_value is the wave value at x (or scale) value.
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Post-Processing Library
IIPX
IIPX
Eldo RF built-in waveform function
Returns the input referred intercept point of order x from the value of the circuit input and
output, wv_in and wave_out respectively. wv_in and wave_out must be in dB or dBm. The
intercept order is directly calculated from the intermodulation of freq1 and freq2.
Usage
set out_value [iipx $wv_in $wave_out $freq1 $freq2]
Arguments
• wv_in
The input waveform the function is acting upon.
• wave_out
The output waveform the function is acting upon.
• freq1
First intermodulation frequency.
• freq2
Second intermodulation frequency.
Return Values
out_value is the input referred intercept point.
Eldo® User's Manual, 15.3 1213

Post-Processing Library
OIPX
OIPX
Eldo RF built-in waveform function
Returns the output referred intercept point of order x from the value of the circuit output wave,
this must be in dB or dBm. The intercept order is directly calculated from the intermodulation of
freq1 and freq2.
Usage
set out_value [oipx $wv_in $freq1 $freq2]
Arguments
• wv_in
The input waveform the function is acting upon.
• freq1
First intermodulation frequency.
• freq2
Second intermodulation frequency.
Return Values
out_value is the output referred intercept point.
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Post-Processing Library
Built-In DSP Functions
Built-In DSP Functions
Lists the built-in DSP functions.
Table 19-5. Built-In DSP Functions
AUTOCOR CONV CORRELO CT FFT
HARMONICS HDIST IFFT PERIODO PSD
SAMPLER SNR
See also:
• Built-In Waveform Functions
Eldo® User's Manual, 15.3 1215

Post-Processing Library
AUTOCOR
AUTOCOR
Eldo built-in DSP function
Calculates the Auto Correlation Function (AF) of a waveform. The AF of a signal waveform is
an average measure of its time domain properties and therefore especially relevant when the
signal is random.
Tip
There are two methods available for calculating the auto correlation, namely the
Correlogram and Periodogram methods. For more explanation refer to the Autocorrelation
function description in the EZwave User’s and Reference Manual.
Usage
set wv_out [autocor $wv_in $method]
set wv_out [autocor $wv_in $method $nbpts]
Arguments
• wv_in
The input waveform the function is acting upon.
• method
Select the AF calculation method.
0 for correlogram (default)
1 for periodogram
• nbpts
Number of points for the AF result.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
CONV
CONV
Eldo built-in DSP function
Calculates the convolution of two signals.
Tip
For more explanation refer to the Convolution function description EZwave User’s and
Reference Manual.
Usage
set wv_out [conv $wv_in1 $wv_in2 $nptsa $nptsb $fs]
Arguments
• wv_in1
First input waveform the function is acting upon.
• wv_in2
Second input waveform the function is acting upon.
• nptsa
Number of points for wave1.
• nptsb
Number of points for wave2.
• fs
Sampling Frequency.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1217

Post-Processing Library
CORRELO
CORRELO
Eldo built-in DSP function
Calculates the Power Spectral Density using correlogram method.
Tip
For more explanation refer to the Autocorrelation Function and Power Spectral Density
section in the EZwave User’s and Reference Manual.
Usage
set wv_out [correlo $wv_in $tstart $tstop $fs $nbpts $padding
+ $sample $fmin $fmax $normalized $ncor $nauto $npsd]
Arguments
• wv_in
The input waveform the function is acting upon.
• tstart
Start time for the signal.
• tstop
Stop time for the signal.
• fs
Sampling frequency.
• nbpts
Number of sampling points.
• padding
Selects the padding zeros type:
0 No Padding
1 Padding at the end
2 Padding at the start
3 Center wave
• sample
Selects the sampling type:
0 No sampling
1 Interpolation
2 Sample and Hold
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Post-Processing Library
CORRELO
• fmin
Starting frequency used inside the FFT result window.
• fmax
Last frequency used inside the FFT result window.
• normalized
0 No normalization
1 All real and imaginary parts of the result are divided by Nbpts/2 except for the first
point, which is divided by Nbpts.
• ncor
Number of auto correlation points used for the PSD computation. Default value is Nauto.
• nauto
Number of points for the auto correlation result. Default value is Nbpts. Necessary condition
is Nauto 2 >= 2
• npsd
Number of points for the PSD result. Default value is Ncorr/2 + 1. Necessary condition is
npsd >= Ncorr/2 + 1.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1219

Post-Processing Library
CT
CT
Eldo built-in DSP function
Calculates the Chirp Transformed (CT) wave.
Tip
For more explanation refer to the Chirp transform sections in the EZwave User’s and
Reference Manual.
Usage
set wv_out [ct $wv_in $tstart $tstop $fs $nbpts $padding $sample $fmin
$fmax $normalized $nzoom]
Arguments
• wv_in
The input waveform the function is acting upon.
• tstart
Start time for the signal.
• tstop
Stop time for the signal.
• fs
Sampling frequency.
• nbpts
Number of sampling points.
• padding
Selects the padding zeros type:
0 No Padding
1 Padding at the end
2 Padding at the start
3 Center wave
• sample
Selects the sampling type:
0 No sampling
1 Interpolation
2 Sample and Hold
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Post-Processing Library
CT
• fmin
Starting frequency used inside the FFT result window.
• fmax
Last frequency used inside the FFT result window.
• normalized
0 No normalization
1 All real and imaginary parts of the result are divided by Nbpts/2 except for the first
point, which is divided by Nbpts.
• nzoom
Number of points for the zooming.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1221

Post-Processing Library
FFT
FFT
Eldo built-in DSP function
Calculates the Fast Fourier Transform (FFT) of a wave. FFT is the fastest and most efficient
available algorithm for computing the DFT.
Usage
set wv_out [fft $wv_in $tstart $tstop $fs $nbpts $padding $sample $fmin
$fmax $normalized]
Arguments
• wv_in
The input waveform the function is acting upon.
• tstart
Start time for the signal.
• tstop
Stop time for the signal.
• fs
Sampling frequency.
• nbpts
Number of sampling points.
• padding
Selects the padding zeros type:
0 No Padding
1 Padding at the end
2 Padding at the start
3 Center wave
• sample
Selects the sampling type:
0 No sampling
1 Interpolation
2 Sample and Hold
• fmin
Starting frequency used inside the FFT result window.
• fmax
Last frequency used inside the FFT result window.
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Post-Processing Library
FFT
• normalized
0 No normalization
1 All real and imaginary parts of the result are divided by Nbpts/2 except for the first
point, which is divided by Nbpts.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1223

Post-Processing Library
HARMONICS
HARMONICS
Eldo built-in DSP function
Calculates harmonics inside the interval [fmin, fmax] then generates the harmonics wave.
Usage
set wv_out [harmonics $wv_in $fundf]
set wv_out [harmonics $wv_in $fundf $fmin $fmax]
Arguments
• wv_in
The input waveform the function is acting upon.
• fundf
Fundamental Frequency.
• fmin, fmax
frequency band that should be taken for the computation.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
HDIST
HDIST
Eldo built-in DSP function
Calculates the Total Harmonic Distortion (THD) of a signal.
Usage
set out_value [hdist $wv_in $fundf]
set out_value [hdist $wv_in $fundf $fmin $fmax]
Arguments
• wv_in
The input waveform the function is acting upon.
• fundf
Fundamental frequency.
• fmin, fmax
Frequency band that should be taken for the computation.
Return Values
out_value is the THD.
Eldo® User's Manual, 15.3 1225

Post-Processing Library
IFFT
IFFT
Eldo built-in DSP function
Calculates the Inverse Fast Fourier Transform.
Usage
set wv_out [ifft $wv_in]
Arguments
• wv_in
The input waveform the function is acting upon.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
PERIODO
PERIODO
Eldo built-in DSP function
Calculates the Power Spectral Density using periodogram method.
Tip
For more explanation refer to the Autocorrelation Function and Power Spectral Density
section in the EZwave User’s and Reference Manual.
Usage
set wv_out [periodo $wv_in $tstart $tstop $fs $nbpts $padding
+ $sample $fmin $fmax $normalized $ncor $nauto $npsd]
Arguments
• wv_in
The input waveform the function is acting upon.
• tstart
Start time for the signal.
• tstop
Stop time for the signal.
• fs
Sampling frequency.
• nbpts
Number of sampling points.
• padding
Selects the padding zeros type:
0 No Padding
1 Padding at the end
2 Padding at the start
3 Center wave
• sample
Selects the sampling type:
0 No sampling
1 Interpolation
2 Sample and Hold
Eldo® User's Manual, 15.3 1227

Post-Processing Library
PERIODO
• fmin
Starting frequency used inside the FFT result window.
• fmax
Last frequency used inside the FFT result window.
• normalized
0 No normalization
1 All real and imaginary parts of the result are divided by Nbpts/2 except for the first
point, which is divided by Nbpts.
• ncor
Number of auto correlation points used for the PSD computation. Default value is Nauto.
• nauto
Number of points for the auto correlation result. Default value is Nbpts. Necessary condition
is Nauto 2 >= 2
• npsd
Number of points for the PSD result. Default value is Ncorr/2 + 1. Necessary condition is
npsd >= Ncorr/2 + 1.
Return Values
wv_out is the resulting output waveform.
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Post-Processing Library
PSD
PSD
Eldo built-in DSP function
Calculates the Power Spectral Density (PSD) of a waveform. The PSD of a signal waveform is
an average measure of its time domain properties and therefore especially relevant when the
signal is random.
Tip
There are two methods available for calculating the PSD, namely the Correlogram and
Periodogram methods. For more explanation refer to the Autocorrelation Function and
Power Spectral Density section in the EZwave User’s and Reference Manual.
Usage
set wv_out [psd $wv_in $method]
set wv_out [psd $wv_in $method $nbpts]
Arguments
• wv_in
The input waveform the function is acting upon.
• method
Select the PSD calculation method.
0 for correlogram (default)
1 for periodogram
• nbpts
Number of points for the PSD result.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1229

Post-Processing Library
SAMPLER
SAMPLER
Eldo built-in DSP function
Generates a sampled wave using some types of windowing.
Usage
set wv_out [sampler $tstart $tstop $fs $nbpts $padding $wtype $wparam]
Arguments
• tstart
Start time for the signal.
• tstop
Last time for the signal.
• fs
Sampling frequency.
• Nbpts
Number of sampling points.
• padding
Selects the padding zeros type:
0 No Padding
1 Padding at the end
2 Padding at the start
3 Center wave
• wtype
Window type:
0 Rectangular (no wparam)
1 Hamming (no wparam)
2 Hanning (Alpha= w_param, default is 0.5)
3 Parzen (no wparam)
4 Welch (no wparam)
5 Blackman (no wparam)
6 Blackman7 (no wparam)
7 Bartlett (no wparam)
8 Kaiser (Beta= wparam, default is 10.056)
9 Klein (no wparam)
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Post-Processing Library
SAMPLER
10 Tukey (no wparam)
11 Dolph Chebyshev (Alpha=w_param, default: 3.0)
• wparam
Window optional parameter.
Return Values
wv_out is the resulting output waveform.
Eldo® User's Manual, 15.3 1231

Post-Processing Library
SNR
SNR
Eldo built-in DSP function
Calculates the Signal to Noise Ratio of a noisy wave by using a specific frequency list.
Usage
set out_value [snr $wv_in $fmin $fmax $freq_list]
Arguments
• wv_in
Input waveform the function is acting upon. If wv_in is neither a complex waveform nor a
magnitude then an error is generated. If wv_in is a complex waveform, it is automatically
transformed into magnitude.
• fmin, fmax
Frequency band that should be taken for the computation.
• freq_list
List of frequencies which should be used in the computation.
Return Values
out_value is the signal to noise ratio, in dB.
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Post-Processing Library
Accessing Waves Inside an External Database Functions
Accessing Waves Inside an External Database
Functions
Lists the functions for accessing waves inside an external database.
Table 19-6. Functions to Access Waves Inside an External Database
LOAD_FILE DISP_FILE UNLOAD_FILE
Eldo® User's Manual, 15.3 1233

Post-Processing Library
LOAD_FILE
LOAD_FILE
Eldo PPL function to access waves inside an external database
Loads a .wdb, .cou, .tr0, .fsdb, or .csv file in memory. The extension of the file is used to
identify which format to use.
Usage
load_file $filename
Arguments
• filename
The name of the file.
Return Values
Returns a list of run identifiers. These identifiers are labelled RunX where X is an absolute
counter starting from 0.
Examples
If a file test.wdb contains one run:
puts "[load_file test.wdb]"
Implies “Run0” will be used as the run identifier label.
If a file test2.wdb contains three runs:
puts "[load_file test2.wdb]"
Implies “Run0 Run1 Run2” will be used as the run identifier labels.
If both commands are called in the same UDF:
puts "[load_file test.wdb]"
Implies “Run0” will be used as the run identifier label.
puts "[load_file test2.wdb]"
Implies “Run1 Run2 Run3” will be used as the run identifier labels.
These identifiers are used to identify waves. For example if file test.wdb contains waves v(1)
and i(r1), their internal names inside the PPL will be Run0::v(1) and Run0::i(r1). These names
can be used in all expressions.
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Post-Processing Library
DISP_FILE
DISP_FILE
Eldo PPL function to access waves inside an external database
Displays the list of runs inside the PPL or the list of waves inside a given run.
Usage
disp_file
disp_file $identifier
Arguments
• identifier
The identifier label.
Examples
Considering that test.wdb contains one run and test2.wdb contains three runs,
puts "[load_file test.wdb]"
Implies “Run0” will be used as the run identifier label.
puts "[load_file test2.wdb]"
Implies “Run1 Run2 Run3” will be used as the identifier labels.
puts "[disp_file]"
Implies “Run0 Run1 Run2 Run3” will be used as the identifier labels.
puts "[disp_file Run0]"
Implies “V(1) I(R1)” will be used as the identifier labels.
Eldo® User's Manual, 15.3 1235

Post-Processing Library
UNLOAD_FILE
UNLOAD_FILE
Eldo PPL function to access waves inside an external database
Removes all or a single run from memory.
Usage
unload_file all
unload_file $identifier
Arguments
• identifier
A valid run identifier or keyword “all” to remove all runs.
Related Topics
General Usage
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Post-Processing Library
Additional PPL Functions
Additional PPL Functions
Lists additional PPL functions.
Table 19-7. Additional PPL Functions
DISPLAY GETSIZE GETPOINT
SETPOINT
CREATEVECTOR
See also:
• General Usage
Eldo® User's Manual, 15.3 1237

Post-Processing Library
DISPLAY
DISPLAY
Eldo PPL function
Writes the content of PPL objects to the standard output.
Usage
display ppl_object
Arguments
• ppl_object
A reference to a PPL object. Usually, references for waves start with WV and references for
numbers start with DB (DouBle).
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Post-Processing Library
GETSIZE
GETSIZE
Eldo PPL function
Returns the number of points in a wave.
Usage
getsize $wv_in
Arguments
• wv_in
Input waveform the function is acting upon.
Eldo® User's Manual, 15.3 1239

Post-Processing Library
GETPOINT
GETPOINT
Eldo PPL function
Returns the x value, real and imaginary parts of a wave point.
Usage
getpoint $wv_in $ptindex
Arguments
• wv_in
Input waveform the function is acting upon.
• ptindex
Index of a point (between [0; size[).
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Post-Processing Library
SETPOINT
SETPOINT
Eldo PPL command
Modifies a wave point value.
Usage
setpoint $wv_in $ptindex $xvalue $yvalue $yimgvalue
Arguments
• wv_in
Input waveform the function is acting upon.
• ptindex
Index of a point (between [0; size]).
• xvalue
New x-axis value.
• yvalue
New real part value.
• yimgvalue
New imaginary part value.
Eldo® User's Manual, 15.3 1241

Post-Processing Library
CREATEVECTOR
CREATEVECTOR
Eldo PPL command
Creates a vector from a list of (x,y) values.
Usage
createVector vectorName $xlist $ylist
Arguments
• vectorName
The name of the PPL object which will represent the vector in the library.
• xlist
A list of ordered x values.
• ylist
A list of values (same length as xlist).
Examples
createVector test "0 1e-9 2e-9 3e-9 4e-9" "1.1 2.2 3.3 4.4 5.5"
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Chapter 20
Speed and Accuracy
Eldo provides different algorithms and control options, which are used to balance speed with
accuracy. Most of the information in this chapter relates to transient analysis, as it is the most
time-consuming analysis, and also the most frequently used analysis.
Introduction to Speed and Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1243
Speed and Accuracy in Eldo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1245
Integration Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1246
Time Step Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1248
Newton Iterations Accuracy Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1252
Global Tuning of the Accuracy—EPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1253
Global Tuning of the Accuracy—TUNING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1255
Simulation of Large Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1256
Tips for Improving Simulation Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1259
Integral Equation Method (IEM) Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1260
IEM Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1261
IEM—Supported Circuit Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1262
IEM Tolerance Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1263
Efficient Usage of IEM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1264
One Step Relaxation (OSR) Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1265
Introduction to Speed and Accuracy
The trade-off between speed and accuracy is the primary concern of users designing
simulations. Circuit-level transient simulation is the numerical resolution of an algebraic
differential system of equations; as such, it is not an exact procedure (unlike the linear AC or
NOISE analyses), and many switches can be used to control the accuracy of the results.
Typically, improved accuracy comes with an increased CPU time.
Eldo includes three different algorithms: NR (Newton-Raphson), OSR (One Step Relaxation),
and IEM (Integral Equation Method). The majority of information in this chapter is dedicated to
speed and accuracy with the default Newton-Raphson algorithm.
Caution
OSR and IEM are legacy algorithms, there are no active developments, enhancements, nor
bug fixing. To simulate with a higher performance than Eldo Classic, consider Eldo
Premier.
Eldo® User's Manual, 15.3 1243

Speed and Accuracy
Introduction to Speed and Accuracy
NR is the most general and robust algorithm, and it is always used by default. It is very accurate,
and applicable to all kinds of circuits without restriction. NR is used by the vast majority of
commercial SPICE simulators because of its generality.
Unless explicitly triggered by the user with commands and/or by switches in the netlist, neither
OSR nor IEM are used by Eldo. By default only NR is used for the whole circuit.
Eldo can partition a circuit into different parts that are simulated with different algorithms. For
example, some partitions can be simulated with classical NR, whereas others are simulated with
OSR or IEM. Each partition can use its own accuracy control parameters.
Related Topics
Speed and Accuracy in Eldo
Integration Methods
Simulation of Large Circuits
Tips for Improving Simulation Performance
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Speed and Accuracy
Speed and Accuracy in Eldo
Speed and Accuracy in Eldo
The system of equations that represent the behavior of a circuit cannot be solved analytically,
apart from trivial cases. Thus a simulator has to use numerical algorithms to find an
approximate solution.
In the case of transient analysis, the problem to solve is to find the solution of a DAE
(Differential Algebraic Equations) system. To simplify, and deliberately using loose notations,
the ‘solution’ that the simulator tries to find is a set of N voltage waveforms vn(t), where n
ranges from 1 to N—N being the number of nodes in the circuit—and t represents the time
variable. These voltages are the solution of f(v(t), q’(v(t)), t)=0, where f() and q() are non-linear
functions. Equation f()=0 is nothing but the expression of the Kirchoff law, that is, the sum of
all currents entering a node is null, at any time. Function q() models the dynamic part of the
circuit, that is, the generally bias-dependent charges in the circuit.
This system is differential and non-linear. To solve it numerically, time is discretized, and the
equations are solved at discrete time points. The time-derivatives are approximated using a socalled
integration scheme or method, using current and previous values of the solution v(ti),
v(ti-1),…, v(ti-m). The number m of previous time points used to approximate the timederivatives
depends on the ‘order’ of the integration method. In all cases, an approximation
error is introduced in this process.
Once the time-derivatives have been eliminated, the system to solve is ‘simply’ non-linear.
Many numerical methods exist to solve this numerically; they typically requiring a certain
number of iterations, starting from an initial guess v0, and each iteration providing, hopefully, a
better estimate vj of the solution vexact. This iterative process will normally converge, although
some criterion are needed to decide when to stop the iterative process and accept the last
estimate as the ‘solution’ at the current time point. Again, an approximation error is introduced
here. One of the commonly used methods to solve non-linear systems of equations is the socalled
Newton-Raphson method. It is commonly used mainly because of its generality and also
for its relative robustness.
In summary, primarily two types of error are involved in the resolution of the system:
• Errors due to the numerical integration process.
• Errors due to the numerical resolution of non-linear equations.
Integration Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1246
Time Step Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1248
Newton Iterations Accuracy Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1252
Global Tuning of the Accuracy—EPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1253
Global Tuning of the Accuracy—TUNING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1255
Eldo® User's Manual, 15.3 1245

Speed and Accuracy
Integration Methods
Integration Methods
The process of ‘eliminating’ the time-derivatives in the original circuit equations is a source of
error.
Tip
See “Speed and Accuracy in Eldo” on page 1245.
These time-derivatives are replaced with finite differences, which only approximate the true
time-derivatives. One of the most basic approximation schemes is the Backward-Euler method,
which approximates v’(ti) using the finite difference (v(ti)-v(ti-1)) / (ti-ti-1). Intuitively, it is
easy to understand that the smaller the time step (h=ti-ti-1) the smaller the error. More
sophisticated schemes exist, which provide less error with the same time step, such as the socalled
trapezoidal and Gear methods.
The numerical resolution of differential equations is a vast subject. Dozens of methods have
been proposed and studied in depth, some of them having very attractive properties, particularly
allowing the use of very large time steps without encountering stability issues. However, in the
context of circuit simulation, many of these methods are not practically applicable. The
differential equations that model an electrical network (either IC or PCB) dynamics
unfortunately have undesirable characteristics. For example, they are implicit (in most if not all
formulations used in commercial simulators) and very often ‘stiff’ (which means that the
individual time constants involved in the system can routinely exhibit orders of magnitude
differences). The cost of evaluation of the non-linear functions is also very high. This
unfortunate situation leaves very few good practical candidates as integration methods.
Eldo implements three integration methods, namely the simple Backward-Euler (BE) method,
the trapezoidal method (TRAP), and the Gear method (GEAR). The trapezoidal method is the
default in Eldo; it provides a very good speed/accuracy compromise. TRAP and GEAR are both
second-order methods, whereas BE is a first-order method. The accuracy of BE is theoretically
one order of magnitude worse than TRAP or GEAR, so it is usually reserved for cases where
speed is the most important criterion, and accuracy, to a certain extent, can be sacrificed. In
many cases, the speed increase obtained with BE is not considerable, although the loss in
accuracy can be significant. This is because the GEAR and TRAP methods are still relatively
simple methods (the derivative approximations are not too complicated). Thus the accuracy
improvement with TRAP or GEAR over BE is generally worth the increased CPU time.
Although TRAP and GEAR have similar theoretical accuracy, they still have their own
characteristics. TRAP has the very undesirable tendency to generate numerical ‘ringing’,
particularly on the current variables. Ringing shows up as obviously non-physical oscillations
of small (or large!) amplitude riding on top of a correct and accurate average value. The
oscillations have the rhythm of the time steps (they don’t belong to the circuit intrinsic time
constant(s)) and they usually dampen over time if the simulator properly controls the time step.
This does not happen systematically with all test cases, but it is a well-known artifact of the
TRAP method. All simulators, including Eldo, implement some code that tries to eliminate or
reduce these oscillations, but sometimes it may be very difficult to eliminate them entirely.
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Speed and Accuracy
Integration Methods
From the user perspective, there are not many options. Clamping the maximum allowed time
step is usually the most radical solution, however this may slow down the whole simulation
significantly. Increasing the accuracy may also help.
If these oscillations occur, and they are a problem (for example because the testbench attempts
to measure currents with high accuracy), the solution is to switch to the GEAR method. Much
cleaner current waveforms will be produced by GEAR, however GEAR has its own undesirable
property to artificially damp natural oscillations of the circuit. Thus, for the analysis of pure
oscillators, or when trying to identify local or global instability problems in a design, GEAR is
not recommended, because it will tend to artificially stabilize any circuit. BE is even worse in
this respect.
If you want to gauge how these methods behave with respect to the damping of natural
oscillations, try the following: create a pure parallel LC network between a node you will
initialize at 1Volt (using a .IC statement) and the ground (0). Pick L and C and the transient
analysis duration, T, so that you can see about one hundred periods of the waveform
(T=100.sqrt(L.C).2.pi). Try it with TRAP, then with GEAR, and then with BE.
Related Topics
Time Step Control
Newton Iterations Accuracy Control
Global Tuning of the Accuracy—EPS
Global Tuning of the Accuracy—TUNING
Simulation of Large Circuits
Tips for Improving Simulation Performance
Eldo® User's Manual, 15.3 1247

Speed and Accuracy
Time Step Control
Time Step Control
The resolution of the system of equations uses discrete time steps, and errors are unavoidable in
all realistic cases.
Tip
See “Speed and Accuracy in Eldo” on page 1245.
Time step control designates the set of methods used by the simulator to select these time steps,
so that the accuracy of the solution is maintained within predefined tolerances.
Overview of Time Step Control Algorithms
To simplify, the time step can be controlled in three different ways.
Eldo can use either:
• Local Truncation Error control (LTE)
• Rate-of-change control (DVDT)
• Iteration Count control (IC)
Some variants on these schemes are also available and detailed below, but these are the main
three strategies. To select one of these time step control methods, use .OPTION LVLTIM.
Tip
See “.OPTION LVLTIM” in the Eldo Reference Manual.
By default, Eldo controls the local truncation error (LTE) and determines the time steps it can
take based on estimations of this error. When a solution at time t has been accepted, to progress
in time, Eldo will compute the value h of the largest time step it can take while still maintaining
an acceptable LTE. Note that this is just a guess. The solution at time point t+h is predicted
using the previous solutions at the previous time points. This serves as the initial guess. Next,
Eldo tries to achieve convergence at the new point t+h. If convergence cannot be achieved, the
time step is reduced using a smaller time step h’ (h’

Speed and Accuracy
Time Step Control
To monitor this, by default .OPTION NEWACCT is set (see “.OPTION NEWACCT” in the
Eldo Reference Manual). Eldo reports interesting (and readable) statistics about the iteration
counts, average number of iterations per time step, number of time step rejections, and so on.
This can be used to double-check whether the simulator runs ‘normally’ or not. These statistics
are reported at the very end of the output .chi file. Eldo also reports some statistics in the
original SPICE style, but the newacct reporting is much more readable and useful.
Convergence failure in the Newton iterations has several possible reasons. The initial guess may
be simply too distant from the solution. This might happen if the chosen time step is ‘overoptimistic’
or if a sharp change in the circuit’s state occurs within the time step. Note that the
simulator anticipates sharp changes in the stimuli, and all ‘break’ points such as the edges in
PWL or PULSE signals force coinciding time points. Another reason for convergence failure
can be discontinuities in the model equations, or simply strong non-linearities.
Controlling the local truncation error (the error incurred while approximating the time
derivatives with finite differences) is the most conservative and rigorous way to control the time
steps. It usually provides more reliable and accurate results. This is the method Eldo selects by
default.
The rate-of-change control method uses the rate of change of the voltages to control the time
steps. The premise behind this method is to control the time steps used so that the voltages do
not change ‘too fast’. It is simpler than the LTE method, but also less accurate, and there is no
direct general relationship between the rate of change of the voltage and the actual truncation
error, at least not under all conditions. The method can, however, provide accurate results if the
rate of change is forced to remain small enough.
The iteration count method attempts to control the time step by monitoring only the rate of
convergence of the Newton iterations. The idea being that if convergence is obtained rapidly,
with just a few iterations, it probably means that the initial predicted guess was ‘good’ and,
conversely, if many iterations are required, it probably means that the guess was incorrect.
There is no attempt to estimate the truncation error. The control is entirely indirect, through the
monitoring of the iteration count. This method is the least reliable of all and not necessarily any
faster.
When selecting the time points, Eldo may also use internal heuristic rules and, for example,
adjust the time steps depending on the types of devices, the way they are connected, the scale of
the simulation time, and so on, to obtain optimal results given the requested tolerances.
As a consequence there is no guarantee that from one release to another, the exact time point
locations, or the time point density (local or global) will be the same. If the time points that Eldo
selects naturally are not convenient for one reason or another, users must add explicit control
options to alter this density. This can be done using options such as HMAX, INTERP,
OUT_STEP, OUT_RESOL, and so on. See also .PLOT in the Eldo Reference Manual.
Related Topics
Control of the Local Truncation Error (LTE)
Eldo® User's Manual, 15.3 1249

Speed and Accuracy
Time Step Control
More About Time Step Control
Usage of a Fixed Time Step
Control of the Local Truncation Error (LTE)
When LVLTIM equals 2 or 3, LTE estimates are used to monitor the time step selection.
Truncation error is the part of the solution error that originates from the approximation of the
time-derivative terms (for example, in the case of a simple capacitor, the dv/dt term in the
I=C.dv/dt equation) with finite-differences expressions. LTE can be estimated and monitored
using the dv/dt terms or the v term itself.
Tip
See “.OPTION LVLTIM” in the Eldo Reference Manual.
When using LTE control to determine the acceptable time steps, Eldo may use the voltage
quantities and/or the charge/flux quantities.
By default Eldo uses voltage quantities for LTE estimates. There are, however, situations where
LTE on charge/flux is used:
• If .OPTION QTRUNC is specified, LTE will be computed on charges/flux, not on
voltages. This corresponds to the way SPICE operates. This is sometimes more efficient
and/or accurate for PCB applications, but often seems indirect to IC designers.
• If Eldo detects ‘PCB-like’ devices such as those shown in the list below, then LTE will
be computed on charges/flux:
o
o
o
o
o
Current sources above 1A
Voltage sources above 500V
Negative capacitors or capacitors above 900pF
Inductors above 0.1μH
Magnetic core devices
If option QTRUNC is set, LTE is computed using charges and flux quantities. In this case
parameters NGTOL, CHGTOL, and FLUXTOL designate the absolute tolerances on voltages,
charges and fluxes respectively, and RELTRUNC is the associated relative tolerance.
Tip
See “.OPTION QTRUNC” in the Eldo Reference Manual.
Related Topics
More About Time Step Control
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Speed and Accuracy
Time Step Control
Usage of a Fixed Time Step
More About Time Step Control
Eldo can also ‘clamp’ the time step to both a minimum value and a maximum value.
To clamp the maximum time step you want to allow, use the HMAX option. Eldo will perform
all of its normal time step control as explained in “Overview of Time Step Control Algorithms”
on page 1248, but still not take any step larger than HMAX. Use this option carefully, as setting
HMAX to a smaller value than required may force long simulation times. Unless very clear
suspicion exists that the result is corrupted due to the selected time steps being too large, this
option should not be used.
To clamp the time step to a minimum value, use the HMIN or ABSOLUTE_HMIN options.
These are potentially dangerous options: if HMIN/ABSOLUTE_HMIN is set to too large
values, it prevents Eldo from using the time step it should use to maintain the accuracy within
the specified tolerances. Unexpected results or failures are possible if using an inappropriate
HMIN/ABSOLUTE_HMIN value. The default value for HMIN/ABSOLUTE_HMIN is 1ps.
Unless speed improvements are a necessity, it is best not to increase HMIN/
ABSOLUTE_HMIN. Setting HMIN/ABSOLUTE_HMIN to lower values can be useful for
designs with very fast transitions.
To control the ‘acceleration’ of the time step when convergence is easily obtained, use the
HACC option. The overall goal of Eldo is to take the largest time step possible, while still
providing results that are within the requested tolerances (typically specified with EPS,
RELTOL, etc.). Every time a time point has been computed and accepted, Eldo will perform
some analysis and computations to determine what the next optimal time step should be for the
next time point. If convergence is easily obtained (that is, with very few iterations) and if the
LTE constraints are verified with a large margin, Eldo will attempt to take a larger time step for
the next time point by multiplying the current time step by a certain acceleration factor, as
specified by HACC. The default value for HACC is 2, which means that Eldo will attempt to
multiply the current time step by 2 at most.
Specifying a value with option HACC overrides the default value of 2. This time step
acceleration strategy is a compromise; choosing a conservative value (1.1x for example) would
provide very little speedup, but the next time point would most likely easily converge.
Alternatively, choosing a large factor (10x for example) when convergence is easily obtained is
tempting, and would in theory provide a significant speedup. However, chances are high that
the time point computed with the new (too) large time step will either not converge because of
non-linearity, or will have to be rejected because the LTE constraints will be violated. In these
cases, Eldo would then step back and recompute a new time point with a smaller time step (see
the option FT). Therefore, an aggressive value might be a worse choice than a conservative one.
The default value, 2, reflects this compromise and is a robust choice providing, on average, the
best results. Unless you have very good reasons to do so, you are advised against changing the
value of HACC.
Eldo® User's Manual, 15.3 1251

Speed and Accuracy
Newton Iterations Accuracy Control
Related Options
• .OPTION FT in the Eldo Reference Manual
• .OPTION HACC in the Eldo Reference Manual
• .OPTION HMAX, .OPTION HMIN and .OPTION ABSOLUTE_HMIN in the Eldo
Reference Manual
Related Topics
Overview of Time Step Control Algorithms
Usage of a Fixed Time Step
Usage of a Fixed Time Step
A fixed internal time step can be specified by the STEP parameter; this may be useful when
simulating certain classes of circuit (for example switched-capacitor circuits), however, care
must be taken. Overall, it is not safe, and may cause excessively long simulation times.
If the requested STEP value is unreasonably small, it may appear to the simulator that some
nodes are not changing, and as a result it will set them into ‘latency’. A badly chosen fixed time
step can thus sometimes have unwelcome results.
A STEP value that is too large may similarly cause problems. Consider a bipolar circuit when a
large transition of an input signal occurs between two steps. This will be nearly impossible to
handle for the simulator.
Overall, using this option in the case of regular IC circuit analysis is highly discouraged.
Related Topics
Overview of Time Step Control Algorithms
More About Time Step Control
Newton Iterations Accuracy Control
The main parameters controlling the accuracy of the Newton iterations are RELTOL, VNTOL,
ABSTOL, and CHGTOL.
Whenever Newton iterations are used to solve the non-linear system of equations, the following
convergence criteria for voltages, currents and charges are used:
• For node voltages:
|V(i) − V(i − 1)| < RELTOL × |max(|V(i)|, |V(i − 1)|)| + VNTOL
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Speed and Accuracy
Global Tuning of the Accuracy—EPS
where V(i) is the voltage value at the current iteration i and V(i-1) is the value at the
previous iteration.
• For branch currents:
|I(i) − I(i − 1)| < RELTOL × |max(|I(i)|, |I(i − 1)|)| + ABSTOL
where I(i) is the current value at the current iteration i and I(i-1) is the value at the
previous iteration.
• For charges:
|Q(i) - Q(i-1)| < RELTOL*|max(|Q(i)|, |Q(i-1)| + CHGTOL
where Q(i) is the value at current iteration i and Q(i-1) the value of the previous
iteration.
The same RELTOL parameter controls the relative tolerance for voltages, currents, and charges.
However, when voltages, currents, or charges become ‘small’ in absolute value, a relative
tolerance becomes useless, thus absolute tolerances are required. Of course the typical orders of
magnitude of voltages, currents, and charges are quite different, thus the necessity to have
specific absolute tolerances (VNTOL, ABSTOL, CHGTOL).
As a rule, if using the default settings, a simulation that goes well should use at most three or
four Newton iterations per time step. This can be less if the circuit is almost linear, or if the
settings such as the RELTOL value are relaxed. If many more iterations are needed, it means
that either the time step control options have been relaxed a lot (and potentially the truncation
error is large), or there are strongly non-linear characteristics in the circuit, which are difficult to
solve. The number of Newton iteration will also increase if the RELTOL value is reduced to
obtain more accuracy.
Related Topics
Speed and Accuracy in Eldo
Tips for Improving Simulation Performance
Global Tuning of the Accuracy—EPS
A global parameter, EPS, is used as a general controller to set the required accuracy of a
simulation. When this parameter is changed, a collection of lower-level parameters are adjusted
accordingly, affecting both the Newton convergence tolerances and the time step control
tolerances.
Is is always possible to set these low-level parameters individually. However using EPS
guarantees that the adjustments to the low-level parameters are consistent, which is not always
easy to achieve.
Eldo® User's Manual, 15.3 1253

Speed and Accuracy
Global Tuning of the Accuracy—EPS
The parameter adjustments induced by EPS are shown in Table 20-1 (the global TUNING
parameter which appears in the first line of the table is explained in “Global Tuning of the
Accuracy—TUNING” on page 1255).
Table 20-1. Global Tuning of Accuracy
TUNING STANDARD ACCURATE VHIGH
EPS 1 1e−1 1e−2 1e-3 1e−4 1e−5 1e-6 1e−7 1e-8 1e−9
RELTOL 5e−2 5e−3 1e-3 5e−4 2.5e−4 1e-4 5e−5 1e-5 1e−6
VNTOL 1e−6 1e−6 1e-6 1e−6 1e−6 1e-6 1e−7 1e-8 1e−9
CHGTOL 1e−9 1e−9 1e-14 1e−14 1e−14 1e-15 1e−16 1e-18 1e−18
FLUXTOL 1e−11 1e−11 1e-11 1e−11 1e−11 1e-11 1e−11 1e-11 1e−11
ITOL 1e−6 1e−6 1e-6 1e−6 1e−6 1e-6 1e−6 1e-6 1e−6
ABSTOL 1e−12 1e−12 1e-12 1e−12 1e−12 1e-12 1e−13 1e-14 1e−15
RELTRUNC 2
CHGTRUNC 3
5e−2 5e−3 1e-3 5e−4 2.5e−4 1e-4 5e−5 1e-5 1e−6
1e−9 1e−9 1e-14 1e−14 1e−14 1e-15 1e−16 1e-18 1e−18
1.See .OPTION EPS for
furtherinformation.
2.When set indirectly thoughEPS, RELTRUNC always gets the same value as RELTOL.
RELTRUNC isonly used if LTE is controlled
on charges/flux, that is when optionQTRUNC
is set.
3.When set indirectly thoughEPS, CHGTRUNC always gets the same value as CHGTOL.
CHGTRUNC isonly used if LTE is controlled
on charges/flux, that is when optionQTRUNC
is set.
Setting EPS automatically changes the low-level parameters shown in the table above. However
it is still possible to override some of them. For example, if specifying:
.option eps=1e-3 reltol=1e-8
RELTOL will be set to 1e-8 instead of 1e-3. VNTOL will be set to 1e-6, indirectly through EPS.
Although this may be considered inconsistent, it is allowed.
It is important to note that RELTOL, which is one of the main parameters defining the global
accuracy, does NOT scale linearly with EPS.
Transient noise (.NOISETRAN) analysis requires more accuracy so the accuracy values
Table 20-1 are not valid and are overridden by default, see “Transient Noise Analysis” on
page 241.
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Speed and Accuracy
Global Tuning of the Accuracy—TUNING
Related Topics
Speed and Accuracy in Eldo
Global Tuning of the Accuracy—TUNING
Global Tuning of the Accuracy—TUNING
Another global parameter, TUNING, may be used as a general controller to define the accuracy
of a given simulation. With TUNING, the user does not provide numerical values for the
accuracy control switches. Instead, a qualitative flag is specified for the desired accuracy, and
similarly to the effect of EPS, a number of adjustments are activated. Actually, ‘accuracy’ in
this context should be understood as ‘speed/accuracy compromise’.
The TUNING parameter can take four values: FAST, STANDARD, ACCURATE, and
VHIGH.
FAST can be used when the primary concern is to accelerate a simulation, and you are ready to
sacrifice a degree of accuracy to achieve this. The FAST setting is equivalent to EPS=1e-3,
overridden with VNTOL=10e-6, ABSTOL=100e-12, RELTOL=1.25e-3 and CHGTOL=1e-12.
Thus FAST is not entirely equivalent to any given value of EPS. It is an adequate setting if you
are not too worried about picoAmps and nanoVolts accuracy, and your primary requirement is a
short runtime.
STANDARD, ACCURATE, and VHIGH are equivalent to specific values of EPS (see
Table 20-1 on page 1254).
STANDARD corresponds to the Eldo default settings, in other words it is equivalent to setting
EPS=1e-3. If you do not set any option in the netlist file, this is what Eldo will use. Thousands
of test cases covering all possible IC technologies have shown that this is the best compromise
for what Eldo tries to achieve by default—in other words reliable and accurate results in the
shortest CPU time.
Finally ACCURATE and VHIGH (which stands for Very HIGH accuracy) alter the tolerance
switches to achieve higher degrees of accuracy, usually at the expense of longer simulation
times. ACCURATE is equivalent to setting EPS=1e-6, and VHIGH is equivalent to EPS=1e-8.
The VHIGH setting must be used carefully, as it can lead to excessively long simulation times.
It is, however, sometimes necessary, particularly for the cases of the startup phase of sensitive
oscillators.
Note
Using EPS settings smaller than 1e-9/1e-10 is not recommended.
Setting the TUNING flag simply uses the .option mechanism. For example:
.option TUNING=ACCURATE
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Speed and Accuracy
Simulation of Large Circuits
Related Topics
Speed and Accuracy in Eldo
Global Tuning of the Accuracy—EPS
Simulation of Large Circuits
The Eldo circuit simulator is capable of handling very large circuits. To handle such circuits,
containing several hundreds of thousands of components, memory usage becomes an important
consideration.
Tip
For more information on memory requirements and dimensioning, please refer to the AMS
Installation Guide.
For the simulation of large circuits, the following suggestions may help:
• Explore the manual.
There are many options and features that can significantly improve speed, and help with
the simulation of large circuits. Some of them are extremely specific and relevant only
in the presence of specific elements. A good place to start is the Simulator and Control
Options chapter in the Eldo Reference Manual, which lists all available .OPTION
statements. Of particular importance are those listed in the Simulation Speed, Accuracy,
and Efficiency Options table.
• Use a workstation with sufficient RAM and SWAP.
As with any software, an attempt to run a simulation with real memory far lower than
that required to contain the circuit can result in a phenomena known as “thrashing.”
When this occurs, CPU time is almost totally taken up in swapping data in and out of
main memory, with little or no useful computation being made. Any tool that monitors
process activity will report CPU usage, real memory usage, and swap usage. When
running large simulations, it is highly recommended to use of these tools to monitor the
simulation processes.
• Use the 64-bit version of Eldo.
If more than 2 GB of real memory is needed, consider using the 64-bit version of Eldo.
See “Running Eldo in 32-bit and 64-bit Modes” on page 42.
• Specify node number via MAXNODES and MAXTRAN options.
If you have an idea of the number of nodes and components (grounded capacitors not
included) your circuit has, it is wise to specify these options:
.OPTION MAXNODES=VALUE MAXTRAN=VALUE
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Speed and Accuracy
Simulation of Large Circuits
In this case, Eldo directly allocates the correct amount of memory, reducing the
requirement of using the expensive C function realloc().
See .OPTION MAXNODES and .OPTION MAXTRAN in the Eldo Reference Manual.
• Collapse the intrinsic MOS transistor nodes.
When simulating large circuits containing mostly MOS transistors, the number of nodes
grows very quickly with the number of MOSs. By default, Eldo creates explicit internal
nodes for the drain and source parasitic access resistors. Thus each MOS transistor with
non-zero access resistors adds two internal nodes to the system. Although these nodes
do not connect to anything else, and the sparse techniques used to solve the matrices
greatly reduce the impact of these additional nodes upon the CPU time, they still
contribute to create a much larger system. For example if 50,000 MOSs are instantiated,
the typical size of the circuit could be 30,000 or 50,000 ‘true’ nodes, but grows to
130,000 or 150,000 with two internal nodes per MOS transistor. Even for Eldo, this is
quite a change in problem size.
An option exists to collapse these resistors into the drain current calculation, thus
avoiding explicit creation of these intrinsic nodes. This option is NONWRMOS. With
this option, the effect of the parasitic resistors upon the drain current is still taken into
account, although not as accurately as when the nodes are explicitly created.
Particularly, some of the overlap capacitances in the MOS model become connected to
the external drain/source, whereas they really are connected to the internal nodes. This
may change results slightly.
However, experience has shown that the accuracy degradation is barely measurable,
particularly when these resistors remain small. When having to simulate huge circuits,
this is worth considering. It is, however, recommended to calibrate the accuracy
degradation caused by the option with a reasonably small circuit first, and then to decide
whether this degradation is acceptable or not for the larger circuit.
This option, as its name indicates, only affects MOS transistors. It has no effect upon the
handling of the internal base, collector, and emitter nodes of bipolar transistors, nor
upon diodes.
When this option is active, there might be situations where DC cannot be found. If this
happens, remove the option. Even when DC is found, if the netlist contains some MOS
devices with forward-biased bulk-source and bulk-drain junctions, Eldo will detect such
situations during DC convergence, and will re-simulate with the option disabled.
See .OPTION NONWRMOS in the Eldo Reference Manual.
• Optimize the density of time points.
Is not always possible to directly alter the density of time points that the simulator must
compute to maintain a given accuracy. However, it is highly recommended to
familiarize yourself with some of the options that affect the number of time points; the
OUT_STEP, INTERP, FREQSMP, and OUT_RESOL options might have very
Eldo® User's Manual, 15.3 1257

Speed and Accuracy
Simulation of Large Circuits
significant impacts. Detailed discussion of these options can be found in “Limiting the
Size of Transient Output Files” on page 353.
See .OPTION OUT_STEP, .OPTION INTERP, .OPTION FREQSMP and .OPTION
OUT_RESOL in the Eldo Reference Manual.
• Use the Periodic Circuit Speedup(PCS) option.
Used to increase the simulation speed for circuits with periodic or nearly periodic
nature. PLLs in near-lock state belong to this category. The amount of speedup depends
on the design nature; the speedup will be more significant with relatively large circuits.
With circuits showing no periodicity at all, the option will not usually provide any
speedup. Periodic Circuit Speedup is invoked by setting PCS=1|2 for BSIM3v3 models
only (PCS=1|2 represent two possible speed optimization methods, PCS=1 is
recommended) or PCS=3 for BSIM4 and BSIM3v3 models (with same speed
optimization as PCS=1). The default is 0. This option only supports the BSIM3v3 and
BSIM4 models.
BSIM4, unlike BSIM3, has many parasitic configurations: gate resistors, body resistors
network, bias dependent access resistors, and so on. These parasitic configurations are
controlled by a set of instance and model parameters (Rdsmod, Rbodymod, and
Rgatemod). As the complexity of the parasitic configuration around the core model
increases, the gain expected by the PCS decreases.
This option should not affect the accuracy of the results.
See .OPTION PCS in the Eldo Reference Manual.
• Try suppressing DC analysis for large digital circuits.
This is achieved by setting the UIC option of the .TRAN command. Very large circuits
are often digital circuits for which an accurate and time-consuming DC analysis may not
be necessary. The logical initialization performed by Eldo prior to any analysis should
ensure that the transient analysis that follows will start with nodes correctly preset.
Initial voltage conditions are specified using the .IC command.
• Decrease the accuracy for MOS digital circuits.
For MOS digital circuits, accuracy can often be decreased to 10mV instead of the
default value of 5mV. This can significantly reduce CPU time.
• Employ the .USE command.
It may be useful to split the circuit into a number of blocks, find DC solutions for each
block, and then find the DC solution of the circuit as a whole using the separate
solutions as a starting point.
Related Topics
Tips for Improving Simulation Performance
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Speed and Accuracy
Tips for Improving Simulation Performance
Tips for Improving Simulation Performance
For saving and restarting DC and transient simulations, refer to the following topics:
• “.SAVE DC in Combination with .RESTART” in “Saving and Restarting DC
Simulations” on page 215
• “.SAVE DC in Combination with .USE” in “Saving and Restarting DC Simulations” on
page 215
• “.SAVE END in Combination with .RESTART” in “Saving and Restarting Transient
Simulations” on page 219
• “More Sophisticated .SAVE and .RESTART Procedures” in “Saving and Restarting
Transient Simulations” on page 219
• “Aborting Simulation and Saving Current State” in “Saving and Restarting Transient
Simulations” on page 219
Related Topics
Speed and Accuracy in Eldo
Simulation of Large Circuits
Eldo® User's Manual, 15.3 1259

Speed and Accuracy
Integral Equation Method (IEM) Algorithm
Integral Equation Method (IEM) Algorithm
IEM is a unique algorithm to Eldo. It is useful when very high accuracy is desired and/or when
NR shows stability issues. Some components cannot be formulated in a way that is compatible
with IEM, thus it is also less general than NR.
Caution
The IEM algorithm only works well using simple models. Models are now quite
complicated due to latest process technology nodes. They require a more flexible interface,
GUDM, where you can specify any number of nodes as required. They are not supported by
IEM. This applies to almost all the newer families of models, including: BSIM4, BSIM5,
MM11, PSP, TFT, HISIM, HICUM, VBIC and MEXTRAM. Eldo built-in analog macromodels
and Verilog-A user-defined models are also not supported by IEM.
With IEM, the differential system is first transformed into a system of integral equations, which
is then transformed into an algebraic system by series expansion. The truncation error results
from the finite number of terms in the series. In all cases, truncation error is also a function of
the time step size.
Once the non-linear algebraic system is obtained, it is solved by an iteration loop. IEM targets
improvements of the accuracy of the solution (compared to Newton); it does not specifically
target large circuits, so it is mostly used for cell or macro-block simulations where accuracy is
critical.
IEM is of interest for cases where high accuracy is required and/or when the default Newton
method runs into numerical stability issues due to the integration methods (trapezoidal ringing
for example). IEM however does not support all devices, macro-models, and so on, that Newton
supports. Some devices cannot be efficiently formulated in a way that is compatible with the
IEM algorithm. Thus the applicability of IEM is somewhat limited, and it is mostly used for cell
characterization applications.
• Integration Method
When using IEM, the notion of integration method, such as BE, TRAP, or GEAR, is
irrelevant. The equations are cast to an integral form prior to the resolution. Thus there
are no choices about a numerical integration method to use.
• Time Step Control
When using IEM, the time step control algorithm uses local truncation error (LTE)
control. Only the LVLTIM=2 and LVLTIM=3 methods are selectable together with
IEM. The other methods are not reliable enough when used together with IEM, and they
will be refused by Eldo.
• Accuracy Control
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Speed and Accuracy
IEM Overview
When using IEM, the same accuracy control parameters as those used for the default
Newton method are available. Thus the RELTOL and ABSTOL parameters will
primarily control the accuracy of the resolution.
The IEM method is described in more detail, including its limitations, in the following sections:
• “IEM Overview” on page 1261
• “IEM—Supported Circuit Elements” on page 1262
• “IEM Tolerance Parameters” on page 1263
• “Efficient Usage of IEM” on page 1264
IEM Overview
The Integral Equation Method (IEM) is a simulation algorithm developed for transient analog
circuit simulation. With some circuits, IEM provides better performance than classic algorithms
based on the Newton-Raphson method combined with a multi-step discretization scheme (for
example Backward-Euler, Trapezoidal, Gear, and so on).
In some cases, IEM may perform better than Newton methods in terms of stability and
accuracy, which has a favorable incidence on speed. The improvements appear particularly for
circuits requiring high precision or those which exhibit tight coupling or stability problems.
IEM’s performance enhancement derives from the use of a semi-analytic approach combined
with efficient numerical techniques.
Application Domains
IEM is invoked for TRANSIENT analysis of ANALOG circuits only. DC and AC analyses can
only be performed using Newton-Raphson methods.
In a case where Eldo works together with another simulation kernel—digital or analog—then
IEM is not supported.
Related Topics
Integral Equation Method (IEM) Algorithm
IEM—Supported Circuit Elements
IEM Tolerance Parameters
Efficient Usage of IEM
Eldo® User's Manual, 15.3 1261

Speed and Accuracy
IEM—Supported Circuit Elements
IEM—Supported Circuit Elements
Most simple circuit elements accepted by Eldo are supported by IEM, except objects described
by FAS or GUDM. The following list explicitly states those elements supported by IEM.
• MOS models:
o
o
o
o
o
o
o
o
o
o
o
MERCK2, MERCK3, and MERCK4
BERK1, BERK2, and BERK3
BSIM1 and BSIM2
STMOS1 and STMOS3
EKV
MISNAN
BSIM3
CSEM
BSIM3V3
MOTOROLA
MOSP9
• BJT models:
o
o
BERKBIP
STBIP
• Diodes:
o
o
o
o
o
o
o
BERKDIO
ELDIO2
TUNNELD
STDIO
STFOWL
STMIS
JUNCAP
• All other electrical device models, except:
o
o
R, L, and C defined by the VALUE statement.
S and Z domain filters.
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Speed and Accuracy
IEM Tolerance Parameters
• All independent or controlled sources, except:
o
Controlled sources defined by either the VALUE or TABLE statements (note: linear
and polynomial controlled sources are supported).
• All digital and mixed-signal macromodels.
• Only comparator and delay elements are supported among analog macromodels.
• Only the switch element is supported among switched capacitor macromodels.
• Accusim magnetic models are supported, but not those of Eldo.
In case a circuit or block contains an element not supported by IEM, this circuit or block is
simulated using Newton-Raphson and a warning message is issued.
Related Topics
Integral Equation Method (IEM) Algorithm
IEM Overview
IEM Tolerance Parameters
The following simulation algorithms may be used on a circuit depending on the setting of the
.OPTION line in the netlist and/or on the use of the (ANALOG) attribute on subcircuits:
• .OPTION NEWTON
In this case, the whole circuit is simulated in a single block using the Newton method.
This is the default algorithm.
• .OPTION IEM
In this case, the whole circuit is simulated in a single block using IEM.
• .OPTION BLOCKS=NEWTON
In this case, the circuit is partitioned (whenever possible) into one or more blocks.
Simulation inside each block is performed using the Newton method and relaxation is
undertaken between blocks using OSR. OSR is also used to simulate the non-Newton
part of the circuit.
• .OPTION BLOCKS=IEM
In this case, the circuit is partitioned (whenever possible) into one or more blocks.
Simulation inside each block is performed using IEM and relaxation is undertaken
between blocks using OSR. OSR is also used to simulate the non-IEM part of the circuit.
If a block contains either a GUDM, HDL-A, or FAS model, then simulation inside that
particular block will be performed using the Newton method. If no IEM blocks are created
Eldo® User's Manual, 15.3 1263

Speed and Accuracy
Efficient Usage of IEM
(because all blocks contain unsupported objects or the circuit is loosely coupled and can be
simulated with OSR) then the IEM option is removed, and a warning message is issued.
RELTOL and VNTOL parameters can be used in the same way as for SPICE-like simulators.
These control both convergence of iteration loops and step size.
Note
For Newton-Raphson, RELTOL does not control the step size.
If RELTOL or VNTOL are not explicitly specified in the netlist, then EPS can be used to
control their values, as follows:
• RELTOL = (1.0×10 −9 × EPS) 1/4
RELTOL is then limited in the range 1.0×10 −2 to 1.0×10 −5
• VNTOL = (1.0×10 −7 × EPS) 1/2
VNTOL is then limited in the range 1.0×10 −3 to 1.0×10 −9
For IEM, the option LVLTIM is set to 2 by default, in other words, truncation error is used to
control the time step. It is possible to set LVLTIM=3 in the netlist, which will also enable the
truncation error to control the time step. Additionally, it will impose calculated points at
TPRINT values in the .TRAN command. Other settings of LVLTIM are not allowed since they
produce less accurate results that would be meaningless with IEM.
All other SPICE-compatible options (for example ABSTOL, ITOL, and so on) behave in the
same way as for Newton-Raphson. This of course does not include integration scheme options
(BE, TRAP, GEAR, ...) which do not apply to IEM.
To maintain compatibility with previous Eldo versions and Newton usage, EPS may still be
used in the Eldo sense—that is, as a means to control all precision parameters.
Related Topics
Integral Equation Method (IEM) Algorithm
One Step Relaxation (OSR) Algorithm
Efficient Usage of IEM
Efficient Usage of IEM
This section describes approaches to achieve the best accuracy and performance results with
IEM, used alone or in combination with OSR.
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IEM Alone (.OPTION IEM)
Speed and Accuracy
One Step Relaxation (OSR) Algorithm
As discussed in “IEM Tolerance Parameters” on page 1263, this setup enables IEM to simulate
the whole circuit in a single block. This is required for all-analog designs, or at least when the
analog part of the circuit is much larger than the logic circuitry (in other words, approximately
75% of devices or more). This option is particularly recommended for circuits requiring high
precision and/or those manifesting stability problems. IEM intrinsically gives very good
accuracy and doesn’t require tightening of accuracy parameters. Hence, the default EPS value is
usually enough to achieve high quality simulation results. Lowering EPS will give even higher
precision, but at the expense of CPU time.
IEM + OSR (.OPTION BLOCKS=IEM)
This setup enables Eldo to partition the circuit, assigning tightly coupled blocks to IEM, the
remaining part being simulated with OSR. By default, MOS and grounded capacitors are
assigned to OSR, hence it is recommended to use this setup in conjunction with a correct
imposition of the attribute (ANALOG) for relevant circuits. This way, BJTs, resistors, and all
MOS analog subcircuits will be simulated by IEM while other MOS blocks will be considered
as logic ones and efficiently simulated by OSR (whenever possible).
As usual, it is possible to increase accuracy by reducing EPS, however, as in all-IEM simulation
this is not particularly recommended.
Note
The combination of IEM (a highly precise algorithm) with OSR (a fast but less precise
algorithm) may not be justified in some cases.
Related Topics
Integral Equation Method (IEM) Algorithm
One Step Relaxation (OSR) Algorithm
IEM Tolerance Parameters
One Step Relaxation (OSR) Algorithm
The OSR algorithm of Eldo is dedicated to the simulation of large MOS circuits showing weak
local couplings (large-scale feedback loops are not a problem). It is a unique algorithm to Eldo.
Its primary usage is the fast transistor-level simulation of large digital CMOS circuits, for which
the weak local coupling assumption is generally valid.
Caution
OSR is applicable to legacy processes only, typically 0.5μm or larger, and does not perform
efficiently with state-of-the-art processes. This is because OSR is based on fundamental
assumptions about the signal flow and weak electrical couplings between gates, drains, and
sources in MOS devices. These assumptions are no longer true with short-channel processes,
Eldo® User's Manual, 15.3 1265

Speed and Accuracy
One Step Relaxation (OSR) Algorithm
and thus OSR cannot perform equally well. Specifically, gate-drain and gate-source leakage
currents can easily prevent the algorithm from working efficiently. For these reasons OSR is
considered a legacy feature, and there are no active developments, enhancements, nor bug
fixing. To perform large-scale digital (CMOS) simulation with a higher performance than Eldo
Classic, consider the ADiT and Eldo Premier solutions.
When the conditions for its applicability are met, the speed and accuracy of OSR are excellent.
In many cases, it is just as accurate as the Newton method, but much faster, and also the growth
of the CPU time with the circuit size is almost linear, which enables the simulation of larger
circuits. Although its capacity is still less than that of fast-SPICE timing simulators such as
ADiT, it provides an interesting point in the speed/accuracy plane.
OSR is not particularly efficient with tightly coupled analog circuits. Better results will be
obtained using the default Newton-Raphson method.
OSR can be activated explicitly or indirectly. The most straightforward way to activate OSR is
to use .option OSR. If this option is set, Eldo attempts to simulate the whole circuit with OSR.
However, if the circuit contains elements that prevent OSR from being effective, or if its
connectivity is such that OSR will fail, Eldo reverts back to the default Newton algorithm, for
part or all of the circuit and will issue a warning.
Note
Eldo is able to simulate a circuit with certain parts handled by OSR, and other parts handled
by Newton. See “Combined OSR/Newton Simulation” below for more information.
OSR and the Notion of Latency
When OSR is used, Eldo places the nodes for which the surrounding nodes do not show any
voltage variation greater than EPS volts into ‘latency’. Thereafter, Eldo effectively bypasses the
calculation of such nodes. This enables significant CPU time savings, especially for large digital
circuits where, often, only a fraction of the nodes are changing over one time step.
Due to the formulation of OSR, latency exploitation is very natural and effective. Latency is
much more complicated to control in a reliable way in the context of the regular Newton
method.
Even with OSR, latency, and above all ‘wake-up from latency’, is always tricky. When slowly
varying signals are applied to a circuit with high capacitances, Eldo may not detect any voltage
variation within one time step, resulting in nodes being placed in latency. Depending on the
tolerances (EPS) this may cause incorrect simulation results. In case latency is potentially the
source of problems, the .OPTION NOLAT command may be used to suppress the use of
latency. If this option is set, Eldo will not attempt to use latency, and will solve all nodes,
whatever their activity.
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Integration Method
Speed and Accuracy
One Step Relaxation (OSR) Algorithm
When using OSR, the same integration methods as for the case of Newton (namely BE, TRAP,
and GEAR) can be used (using .OPTION METHOD=).
Time Step Control
When using OSR, the default time step control algorithm is the same as in the case of Newton
(LVLTIM=2), and thus it uses local truncation error (LTE) control. Only the LVLTIM=1,
LVLTIM=2 and LVLTIM=3 methods are selectable together with OSR. The other method
(LVLTIM=0 is meaningless in the context of OSR (there are no Newton iterations when using
OSR).
Accuracy Control
The accuracy control when using OSR is much simpler than with Newton. The global parameter
EPS is used to control everything. Furthermore, the actual value of EPS (in Volts) is directly
used for the convergence control.
Accuracy of the relaxation loop and the inner loop is directly controlled by EPS.
• Relaxation loop is stopped when:
|V(irelax) - V(irelax-1)| < EPS for all nodes
• Inner loop:
|V(iter) - V(iter-1)| < EPS/50 on the current node
Combined OSR/Newton Simulation
Eldo can partition a circuit so that some blocks are simulated using OSR and other blocks are
simulated using the standard Newton algorithm. Typical candidate examples would include
circuits with large digital CMOS blocks driving and/or driven by analog blocks such as voltage
regulators, bandgap references, high-gain operational amplifiers, and so on.
In these cases, the speed and capacity of OSR is used to handle the large weakly-coupled
sections of the circuits, and Newton, with its accuracy and ability to handle tightly coupled
devices, is used for the analog blocks.
The partitioning can be left entirely to the discretion of Eldo, or the user can try to help and
indicate which blocks (subcircuits) must be simulated with OSR or Newton. In the latter case,
the partitioning is always indicative only, and Eldo may choose to alter the boundaries of the
partitions to accommodate the requirements of the OSR algorithm.
There are several ways to trigger these mixed OSR/Newton simulations:
• .OPTION BLOCKS=NEWTON
Eldo® User's Manual, 15.3 1267

Speed and Accuracy
One Step Relaxation (OSR) Algorithm
This first partitioning method is automatic, based on the degree of coupling between
devices. A global option is set (.OPTION BLOCKS=NEWTON). Eldo will identify the
blocks consisting of tightly coupled devices and place them in partitions that will be
solved using the Newton method. The loosely coupled nodes are placed in the OSR
partition. The global circuit is solved using a relaxation loop. Simply, the relaxation loop
operates with individual nodes and also groups of tightly coupled nodes (the Newton
partitions). Note that the identification of tightly coupled devices is not based on the
netlist hierarchy (.SUBCKT, and so on).
• Flag (ANALOG) given on SUBCKT definition
This partitioning methods ‘tags’ the subcircuit definitions. The subcircuit definitions
tagged with (ANALOG) will be solved using the Newton method. This is useful when
the netlist hierarchy reflects the nature and coupling level of the blocks. All nodes that
are not inside a user-defined (ANALOG) SUBCKT, and which are connected only to
MOSFET, grounded capacitances, or low-value floating capacitances (the threshold
value for floating capacitance is set with .OPTION CAPANW= ) will be solved by OSR,
with all other nodes being solved by Newton. See the subcircuit definition syntax in the
.SUBCKT command in the Eldo Reference Manual.
• .NWBLOCK [RELTOL=val] [VNTOL=val]
This method is the most ‘manual’ one. Each Newton block is defined explicitly, with a
list of nodes. Hierarchical names and wildcards in such names are allowed. Optionally
the required Newton accuracy can be redefined for each block, using the RELTOL and
VNTOL parameters.
With any of the partitioning methods described above, OSR is implicitly activated. OSR
becomes the default method, and Eldo (or the user) defines what still has to be simulated with
Newton.
Whenever OSR and Newton are activated simultaneously, the OSR and Newton rules for
accuracy control apply to the OSR and Newton partitions respectively. For example the
RELTOL and VNTOL parameters still define the accuracy of the nodes inside the Newton
partitions, whereas EPS defines the accuracy of the OSR nodes.
Related Topics
Integral Equation Method (IEM) Algorithm
Tips for Improving Simulation Performance
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Chapter 21
Examples
The most productive way of learning a simulation tool such as Eldo is to get ‘hands-on’
experience by sitting at a terminal and working through, stage by stage, a number of practical
circuit simulation examples.
The examples cover a wide range of simple but concise circuit applications. They should be of
interest not only to the novice user, but also to the experienced user wishing to learn more about
specific simulation techniques within Eldo. Upon completion, a wide range of techniques
needed to perform efficient and productive analysis using Eldo should have been learnt.
A summary of the circuits used in this chapter, together with a brief description of the Eldo
subject areas dealt with are listed in Table 21-1. Listings for these examples may be found in the
following subdirectories included with your software:
$MGC_AMS_HOME/examples/eldo
where $MGC_AMS_HOME is the directory where the software resides.
Table 21-1. Eldo Examples
Example Circuit Name Eldo Description
Example 1—AC Analysis of a
Parallel LCR Circuit
Example 2—Transient and AC
Analysis of a 4th Order Butterworth
Filter
Example 3—AC and Noise
Analysis of a Band Pass Filter
Example 4—AC Analysis of a Low
Pass Filter
Example 5—Transient Analysis of a
Colpitts Oscillator
Example 6—Transient Analysis of a
High Voltage Cascade
Example 7—Monte Carlo Analysis
Basic
Example 8—DC Sensitivity of a
Bipolar Amplifier
ac_basic.cir
ac_tran_filter.cir
ac_noise_filter.cir
ac_lowpass.cir
tran_oscillator.cir
tran_high_voltage.cir
monte_carlo_basic.cir
dc_sensitivity.cir
General introduction to AC
analysis.
Transient and AC analysis.
AC, noise analysis, and
model description.
AC analysis and subcircuit
definition.
Transient analysis and
model description.
Transient analysis and
model description.
AC, Monte Carlo analysis,
and model description.
DC sensitivity analysis.
Eldo® User's Manual, 15.3 1269

Examples
Table 21-1. Eldo Examples (cont.)
Example Circuit Name Eldo Description
Example 9—Transient and AC
Analysis of a Switched Capacitor
Low Pass Filter
Example 10—Transient Analysis of
a Switched Capacitor Schmitt
Trigger
Example 11—Loop Stability of an
Opamp
Example 12—Overshoot Extraction
of an Opamp
Example 13—Transient Analysis of
a 5th Order Elliptic SC Low Pass
Filter
Example 14—Charge Conservation
in MOS Models
Example 15—AC Analysis of an
Active RC Band Pass Filter
Example 16—Transient Analysis of
an Integrator
Example 17—Monte Carlo
Sensitivity of a Two-Stage
Operational Amplifier
Example 18—Numerical
Integration: TRAP versus GEAR
Example 19—DC Mismatch
Comparison with Monte Carlo
Analysis
tran_ac_switched.cir
tran_sc_trigger.cir
loop_stability_opamp.cir
extract_overshoot_opamp.cir
tran_switched_filter.cir
mos_charge_conservation.cir
ac_pcb_ua741.cir
tran_integrator.cir
monte_carlo_sensitivity.cir
trap_vs_gear.cir
dcmismatch_contributors.cir
Transient and small signal
AC analyses using
Z-domain switched
capacitor models.
Transient analysis of a
switched capacitor Schmitt
trigger circuit, using an
operational amplifier and
switch macromodels.
Loop Stability analysis.
Plot and extract the
overshoot of an opamp
connected.
Transient analysis of a 5th
order elliptic low pass filter
using opamp and switched
capacitor macromodels.
Charge conservation
comparison between old and
new device models.
AC analysis of an active RC
band pass filter circuit
containing a standard
discrete UA741 operational
amplifier.
Transient analysis of a
second order delta sigma
modulator circuit using
analog macromodels.
Monte Carlo sensitivity
value computation.
Comparison of the TRAP
and GEAR numerical
integration methods.
Comparison of
DCMISMATCH analysis
and Monte Carlo analysis.
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Examples
Table 21-1. Eldo Examples (cont.)
Example Circuit Name Eldo Description
Example 20—DC Mismatch
Comparison with Monte Carlo
Analysis using ECL
Example 21—Post-Layout
Simulation using DSPF
Example 22—Extract Gain and
Phase Margin of a 2-Stage Opamp
Example 23—Parametric
Sensitivity Analysis
Example 24—Cell
Characterization: Setup Time
Extraction
Example 25—Setting up and
Handling Analog Busses
Example 26—Spectre
Compatibility Example
Example 27—Monte Carlo
Analysis Autostop
Tutorial—Using Power Analysis for
Static Leakage Analysis of a PLL
Circuit
Tutorial—High Impedance Fault
Detection of a PLL Circuit
Transient Noise Analysis Example
1—High-Rate Particle Detector
Transient Noise Analysis Example
2—Switched Capacitor Filter
dcmismatch_vs_mcsens.cir
dspf_backannotation.cir
gain_phase_margins.cir
sensitivity_parametric.cir
extract_setup_time_passfail.c
ir
sigbus_plotbus.cir
spectre_compatibility.scs
monte_carlo_autostop.cir
../power_analysis/
Power_Analysis_PLL.cir
../hiz/HiZ_PLL.cir
transient_noise_detector.cir
transient_noise_filter.cir
Eldo Control Language
comparison of
DCMISMATCH analysis
and Monte Carlo analysis.
Shows how to import a .dspf
file containing layout
parasitics.
Extract the gain and phase
margin of an opamp.
Parametric sensitivity
analysis (.SENSPARAM).
Extract the setup time of a
D-type flip-flop, using the
pass-fail method of the Eldo
optimizer.
Setting up and handling
analog busses .SIGBUS,
.SETBUS, .CHECKBUS.
Eldo support of Spectre
format netlist.
Monte Carlo analysis with
autostop.
Power Analysis tutorial.
High Impedance fault
detection tutorial.
Legacy transient noise
analysis example.
Legacy transient noise
analysis example.
Each example starts with a brief description of the circuit in question together with a circuit
diagram. A short summary of the Eldo commands used within the example follows this, to aid
users wishing to learn about a specific topic or the use of certain commands within Eldo. A
breakdown and explanation of each section of the netlist is then shown. Actual output results
from the circuit conclude each example using EZwave, the Eldo waveform viewer.
Additional examples are documented throughout the manual as listed in Table 21-2:
Eldo® User's Manual, 15.3 1271

Examples
Example 1—AC Analysis of a Parallel LCR Circuit
Table 21-2. Additional Eldo Examples
Type Examples Directory Description and Link
Using IBIS in Eldo ibis IBIS Examples
Monte Carlo Analysis
Further Monte Carlo Analysis
Examples
Statistical Experimental dex
DEX Example Files
Design and Analysis
Optimization optimizer Examples of Circuit
Optimization
Eldo Control Language ecl Eldo Control Language
Examples
Post-Processing Library ppl Post-Processing Library
Example Files
Example 1—AC Analysis of a Parallel LCR
Circuit
Netlist file: ac_basic.cir
This simple circuit simulation gives a general introduction to the syntax of Eldo by performing
an AC analysis on a parallel LCR circuit.
Figure 21-1. Parallel LCR Circuit
Summary of Eldo commands used in this example:
• .AC—AC analysis.
• .PLOT—Plot simulator results.
Tip
See the “.AC” and “.PLOT” commands in the Eldo Reference Manual.
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Netlist Explanation
Examples
Example 1—AC Analysis of a Parallel LCR Circuit
The first line is the circuit title. It must always be the first line of a simulation.
LCR Parallel Network
The first part of the Eldo netlist is a description of the circuit components.
The line below defines an AC voltage source vin connected between the nodes 1 and 0 of value
1V and 0º phase.
vin 1 0 ac 1 0
The lines below define the devices present in the circuit to be simulated. Each device
instantiation gives the component name, the nodes to which the component is connected and the
value of the component.
r2 1 2 50
r3 2 3 50k
r5 3 0 50
l1 2 3 100u
c4 2 3 10n
The next part of the netlist specifies the simulation control directives indicating the type of
simulation Eldo will perform on the circuit.
The line below indicates that Eldo will perform an AC analysis on the circuit within the
frequency range 100Hz to 1 GHz with 1000 steps per decade.
.ac dec 1000 100 1g
The line below specifies a dB/frequency plot of the nodes 2 and 3 on the same graph.
.plot ac vdb(2) vdb(3)
The netlist is terminated with the command below. This is not mandatory, but recommended.
.end
Simulation Results
The results are stored in the ac_basic.wdb file and can be displayed using the EZwave graphical
results post-processor. Figure 21-2 shows the results using the EZwave waveform viewer.
Eldo® User's Manual, 15.3 1273

Examples
Example 2—Transient and AC Analysis of a 4th Order Butterworth Filter
Figure 21-2. Example 1—Simulation Results
Example 2—Transient and AC Analysis of a
4th Order Butterworth Filter
Netlist file: ac_tran_filter.cir
This example simulates a 4th order Butterworth filter with a transient and an AC analysis being
performed on the circuit.
Figure 21-3. 4th Order Butterworth Filter
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Examples
Example 2—Transient and AC Analysis of a 4th Order Butterworth Filter
Summary of Eldo commands used in this example:
• .AC—AC analysis.
• .TRAN—Transient analysis.
• .PLOT—Plot simulator results.
Netlist Explanation
The first group of lines define the devices in the circuit to be simulated. Each device
instantiation specifies the component name, the nodes to which the component is connected and
the value of the component.
4th Order Butterworth Filter
c1 4 0 1.5307n
c2 3 0 1.0824n
l1 3 4 1.5772u
l2 2 3 .38268u
r1 1 2 1
This line defines an AC source of 1V and a time dependent Piece Wise Linear function between
the nodes 1 and 0. The pwl parameters describe a signal that stays at 0V until 1μs where it rises
to 1V in 1μs. The signal stays at 1V until 20μs where it drops back to 0V in 0.1μs.
v1 1 0 ac 1 pwl (0 0 1u 0 2u 1 20u 1 20.1u 0)
Tip
Refer to the output results for a pictorial representation of this signal.
The line below specifies that Eldo will perform a transient analysis on the circuit lasting 40μs
with a plotting increment for the line printer of 0.2μs.
.tran 0.2u 40u
The lines below specify that voltage/time plots will be generated on separate graphs of the
voltage at node 4 and the voltage at node 1.
.plot tran v(4)
.plot tran v(1)
The line below indicates that Eldo performs an AC analysis on the circuit within the frequency
range 10000Hz to 100MHz with 20 steps per decade. This AC analysis statement specifies that
an AC analysis is performed in addition to the transient analysis. Eldo first performs the AC
analysis, followed by the transient analysis.
.ac dec 20 10000 100meg
The line below sets the simulator accuracy.
Eldo® User's Manual, 15.3 1275

Examples
Example 2—Transient and AC Analysis of a 4th Order Butterworth Filter
.option eps=1.0e-6
The lines below specify that dB/frequency and phase/frequency plots will be generated of the
voltage at node 4. These commands are added to the first simulation run netlist.
.plot ac vdb(4)
.plot ac vp(4)
Simulation Results
The results are also added to the file ac_tran_filter.wdb and can be displayed as a second
simulation page using the EZwave graphical post-processor.
Figure 21-4. Example 2—Simulation Results—AC
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Examples
Example 3—AC and Noise Analysis of a Band Pass Filter
Figure 21-5. Example 2—Simulation Results—Transient
Example 3—AC and Noise Analysis of a Band
Pass Filter
Netlist file: ac_noise_filter.cir
This example deals with a typical PCB example of a simple opamp band pass active filter using
opamp macromodels. The simulation performs an AC analysis of the circuit, together with a
noise analysis, of the output stage of the filter to obtain the small-signal frequency and noise
responses respectively.
Eldo® User's Manual, 15.3 1277

Examples
Example 3—AC and Noise Analysis of a Band Pass Filter
Figure 21-6. Band Pass Filter
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .AC—AC analysis.
• .NOISE—Noise analysis.
Netlist Explanation
Band-Pass filter
.model ampop modfas gain=10000.0 p1=5e3
The above line describes the electrical parameters of the user defined model ampop based on the
opamp2 macromodel. The gain (gain) and dominant pole frequency (p1) of the model are set to
10000 and 5×10 3 Hz.
Tip
For more details on the opamp2 macromodel and its parameters, refer to “Analog
Macromodels” in the Eldo Reference Manual.
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Examples
Example 3—AC and Noise Analysis of a Band Pass Filter
yopa1 opamp2 pin: 5 6 4 0 model: ampop
yopa2 opamp2 pin: 9 11 10 0 model: ampop
The above lines instantiate two operational amplifiers yopa1 and yopa2 of macromodel type
opamp2 (linear 2-pole) connected between the nodes 5, 6, 4 and 0 and between the nodes 9, 11,
10 and 0 respectively. The electrical parameters of the macromodel are defined in the model
ampop.
.ac dec 80 100 10k
.plot ac vdb(10)
The above lines indicate that an AC analysis should be performed on the circuit within the
frequency range 100Hz to 10kHz with 80 steps per decade. A dB/frequency plot of the voltage
at node 10, the output stage of the filter, is requested.
.noise v(10) v1 80
.plot noise db(inoise)
.plot noise db(onoise)
The above lines indicate that a noise analysis should be performed of the voltage at node 10
with the voltage source v1 as input noise voltage. The analysis should be averaged over 80
frequency points. A dB/frequency plot is requested on the input and output noise.
Eldo® User's Manual, 15.3 1279

Examples
Example 4—AC Analysis of a Low Pass Filter
Simulation Results
Figure 21-7. Example 3—Simulation Results
Related Topics
AC Analysis
Noise Analysis
Example 4—AC Analysis of a Low Pass Filter
Netlist file: ac_lowpass.cir
This example deals with a typical PCB example of the AC analysis of a low pass filter using
bipolar standard parts. The low pass filter incorporates a voltage amplifier, illustrating the use of
the subcircuit capabilities of Eldo, as the voltage amplifier part of the circuit itself is defined in
this manner.
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Figure 21-8. Low Pass Filter
Examples
Example 4—AC Analysis of a Low Pass Filter
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .SUBCKT—Subcircuit definition.
• .AC—AC analysis.
• .PLOT—Plot simulator results.
Netlist Explanation
Low Pass Filter incorporating a Voltage Amplifier
.model q2n2222 npn is=1.9e-14 bf=150 vaf=100 ikf=.175
+ ise=5e-11 ne=2.5 br=7.5 var=6.38 ikr=.012 isc=1.9e-13
+ nc=1.2 rc=.4 cje=26p tf=.5e-9 cjc=11p tr=30e-9 xtb=1.5
+ kf=3.2e-16 af=1.0
The above lines describe the electrical parameters of the npn bipolar transistor model q2n2222.
.subckt amp in out vdd
The above line indicates the start of the voltage amplifier subcircuit definition. The subcircuit is
called amp and is connected between the nodes in, out and vdd.
c30 in 31 47u
r30 31 33 390
r31 vdd 33 50k
r32 33 0 15k
q30 out 33 0 q2n2222
r33 vdd out 750
.ends amp
The above line indicates the end of the definition of the subcircuit amp.
Eldo® User's Manual, 15.3 1281

Examples
Example 4—AC Analysis of a Low Pass Filter
Note
All nodes used within the subcircuit are local nodes, in that they are only referenced within
the subcircuit itself and that they do not have to correspond with the names of the nodes
outside the subcircuit.
r1 1 2 10
l1 2 3 1.3m
c1 3 0 100n
r2 4 0 50k
x1 3 4 9 amp
The above line instantiates the subcircuit x1 of type amp connected between the nodes 3, 4, and
9. As explained earlier, these nodes correspond to the nodes in, out and vdd within the
subcircuit.
vb 9 0 5
v1 1 0 ac 1
The above lines define the voltage sources in the circuit. A DC voltage source vb between the
nodes 9 and 0 of value 5V, and an AC voltage source v1 connected between the nodes 1 and 0
of value 1V.
.ac dec 10 1 1g
.plot ac vdb(3) vdb(4)
.plot ac vp(3) vp(4)
.end
The above lines indicate that an AC analysis should be performed on the circuit within the
frequency range 1Hz to 1GHz with 10 steps per decade. A dB/frequency plot of the voltage at
nodes 3 and 4 is requested, together with a phase/frequency plot at the same nodes.
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Examples
Example 5—Transient Analysis of a Colpitts Oscillator
Simulation Results
Figure 21-9. Example 4—Simulation Results
Example 5—Transient Analysis of a Colpitts
Oscillator
Netlist file: tran_oscillator.cir
This example deals with the transient analysis of a simple oscillator circuit. This example is a
Colpitts oscillator, a very classical circuit example.
Eldo® User's Manual, 15.3 1283

Examples
Example 5—Transient Analysis of a Colpitts Oscillator
Figure 21-10. Colpitts Oscillator
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .OPTION—Simulator configuration.
• .TRAN—Transient analysis.
• .PLOT—Plot simulator results.
Netlist Explanation
.model ts2 npn
+ bf=10 br=1 xtb=3 is=10f eg=1.11 rb=100
+ rc=10 vaf=50 tr=6n mjc=0.75 mje=0.33 vje=0.75
The above lines describe the electrical parameters of the npn bipolar transistor model ts2.
Tip
For a detailed description of each of these parameters, refer to the “BJT Model Syntax” in
the Eldo Reference Manual.
L1 1 3 5u
C1 1 2 2n
C2 2 3 100p
R3 2 4 2200
Q1 3 0 2 ts2
The above line defines a transistor q1 between nodes 3, 0 and 2 with electrical parameters
defined by the model ts2.
V1 1 0 5
V2 4 0 -5
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Examples
Example 5—Transient Analysis of a Colpitts Oscillator
The above lines define the voltage sources in the circuit. A DC voltage source v1 connected
between the nodes 1 and 0 of value 5V and also a DC voltage source between the nodes 4 and 0
of value −5V.
i1 2 4 pulse(0 10u 0 5n 5n 25n 50n)
This line defines a time dependent pulse function between nodes 2 and 4 describing the
following signal:
0 A at 0s (delay time is 0s)
0 A to 10μA in a rise time of 5ns
10μA from 5 to 30ns (pulse width is 25ns)
10μA to 0A in a fall time of 5ns
0 A at 35ns
Cycle repeats starting from 50ns.
.option eps=1.0e-6
The above line sets the simulator accuracy.
.TRAN 1u 12u
The above specifies a transient analysis is to be performed lasting 12μs with a plotting
increment of 1μs.
.plot tran v(1,3) (10,-10)
The above line specifies a voltage/time plot to be performed of the voltage difference between
the nodes 1 and 3 between the limits ±10V.
Eldo® User's Manual, 15.3 1285

Examples
Example 6—Transient Analysis of a High Voltage Cascade
Simulation Results
Figure 21-11. Example 5—Simulation Results
Example 6—Transient Analysis of a High
Voltage Cascade
Netlist file: tran_high_voltage.cir
This example deals with the transient analysis of a high voltage cascade circuit.
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Examples
Example 6—Transient Analysis of a High Voltage Cascade
Figure 21-12. High Voltage Cascade
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .PARAM—Global parameter setting.
• .OPTION—Simulator configuration.
• .TRAN—Transient analysis.
• .PLOT—Plot simulator results.
Netlist Explanation
high voltage cascade
.model dl1001 d rs=10 vj=0.8
The above line describes the electrical parameters of the diode model dl1001.
Tip
For a detailed description of each of these parameters, refer to the “Diode Model Syntax” in
the Eldo Reference Manual.
d1 1 2 dl1001
d2 2 3 dl1001
d3 3 4 dl1001
d4 4 5 dl1001
d5 5 6 dl1001
c1 2 0 cap1
c2 1 3 cap1
c3 2 4 cap1
c4 3 5 cap1
c5 4 6 cap1
c6 5 0 cap2
vin 0 1 sin(0 2500 50k 0 0)
The above line defines a sinusoidal function between the nodes 1 and 0, with a starting
amplitude of 2500V and a frequency of 50kHz.
.param cap1=1n cap2=10n
Eldo® User's Manual, 15.3 1287

Examples
Example 6—Transient Analysis of a High Voltage Cascade
The above line defines the global parameters cap1 and cap2 that are used in the capacitor and
diode definitions to be 1nF and 10nF respectively.
.option reltol=0.01 vmax=100000 vmin=-100000
The above line sets the relative accuracy to a value of 0.01 and output voltage limits between
100,000 and -100,000V due to the high voltage levels present in this circuit.
.tran 0.5m 5m
The above line specifies that a transient analysis should be performed on the circuit lasting 5ms
with a plotting increment for the line printer of 0.5ms.
.plot tran v(5)
.plot tran v(1)
The above lines specify voltage/time plots to be performed on separate graphs of the voltages at
nodes 5 and 1.
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Simulation Results
Examples
Example 6—Transient Analysis of a High Voltage Cascade
Figure 21-13. Example 6—Simulation Results 1
The following shows a zoom of the results between zero and 600 μs.
Eldo® User's Manual, 15.3 1289

Examples
Example 7—Monte Carlo Analysis Basic
Figure 21-14. Example 6—Simulation Results 2
Example 7—Monte Carlo Analysis Basic
Netlist file: monte_carlo_basic.cir
This example deals with Monte Carlo analysis on a non-inverting amplifier circuit. A specified
number of simulation runs are carried out to see the effect on the circuit of changing component
values within a specified range during each simulation run. Upper and lower limits of the
outputs are then displayed by Eldo at the end of the simulation.
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Eldo® User's Manual, 15.3

Figure 21-15. Non-inverting Amplifier
Examples
Example 7—Monte Carlo Analysis Basic
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .OPTION—Simulator configuration.
• .AC—AC analysis.
• .MC—Monte Carlo analysis.
• .PLOT—Plot simulator results.
Netlist Explanation
.model modres res lot=50% dev=60%
The above line specifies the Monte Carlo parameter limits for resistor model type modres. It
indicates that for each Monte Carlo run the resistor values can change together by as much as
50% (lot tolerance). Additionally, the resistor values are allowed to change independently of
each other by as much as 60% (dev tolerance). As can be seen below, the interval of variations
is more important on the resistor r2 than on r1.
r1 5 3 modres 100k
r2 5 0 modres 1k
c1 3 0 1p
The above lines give the information of the resistors and capacitors that are present in the circuit
to be simulated. Listed is the component name, the nodes between which the component is
connected and the value of the component.
Note
The resistors are also defined to be of model type modres. This is to specify Monte Carlo
parameter limits for the resistors during the simulation runs.
Eldo® User's Manual, 15.3 1291

Examples
Example 7—Monte Carlo Analysis Basic
yopa opamp2 pin: 2 5 3 0 param: p1=1e3 p2=5e8 gain=5000
vin1 2 0 ac
.ac dec 30 1.0 100meg
.option eps=1.0e-6
.mc 500
The above lines indicate that an AC analysis should be performed on the circuit within the
frequency range 1Hz to 100MHz with 30 steps per decade. 500 Monte Carlo simulation runs
are carried out.
.print ac vdb(3)
.plot ac vdb(3)(-40,60)
.plot ac vp(3) (0,-90)
.end
A dB/frequency plot of the voltage at node 3 is requested, together with a phase/frequency plot
at the same node.
The plotted output results on the voltage at node 3 contain nominal simulation results without
any change in the circuit values, together with highest and lowest deviation results over the
simulation runs.
Tip
For more information on Monte Carlo analysis, refer to “Monte Carlo Analysis” on
page 265.
1292
Eldo® User's Manual, 15.3

Examples
Example 8—DC Sensitivity of a Bipolar Amplifier
Simulation Results
Figure 21-16. Example 7—Simulation Results
Example 8—DC Sensitivity of a Bipolar
Amplifier
Netlist file: dc_sensitivity.cir
This example deals with a DC sensitivity analysis on the output of a simple bipolar amplifier
circuit. The results show us which DC components have the most effect on the output of the
circuit if they were to be changed.
Eldo® User's Manual, 15.3 1293

Examples
Example 8—DC Sensitivity of a Bipolar Amplifier
Figure 21-17. Bipolar Amplifier
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .SENS—DC sensitivity analysis.
Tip
See “.SENS” in the Eldo Reference Manual.
Netlist Explanation
.sens v(4)
The above line indicates that a DC sensitivity analysis should be performed showing the relative
sensitivities that the DC components have on the voltage on node 4, the output node of the
amplifier. The results are listed in the dc_sensitivity.chi file.
The results of the sensitivity analysis, found in the dc_sensitivity.chi file, are listed in
Figure 21-18.
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Eldo® User's Manual, 15.3

Simulation Results
Examples
Example 9—Transient and AC Analysis of a Switched Capacitor Low Pass Filter
Figure 21-18. Example 8—Simulation Results
Referring to the above results, the element sensitivity is the change in the output of interest (in
this case the voltage at node 4) due to a one unit change in the value of the element of interest
(for example r1) and the normalized sensitivity is the change in the output of interest due to a
one percent change in the value of the element of interest.
Looking at the sensitivity output in normalized sensitivity (volts/percent), it can be seen that the
output at node 4 is most sensitive to the voltage source v2 and also to the bf parameter in q1. As
a result, variation in these values causes a significant effect on the output voltage.
Example 9—Transient and AC Analysis of a
Switched Capacitor Low Pass Filter
Netlist file: tran_ac_switched.cir
This example deals with the transient and small signal AC analysis of an SC low pass filter
using the Z-domain switched capacitor macromodels. Notice the periodic AC response.
Summary of Eldo commands used in this example:
• .AC—AC analysis.
• .TRAN—Transient analysis.
Eldo® User's Manual, 15.3 1295

Examples
Example 9—Transient and AC Analysis of a Switched Capacitor Low Pass Filter
• .PLOT—Plot simulator results.
Netlist Explanation
.param ts = 1.000000e-05
The above line specifies the sampling period used in the integrator instances.
.subckt sc_int inp inm out
y1 sc_ideal inp inm out
y2 sc_u inm out param: c=c tp=tp
.ends sc_int
The above lines indicate the switched capacitor integrator subcircuit definition. The subcircuit
is called sc_int and is connected between the nodes inp, inm and out.
* INTEGRATOR 1
xi01 0 501 1 SC_INT c=5.173415p tp=ts
y002 sc_n pin: 2 0 501 0 param: c=1.347451p tp=ts
y003 sc_n pin: INPUT 0 501 0 param: c=1.623277p tp=ts
y004 sc_n pin: 1 0 501 0 param: c=1.000000p tp=ts
* INTEGRATOR 2
xi05 0 502 2 sc_int c=5.839726p tp=ts
y006 sc_i pin: 1 0 502 0 param: c=1.232076p tp=ts ldi=2
y007 sc_i pin: 3 0 502 0 param: c=1.000000p tp=ts ldi=2
* INTEGRATOR 3
xi08 0 503 3 sc_int c=4.117249p tp=ts
y009 sc_n pin: 2 0 503 0 param: c=1.660161p tp=ts
y010 sc_n pin: 3 0 503 0 param: c=1.000000p tp=ts
.tran 1u 500u
.ac dec 500 100 1meg
The above lines specify that a transient analysis should be performed on the circuit lasting
500μs with a plotting increment of 1μs; and an AC analysis within the frequency range 100Hz
to 1MHz with 500 steps per decade.
.plot tran v(input)
.plot tran v(1)
.plot tran v(2)
.plot tran v(3)
The above lines specify that voltage/time plots should be performed on separate graphs of the
voltage at nodes input, 1, 2, and 3.
.plot ac vdb(1)
.plot ac vdb(2)
.plot ac vdb(3)
The above lines specify that dB/frequency plots of the nodes 1, 2 and 3 are requested on
separate graphs.
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Eldo® User's Manual, 15.3

Examples
Example 9—Transient and AC Analysis of a Switched Capacitor Low Pass Filter
The above lines specify that voltage/time plots should be performed on separate graphs of the
voltage at node 4 and the voltage at node 1.
vin input 0 dc 1.0 ac 1.0 pwl(0.0 0.0 10n 1.0)
The above line defines an AC source of 1V and a time dependent Piece Wise Linear function
between the nodes input and 0. The pwl parameters describe a signal that stays at 0V until 10ns
where it rises to 1V.
Simulation Results
Figure 21-19. Example 9—Simulation Results—AC
Eldo® User's Manual, 15.3 1297

Examples
Example 10—Transient Analysis of a Switched Capacitor Schmitt Trigger
Figure 21-20. Example 9—Simulation Results—Transient
Example 10—Transient Analysis of a Switched
Capacitor Schmitt Trigger
Netlist file: tran_sc_trigger.cir
This example deals with a transient analysis of an switched capacitor Schmitt trigger circuit,
using an operational amplifier and switch macromodels.
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .TRAN—Transient analysis.
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Eldo® User's Manual, 15.3

Examples
Example 11—Loop Stability of an Opamp
Simulation Results
Figure 21-21. Example 10—Simulation Results
Example 11—Loop Stability of an Opamp
Netlist file: loop_stability_opamp.cir
This example shows usage of the Loop Stability analysis (.LSTB).
Summary of Eldo commands used in this example:
• .LSTB—Loop Stability analysis.
Netlist Explanation
XM2 M2D OUTL COM COM N W=0.8U L=0.6U
VSTB OUTL OUT
The above lines specify that node OUT is split into nodes OUT and OUTL, and inserts the
VSTB source.
Eldo® User's Manual, 15.3 1299

Examples
Example 11—Loop Stability of an Opamp
.PARAM pCX=0.2P
CX M8D OUT pCX ! COMPENSATION CAP.
CL OUT 0 1p ! LOAD CAP.
The above lines specify the circuit has a capacitive load, and a compensation capacitor is set so
that phase margin is approx. 45°.
.OPTION tuning=vhigh
The above line sets the simulator accuracy to very high.
VDD VDD 0 1.65V
VSS VSS 0 -1.65V
VB BIAS 0 0.95V
VINP INP 0 AC 1 0
The above lines specify the power supplies, bias, and input.
.ac dec 10 1 1e8
The above line indicates that an AC analysis is performed on the circuit within the frequency
range 1Hz to 100MHz with 10 steps per decade.
.LSTB VSTB
The above line indicates that a loop stability analysis is performed on the circuit.
.plot ac lstb_db
.plot ac lstb_p
The above lines request the loop stability output plots of loop gain and phase.
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Eldo® User's Manual, 15.3

Examples
Example 12—Overshoot Extraction of an Opamp
Simulation Results
Figure 21-22. Example 11—Simulation Results
Example 12—Overshoot Extraction of an
Opamp
Netlist file: extract_overshoot_opamp.cir
This example shows how to plot and extract the overshoot of an opamp connected in follower
configuration. The various extracted metrics are printed to a tabular output file.
Summary of Eldo commands used in this example:
• .TRAN—Transient analysis.
• .EXTRACT—Extract characteristics from the simulator results.
• .PRINTFILE—Print simulator results in tabular format.
Eldo® User's Manual, 15.3 1301

Examples
Example 12—Overshoot Extraction of an Opamp
Netlist Explanation
.PARAM pCX=0.2P
CX M8D OUT pCX ! COMPENSATION CAP.
CL OUT 0 1p ! LOAD CAP.
The above lines specifies the circuit has a capacitive load, and a compensation capacitor is set
so that phase margin is approx. 45°.
.CONNECT INN OUT
The above line specifies the opamp is connected in follower configuration.
.OPTION tuning=vhigh
The above line sets the simulator accuracy to very high.
.tran 1n 1000n
The above line specifies that a transient analysis should be performed on the circuit lasting
1000ns with a plotting increment of 1ns.
VDD VDD 0 1.65V
VSS VSS 0 -1.65V
VB BIAS 0 0.95V
VINP INP 0 PULSE -0.9 0.9 10n 1n 1n 500n 1000n
The above lines specify the power supplies, bias, and transient input (a step function on the
positive input).
.PLOT TRAN V(INP) V(OUT)
The above lines request voltage plots of the input and output signals.
.EXTRACT TRAN LABEL=povershoot abs((MAX(V(OUT)) - 0.9)/0.9)*100
.EXTRACT TRAN LABEL=novershoot abs((MIN(V(OUT)) + 0.9)/0.9)*100
The above lines extract the overshoot in as a percentage.
.OPTION numdgt=3
.PRINTFILE TRAN extract(povershoot) extract(novershoot)
+ file=opamp_overshoot.txt
The .PRINTFILE statement is used to print results in tabular format to an ASCII file,
opamp_overshoot.txt. The measurements from the .EXTRACT statements are printed to the
file. The NUMDGT option is specified to limit the number of decimals used when printing
numbers.
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Eldo® User's Manual, 15.3

Simulation Results
Examples
Example 13—Transient Analysis of a 5th Order Elliptic SC Low Pass Filter
Figure 21-23. Example 12—Simulation Results
The extracted metrics in the generated ASCII file are as follows:
# TEMPERATURE = 2.700000e+01
# X MEAS(POVERSHOOT) MEAS(NOVERSHOOT)
0.000e+00 2.080e+01 3.962e+00
Example 13—Transient Analysis of a 5th Order
Elliptic SC Low Pass Filter
Netlist file: tran_switched_filter.cir
This example deals with a transient analysis on a 5th order elliptic low pass filter using opamp
and switched capacitor macromodels. This type of circuit is used in those applications requiring
the analysis of sampled data in analog circuits, being used in certain ADC/DAC and switched
capacitor filter designs. This shows a typical simulation to illustrate time domain analysis of
switched capacitor filters.
Summary of Eldo commands used in this example:
Eldo® User's Manual, 15.3 1303

Examples
Example 14—Charge Conservation in MOS Models
• .MODEL—Model definition.
• .TRAN—Transient analysis.
• .PLOT—Plot simulator results.
Simulation Results
Figure 21-24. Example 13—Simulation Results
Example 14—Charge Conservation in
MOS Models
Netlist file: mos_charge_conservation.cir
This example illustrates charge conservation issues that can occur with old device models such
as a Berkeley level 3 MOS model, compared to a Berkeley BSIM3 MOS model. A transient
analysis simulation is performed on the MOS circuit, illustrating the differences in model
performance.
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Eldo® User's Manual, 15.3

Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .TRAN—Transient analysis.
• .PLOT—Plot simulator results.
Netlist Explanation
.MODEL M3 NMOS LEVEL=3 VTO=0.25V TOX=2.5N UO=600
Examples
Example 14—Charge Conservation in MOS Models
The above line describes the electrical parameters of the nmos model M3. This is an old level 3
model that does not conserve charge properly.
.MODEL M53 NMOS LEVEL=53 VTH0=0.25V TOX=2.5N U0=600
The above line describes the electrical parameters of the nmos model M53. This is a BSIM3
model, that conserves charge.
Simulation Results
In the simulation waveforms in Figure 21-25, V(3) is the result of the charge control model and
V(1) is the result of the capacitive model. For V(1) the error on the charge is accumulated and
error is increasing at each period. However, for V(3) there is no error on the charges.
Eldo® User's Manual, 15.3 1305

Examples
Example 15—AC Analysis of an Active RC Band Pass Filter
Figure 21-25. Example 14—Simulation Results
Example 15—AC Analysis of an Active RC
Band Pass Filter
Netlist file: ac_pcb_ua741.cir
This example deals with the AC analysis of an active RC band pass filter circuit containing a
standard discrete UA741 operational amplifier. This example is a typical PCB example.
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .SUBCKT—Subcircuit definition.
• .AC—AC analysis.
• .PLOT—Plot simulator results.
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Eldo® User's Manual, 15.3

Examples
Example 16—Transient Analysis of an Integrator
Simulation Results
Figure 21-26. Example 15—Simulation Results
Example 16—Transient Analysis of an
Integrator
Netlist file: tran_integrator.cir
This example deals with the transient analysis of a second order delta sigma modulator circuit.
A simple integrator, using analog macromodels (ideal switches, comparator, nand gates, and so
on). Eldo provides a rich library of analog, digital, and switched capacitor macromodels, which
can be useful for system simulations. All these macromodels are described in the Eldo
Reference Manual. Transient analysis is performed to obtain the time domain response.
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .TRAN—Transient analysis.
Eldo® User's Manual, 15.3 1307

Examples
Example 16—Transient Analysis of an Integrator
• .PLOT—Plot simulator results.
Netlist Explanation
compdiff ism isp voutp voutn vhi = 2.5 vlo = -2.5 tcom = 0.0n tpd = 0.0n
The above line specifies a comparator.
sl1 phi voutn memn switch
sl2 phi voutp memp switch
nand1 memp qu qubar vhi = 2.5 vlo = -2.5 tpd = 0.0n vthi = 0.1 vtlo = -0.1
nand2 memn qubar qu vhi = 2.5 vlo = -2.5 tpd = 0.0n vthi = 0.1 vtlo = -0.1
The above lines specify a latch.
delayn qubar compb 81.3802n
delayp qu comp 81.3802n
The above lines specify a delay.
vin1 inp 0 sin(0 0.5 12.288k 0 0)
vin2 inm 0 sin(0 -0.5 12.288k 0 0)
vphib phib 0 PWL 0 -5 41.6901n -5 42.6901n 5 79.3802n 5 80.3802n -5
81.3802n -5 R
vphi phi 0 PWL 0 5 40.6901n 5 41.6901n -5 80.3802n -5 81.3802n 5
The above lines specify the voltage source inputs.
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Eldo® User's Manual, 15.3

Simulation Results
Examples
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier
Figure 21-27. Example 16—Simulation Results
Example 17—Monte Carlo Sensitivity of a Two-
Stage Operational Amplifier
Netlist file: monte_carlo_sensitivity.cir
This example demonstrates the Monte Carlo sensitivity feature of Eldo. At the end of the Monte
Carlo analysis (.MC command) Eldo computes sensitivity values. These quantities are sorted by
decreasing order and help understanding which statistical variables have the most influence on
the output metrics. See the tables at the very end of the output .chi file.
Summary of Eldo commands used in this example:
• .MODEL—Model definition.
• .AC—AC analysis.
Eldo® User's Manual, 15.3 1309

Examples
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier
• .MC—Monte Carlo analysis.
• .EXTRACT—Extract characteristics from the simulator results.
• .PLOT—Plot simulator results.
Netlist Explanation
.EXTRACT AC LABEL=MAX MAX(VDB(OUT))
.EXTRACT AC LABEL=BW 'CROSSING(VDB(OUT), -3) / 10E6'
.PLOT AC VDB(OUT)
.EXTRACT DC LABEL=IVDD I(VDD)
The above lines specify the outputs. The output metrics are the maximum value of the closed
loop response, the -3dB bandwidth, and the power consumption. The Monte Carlo sensitivity
analysis enables understanding which statistical parameters are impacting these output
quantities, and which ones are not. The different metrics are not necessarily affected by the
same statistical variables, so Eldo provides one table per metric.
.MC 1000
The Monte Carlo analysis is run with NRUN=1000 to obtain very accurate estimations of the
sensitivity indices Si. Results are extracted for the IVDD extract.
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Eldo® User's Manual, 15.3

Examples
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier
0**** EXTRACT DISTRIBUTION TEMPERATURE = 27.000 DEG C
:
:0*****************************************************************************************
*
:
:
:
:
:Distribution of MAX
: Range [ 7.0368E-01 9.6618E-01]
: Number of runs: 1000
: Nominal value: 8.3817E-01
: Average value: 8.3912E-01
Standard Deviation: 4.1165E-02 ( 4.9%)
Standard Deviation based on nominal run: 4.1176E-02 ( 4.9%)
[ 700.00000M 727.50000M] NB = 2 FREQ = 0.2% |
[ 727.50000M 755.00000M] NB = 20 FREQ = 2% |*
[ 755.00000M 782.50000M] NB = 73 FREQ = 7.3% |***
[ 782.50000M 810.00000M] NB = 136 FREQ = 13.6% |******
[ 810.00000M 837.50000M] NB = 266 FREQ = 26.6% |*************
[ 837.50000M 865.00000M] NB = 242 FREQ = 24.2% |************
[ 865.00000M 892.50000M] NB = 161 FREQ = 16.1% |********
[ 892.50000M 920.00000M] NB = 74 FREQ = 7.4% |***
[ 920.00000M 947.50000M] NB = 23 FREQ = 2.3% |*
[ 947.50000M 975.00000M] NB = 3 FREQ = 0.3% |
Bootstrap Confidence Interval for MAX
[--------- Average Value ---------] [------- Standard Deviation ------]
Level LeftLimit Estimate RightLimit LeftLimit Estimate RightLimit
95.0000% 8.3639E-01 8.3912E-01 8.4143E-01 3.9649E-02 4.1185E-02 4.2947E-02
99.0000% 8.3603E-01 8.3912E-01 8.4261E-01 3.8779E-02 4.1185E-02 4.3632E-02
99.9000% 8.3599E-01 8.3912E-01 8.4352E-01 3.8388E-02 4.1185E-02 4.3770E-02
99.9900% 8.3599E-01 8.3912E-01 8.4352E-01 3.8388E-02 4.1185E-02 4.3770E-02
99.9990% 8.3599E-01 8.3912E-01 8.4352E-01 3.8388E-02 4.1185E-02 4.3770E-02
Distribution of BW
Range [ 2.1341E+00 2.2592E+00]
Number of runs: 1000
Nominal value: 2.1966E+00
Average value: 2.1962E+00
Standard Deviation: 2.0633E-02 ( 0.9%)
Standard Deviation based on nominal run: 2.0636E-02 ( 0.9%)
[ 2.13400 2.14660 ] NB = 5 FREQ = 0.5% |
[ 2.14660 2.15920 ] NB = 33 FREQ = 3.3% |*
[ 2.15920 2.17180 ] NB = 78 FREQ = 7.8% |***
[ 2.17180 2.18440 ] NB = 175 FREQ = 17.5% |********
[ 2.18440 2.19700 ] NB = 232 FREQ = 23.2% |***********
[ 2.19700 2.20960 ] NB = 205 FREQ = 20.5% |**********
[ 2.20960 2.22220 ] NB = 167 FREQ = 16.7% |********
[ 2.22220 2.23480 ] NB = 79 FREQ = 7.9% |***
[ 2.23480 2.24740 ] NB = 19 FREQ = 1.9% |
[ 2.24740 2.26000 ] NB = 7 FREQ = 0.7% |
Bootstrap Confidence Interval for BW
Eldo® User's Manual, 15.3 1311

Examples
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier
[--------- Average Value ---------] [------- Standard Deviation ------]
Level LeftLimit Estimate RightLimit LeftLimit Estimate RightLimit
95.0000% 2.1946E+00 2.1962E+00 2.1975E+00 1.9857E-02 2.0643E-02 2.1572E-02
99.0000% 2.1943E+00 2.1962E+00 2.1978E+00 1.9498E-02 2.0643E-02 2.1925E-02
99.9000% 2.1943E+00 2.1962E+00 2.1978E+00 1.9470E-02 2.0643E-02 2.1995E-02
99.9900% 2.1943E+00 2.1962E+00 2.1978E+00 1.9470E-02 2.0643E-02 2.1995E-02
99.9990% 2.1943E+00 2.1962E+00 2.1978E+00 1.9470E-02 2.0643E-02 2.1995E-02
Distribution of IVDD
Range [-5.6906E-05 -5.1855E-05]
Number of runs: 1000
Nominal value: -5.4433E-05
Average value: -5.4406E-05
Standard Deviation: 8.0321E-07 ( 1.5%)
Standard Deviation based on nominal run: 8.0368E-07 ( 1.5%)
[ -56.92000U -56.41200U ] NB = 5 FREQ = 0.5% |
[ -56.41200U -55.90400U ] NB = 23 FREQ = 2.3% |*
[ -55.90400U -55.39600U ] NB = 90 FREQ = 9% |****
[ -55.39600U -54.88800U ] NB = 148 FREQ = 14.8% |*******
[ -54.88800U -54.38000U ] NB = 248 FREQ = 24.8% |************
[ -54.38000U -53.87200U ] NB = 227 FREQ = 22.7% |***********
[ -53.87200U -53.36400U ] NB = 166 FREQ = 16.6% |********
[ -53.36400U -52.85600U ] NB = 67 FREQ = 6.7% |***
[ -52.85600U -52.34800U ] NB = 20 FREQ = 2% |*
[ -52.34800U -51.84000U ] NB = 6 FREQ = 0.6% |
Bootstrap Confidence Interval for IVDD
[--------- Average Value ---------] [------- Standard Deviation ------]
Level LeftLimit Estimate RightLimit LeftLimit Estimate RightLimit
95.0000% -5.4454E-05 -5.4406E-05 -5.4357E-05 7.7032E-07 8.0361E-07 8.4200E-07
99.0000% -5.4483E-05 -5.4406E-05 -5.4322E-05 7.6075E-07 8.0361E-07 8.4942E-07
99.9000% -5.4497E-05 -5.4406E-05 -5.4314E-05 7.6073E-07 8.0361E-07 8.5248E-07
99.9900% -5.4497E-05 -5.4406E-05 -5.4314E-05 7.6073E-07 8.0361E-07 8.5248E-07
99.9990% -5.4497E-05 -5.4406E-05 -5.4314E-05 7.6073E-07 8.0361E-07 8.5248E-07
Estimation of Sensitivity Indices for Response Y : MAX
Mode of Computation : fast
Number of Runs : 1001
Number of Random Variables : 51
List of Important Parameters :
Index(I) Histo S(I) (percent / cumulative) Variable
Value
Name
11 |-------------------- 14.69% 14.69% EM(XM13.M1,VTH0)
17 |-------------- 10.69% 25.37% EM(XM12.M1,VTH0)
35 |------------- 9.95% 35.32% EM(XM9.M1,VTH0)
12 |------------- 9.95% 45.27% EM(XM13.M1,U0)
18 |------------ 8.90% 54.18% EM(XM12.M1,U0)
30 |---------- 7.78% 61.95% EM(XM1.M1,U0)
1312
Eldo® User's Manual, 15.3

Examples
Example 17—Monte Carlo Sensitivity of a Two-Stage Operational Amplifier
48 |-------- 6.36% 68.31% EM(XM8.M1,U0)
36 |------- 5.81% 74.12% EM(XM9.M1,U0)
45 |------- 5.33% 79.45% EM(XM7.M1,U0)
28 |----- 4.11% 83.56% EM(XM1.M1,TOX)
51 |---- 3.47% 87.03% EM(XM10.M1,U0)
26 |---- 3.28% 90.32% EM(XM11.M1,VTH0)
27 |---- 3.07% 93.39% EM(XM11.M1,U0)
33 |---- 2.95% 96.34% EM(XM2.M1,U0)
8 |--- 2.49% 98.83% EM(XM15.M1,VTH0)
44 |--- 2.45% 101.28% EM(XM7.M1,VTH0)
24 |--- 2.23% 103.51% EM(XM4.M1,U0)
49 |-- 1.97% 105.48% EM(XM10.M1,TOX)
Estimation of Sensitivity Indices for Response Y : BW
Mode of Computation : fast
Number of Runs : 1001
Number of Random Variables : 51
List of Important Parameters :
Index(I) Histo S(I) (percent / cumulative) Variable
Value
Name
45 |-------------------- 12.22% 12.22% EM(XM7.M1,U0)
35 |------------------ 11.47% 23.69% EM(XM9.M1,VTH0)
5 |------------------ 11.22% 34.91% EM(XM17.M1,VTH0)
48 |----------------- 10.87% 45.78% EM(XM8.M1,U0)
3 |--------------- 9.54% 55.33% EM(XM16.M1,U0)
2 |--------------- 9.52% 64.85% EM(XM16.M1,VTH0)
36 |--------- 5.57% 70.42% EM(XM9.M1,U0)
30 |------- 4.82% 75.25% EM(XM1.M1,U0)
44 |------- 4.53% 79.77% EM(XM7.M1,VTH0)
33 |------ 4.05% 83.82% EM(XM2.M1,U0)
6 |------ 3.95% 87.77% EM(XM17.M1,U0)
47 |------ 3.75% 91.52% EM(XM8.M1,VTH0)
31 |----- 3.35% 94.86% EM(XM2.M1,TOX)
4 |---- 2.61% 97.48% EM(XM17.M1,TOX)
46 |---- 2.50% 99.98% EM(XM8.M1,TOX)
Estimation of Sensitivity Indices for Response Y : IVDD
Mode of Computation : fast
Number of Runs : 1001
Number of Random Variables : 51
List of Important Parameters :
Index(I) Histo S(I) (percent / cumulative) Variable
Value
Name
5 |-------------------- 20.30% 20.30% EM(XM17.M1,VTH0)
2 |----------------- 17.60% 37.90% EM(XM16.M1,VTH0)
3 |------------- 13.84% 51.74% EM(XM16.M1,U0)
11 |------------- 13.59% 65.34% EM(XM13.M1,VTH0)
12 |---------- 11.14% 76.48% EM(XM13.M1,U0)
Eldo® User's Manual, 15.3 1313

Examples
Example 18—Numerical Integration: TRAP versus GEAR
18 |------- 8.11% 84.59% EM(XM12.M1,U0)
6 |------- 7.21% 91.80% EM(XM17.M1,U0)
17 |---- 4.52% 96.32% EM(XM12.M1,VTH0)
27 |--- 3.92% 100.24% EM(XM11.M1,U0)
4 |-- 2.43% 102.67% EM(XM17.M1,TOX)
10 |-- 2.41% 105.08% EM(XM13.M1,TOX)
15 |- 1.50% 106.58% EM(XM14.M1,U0)
26 |- 1.46% 108.04% EM(XM11.M1,VTH0)
1 |- 1.42% 109.46% EM(XM16.M1,TOX)
Simulation Results
Figure 21-28. Example 17—Simulation Results
Example 18—Numerical Integration: TRAP
versus GEAR
Netlist file: trap_vs_gear.cir
This example compares the TRAP method with the GEAR method. The default TRAP method
sometimes causes “numerical ringing” (non-physical oscillations) centered on the correct
1314
Eldo® User's Manual, 15.3

Examples
Example 18—Numerical Integration: TRAP versus GEAR
average value. Sometimes even high accuracy and limitation of the timestep cannot totally
prevent these numerical oscillations. In these cases, switching to the GEAR method is a possible
remedy.
Summary of Eldo commands used in this example:
• .ALTER—Simulation rerun.
Netlist Explanation
.alter
.option gear
The above lines rerun the same simulation using GEAR method instead of the default TRAP
method.
Simulation Results
Figure 21-29. Example 18—Simulation Results
Eldo® User's Manual, 15.3 1315

Examples
Example 19—DC Mismatch Comparison with Monte Carlo Analysis
Example 19—DC Mismatch Comparison with
Monte Carlo Analysis
Netlist file: dcmismatch_contributors.cir
This example shows how to use the DCMISMATCH analysis, and compares its results to an
equivalent Monte Carlo analysis. You can refer to the .chi output file and look for the
DCMISMATCH and Monte Carlo results respectively.
Particularly, from the DCMISMATCH results, devices M1 and M2 are primarily responsible
for the output offset distribution, whereas M17 and M16 have the greatest impact on power
consumption.
These results are confirmed by the fully non-linear .MC sensitivity analysis. You can also refer
to the example dcmismatch_vs_mcsens.cir which shows how to compare the results of the two
analyses using some simple ECL (Eldo Control Language) code.
Summary of Eldo commands used in this example:
• .DCMISMATCH—DC mismatch analysis.
• .MC—Monte Carlo analysis.
• .ALTER—Simulation rerun.
• .EXTRACT—Extract characteristics from the simulator results.
Netlist Explanation
.EXTRACT DC LABEL=offset v(out)
The above line specifies to extract the output offset voltage.
.EXTRACT DC LABEL=power -i(vdd)*v(vdd)
The above line specifies to extract the DC power consumption.
.alter
.DCMISMATCH nsigma=1
.extract dc label= dcm_offset dcm(offset)
.extract dc label= dcm_power dcm(power)
The above lines rerun the same simulation using a DC mismatch analysis.
.alter
.mc 10000
.extract mc label=mc_offset mcstd(offset)
.extract mc label=mc_power mcstd(power)
The above lines rerun the same simulation using a Monte Carlo analysis. The Monte Carlo
sensitivity is run automatically.
1316
Eldo® User's Manual, 15.3

Simulation Results
Examples
Example 19—DC Mismatch Comparison with Monte Carlo Analysis
Figure 21-30. Example 19—Simulation Results
Results Comparison
The extracted information from the DCMISMATCH results are as follows:
* OFFSET = -3.5800E-04 Volts
* POWER = 8.7764E-05 Watt
* DCM_OFFSET = 6.0338E-03 Volts
* DCM_POWER = 1.2859E-06
The extracted information from the Monte Carlo results are as follows:
* MC_OFFSET = 6.0033E-03
* MC_POWER = 1.2706E-06
Comparing the results shows the DCMISMATCH analysis and equivalent Monte Carlo analysis
generate similar offset and power results.
DCMISMATCH Results
The full DCMISMATCH results are as follows:
Eldo® User's Manual, 15.3 1317

Examples
Example 19—DC Mismatch Comparison with Monte Carlo Analysis
#.DCMISMATCH OFFSET SORT_REL = 1.000000e-03 NSIGMA = 1.000000e+00
:
:Analysis results:
:
:Output DC value : -3.5800E-04 Volts
:Total output deviation
: +/- 6.0338E-03 Volts
:Output deviation due to the
:contributors in the report table : +/- 6.0338E-03 Volts
:
:
:
:Report table
:----------------------------------------
:
: Output deviation Contributor Parameter
: 2.9358E-03 XM1.M1
: 1.4441E-03 EM(XM1.M1,U0)
: 2.5196E-03 EM(XM1.M1,VTH0)
: 4.2981E-04 EM(XM1.M1,TOX)
: 2.9345E-03 XM2.M1
: 1.4422E-03 EM(XM2.M1,U0)
: 2.5191E-03 EM(XM2.M1,VTH0)
: 4.3088E-04 EM(XM2.M1,TOX)
2.4853E-03
XM3.M1
1.7981E-03
EM(XM3.M1,U0)
1.6560E-03
EM(XM3.M1,VTH0)
4.4819E-04
EM(XM3.M1,TOX)
2.4439E-03
XM4.M1
1.7683E-03
EM(XM4.M1,U0)
1.6284E-03
EM(XM4.M1,VTH0)
4.4077E-04
EM(XM4.M1,TOX)
1.8849E-03
XM8.M1
1.0858E-03
EM(XM8.M1,U0)
1.4633E-03
EM(XM8.M1,VTH0)
4.8214E-04
EM(XM8.M1,TOX)
1.8585E-03
XM7.M1
1.0708E-03
EM(XM7.M1,U0)
1.4429E-03
EM(XM7.M1,VTH0)
4.7476E-04
EM(XM7.M1,TOX)
...
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Examples
Example 19—DC Mismatch Comparison with Monte Carlo Analysis
#.DCMISMATCH POWER SORT_REL = 1.000000e-03 NSIGMA = 1.000000e+00
Analysis results:
Output DC value : 8.7764E-05 Watt
Total output deviation
: +/- 1.2859E-06 Watt
Output deviation due to the
contributors in the report table : +/- 1.2859E-06 Watt
Report table
----------------------------------------
Output deviation Contributor Parameter
7.0194E-07
XM17.M1
3.9387E-07
EM(XM17.M1,U0)
5.5264E-07
EM(XM17.M1,VTH0)
1.7937E-07
EM(XM17.M1,TOX)
7.0148E-07
XM16.M1
4.9576E-07
EM(XM16.M1,U0)
4.8544E-07
EM(XM16.M1,VTH0)
1.0313E-07
EM(XM16.M1,TOX)
6.1591E-07
XM13.M1
3.5212E-07
EM(XM13.M1,U0)
4.8175E-07
EM(XM13.M1,VTH0)
1.5256E-07
EM(XM13.M1,TOX)
4.5102E-07
XM12.M1
3.2720E-07
EM(XM12.M1,U0)
3.0011E-07
EM(XM12.M1,VTH0)
7.9330E-08
EM(XM12.M1,TOX)
2.5028E-07
XM11.M1
1.8945E-07
EM(XM11.M1,U0)
1.6110E-07
EM(XM11.M1,VTH0)
2.8193E-08
EM(XM11.M1,TOX)
1.0420E-07
XM15.M1
5.9224E-08
EM(XM15.M1,U0)
8.1720E-08
EM(XM15.M1,VTH0)
2.5943E-08
EM(XM15.M1,TOX)
...
Monte Carlo Results
The full Monte Carlo results are as follows:
Eldo® User's Manual, 15.3 1319

Examples
Example 19—DC Mismatch Comparison with Monte Carlo Analysis
Distribution of OFFSET
Range [-2.6290E-02 2.2602E-02] Volts
Number of runs: 10000
Nominal value: -3.5800E-04 Volts
Average value: -3.0223E-04 Volts
Standard Deviation: 6.0033E-03 Volts (1986.4%)
Standard Deviation based on nominal run: 6.0036E-03 Volts (1677.0%)
[ -26.37500M -21.47500M ] NB = 1 FREQ = 0.01% |
[ -21.47500M -16.57500M ] NB = 32 FREQ = 0.32% |
[ -16.57500M -11.67500M ] NB = 250 FREQ = 2.5% |*
[ -11.67500M -6.77500M ] NB = 1126 FREQ = 11.3% |*****
[ -6.77500M -1.87500M ] NB = 2560 FREQ = 25.6% |************
[ -1.87500M 3.02500M ] NB = 3084 FREQ = 30.8% |***************
[ 3.02500M 7.92500M ] NB = 2115 FREQ = 21.1% |**********
[ 7.92500M 12.82500M ] NB = 687 FREQ = 6.87% |***
[ 12.82500M 17.72500M ] NB = 122 FREQ = 1.22% |
[ 17.72500M 22.62500M ] NB = 23 FREQ = 0.23% |
Bootstrap Confidence Interval for OFFSET
[--------- Average Value -------] [------- Standard Deviation ----]
Level LeftLimit Estimate RightLimit LeftLimit Estimate RightLimit
95.0000% -4.1870E-04 -3.0223E-04 -1.9015E-04 5.9270E-03 6.0036E-03 6.1124E-03
99.0000% -4.4216E-04 -3.0223E-04 -1.6089E-04 5.9184E-03 6.0036E-03 6.1277E-03
99.9000% -4.5041E-04 -3.0223E-04 -1.6023E-04 5.9115E-03 6.0036E-03 6.1304E-03
99.9900% -4.5041E-04 -3.0223E-04 -1.6023E-04 5.9115E-03 6.0036E-03 6.1304E-03
99.9990% -4.5041E-04 -3.0223E-04 -1.6023E-04 5.9115E-03 6.0036E-03 6.1304E-03
Distribution of POWER
Range [ 8.2877E-05 9.2169E-05] Watt
Number of runs: 10000
Nominal value: 8.7764E-05 Watt
Average value: 8.7786E-05 Watt
Standard Deviation: 1.2706E-06 Watt ( 1.4%)
Standard Deviation based on nominal run: 1.2708E-06 Watt ( 1.4%)
[ 82.75000U 83.70000U ] NB = 6 FREQ = 0.06% |
[ 83.70000U 84.65000U ] NB = 52 FREQ = 0.52% |
[ 84.65000U 85.60000U ] NB = 356 FREQ = 3.56% |*
[ 85.60000U 86.55000U ] NB = 1276 FREQ = 12.8% |******
[ 86.55000U 87.50000U ] NB = 2359 FREQ = 23.6% |***********
[ 87.50000U 88.45000U ] NB = 2977 FREQ = 29.8% |**************
[ 88.45000U 89.40000U ] NB = 1952 FREQ = 19.5% |*********
[ 89.40000U 90.35000U ] NB = 811 FREQ = 8.11% |****
[ 90.35000U 91.30000U ] NB = 176 FREQ = 1.76% |
[ 91.30000U 92.25000U ] NB = 35 FREQ = 0.35% |
Bootstrap Confidence Interval for POWER
[-------- Average Value --------] [------- Standard Deviation ------]
Level LeftLimit Estimate RightLimit LeftLimit Estimate RightLimit
95.0000% 8.7765E-05 8.7786E-05 8.7812E-05 1.2543E-06 1.2706E-06 1.2895E-06
99.0000% 8.7753E-05 8.7786E-05 8.7820E-05 1.2500E-06 1.2706E-06 1.2947E-06
99.9000% 8.7744E-05 8.7786E-05 8.7823E-05 1.2498E-06 1.2706E-06 1.2962E-06
99.9900% 8.7744E-05 8.7786E-05 8.7823E-05 1.2498E-06 1.2706E-06 1.2962E-06
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Examples
Example 19—DC Mismatch Comparison with Monte Carlo Analysis
99.9990% 8.7744E-05 8.7786E-05 8.7823E-05 1.2498E-06 1.2706E-06 1.2962E-06
1***** 9-Nov-2012 ************* ELDO 12.2 alpha1 (v7.8_1.1) **************17:06:53*******
02-STAGES OPAMP
0**** EXTRACT INFORMATION
0**** TEMPERATURE = 2.7000E+01 Celsius
0**** ICARLO = 10000
0**** ALTER index 2
0******************************************************************************************
* MC_OFFSET = 6.0033E-03
* MC_POWER = 1.2706E-06
Estimation of Sensitivity Indices for Response Y : OFFSET
Mode of Computation : fast
Number of Runs : 10001
Number of Random Variables : 51
List of Important Parameters :
Index(I) Histo S(I) (percent / cumulative) Variable
Value
Name
29 |-------------------- 17.62% 17.62% EM(XM1.M1,VTH0)
32 |------------------- 16.86% 34.47% EM(XM2.M1,VTH0)
24 |---------- 9.27% 43.75% EM(XM4.M1,U0)
21 |---------- 8.89% 52.64% EM(XM3.M1,U0)
23 |-------- 7.34% 59.98% EM(XM4.M1,VTH0)
20 |------- 6.62% 66.60% EM(XM3.M1,VTH0)
30 |------ 6.04% 72.64% EM(XM1.M1,U0)
33 |------ 5.82% 78.46% EM(XM2.M1,U0)
47 |------ 5.65% 84.11% EM(XM8.M1,VTH0)
44 |------ 5.40% 89.51% EM(XM7.M1,VTH0)
48 |--- 3.49% 93.00% EM(XM8.M1,U0)
45 |--- 3.22% 96.22% EM(XM7.M1,U0)
46 | 0.78% 97.00% EM(XM8.M1,TOX)
31 | 0.71% 97.71% EM(XM2.M1,TOX)
19 | 0.62% 98.33% EM(XM3.M1,TOX)
43 | 0.61% 98.94% EM(XM7.M1,TOX)
28 | 0.58% 99.52% EM(XM1.M1,TOX)
22 | 0.51% 100.03% EM(XM4.M1,TOX)
39 | 0.17% 100.20% EM(XM5.M1,U0)
4 | 0.13% 100.32% EM(XM17.M1,TOX)
13 | 0.12% 100.44% EM(XM14.M1,TOX)
Estimation of Sensitivity Indices for Response Y : POWER
Mode of Computation : fast
Number of Runs : 10001
Number of Random Variables : 51
List of Important Parameters :
Index(I) Histo S(I) ( percent / cumulative) Variable
Value
Name
5 |-------------------- 18.92% 18.92% EM(XM17.M1,VTH0)
3 |-------------- 14.16% 33.08% EM(XM16.M1,U0)
2 |-------------- 13.94% 47.02% EM(XM16.M1,VTH0)
11 |-------------- 13.89% 60.92% EM(XM13.M1,VTH0)
Eldo® User's Manual, 15.3 1321

Examples
Example 20—DC Mismatch Comparison with Monte Carlo Analysis using ECL
6 |--------- 8.92% 69.84% EM(XM17.M1,U0)
12 |-------- 8.07% 77.90% EM(XM13.M1,U0)
18 |------- 6.66% 84.56% EM(XM12.M1,U0)
17 |----- 5.57% 90.14% EM(XM12.M1,VTH0)
4 |-- 2.16% 92.30% EM(XM17.M1,TOX)
27 |-- 2.06% 94.36% EM(XM11.M1,U0)
10 |- 1.45% 95.80% EM(XM13.M1,TOX)
26 |- 1.36% 97.17% EM(XM11.M1,VTH0)
1 | 0.57% 97.73% EM(XM16.M1,TOX)
16 | 0.33% 98.06% EM(XM12.M1,TOX)
8 | 0.19% 98.25% EM(XM15.M1,VTH0)
24 | 0.18% 98.43% EM(XM4.M1,U0)
20 | 0.15% 98.58% EM(XM3.M1,VTH0)
21 | 0.14% 98.72% EM(XM3.M1,U0)
25 | 0.13% 98.85% EM(XM11.M1,TOX)
19 | 0.13% 98.98% EM(XM3.M1,TOX)
Example 20—DC Mismatch Comparison with
Monte Carlo Analysis using ECL
Netlist file: dcmismatch_vs_mcsens.cir
This example shows how to use the DCMISMATCH analysis, and compares its results to an
equivalent Monte Carlo analysis. It uses some ECL code to present the results in a compact
format (this is written to the standard output).
Please refer to the Eldo Control Language chapter and the ../examples/ecl directory for more
ECL examples.
Summary of Eldo commands used in this example:
• .DCMISMATCH—DC mismatch analysis.
• .MC—Monte Carlo analysis.
• .EXTRACT—Extract characteristics from the simulator results.
• Eldo Control Language.
Netlist Explanation
The netlist is similar to the previous example, except that the Eldo Control Language is used to
run the simulations and extract the results in a compact format.
.define_testbench dcm()
.DCMISMATCH nsigma=1
.extract dc label= dcm_offset dcm(offset)
.extract dc label= dcm_power dcm(power)
.end_define_testbench
The above lines define the testbench to be used for the DCMISMATCH analysis including the
information to be extracted.
1322
Eldo® User's Manual, 15.3

Examples
Example 20—DC Mismatch Comparison with Monte Carlo Analysis using ECL
.define_testbench _mc(nb_mc_run=10)
.mc nb_mc_run
.extract mc label=mc_offset mcstd(offset)
.extract mc label=mc_power mcstd(power)
.end_define_testbench
The above lines define the testbench to be used for the Monte Carlo analysis including
information to be extracted.
.define_task run()
set dcm_offset=0
set dcm_power=0
set mc_offset=0
set mc_power=0
simulation( dcm(), dcm_power=@dcm_power, dcm_offset= @dcm_offset )
simulation( _mc(nb_mc_run=500), mc_power=@mc_power, mc_offset=
@mc_offset )
The above lines define the task to be used for the DCMISMATCH and Monte Carlo analyses.
fprint(stdout, "\nThis is an ECL-controlled simulation, comparing the
global results of DCMISMATCH and MONTECARLO.\n")
fprint(stdout, "The values reported below are the 1-sigma estimates of
the offset and power quantities, as estimated with both methods.\n\n")
fprint(stdout, "DC mismatch : offset : %e\n", dcm_offset)
fprint(stdout, "DC mismatch : power : %e\n", dcm_power)
fprint(stdout, "Monte Carlo : offset : %e\n", mc_offset)
fprint(stdout, "Monte Carlo : power : %e\n", mc_power)
.end_define_task
The above lines specify the printing of the extracted results in a custom format.
.run
The above line executes the previously defined task named run.
Simulation Results
This is an ECL-controlled simulation, comparing the global results of
DCMISMATCH and MONTECARLO.
The values reported below are the 1-sigma estimates of the offset and
power quantities, as estimated with both methods.
DC mismatch : offset : 6.033827e-03
DC mismatch : power : 1.285868e-06
Monte Carlo : offset : 6.071414e-03
Monte Carlo : power : 1.278497e-06
Eldo® User's Manual, 15.3 1323

Examples
Example 21—Post-Layout Simulation using DSPF
Example 21—Post-Layout Simulation using
DSPF
Netlist file: dspf_backannotation.cir
Additional files: dspf_opamp_follower.dspf and ./dspf_opamp_follower.models/lib.eldo.
This example shows how to import a .dspf file containing layout parasitics. Using .ALTER
statements, several simulations with different degrees of backannotation can be overlapped and
compared. The circuit is a 2-stage opamp, connected in follower mode.
Summary of Eldo commands used in this example:
• .LIB—Library file.
• .DSPF_INCLUDE—DSPF file inclusion.
• .ALTER—Simulation rerun.
Netlist Explanation
.LIB key=MOS
.LIB key=MOS_33
./dspf_opamp_follower.models/lib.eldo TT
./dspf_opamp_follower.models/lib.eldo TT_33
The above lines define the location of the model libraries to be included.
Vin IP GROUND DC 0V PULSE -0.6 0.6 10n 1n 1n 250n 500n
The above line specifies the opamp is connected with the positive input (IP) driven with a pulsetype
signal.
.tran 1n 500n
The above specifies a transient analysis is to be performed lasting 500ns with a plotting
increment of 1ns.
.option eps=1e-8 hmax=1n
The above line specifies a high accuracy is required to catch the details of the overshoot
waveform.
.PROBE I V
The above line specifies all current and voltage signals to be probed.
.plot tran v(ip) v(op)
The above line specifies that voltage/time plots should be performed of the input and output
voltages at nodes ip and op respectively.
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Examples
Example 21—Post-Layout Simulation using DSPF
.alter
.DSPF_INCLUDE FILE=./dspf_opamp_follower.dspf DEV=DSPF
+ LEVEL=C
The nominal run is the pre-layout reference. The first .alter statement above runs the same
simulation, but this time using post-layout information from the dspf_opamp_follower.dspf
DSPF file (extracted from the opamp GDSII layout with Mentor Calibre xRC). Specifying
DEV=DSPF means that we also use the Instance section of the .dspf file. The instance section
basically contains the intentional devices (the MOS devices in this case). As the LEVEL is set
to C, only the grounded capacitors are taken into account (more precisely, the compound
capacitors indicated with the *|NET statements in the .dspf file are included). In this example
there are 9 such capacitors. The output waveform V(OP) is slightly degraded (slower and less
stable) compared to the pre-layout reference.
.alter
.DSPF_INCLUDE FILE=./dspf_opamp_follower.dspf DEV=DSPF
+ LEVEL=RCC
+ RMINVAL=0.1 CCMINVAL=0.001f
In the second .alter statement the command is specified with a different filtering. As the LEVEL
is set to RCC, the full DPSF content is used (all resistors, coupling and grounded capacitors).
However we apply some clamping to the values of the resistors and coupling capacitors. All
resistors smaller than 0.1 Ohm are ignored (shorted), and all coupling capacitors smaller than
0.001fF are ignored. The output waveform V(OP) is marginally different compared to the
previous case.
Notice the notes that are generated relating to the replacement of nodes in the original netlist by
DSPF networks:
Note 70: Node X_OPAMP1.DIFFP has been replaced by a DSPF network.
Note 70: Node X_OPAMP1.DIFFN has been replaced by a DSPF network.
Note 70: Node X_OPAMP1.CURMIR has been replaced by a DSPF network.
Eldo® User's Manual, 15.3 1325

Examples
Example 21—Post-Layout Simulation using DSPF
Simulation Results
Figure 21-31. Example 21—Simulation Results 1
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Examples
Example 22—Extract Gain and Phase Margin of a 2-Stage Opamp
Figure 21-32. Example 21—Simulation Results Zoom
Example 22—Extract Gain and Phase Margin
of a 2-Stage Opamp
Netlist file: gain_phase_margins.cir
This example shows how to extract the gain and phase margin for an opamp. The opamp is
configured in open loop. The gain and phase margins are extracted in two different ways, to
illustrate the capabilities of the .EXTRACT statements and functions.
• The bandwidth is plotted versus the phase margin. With EZwave, open the
gain_phase_margins.swd file.
• The various extracted metrics are printed to a tabular output file.
The simulation is stepped using the compensation capacitor as the parameter. The gain and
phase margin quantities are automatically plotted versus the compensation capacitor value.
Summary of Eldo commands used in this example:
Eldo® User's Manual, 15.3 1327

Examples
Example 22—Extract Gain and Phase Margin of a 2-Stage Opamp
• .EXTRACT—Extract characteristics from the simulator results.
• .PARAM—Global parameter setting.
• .STEP—Sweeping parameters.
Netlist Explanation
.param pCX=0.2p
.step param pCX DEC 10 0.01p 1p
The .STEP statement is used to observe the impact of the compensation capacitance upon
stability. The .EXTRACT quantities (see below) such as phase and margins are automatically
plotted versus the swept parameter, pCX.
.option nobound_phase
The nobound_phase option can be used if you prefer a continuous phase plot. By default the
phase plots are displayed modulo 360.
.AC DEC 1000 1 100E6
The above specifies a .AC statement to sweep the frequency from 1Hz to 100MHz.
.PLOT AC VDB(OUT)
.PLOT AC VP(OUT)
The above lines specify that the output response is plotted in Bode format.
.EXTRACT AC LABEL=MAX MAX(VDB(OUT))
The above line specifies to extract the open loop gain.
.EXTRACT AC LABEL=bandwidth 'CROSSING(VDB(OUT), -3)'
The above line specifies to extract the 3db bandwidth.
.EXTRACT ac label=phase_margin_1 {180 + xycond(vp(OUT), vdb(OUT) == 0)}
.EXTRACT ac label=gain_margin_1 -xycond(vdb(OUT), vp(OUT) < -180)
The above lines show the first compact method to extract the Gain and Phase margins, using the
XYCOND() function.
.EXTRACT AC label=unit_gain_freq crossing(vdb(OUT), 0)
.EXTRACT AC label=phase_margin_2 180 - yval(vp(OUT), 1) + yval( vp(OUT),
unit_gain_freq )
.EXTRACT AC label=opp_phase_freq crossing(vp(OUT), -180)
.EXTRACT AC label=gain_margin_2 -yval(vdb(OUT), opp_phase_freq)
The above lines show the second method to extract the Gain and Phase margins, using explicit
extraction of the zero-crossing and -180°-crossing frequencies.
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Examples
Example 22—Extract Gain and Phase Margin of a 2-Stage Opamp
.plot extract extract(bandwidth) (versus) extract(phase_margin_2)
The above line specifies to plot “compromise” graphs. For example, as the compensation
capacitance is swept, you can view the bandwidth versus the phase margin.
.option numdgt=3
.printfile AC meas(*) file=opamp_margins.txt
The .PRINTFILE statement is used to print results in tabular format to an ASCII file,
opamp_margins.txt. The measurements from all the .EXTRACT statements are printed to the
file. The NUMDGT option is specified to limit the number of decimals used when printing
numbers.
Simulation Results
Figure 21-33. Example 22—Simulation Results 1
Eldo® User's Manual, 15.3 1329

Examples
Example 22—Extract Gain and Phase Margin of a 2-Stage Opamp
Figure 21-34. Example 22—Simulation Results 2
The following is the tabular format output generated in the ASCII file, opamp_margins.txt:
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Examples
Example 23—Parametric Sensitivity Analysis
# PARAM PCX = 1.000000e-14
:# TEMPERATURE = 2.700000e+01
:# X MEAS(MAX) MEAS(BANDWIDTH) MEAS(PHASE_MARGIN_1) MEAS(GAIN_MARGIN_1) MEAS(UNIT_GAIN_FREQ)
MEAS(PHASE_MARGIN_2) MEAS(OPP_PHASE_FREQ) MEAS(GAIN_MARGIN_2)
:1.000e-14 7.239e+01 5.542e+07 4.868e+00 3.995e+00 4.648e+07 4.869e+00 5.873e+07 3.995e+00
:
:
:# PARAM PCX = 1.258925e-14
:# TEMPERATURE = 2.700000e+01
:# X MEAS(MAX) MEAS(BANDWIDTH) MEAS(PHASE_MARGIN_1) MEAS(GAIN_MARGIN_1) MEAS(UNIT_GAIN_FREQ)
MEAS(PHASE_MARGIN_2) MEAS(OPP_PHASE_FREQ) MEAS(GAIN_MARGIN_2)
:1.259e-14 7.239e+01 5.320e+07 6.736e+00 5.175e+00 4.456e+07 6.737e+00 6.042e+07 5.175e+00
:
:
:# PARAM PCX = 1.584893e-14
:# TEMPERATURE = 2.700000e+01
:# X MEAS(MAX) MEAS(BANDWIDTH) MEAS(PHASE_MARGIN_1) MEAS(GAIN_MARGIN_1) MEAS(UNIT_GAIN_FREQ)
MEAS(PHASE_MARGIN_2) MEAS(OPP_PHASE_FREQ) MEAS(GAIN_MARGIN_2)
:1.585e-14 7.239e+01 5.071e+07 8.906e+00 6.381e+00 4.241e+07 8.907e+00 6.187e+07 6.381e+00
:
:
:# PARAM PCX = 1.995262e-14
:# TEMPERATURE = 2.700000e+01
:# X MEAS(MAX) MEAS(BANDWIDTH) MEAS(PHASE_MARGIN_1) MEAS(GAIN_MARGIN_1) MEAS(UNIT_GAIN_FREQ)
MEAS(PHASE_MARGIN_2) MEAS(OPP_PHASE_FREQ) MEAS(GAIN_MARGIN_2)
:1.995e-14 7.239e+01 4.797e+07 1.140e+01 7.594e+00 4.003e+07 1.140e+01 6.297e+07 7.594e+00
:
:
:# PARAM PCX = 2.511886e-14
:# TEMPERATURE = 2.700000e+01
:# X MEAS(MAX) MEAS(BANDWIDTH) MEAS(PHASE_MARGIN_1) MEAS(GAIN_MARGIN_1) MEAS(UNIT_GAIN_FREQ)
MEAS(PHASE_MARGIN_2) MEAS(OPP_PHASE_FREQ) MEAS(GAIN_MARGIN_2)
2.512e-14 7.239e+01 4.501e+07 1.423e+01 8.791e+00 3.746e+07 1.423e+01 6.360e+07 8.791e+00
# PARAM PCX = 3.162278e-14
# TEMPERATURE = 2.700000e+01
# X MEAS(MAX) MEAS(BANDWIDTH) MEAS(PHASE_MARGIN_1) MEAS(GAIN_MARGIN_1) MEAS(UNIT_GAIN_FREQ)
MEAS(PHASE_MARGIN_2) MEAS(OPP_PHASE_FREQ) MEAS(GAIN_MARGIN_2)
3.162e-14 7.239e+01 4.187e+07 1.741e+01 9.952e+00 3.472e+07 1.742e+01 6.369e+07 9.952e+00
...
...
Example 23—Parametric Sensitivity Analysis
Netlist file: sensitivity_parametric.cir
This example shows how to use the .SENSPARAM analysis. This parametric sensitivity
analysis computes the sensitivity of the output metrics (all the .EXTRACT statements) to
selected subcircuit parameters. The example is an opamp whose MOS geometries are
parameterized. A transient analysis is setup to compute the relative overshoot of the output
signal (the opamp is connected in voltage follower configuration, and driven with a pulse type
Eldo® User's Manual, 15.3 1331

Examples
Example 23—Parametric Sensitivity Analysis
signal). The .SENSPARAM command computes the absolute and relative sensitivities of the
overshoot to the MOS geometries (see .SENSPARAM statement in this netlist).
Notice that .SENSPARAM is a “brute force” sensitivity analysis (it uses simple numerical
differences) and thus is less efficient as the duration of the analysis and/or the number of
parameters increase, but is applicable to any type of circuit and analyses.
Note
The circuit in this example is similar to that in Example 21—Post-Layout Simulation using
DSPF.
Summary of Eldo commands used in this example:
• .LIB—Library file.
• .SENSPARAM—Parametric sensitivity analysis.
• .EXTRACT—Extract characteristics from the simulator results.
Netlist Explanation
.LIB key=MOS
.LIB key=MOS_33
./dspf_opamp_follower.models/lib.eldo TT
./dspf_opamp_follower.models/lib.eldo TT_33
The above lines define the location of the model libraries to be included.
Vin IP GROUND DC 0V PULSE -0.6 0.6 10n 1n 1n 250n 500n
The above line specifies the opamp is connected with the positive input (IP) driven with a pulsetype
signal.
.tran 1n 500n
The above specifies a transient analysis is to be performed lasting 500ns with a plotting
increment of 1ns.
.option eps=1e-8 hmax=1n simudiv=0
The above line specifies a high accuracy is required to catch the details of the overshoot
waveform.
.PROBE I V
The above line specifies all current and voltage signals to be probed.
.plot tran v(ip) v(op)
The above line specifies that voltage/time plots should be performed of the input and output
voltages at nodes ip and op respectively.
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Examples
Example 23—Parametric Sensitivity Analysis
.extract tran label=overshoot (max(v(op)) - 0.6) / 0.6 * 100
The above line specifies to extract the relative overshoot value.
.sensparam subckt=opamp inst=x_opamp1 param=w1,w2,w4,w5,w7 sort=dec
variation=1%
The .SENSPARAM statement triggers computation of the sensitivities of the .EXTRACT
quantities to parameters “w1,w2,w4,w5 and w7” of instance “x_opamp1.” The results are
presented in decreasing order, and the increment used for sensitivity calculation is 1%. The
results appear in the table at the end of the output .chi file.
Simulation Results
Figure 21-35. Example 23—Simulation Results
The following are the parametric sensitivity analysis results, in decreasing order:
Eldo® User's Manual, 15.3 1333

Examples
Example 24—Cell Characterization: Setup Time Extraction
* OVERSHOOT NOM: 6.9442E+00
*| Absolute Relative Parameter Parameter Parameter
*| Sensitivity Sensitivity (%/%) Nominal Value Variation Name
*| 1.7559E+06 2.5286E+00 1.00000e-05 1.000e+00% X_OPAMP1.W4
*| -9.2694E+05 -1.3348E+00 1.00000e-05 1.000e+00% X_OPAMP1.W5
*| 9.0192E+04 2.5976E-01 2.00000e-05 1.000e+00% X_OPAMP1.W1
*| -9.1152E+04 -1.5752E-01 1.20000e-05 1.000e+00% X_OPAMP1.W7
*| 3.6566E+04 1.3164E-01 2.50000e-05 1.000e+00% X_OPAMP1.W2
Example 24—Cell Characterization: Setup
Time Extraction
Netlist file: extract_setup_time_passfail.cir
This example shows how to extract the setup time of a D-type flip-flop, using the pass-fail
method of the built-in optimizer in Eldo. This example contains lots of comments to explain the
simulation commands.
Summary of Eldo commands used in this example:
• .OPTIMIZE—Optimize circuit parameters.
• .PARAMOPT—Specifies the optimizer design variables.
• .EXTRACT—Extract characteristics from the simulator results.
Netlist Explanation
xdff out nout in ck nr vss vdd dspc_ff
The above line defines the circuit, a simple flip-flop.
.param tck=20n
.param trf=0.1n
vnr nr 0 pwl 0 ps 1n 0 2n 0 3n ps
vin in 0 pwl 0 0 'tck-ts' 0 'tck-ts+trf' ps
vck ck 0 pwl 0 ps 'tck' ps 'tck+trf' 0
The above lines specify the parameterized input signals, specifically the IN input and the CK
input.
.tran 1n 100n
The above specifies a transient analysis is to be performed lasting 100ns with a plotting
increment of 1ns.
.option eps=2e-8
The above line specifies a tightened accuracy to measure delays in picoseconds. Note that this
value for EPS triggers a (normal) warning 382, stating that the value is unusually small.
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Examples
Example 24—Cell Characterization: Setup Time Extraction
.option mtfile
The above line forces the creation of a .mt0 file, where the final values of all measurements
(including ts) can be read (view extract_setup_time_passfail.mt0).
.plot tran v(in) v(ck) v(out)
The above line specifies that voltage/time plots should be performed of the inputs and output
voltages at nodes in, ck and out respectively.
.extract tran label=tp (xup(v(out), 'ps/2', 0n, 100n, 1) - xdown(v(ck),
'ps/2', 0n, 100n, 1))
The above line specifies to extract the tp variable, which is the delay between the clock edge
and the output signal edge.
.optimize method=passfail results=tp relin=0.001
.paramopt ts=(1n, -5n, 5n)
The above lines specify the .OPTIMIZE command is used with the passfail method. The goal is
the tp variable, and the variable to optimize is ts (the setup time)
The command is very compact and requires further explanation:
The parameter to optimize is defined with the .PARAMOPT statement: it is the value of the
setup time ts (see the VIN source definition). If the edge of the IN signal occurs early enough,
the flip-flop will be able to sample the input data. If it is too late (too close to the clock edge),
the flip-flop will not be able to sample the data and the output will not switch. The purpose of
the setup time extraction is to find the exact transition between these two behaviors, using a
dichotomy algorithm on the input optimization variable (tin in this example). A dichotomy
algorithm find a solution by dividing in half the search interval at each iteration.
As in any numerical root-finding algorithm, it is very important to feed the command with
initial values that 'bracket' the solution. Eldo will start anyway by verifying that the lowest value
corresponds to a 'pass', and the highest value corresponds to a 'fail' situation (you can easily see
this if you look into the standard output of the simulation). In this example, we use the interval
[-5n 5n] for the initial bracketing of 'ts'. If the edge happens at tck-5n, we are sure that the setup
time will be respected, and it will thus be a 'pass'. If it only happens at tck+5n (well after the
clock edge) we are sure that the setup time will be violated and thus the flip-flop will 'fail' (the
output will not toggle).
To minimize the number of iterations, it is of course desirable to use an initial bracketing
interval that is as narrow as possible. This requires a priori knowledge of the circuit, and needs
to be indicated by the user, Eldo cannot completely 'guess' it.
The iterations will find the value of the parameter to 'optimize', that is 'ts', which corresponds to
the transition from 'pass' to 'fail'. The 'ts' value that corresponds to this pass/fail transition is
nothing but the desired setup time.
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Examples
Example 24—Cell Characterization: Setup Time Extraction
The 'relin' optional parameter on the .optimize command specifies the required relative accuracy
on the optimization variable (directly 'ts' in this example). The default value is 0.001 (0.1%).
In this example, the dichotomy will converge in about 10 iterations, and yield a setup time of
136ps.
Be careful that using unreasonable accuracy may lead to numerous iterations. Also note that the
simulation accuracy itself (as defined with the .option eps=) has to be consistent with the
required optimization accuracy. There is no point asking for 0.01% accuracy on the setup time if
the simulations are only 1-5% accurate because you use a very loose eps value.
Simulation Results
Figure 21-36. Example 24—Simulation Results
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Examples
Example 25—Setting up and Handling Analog Busses
Figure 21-37. Example 24—Simulation Results Zoom
The following are the final values of all measurements (including ts) generated in ASCII file
extract_setup_time_passfail.mt0:
$DATA1 SOURCE='ELDO' VERSION='ELDO 12.1 engr1'
.TITLE 'setup time extraction'
index ts tp temper alter#
1.0000 -5.000e-09 failed 27.0000 1.0000
1.0000 1.270e-10 2.167e-10 27.0000 1.0000
Example 25—Setting up and Handling Analog
Busses
Netlist file: sigbus_plotbus.cir
This example is a 4-bit CMOS adder. One of the inputs is generated with a .SIGBUS command.
Eldo has some provisions to handle busses and thus simplify notation issues throughout the
netlist. For example, you can easily define busses, plot them, use digital patterns to define their
values if they are input signals, check them against their expected values, and so on.
Eldo® User's Manual, 15.3 1337

Examples
Example 25—Setting up and Handling Analog Busses
Tip
Refer to the .SIGBUS, .PLOTBUS, .SETBUS, and .CHECKBUS commands in the Eldo
Reference Manual.
Summary of Eldo commands used in this example:
• .INCLUDE—Library file.
• .SETBUS—Create a bus.
• .SIGBUS—Set signals on a bus.
• .PLOTBUS—Plot bits of a bus.
• .CHECKBUS—Check bus values.
Netlist Explanation
.include bsim46.lib
The above line includes the contents of the library file bsim46.lib in the netlist.
.SETBUS A A
The above line defines a bus A as the vector a.
.SIGBUS A
+ vhi=ps vlo=0
+ base=dec signed=2comp
+ trise=trf tfall=trf thold=per
+ pattern 1 3 5 4 0 -2 -5 2 3 5 6 -1
The A input bus is generated using a .SIGBUS command with the following:
• The bits of the bus toggle between vlo and vhi.
• The rise/fall times and period are defined with trise, tfall and thold.
• The bus values will be given in decimal, and the coding will be in 2’s complement.
• Finally the successive values of the bus are given with the pattern keyword.
.SETBUS B B
.SETBUS S S
The above lines define busses B and S:
.PLOTBUS A VTH=0.6 BASE=DEC RADIX=2COMP
.PLOTBUS B VTH=0.6 BASE=DEC RADIX=2COMP
.PLOTBUS S VTH=0.6 BASE=DEC RADIX=2COMP
The above lines plot the busses, using half/vdd as the threshold, in decimal notation.
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Examples
Example 26—Spectre Compatibility Example
.PLOT TRAN V(S)
.PLOT TRAN V(S)
.PLOT TRAN V(S)
.PLOT TRAN V(S)
The above lines plot the individual bits of output bus S.
Simulation Results
Figure 21-38. Example 25—Simulation Results
Example 26—Spectre Compatibility Example
Netlist file: spectre_compatibility.scs
Additional file: ./spectre_compatibility.models.scs.lib
This example is a Spectre formatted netlist. You need to use the -sp command-line flag to
simulate this netlist with Eldo.
eldo -sp spectre_compatibility.scs
The .scs netlist and all included files are converted on-the-fly to Eldo native format and
simulated. You can check the converted input to Eldo in the .spectre_compatibility_input
directory.
Eldo® User's Manual, 15.3 1339

Examples
Example 27—Monte Carlo Analysis Autostop
Eldo supports most Spectre netlist constructs, but not all analyses and commands. For further
information refer to the topic “Spectre Compatibility” on page 179.
Summary of Eldo commands used in this example:
• Spectre compatibility.
Simulation Results
Figure 21-39. Example 26—Simulation Results
Example 27—Monte Carlo Analysis Autostop
Netlist file: monte_carlo_autostop.cir
This circuit illustrates the autostop feature of Monte Carlo analysis. Eldo can automatically stop
the MC simulation when a preset accuracy condition is met. This can be much more efficient
than setting an arbitrarily fixed number of runs. In this case we setup the analysis so that a
prescribed relative accuracy is reached for the standard deviation of the 3dB bandwidth of the
circuit (a simple opamp in follower mode). In this example, the process should stop after
approximately 800 samples.
Summary of Eldo commands used in this example:
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Examples
Example 27—Monte Carlo Analysis Autostop
• .AC—AC analysis.
• .MC—Monte Carlo analysis.
• .EXTRACT—Extract characteristics from the simulator results.
• .PLOT—Plot simulator results.
Netlist Explanation
.ac dec 1000 1e6 100e6
The above lines indicate that an AC analysis should be performed on the circuit within the
frequency range 1MHz to 100MHz with 1000 steps per decade.
.mc 2000 all nbbins=50 autostop=std_max_conv
The Monte Carlo command specifies 2000 runs as a hard stop. Eldo will add samples until the
autostop condition std_max_conv is met or the 2000 samples limit is reached. Parameter
nbbins=50 is used to obtain better histograms.
.extract ac label=bandwidth 'crossing(vdb(out), -3) / 10e6'
.extract ac label=max_gain max(vm(out))
.extract dc label=ivdd i(vdd)
The above lines extraction the metrics of interest: maximum gain (at overshoot) and 3dB
bandwidth.
.param stdev_confidence=0.95
.param stdev_abs_accuracy=0.00
.param stdev_rel_accuracy=0.05
The above parameters are passed to the mcconv function. The requirement is 5% relative
accuracy, with 95% confidence level.
.extract MC label=std_max_conv
+ mcconv(bandwidth, STD, CONFIDENCE, 50,
+ stdev_confidence, stdev_abs_accuracy, stdev_rel_accuracy)
+ visible=no
This extract is referenced as the austop condition in the .MC command. We look for 5% relative
accuracy on the standard deviation of bandwidth, with 95% confidence level. 50 pilot runs are
used to feed the CONFIDENCE algorithm.
.extract MC label=meanv_bandwidth_MEAN_VALUE
.extract MC label=stdev_bandwidth_CI_95p_INF
+ '(1-stdev_rel_accuracy) * mcstd(bandwidth)'
.extract MC label=stdev_bandwidth_ESTIMATION
.extract MC label=stdev_bandwidth_CI_95p_SUP
+ '(1+stdev_rel_accuracy) * mcstd(bandwidth)'
'mcavg(bandwidth)'
'mcstd(bandwidth)'
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Examples
Example 27—Monte Carlo Analysis Autostop
These additional extracts are simply used to display the standard deviation estimate, and the
lower/upper limits of the obtained confidence interval.
.plot ac vdb(out) vp(out)
A dB/frequency plot and phase/frequency plot of the voltage at node out are requested.
Tip
For more information on Monte Carlo analysis, refer to “Monte Carlo Analysis” on
page 265.
Simulation Results
Figure 21-40. Example 27—Simulation Results
The extract results of the standard deviation estimate, and the lower/upper limits of the obtained
confidence interval are as follows:
* MEANV_BANDWIDTH_MEAN_VALUE = 2.196
* STDEV_BANDWIDTH_CI_95P_INF = 19.500M
* STDEV_BANDWIDTH_ESTIMATION = 20.527M
* STDEV_BANDWIDTH_CI_95P_SUP = 21.553M
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Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
Tutorial—Using Power Analysis for Static
Leakage Analysis of a PLL Circuit
Netlist file: power_analysis/Power_Analysis_PLL.cir
In this tutorial you will use the Eldo power analysis to visualize the power consumption of a
PLL design and its components.
The tutorial demonstrates how to visualize the static leakage of a PLL. To do this, the VDD
supply is set to 1V with all other inputs set to 0V (see Figure 21-41), and then the power
consumption is checked.
Video
To watch this tutorial, see the video Power Analysis.
The following files are provided for this tutorial in the power_analysis directory:
• Power_Analysis_PLL.cir — Main Eldo netlist file. (The PLL circuit is encrypted.)
• PLL_UVM_SUBCKT.include.crypt — Encrypted subckt definitions.
• bsim46.corners.lib.crypt — Encrypted BSIM4 model file.
• dspc_cmos.lib.crypt — Encrypted subckt definitions.
Figure 21-41. PLL Circuit for Power Analysis
Eldo® User's Manual, 15.3 1343

Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
Prerequisites
• Copy the power_analysis example directory into your working directory by entering the
following UNIX shell command:
cp -r $MGC_AMS_HOME/examples/power_analysis .
Procedure
1. The Power_Analysis_PLL.cir main netlist file is delivered with the .power_analysis
command already specified. Run Eldo on the netlist:
eldo Power_Analysis_PLL.cir
2. After the simulation is complete, launch EZwave and open the generated output file
Power_Analysis_PLL.wdb:
ezwave Power_Analysis_PLL.wdb
In the Waveform List panel, expand the Power_Analysis_PLL root folder and you will
see two folders called POWER_TRAN and TRAN.
The POWER_TRAN folder contains all the necessary waveforms used by the Power
Analysis tool. The TRAN folder contains all the usual waveforms related to voltages/
currents.
3. Start the Power Analysis to identify which PLL components consume power. Expand
the POWER_TRAN/Power_Analysis_PLL folder, right-click the XPLL subfolder and
choose Power Analysis from the popup menu:
This opens the Power Analysis dialog box:
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Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
4. Click Analyze at the bottom of the dialog box. The Power Table field is populated with
the power consumption results from the design:
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Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
This shows each component of the PLL and the average consumption of each.
5. Click the Avg column header to re-order the power contributors from the largest
consumer to the smallest:
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Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
The Power Table displays a total average power consumption of 741μW for the entire
PLL design, with 173μW consumed by the XPD block, 166μW by the XTEST block,
and 141μW by the XLD block.
Click Close to close the Power Analysis dialog box.
6. Next we will refine the analysis to the PLL block XPD. From the EZwave Waveform
List panel, expand the XPLL folder, right-click on the XPD subfolder and choose Power
Analysis from the popup menu:
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Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
A new Power Analysis dialog box opens. Click Analyze to obtain the Power Table
results:
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Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
The color scaling range is set by default to the maximum average value for 100%
(173μW) and the minimum Average value for 0% (486pW). In our example, there are
multiple contributors around 10%, as indicated in the blue colors.
7. Edit the fields Max. Avg value and Min. Avg value (highlighted in yellow above),
changing them to 15u and 5u respectively, then press the Return key.
The Power Table results are updated. This helps you read the power map while reducing
the scaling range from 173μW to 10μW. The color map changes from all blue to
orange-green-blue enabling you to refine your search more easily.
Eldo® User's Manual, 15.3 1349

Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
8. You will now identify which active devices are the largest consumers for the XPD
block.
Click the List tab, the Power Table results are updated displaying the full names in the
Name column.
Right-click on the Mode column, uncheck All and choose MOS.
Click the Avg column to re-order the power contributors from the largest consumer to
the smallest. The Power Table results are updated, where you can easily see that MOS
transistor XPD.X12.M4 is the largest consumer with 11.71μW:
1350
Eldo® User's Manual, 15.3

Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
9. Select the XPD.X12.M4 MOS instance, right-click and select Plot from the popup
menu.
In EZwave, the waveform is plotted (you might need to move the Power Analysis
window to one side to show the waveform window). You can see the evolution of the
power consumed by the MOS transistor as a function of time.
Eldo® User's Manual, 15.3 1351

Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
You can observe the peak consumption occurs before 0.1μs, at around 50ns to be more
precise. In the next step, the power analysis is refined to this time window.
10. In the Power Analysis dialog box, edit the time window in the Analysis field by setting
X Start = 53.5n and X Stop = 55n, then press the Return key.
The Power Table automatically updates with the results shown (you might need to scroll
down to see the color coded results of interest):
1352
Eldo® User's Manual, 15.3

Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
You can see there are many entries without a color code, because the color scaling set in
step 7 does not match the results obtained now for the time window [53.5ns - 55ns].
11. Adjust these settings to the new results by editing the Color Scaling values. Set the Max.
Avg value field to 40μW and the Min. Avg value field to 1μW, then press the Return
key.
The Power Table results are updated, with more relevant color codes (compared to
above):
Eldo® User's Manual, 15.3 1353

Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
12. Next you will interactively update the Power Table results based on the time window
you adjusted from EZwave.
As we will interact with EZwave and visualize the power results in the Power Analysis
dialog box, it is recommended that you position both windows next to each other.
You may have noticed the Power Analysis tool has automatically displayed a new wave,
which represents the average power consumption for block XPD.
In EZwave, zoom in on the power peaks in order to obtain the display shown:
1354
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Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
13. In the bottom wave you can see two cursors, which indicate the Power Analysis range
set in step 10 (with time range 53.5ns - 55ns). Select the cursor on the left and drag it to
the right in order to reduce the Power Analysis time window. While doing so, you will
notice that the Power Analysis table automatically recomputes the power. Move the two
cursors in order to obtain a time range from 54.3ns to 55ns, then you will observe the
following results:
Eldo® User's Manual, 15.3 1355

Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
14. In this last part of the tutorial you will reduce the slope of the power supply ramp and
observe the impact of this change on the power consumption.
Edit the main netlist Power_Analysis_PLL.cir in your preferred text editor, and change
the value of the parameter trise (used by the VDD voltage source) from 1ps to 900ns, as
shown below (comment and uncomment the lines in the netlist accordingly):
*.param pvdd=1 trise=1p
.param pvdd=1 trise=900n
Because we want to primarily analyze the impact of this change on the XPD block,
refine the power analysis by updating the Eldo command with the following change to
filter on the name xpd (comment and uncomment the lines in the netlist accordingly):
*.power_analysis
.power_analysis filter(name)=xpd
15. Re-run Eldo and open the file Power_Analysis_PLL.wdb in EZwave. Repeat the actions
described in steps 3 and 4 to run a power analysis on the PLL design. You will obtain the
following result:
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Examples
Tutorial—Using Power Analysis for Static Leakage Analysis of a PLL Circuit
As shown, the Power Analysis tool has been automatically configured to filter the Name
column with the XPD block as specified in the SPICE netlist (.power_analysis
filter(name)=xpd).
The power consumption of block XPD has decreased from 173μW (see step 6) to
217nW (here) by reducing the slope of the power supply ramp from 1ps to 900ns.
Results
This tutorial showed how to use the Eldo .POWER_ANALYSIS command to visualize the
power consumption of a PLL design for the whole circuit and for the phase detector.
Eldo® User's Manual, 15.3 1357

Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
With the help of the EZwave Power Analysis tool, you have analyzed the power contribution
for MOS devices and then refined those for a specific time window, while observing the
instantaneous power at block level and device level.
Tip
See “.POWER_ANALYSIS” in the Eldo Reference Manual.
See “Analyzing Power Consumption” in the EZwave User’s and Reference Manual.
Tutorial—High Impedance Fault Detection of a
PLL Circuit
Netlist file: hiz/HiZ_PLL.cir
In this tutorial you will use the Eldo .HiZ commands to detect high impedance faults on a PLL
design and its components. You will gain familiarity with the HiZ configuration commands, the
impedance plots, and you will also use the AMS Results Browser to refine HiZ results.
The tutorial demonstrates how to detect “abnormal” high impedance values on the PLL input
control (see Figure 21-42 PLL input TPROG1), causing a PLL failure. You will then fix this
problem and use HiZ configurations to detect “expected” high impedance values on the Charge
Pump output (see Figure 21-42 PLL internal net INVCO).
Note
The PLL circuit in this tutorial is encrypted.
The following files are provided for this tutorial in the hiz directory:
• HiZ_PLL.cir — Main Eldo netlist file.
• PLL_UVM_SUBCKT.include.crypt — Encrypted subckt definitions.
• bsim46.corners.lib.crypt — Encrypted BSIM4 model file.
• dspc_cmos.lib.crypt — Encrypted subckt definitions.
• dspf_pll_v01.dspf — Parasitic information in DSPF for backannotation.
1358
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Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
Figure 21-42. PLL Circuit for HiZ Fault Detection
Prerequisites
• Copy the hiz example directory into your working directory by entering the following
UNIX shell command:
cp -r $MGC_AMS_HOME/examples/hiz .
Procedure
1. The HiZ_PLL.cir main netlist file contains a measurement of PLL output period labeled
PERIOD_PLL. In the first part of the lab (steps 1 to 5) the PLL is not working and
therefore its output (net OUT400M) is flat 0.
Run Eldo on the netlist:
eldo HiZ_PLL.cir
After the simulation is complete, you will see the following message at the end of the
simulation (in the terminal and in the ASCII .chi output file):
PERIOD_PLL cannot be measured. Check your input netlist.
The netlist already contains the .hiz command to generate HiZ detection for all the
nodes that exceed 1e8 ohms and stores them in a dedicated high impedance detection
file named HiZ_ALL.hiz. Command:
Eldo® User's Manual, 15.3 1359

Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
.hiz file=HiZ_ALL.hiz r=1e8
2. Open the HiZ_ALL.hiz file with the AMS Results Browser using the command:
amsrb HiZ_ALL.hiz
You will see a table of results, each row in the table displays information about a high
impedance detection:
3. Click twice on the Impedance Average column header (highlighted in yellow) to list
the results in decreasing order, then you will see the following:
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Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
4. From the table, it is easy to find out which nodes have the highest average impedance
values. The first instance in the list points to the PLL input control node TPROG1_1,
which is a subnode inserted through DSPF backannotation. In second and third positions
in the list are the gates of MOS transistors M1 and M2 instantiated within
XPLL.XTEST.XDUM1.
The figure below illustrates the backannotated node TPROG1, highlighted in red:
5. To find out why such a HiZ value is reported by Eldo, look at the contents of the DSPF
file dspf_pll_v01.dspf. There is a mistake in the parasitic values in the corresponding
DSPF section for net TPROG1:
Eldo® User's Manual, 15.3 1361

Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
*|NET TPROG1 1.221451e-14
*|I (XPLL.Xtest.Xdum1.M1.g XPLL.Xtest.Xdum1.M1 g I 0.0 10.0 10.0)
*|I (XPLL.Xtest.Xdum1.M2.g XPLL.Xtest.Xdum1.M2 g I 0.0 10.0 10.0)
*|S (TPROG1_1)
*|P (TPROG1 I )
C5 TPROG1 VSS 1.17763E-01PF
C6 TPROG1_1 VSS 2.76325E-01PF
C7 XPLL.Xtest.Xdum1.M1.g VSS 2.70519E-01PF
C8 XPLL.Xtest.Xdum1.M2.g VSS 2.70519E-01PF
R4 TPROG1 TPROG1_1 1.70333E20
R5 TPROG1_1 XPLL.Xtest.Xdum1.M1.g 1.29167E-01
R6 TPROG1_1 XPLL.Xtest.Xdum1.M2.g 1.29167E-01
The value of R4 has been set to 1.70333E20 Ω by mistake (see the line highlighted in
red). The value should be 1.70333E00 Ω, just like R1 for the backannotated node
TPROG0.
6. Edit the DSPF file dspf_pll_v01.dspf in your preferred text editor, change the value of
R4 from 1.70333E20 to 1.70333E00. Rerun the simulation in Eldo:
eldo HiZ_PLL.cir
Check the PLL output period labeled PERIOD_PLL which should be approximately
23ns. You should see the following message at the end of the simulation:
PERIOD_PLL = 2.2853E-08
7. Reopen the newly generated HiZ output file HiZ_ALL.hiz with the AMS Results
Browser and verify that node TPROG1 is no longer visible (default sort by instance
name):
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Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
8. We need to find which nodes have the highest impedance average value and identify if
this is expected or not. Filter the results in decreasing order to look at the biggest
contributor first; in the AMS Results Browser click twice on the Impedance Average
column to re-order the results:
Eldo® User's Manual, 15.3 1363

Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
You can see from the list (highlighted in yellow) several high impedance detections on
the same node, XPLL.XCPF.INVCO, but for different time windows.
9. To plot the evolution of this impedance with regards to the simulation time, edit the
main netlist file HiZ_PLL.cir in your preferred text editor, and uncomment the following
line in the netlist:
.plot tran IMP(xpll.xcpf.invco)
Add the following plot commands:
.plot tran V(xpll.down)
.plot tran V(xpll.up)
Rerun the simulation in Eldo:
eldo HiZ_PLL.cir
10. After the simulation is complete, launch EZwave and open the generated output file
HiZ_PLL.swd:
ezwave HiZ_PLL.swd
The following waveforms are displayed: IMP(XPLL.XCPF.INVCO),
V(XPLL.DOWN), V(XPLL.UP):
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Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
Observe the impedance of the charge pump output (in green). It goes into high
impedance state only when the charge pump input ports (UP in blue and DOWN in
yellow) are equal to zero.
The circuit schematic for the charge pump (highlighted in yellow) is shown below:
When UP=DOWN=0, both transistors M2R and M1R are turned OFF and therefore
their common node INVCO goes into high impedance state. This is the expected
behavior.
Eldo® User's Manual, 15.3 1365

Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
11. Create a HiZ configuration to filter out detection on the charge pump output and focus
our next analysis on the remaining PLL blocks. Edit the main netlist HiZ_PLL.cir in
your preferred text editor, and uncomment the following lines in the netlist:
.define_group name=without_xcpf inst=xpll except=xpll.xcpf
.end_group
.hiz_cfg name=cfg_withoutXCPF scope=without_xcpf
.hiz use_config=cfg_withoutXCPF file=hiz_withoutXCPF.hiz
The .define_group/.end_group commands create a group of instances/devices excluding
the block XPLL.XCPF, providing the group name without_XCPF.
The .hiz_cfg command creates a HiZ configuration named cfg_withoutXCPF that only
applies to the group defined above.
The .hiz command indicates that the high impedance checks will activate the
configuration you have created.
Remember to comment the previous .hiz command (step 1 in the netlist), otherwise there
will be two .hiz commands used simultaneously which is not allowed by Eldo.
12. Rerun the simulation in Eldo:
eldo HiZ_PLL.cir
After the simulation is complete, open the HiZ output file hiz_withoutXCPF.hiz with the
AMS Results Browser and explore the results.
amsrb hiz_withoutXCPF.hiz
Click twice on the Impedance Average column to re-order the results by decreasing
Impedance average value:
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Examples
Tutorial—High Impedance Fault Detection of a PLL Circuit
Looking at these results, the highest detection reported points to the node
XPLL.XLD.XCNT.XD00.X2.XC.X.
13. Plot the impedance of this node (in a similar way to step 9) and try to identify the cause
of such a high impedance value.
Edit the main netlist file HiZ_PLL.cir in your preferred text editor, and add the
following plot command:
.plot tran IMP(xpll.xld.xcnt.xd00.x2.xc.x)
Rerun the simulation in Eldo:
eldo HiZ_PLL.cir
14. After the simulation is complete, launch EZwave and open the generated output file
HiZ_PLL.swd:
ezwave HiZ_PLL.swd
A new waveform is displayed, IMP(XPLL.XLD.XCNT.XD00.X2.XC.X):
Eldo® User's Manual, 15.3 1367

Examples
Transient Noise Analysis Example 1—High-Rate Particle Detector
Results
This tutorial showed how to use the Eldo .HIZ and .HIZ_CFG commands to detect “abnormal”
high impedance values on the PLL input control, and use HiZ configurations to detect
“expected” high impedance values on the Charge Pump output.
Tip
See “.HIZ” and “.HIZ_CFG” in the Eldo Reference Manual.
See also the AMS Results Browser User’s Manual.
Related Topics
Transient Noise Analysis Example 2—Switched Capacitor Filter
Transient Noise Analysis Example 1—High-Rate Particle Detector
Transient Noise Analysis Example 1—High-
Rate Particle Detector
Netlist file: transient_noise_detector.cir
This circuit was designed at CERN and is used in high-rate particle detection. It comprises a
front-end pre-amplifier and an analog memory port. Transient simulations are performed and
noise characteristics and performance investigated.
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Examples
Transient Noise Analysis Example 1—High-Rate Particle Detector
Figure 21-43. High-Rate Particle Detector Circuit
Description of the Particle Detector Behavior
The pre-amplifier has a rise time of less than 20ns and a large fall time constant compared to the
rise time. Therefore, for this application it can be considered as an integrator. The function of
the analog memory port is signal storage and noise shaping. It takes successive samples of the
signal into the different feedback capacitors. The complete system of analog memories acts as a
charge sampler and is equivalent, from a signal processing point of view, to a discrete
differentiator.
Figure 21-44 shows the signal at the input, the voltage at the amplifier output, and the signal at
the output of the complete system. The simulation was performed for an input charge of 2.5 fC
across a 5pF input capacitor and with a 15ns clock period.
The clock of the analog memory port is synchronized with the input signal to store the
maximum amount of charge in the first feedback capacitor. Note that most of the charge is
deposited in one storage capacitor within the 15ns clock period.
Eldo® User's Manual, 15.3 1369

Examples
Transient Noise Analysis Example 1—High-Rate Particle Detector
Figure 21-44. Simulation Results—Input & Output Signals
Analysis of the Noise Performance
The resolution of this detection system is a function of the noise generated by the circuit. It is
therefore the major performance criterion of the device.
The noise performance of the complete circuit strongly depends on the performance of the preamplifier.
The analog memory port does not generate noise, it only shapes the noise generated
by the amplifier.
A number of transient noise simulations were performed on the complete circuit.
Figure 21-45 shows the results of several transient simulation runs including noise sources, with
different initial conditions and the RMS value of the noise at the amplifier output calculated
from the different runs described above.
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Examples
Transient Noise Analysis Example 1—High-Rate Particle Detector
Figure 21-45. Noise at Amplifier O/P
The RMS value of the noise increases with time, and the Signal to Noise Ratio is limited by the
low frequency noise components.
Figure 21-46 shows the curves related to the different runs with the noise sources, the signal at
the output of the complete circuit, and the RMS value of the corresponding noise.
Eldo® User's Manual, 15.3 1371

Examples
Transient Noise Analysis Example 1—High-Rate Particle Detector
Figure 21-46. Noise at Analog Memory O/P
The effect of the analog memories on the noise behavior acts as a Correlated Double Sampling,
meaning that output noise is reset at each period of the clock.
For this type of circuit, the noise performance is expressed in terms of Equivalent Noise Charge
referred on the input (ENC):
where Noise is the RMS noise value at the output (extracted from the figure above), Signal is
the signal at the output and Qin is the charge injected across the input capacitor (in e − ). In this
case, the ENC is about 2000e − across Cin (Noise = 0.9mV, Signal=7mV, Qin=2.5 fC). This
circuit has been manufactured and experimental measurements match the simulation results
very closely.
Related Topics
Transient Noise Analysis Example 2—Switched Capacitor Filter
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Examples
Transient Noise Analysis Example 2—Switched Capacitor Filter
Transient Noise Analysis Example 2—
Switched Capacitor Filter
Netlist file: transient_noise_filter.cir
This second transient noise analysis example is a 6th order switched capacitor bandpass filter
used in telecommunications applications. Complete simulation results of the circuit and its
noise performance are provided. To increase simulation speed, modeling is implemented at a
macromodel level rather than transistor level. The Eldo macromodels SWITCH and OPA are
used. We first describe the macromodels used and simulation results follow.
Figure 21-47. Switched Capacitor Filter Circuit Schematic
Characterization of the Amplifier
The structure of the amplifier is a classical folded cascade. AC and transient simulations have
been performed at a transistor level to determine the macromodel parameters of the circuit
shown in Figure 21-48:
Eldo® User's Manual, 15.3 1373

Examples
Transient Noise Analysis Example 2—Switched Capacitor Filter
Figure 21-48. Amplifier Schematic
A subcircuit composed of an OPA1 macromodel, and a voltage source representing the
equivalent noise referred at the input, is used for the simulation of the complete circuit.
The dominant pole of the amplifier is defined by the output impedance and load capacitance of
the amplifier. Comparison of simulation results between the amplifier and its macromodel are
shown in Figure 21-49 and Figure 21-50.
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Examples
Transient Noise Analysis Example 2—Switched Capacitor Filter
Figure 21-49. AC & Noise Simulation Results of Amplifier
Eldo® User's Manual, 15.3 1375

Examples
Transient Noise Analysis Example 2—Switched Capacitor Filter
Figure 21-50. AC & Noise Simulation of Amplifier Macromodel
Switch Noise Model
Instead of MOS transistors, a switch macromodel is used to perform the complete circuit
simulations. To compute transient noise simulations, noise sources have been added to the
switches. We have considered that a switch only generates thermal noise. A current source has
been included between the source and the drain and its Power Spectral Density is a function of
R ον , as follows:
Simulation Results of the Complete Circuit
Transient simulation results are shown below. In Figure 21-51 the first curve represents the
impulse response of the circuit. The second curve represents the RMS value of noise generated
at the output of the filter in the frequency band (1Hz, 50kHz). The RMS result is approximately
8μV. This has been obtained by performing about 20 runs including noise sources. This curve
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Examples
Transient Noise Analysis Example 2—Switched Capacitor Filter
would be smoother if more runs had been performed. Figure 21-52 shows the Fourier transform
of the circuit output; it therefore represents the frequency response of the filter.
Figure 21-51. Simulation Results of the Filter
Eldo® User's Manual, 15.3 1377

Examples
Transient Noise Analysis Example 2—Switched Capacitor Filter
Figure 21-52. Frequency Response of the Filter
Related Topics
Transient Noise Analysis Example 1—High-Rate Particle Detector
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Appendix A
Error and Warning Messages
Reference for the error and warning messages that can be generated by Eldo.
Eldo Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1379
Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1380
Global Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1380
Errors Related to Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1384
Errors Related to Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1385
Errors Related to Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1392
Errors Related to Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1399
Errors Related to Macromodels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1401
Errors Related to Subcircuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1402
Miscellaneous Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1403
Errors Related to Eldo Premier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1408
Warning Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1411
Global Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1411
Warnings Related to Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1415
Warnings Related to Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1417
Warnings Related to Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1421
Warnings Related to Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1428
Warnings Related to Subcircuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1431
Miscellaneous Warnings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1431
Warnings Related to Eldo Premier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1450
Eldo Messages
Invoke Eldo with the -ovstatus command-line argument to generate in the standard output
(stdout) a summary message at the end of simulation informing of any warnings and errors.
If errors or warnings have been generated, an error message log file, .errm.log,
is created. This file contains the error and warning messages, specifying:
• Source line number.
• Text containing the error.
Related Topics
Locating Eldo Messages
Error and Warning Message Classification
Eldo® User's Manual, 15.3 1379

Error and Warning Messages
Error Messages
Error Messages
Error messages are divided into the following groups:
• Global Errors
• Errors Related to Nodes
• Errors Related to Objects
• Errors Related to Commands
• Errors Related to Models
• Errors Related to Macromodels
• Errors Related to Subcircuits
• Miscellaneous Errors
• Errors Related to Eldo Premier
Global Errors
Global error messages.
This version of Eldo does not include name
Error
Number
Error 1
Error 2
Error 5
Error 6
Error 7
Error 9
Error 10
Error 11
Error 12
Error 13
Error 14
Table A-1. Global Errors
Description
Unable to open the file name
Unable to open the library file name
Unable to open the temporary file name
Nested #com statements are not allowed
Unable to delete the temporary file name
Internal error in AC analysis
Non invertible matrix
Bad execution of name
Check sum incorrect. Check your key
Error in reading key: (number). Check your key
Error in reading ADC/DAC; file name not specified
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Error
Number
Description
Table A-1. Global Errors (cont.)
Error and Warning Messages
Global Errors
Error 15 The environment variable USER is not set by the system. Set this variable in your
.cshrc or .login script
Error 16 Unable to allocate number bytes. Memory already allocated name
Error 17 MEMALLOC: Unable to allocate number bytes. Memory already allocated name
Error 18 MAMALLOC: Unable to allocate number bytes. Memory already allocated name
Error 19 Unable to load file name. Analysis stopped
Error 20 The number of plots of the current simulation does not match the number of plots
of the previous one. File reading stopped
Error 21 Storage capacity exceeded. Memory already allocated name, eldo_mem_used()
Error 22 Circuit nesting error (please check that all .SUBCKT have a corresponding
.ENDS)
Error 23 Unrecognized character or word
Error 24 Unexpected end of file
Error 25 Line not consistent with language syntax
Error 26 No analysis specified
Error 27 Inductor/Voltage source loop foundTo allow a voltage loop made up of 0 voltage
sources use .OPTION LOOPV0 To downgrade this error to a warning use
.OPTION VOLTAGE_LOOP_SEVERITY = WARNINGVoltage loops may lead
to singular matrix during simulation
Error 28 Unable to reallocate name
Error 29 Trying to add a NULL element into the name. Please contact the office from
which you obtained this product with the message above and the circuit that
causes this error.
Error 30 Mismatch in model specification for device name
Error 31 DATA or SWEEP specification: : POI expects a positive number, name found
Error 32 Switch option cannot be used on device name
Error 33 Spectre file not specified
Error 34 .OPTIMIZE MOD: no parameter specified
Error 36 .OPTION LVLTIM must be 0, 1, 2, 3, or 4
Error 37 Memory allocation failure in name during name while trying to allocate: number
bytes
Error 38 Compilation errors in file name
Eldo® User's Manual, 15.3 1381

Error and Warning Messages
Global Errors
Error
Number
Description
Table A-1. Global Errors (cont.)
Error 39 Not enough memory to handle waves created through the DEFWAVE command
Error 40 FML.exe not found
Error 41 name: Real value expected
Error 42 name: Non-real expression expected
Error 43 Only DC followed by TRANSIENT analysis is allowed.
Error 44 FasC model name already defined
Error 45 .OPTION DVDT must be -1 or 0.
Error 46 No plot to display for name analysis: Simulation stopped.
Error 47 Error in updating the library. Refer to file name
Error 48 No voltage or current AC input source specified
Error 49 Unable to spawn name: There might not be enough memory
Error 50 .OPTION NEWTON and OSR are not compatible
Error 51 No plot matching analysis type: Analysis stopped.
Error 52 No node “0” found in the circuit
Error 54 Syntax error parsing name
Error 55 The following line is too long...Please split your line using continuation line '+'
Error 56 No key to run name
Error 57 Nested DC Sweeps are not allowed within SimPilot
Error 58 Error: Command name not allowed within SimPilot
Error 59 No value given for parameter name
Error 60 Real value expected for name: End of line found
Error 61 .OPTION IEM and OSR are not compatible
Error 62 .OPTION IEM and NEWTON are not compatible
Error 63 Unable to include file name
Error 64 .MODDUP cannot be used in conjunction with LOT|DEV
Error 65 .MODDUP cannot be used in conjunction with .MC
Error 66 .OPTION HMIN: Value must be strictly positive
Error 67 .OPTION LVLCNV must be 0, 2, or 3
Error 68 COMMAND .INCLUDE/.LIB cannot find name
1382
Eldo® User's Manual, 15.3

Error and Warning Messages
Global Errors
Error
Number
Error 69
Error 70
Error 71
Error 72
Error 73
Error 74
Error 75
Error 76
Error 77
Error 78
Error 79
Error 80
Error 81
Error 82
Error 83
Error 84
Error 85
Error 86
Error 87
Error 88
Error 89
Error 90
Error 91
Error 92
Description
Table A-1. Global Errors (cont.)
Cannot find HDLA models
.OPTION name expects an integer value
TUNING: Unexpected parameter name
Probable syntax error in library name
Fatal error in name model, please check output file for details. Eldo Kernel can’t
find the ‘SBVAL.PAR’ file
Cannot find #endcom statement
Questa ADMS command must be used in place of Eldo in order to use
VHDL-AMS models
Internal error: Mismatch in parameter name
Line not allowed inside command file
Unknown command name
DEBUG command number name not found
.RUN: Unknown argument name
Too many files opened
Parameter not known: name
Unable to alter name
Missing parameters
Syntax error or
Syntax error at or near name
Error evaluating name
Command cannot be issued at run time, or
Command name cannot be issued at run time
name cannot change .MODEL card for that kind of element
name disabled because AC analysis performed within transient analysis. However,
with keyword ALL added on the .MC card, simulation should run
SST analysis cannot be performed: Device name is not supported
SST analysis cannot be performed: Gudm model on name not supported
SST analysis cannot be performed: MOS model on name should be a chargecontrolled
model
Eldo® User's Manual, 15.3 1383

Error and Warning Messages
Errors Related to Nodes
Error
Number
Error 93
Error 94
Error 95
Error 96
Error 97
Error 98
Error 99
Error 100
Description
Table A-1. Global Errors (cont.)
SST analysis cannot be performed: Non-Quasi Static effects on name is not
supported
Unknown directive: name
No matching keyword name
Parameter name cannot be evaluated
Mismatch between .iic and .cir files: Simulation stopped
Having both .STEP and SWEEP on AC/TRAN/DC cards is not allowed
Unable to find a .DATA statement named name
This version of Eldo does not include name
Errors Related to Nodes
The following error messages are preceded by NODE :
Table A-2. Errors Related to Nodes
Error Description
Number
Error 101 No sources on this node
Error 102 Multiple input signal applied
Error 103 The DIGITAL to ANALOG Voltage Source Converter conflicts with another
Voltage Source already attached to this node
Error 104 Multiple DTOA on this node and at least one of them is a Voltage Source
Converter. This is not allowed
Error 105 Inconsistencies in the High Voltage specifications of the different RC DTOA
Converters connected to this node
Error 106 Inconsistencies in the Low Voltage specifications of the different RC DTOA
Converters connected to this node
Error 107 Node name not known
Error 108 Iout plot specification ignored on top-level nodes
Error 109 This node is a floating gate
Error 110 This node is a floating bulk
Error 111 Less than two connections
1384
Eldo® User's Manual, 15.3

Error
Number
Description
Table A-2. Errors Related to Nodes (cont.)
Error and Warning Messages
Errors Related to Objects
Error 112 No DC path to ground
Error 113 A2D/D2A cannot be applied on non-existing nodes
Error 114 Connectivity around that node makes Matrix singular
Error 115 Related device not found
Error 116 Only IN port seen, and no signal applied
Error 117 Missing A2D/D2A to connect to object
Error 119 FORCE ignored, discontinuity found
Error 120 This bulk node is not forced
Error 121 .IPROBE command: not all pins connected to that node name may be on the
reference pin list
Error 122 Unexpected hierarchical character found in that node name. It is better to rename
that node, or a workaround could be to use .option dotnode
Error 123 Unexpected hierarchical character '.' found in that node name. Such name must be
enclosed in escape character '\' like in \pin.name\
Error 124 Init Terminal contribution. Current cannot be read. This node is unconnected
Errors Related to Objects
The following error messages are preceded by OBJECT :
Error
Number
Error 201
Error 202
Error 203
Error 204
Error 205
Error 206
Error 207
Error 208
Description
Table A-3. Errors Related to Objects
Cannot be used in AC analysis, or
Cannot be used with CAPTAB
AC input has not been found
Parameter sweep not available for this object
VTH1 and VTH2 are inverted
Not found in file: name
VHI and VLO are equal
VHI and VLO are inverted
Unrecognized character or word: name
Eldo® User's Manual, 15.3 1385

Error and Warning Messages
Errors Related to Objects
Error
Number
Description
Table A-3. Errors Related to Objects (cont.)
Error 209 Incorrect declaration of POLY names
Error 210 Keyword FREQ expected
Error 211 Parameters are missing
Error 212 Unknown signal type: name
Error 213 Incorrect geometrical dimension: name
Error 214 No value specified for object: name
Error 215 Macro already defined
Error 216 Too many controlling nodes (> 3)
Error 217 Model not yet defined: model_name
Error 218 Model not found: model_name
Error 219 Short circuit element
Error 220 Voltage specifications are missing
Error 221 Is a multidimensional element
Error 222 SIN: Frequency below zero
Error 223 SFFM: FC below zero
Error 224 SFFM: FS below zero
Error 225 EXP: TAU1 below zero
Error 226 EXP: TAU2 below zero
Error 227 Unknown signal applied
Error 228 Either TD or F must be specified
Error 229 Multidimensional object. This variable is not declared
Error 230 Output pin is already a voltage source
Error 231 Output pin is already connected to a comparator output
Error 232 Geometries are below zero: please check DW and DL
Error 233 Value becomes zero. Exited
Error 234 Syntax error in the expression
Error 235 Brackets are missing in the TABLE values
Error 236 Table input values must be properly ordered
Error 237 Parameter name: incorrect value found name
1386
Eldo® User's Manual, 15.3

Error and Warning Messages
Errors Related to Objects
Error
Number
Error 238
Error 240
Error 242
Error 243
Error 244
Error 245
Error 246
Error 247
Error 248
Error 249
Error 250
Error 251
Error 252
Error 253
Error 254
Error 255
Error 256
Error 257
Error 258
Error 259
Error 260
Error 261
Error 262
Error 263
Error 264
Error 265
Error 266
Error 267
Error 268
Table A-3. Errors Related to Objects (cont.)
Description
Bus specification ignored
A time or a value specification is missing for this bus
This bus is already defined
PWLFILE: Bad value for parameters ISTART ISTOP ISTEP
A signal has been already applied on this bus
More than one .CHECKBUS applied on this bus
No model specified in this functional call: name
PWLFILE Parameters COL ISTART ISTOP ISTEP can’t be Negative
Unable to plot the capacitances of this device. Only charges are available
PWLFILE: No data read from file
Unable to plot the charges of this device. Only capacitances are available
Unexpected character found
Parameters or pins are missing for this device
Is not accessible
Unknown parameter: name
Unknown keyword: name
The sign : is missing after keyword
‘(‘ found when not expected
Element not found: name
The following element is not a current source: name
The following element is not a voltage source: name
Pin not found: name
Number of pins: number
Number of controlling nodes: number
Number of controlling zero voltage sources: number
Number of controlled voltage sources: number
Number of controlled current sources: number
Number of parameters: number
Error when initializing SOLVE routines
Eldo® User's Manual, 15.3 1387

Error and Warning Messages
Errors Related to Objects
Error
Number
Description
Table A-3. Errors Related to Objects (cont.)
Error 269 Error when initializing INTEGRAL routines
Error 270 Parameter not found
Error 271 Duplicate definition of parameter: name
Error 272 Parameter already assigned to an equivalent: name
Error 273 Parameter index not found: name
Error 274 Error in macro name
Error 275 VSTATUS already called with different pin order on: name
Error 276 Unable to apply the function: name
Error 277 Unable to find previous state: name
Error 278 Error in function
Error 279 No model assigned to this element
Error 280 Model attached to this device is also attached to another device of a different type
Error 281 Its model is also attached to the following component: name
Error 282 Access resistor becomes less than or equal to zero
Error 283 Error when computing R value. Division by 0
Error 284 Keyword PARAM expected instead of: name
Error 285 Equal sign ‘=’ expected instead of: name
Error 286 Unknown Base specification
Error 287 Cannot get the current through non-voltage source
Error 288 Unable to parse expression of
Error 289 Radiation source not found
Error 290 SOI back source not found
Error 291 Radiation source specification error
Error 292 SOI back source specification error
Error 293 The current through cannot be used as argument
Error 294 Inconsistency in voltage specification
Error 295 Unexpected digit found in the bus: name
Error 296 Unable to code
Error 297 Unknown pin number
1388
Eldo® User's Manual, 15.3

Error
Number
Description
Table A-3. Errors Related to Objects (cont.)
Error and Warning Messages
Errors Related to Objects
Error 298 R value is missing
Error 299 Mismatch in POLY specification
Error 801 Parameterizable object not created
Error 802 This RC line refers to a model which is already attached to a standard resistance:
name
Error 803 This resistance refers to a model which is already attached to an RC line: name
Error 804 Probably an RC line: please, specify level = 3 in the relevant .MODEL card
Error 805 Missing model specifications
Error 806 Delay cannot be 0.0
Error 807 .PLOTLOG: Specified object is not 0xx instance
Error 808 .PLOTLOG: Functional instance not defined
Error 809 BSIM1: Parameter K1 = K10 + K1L/Leff + K1W/Weff

Error and Warning Messages
Errors Related to Objects
Error
Number
Error 826
Error 827
Error 828
Error 829
Error 830
Error 831
Error 832
Error 833
Error 834
Error 835
Error 836
Error 838
Error 839
Error 840
Error 841
Error 842
Error 843
Error 844
Error 845
Error 846
Error 855
Error 856
Error 857
Description
Table A-3. Errors Related to Objects (cont.)
LENGTH and AREA must be strictly positive
Mismatch in port specification
Equal sign '=' is missing in parameter list
Unexpected equal sign '=' in parameter list
Several ports with that index
No port index specified
Missing R value
COUPLING: expecting keyword I or V: found name
Syntax error in PATTERN command
Object Error
Mismatch in coupling specification
Already defined
No model assigned to that device (MODDUP)
Short circuit on dipole device
This element cannot be converted into its switch equivalent
Odd number of pins
Pin index number ‘name’ of this object is a character string which contains the
hierarchical character.
But this node name has not been found in the hierarchy.
The problem could be in the naming of that node (solution: do not use the
hierarchical character in local node names).
But if the node name is actually correct (it refers to an actual hierarchical net),
ensure the instantiation of the object is placed after the instantiation of the subckt
which creates this hierarchical node.
Pin specification is missing
None of the models in .MSELECT fits this instance
The node name is a digital signal.
It is not possible to connect directly analog voltage to digital object inside name
description through hierarchical level.
TDEV should be specified on that device
Syntax HDLA_NAME = ELDO_NAME expected
Multiple SST specifications
1390
Eldo® User's Manual, 15.3

Error
Number
Description
Table A-3. Errors Related to Objects (cont.)
Error and Warning Messages
Errors Related to Objects
Error 858 Wrong object inside thermal network: only R/V/C device type can be specified
Error 859 AREA/PERI and W/L cannot be given together
Error 860 Multiple types of input applied
Error 861 Not declared
Error 862 Unable to mix FPORT syntax with RPORT syntax. FPORT must be replaced by a
voltage current source with R/C/L specifications.
Error 863 RPORT can be applied on voltage source only
Error 864 Missing IPORT specification
Error 865 AREA is negative or 0.0
Error 866 First pin of that element is undefined
Error 867 Second pin of that element is undefined
Error 868 .TRAN and .FOUR specification is not allowed on the same device
Error 869 Geometric level expected because w/l specified on instance, but actual model
used is a non-geometric model: ‘level’ parameter might be missing in .model
card.
Error 870 Generic/Parameter field appears twice
Error 871 Only one of argument 'VALUE', 'TABLE' or 'AC' expected
Error 872 Device not found
Error 873 Missing L or W specification to enable appropriate model selection
Error 874 No character string allowed in Param/Generic list
Error 875 DDT or IDT operator allowed on 'E' or 'G' sources only
Error 876 L and W must be specified before M()
Error 877 Character not allowed on pattern
Error 878 Value not specified
Error 879 PORTS specification appears more than once
Error 880 PINS specification appears more than once
Error 881 Only PINS specification allowed on VHDL-AMS instances
Error 882 GENERIC specification appears more than once
Error 883 Dimension must be 1 exclusively
Error 884 Second controlling node must be same as the second pin
Eldo® User's Manual, 15.3 1391

Error and Warning Messages
Errors Related to Commands
Error
Number
Description
Table A-3. Errors Related to Objects (cont.)
Error 885 Second controlling node must be same as the first pin
Error 886 Parameters of denominator for S/Z transform are all zero.
Error 887 More than one value specified for resistor value
Error 888 TSAMPLE not specified for PATTERN .CHECKBUS
Error 889 Undeclared inductor
Error 890 Expects syntax PWL(1) N1 N2 MODEL value
Error 891 Syntax error in IBIS model call
Error 892 Unknown IBIS device
Error 893 Component name is missing inside IBIS model call
Error 894 filename is missing inside IBIS model call
Error 895 MODEL and PIN can’t be both specified
Error 896 Cannot replace source, discontinuity found
Error 897 Expects an even number of parameters
Error 898 PZ or FNS allowed on E elements only
Error 899 Neither MODEL nor PIN specified
Error 900 FNS denominator cannot be 0
Errors Related to Commands
The following error messages are preceded by COMMAND :
Error
Number
Error 301
Error 302
Error 303
Error 304
Error 305
Error 307
Table A-4. Errors Related to Commands
Description
.MC: Monte Carlo analysis is not compatible with .ALTER
.MC: Monte Carlo analysis is not compatible with .STEP
.ALTER: This command is not compatible with .STEP
.MC: Unable to reallocate .MODEL field
.MC: Internal memory error
.CHRSIM: A previous transient analysis is required for the circuit
1392
Eldo® User's Manual, 15.3

Error and Warning Messages
Errors Related to Commands
Error
Number
Error 308
Error 309
Error 310
Error 311
Error 312
Error 313
Error 314
Error 315
Error 316
Error 317
Error 318
Error 319
Error 320
Error 321
Error 322
Error 324
Error 325
Error 326
Error 327
Error 328
Error 329
Error 330
Error 331
Error 332
Error 333
Error 334
Error 335
Error 336
Table A-4. Errors Related to Commands (cont.)
Description
.CHRSIM: A previous DC sweep analysis is required for the circuit
.CHRSIM: No output found in previous circuit to be connected to input
.SENS: Unable to create sensitivity matrix
.SENS: Circuit size too large (>name) for sensitivity analysis
.MC: Type not found
.OPTFOUR: Unknown output format
.INIT: Time values are missing
.IC: Time values are missing
.USE name: Specification unknown
.TRAN: Parameters are missing
.USE name: Specification unknown
.PLOT name: This kind of analysis is not supported
.LOOP: Object type not allowed: name
.PARAM: Attempt to divide by zero
.DC: W or L must be written in place of name
.OPTIMIZE: Name or element name not yet defined
.DC: Too many values specified
.RESTART: The file used to restart has the same name as the current circuit.
Rename the previous .cou file
.OPTIMIZE: name not yet created
.OPTIMIZE: Model name not yet created
.OPTIMIZE name: Incompatible operation
.DC: Unknown object name
.OPTIMIZE: AC output node name not yet defined
.IC: Error on name
.SOLVE: Error in expression
.SOLVE: Element name not yet defined.
.OPTIMIZE: Parameter name not known
.PLOT: Specification name not allowed
Eldo® User's Manual, 15.3 1393

Error and Warning Messages
Errors Related to Commands
Error
Number
Error 337
Error 338
Error 339
Error 340
Error 341
Error 342
Error 344
Error 345
Error 346
Error 347
Error 348
Error 349
Error 350
Error 351
Error 352
Error 353
Error 354
Error 356
Error 358
Error 359
Error 360
Error 361
Error 362
Error 363
Error 364
Error 365
Error 366
Error 367
Table A-4. Errors Related to Commands (cont.)
Description
.DC: Sweep object not specified
.OPTIMIZE: Use ACOUT= to select output
.NOISETRAN: Error with parameter
The Thermal Noise Level (number) is not compatible with values extracted from
MOS model
.NOISE: Element name not found
.SOLVE: Element name not found
.MFTA: Parameter name not found
.MFTA: Missing argument
.SAVE: File name is already specified in a previous .SAVE command
.TSAVE: save time value is required
.INIT cannot be applied on node name: Conflict of signals
.HIER: Not supported in Questa ADMS
.WCASE: Unknown analysis specification name
.TRAN: Unrecognized field (name)
Expression name can accept only items V(node) or I(object)
.TRAN: TSTOP is lower than HMIN
Expression name can accept only items V(node), I(object) or W(w)
.OPTIMIZE MOD: Real value expected, name found
.OPTIMIZE MOD: Parameter name: token ) expected
.PARAM: “=” is missing in expression: name
.OPTIMIZE: Unexpected expression: name
.EXTRACT: Unexpected expression: name
.STEP PARAM: Parameter name not specified
.DC: The parameter name is not specified or is not a primitive. Unable to perform
this analysis
.STEP: Parameter name not defined at the top level
.DC PARAM: Parameter name not defined at the top level
.ALTER: Appears as the title
name: Unknown command
1394
Eldo® User's Manual, 15.3

Error
Number
Table A-4. Errors Related to Commands (cont.)
Description
Error and Warning Messages
Errors Related to Commands
Error 368 .OPTIMIZE: sign = < > expected instead of name
Error 369 .DEFWAVE: Error name =
Error 370 .OPTIMIZE: name not allowed on parameter
Error 371 .PLOTLOG command: ‘->’ sign is missing
Error 372 .PLOT command: Found name while expecting a ( or )
Error 373 .SETSOA: Opening bracket expected after name
Error 374 .SETSOA: Closing bracket expected after name
Error 375 .SETSOA: Error in the expression name
Error 376 .SETSOA: Expected .SETSOA EXPR = (MIN,MAX)
Error 377 .SETSOA: Expected a * or a value for name
Error 378 .SETSOA: Model name not yet created
Error 379 .WC cannot be used with command .MC
Error 380 .CONNECT: Node name not yet created. The X instance which creates the node
must be placed before the .CONNECT card
Error 381 .SIGBUS: No parameters allowed (name)
Error 382 .SIGBUS PATTERN: THOLD must be specified
Error 383 .INIT: Node name not yet defined
Error 384 .DISTRIB name: Opening bracket expected
Error 385 .DISTRIB name: Closing bracket expected
Error 386 .DISTRIB name is already defined
Error 387 name: Specified terms must be properly ordered
Error 388 .DISTRIB name: must be in the range [0 to 1]
Error 389 Distribution name referenced but not defined
Error 390 Error in LOT/DEV specification for expression name
Error 391 .PARAM: Double specification for name
Error 392 .TRAN: No parameter allowed: (name found)
Error 393 .DISTRIB name: must be within the range [-1 to 1]
Error 394 Unable to measure ISUB (name): multiple connections
Error 395 .OPTION name ignored
Eldo® User's Manual, 15.3 1395

Error and Warning Messages
Errors Related to Commands
Error
Number
Error 396
Error 397
Error 398
Error 399
Error 400
Error 401
Error 402
Error 403
Error 404
Error 405
Error 406
Error 407
Error 408
Error 409
Error 410
Error 411
Error 412
Error 413
Error 414
Error 415
Error 416
Error 417
Error 418
Error 419
Error 420
Error 421
Error 422
Error 423
Error 424
Table A-4. Errors Related to Commands (cont.)
Description
.STEP: DEC, LIN or OCT expected: name found
.STEP: No parameter allowed: name found
.STEP: DEC/OCT values must be positive
name: Negative X value found for DEC scale
.LMIN or .WMIN: Parameters are missing
.OPTNOISE: Real value expected after keyword name
.OPTNOISE: Keywords D V TD TV expected: name found
.OPTNOISE: SV: Value must be less than 1 but greater than 0: name found
name: The sign ‘,’ is not allowed
.SOLVE: Cannot accept functions such as YVAL, TPD, MIN, MAX and INTEG
.EXTRACT name: Cannot find a .EXTRACT with this label
.OPTFOUR: Unknown parameter: name
.EXTRACT name: Cannot find a .FOUR with the label name
.SNF: Unknown parameter name
.SNF: Double input specification for name field
Multiple .SNF cards not allowed
.SNF card: name specification expected
.FOUR card: Syntax is [LABEL=]
.EXTRACT name: RMS accepts transient waves or AC noise waves only
.OPTWIND or .OPTPWL: Parameter name cannot be changed
.OPTWIND or .OPTPWL: Missing time-value for name
.OPTWIND or .OPTPWL: Decreasing time-value for name
.AC: Syntax error card: name
.OPTWIND or .OPTWPL: Missing value specification at or near name
.OPTWIND or .OPTWPL: name
.IFT: Unexpected argument name
.OPTNOISE: NOISE and NONOISE cannot both be specified
.OPTNOISE: ALL=OFF and NONOISE cannot both be specified
.OPTNOISE: ALL=ON and NOISE cannot be both specified
1396
Eldo® User's Manual, 15.3

Error and Warning Messages
Errors Related to Commands
Error
Number
Error 425
Error 426
Error 427
Error 428
Error 429
Error 430
Error 431
Error 432
Error 433
Error 434
Error 435
Error 436
Error 437
Error 438
Error 439
Error 440
Error 441
Error 442
Error 443
Error 444
Error 446
Error 447
Error 448
Error 449
Error 450
Error 451
Error 452
Error 453
Table A-4. Errors Related to Commands (cont.)
Description
.SNF: Element name not found
.SNF: Element name appears as both input and output
.OPTFOUR: Parameter FS must be specified
.PZ: This analysis might give unexpected results because several AC sources are
found in the circuit
.ALTER: Not allowed in Accusim netlist
.NOISETRAN: Too many runs specified
.OPTFOUR: Bad value for parameters TSTART, TSTOP, NBPT and FS
.STEP PARAM ( ): Syntax error
.STEP PARAM ( ): Only LIST allowed for multi step
.STEP PARAM ( ): The number of values does not match the number of
parameters
.STEP: TEMP keyword cannot appear more than once
.STEP: Unknown name
.CHECKSOA: Unexpected parameter
.SETSOA: Expecting D, E or M: name found
.STEP: Missing increment parameter
.STEP: Missing boundary specification
.WCASE: Missing analysis specification
.AC LIST: Frequencies are not properly ordered
.DC: Only a real value is expected
.DEFWAVE: Duplicate definition of name
.OPTFOUR: Unexpected expression: name
.DEFMAC: Recursive definition of name
.OPTFOUR: The expression for name could not be evaluated
.OPTFOUR: TSTART > TSTOP
.STEP LIST: name
.NOISETRAN: Cannot be used with .OPTION SAMPLE
.MEAS: Unknown analysis type name
.MEAS: Unknown function name
Eldo® User's Manual, 15.3 1397

Error and Warning Messages
Errors Related to Commands
Error
Number
Table A-4. Errors Related to Commands (cont.)
Description
Error 454 .MEAS: Unexpected wave name
Error 455 .MEAS: Unexpected keyword: name
Error 456 .MEAS: Missing keyword: name
Error 457 .MEAS name: Cannot find a .MEAS of that name
Error 458 .MEAS name: LAST not accepted
Error 459 .DC: name unknown
Error 460 .STEP: Increment is 0.0
Error 461 .SETSOA: unexpected keyword name
Error 462 .EXTRACT: FILE=name must be placed before the expression
Error 463 .STEP: multiple declaration for name
Error 464 .MCDEV: syntax E(devname[,geo]) expected
Error 465 .TRAN: decreasing time not allowed: name
Error 466 .LOTGROUP: double specification for name
Error 467 .FFT: Syntax is .FFT
Error 468 .PLOTBUS: specification error on name
Error 469 .MODEL name HOOK: syntax is .MODEL HOOK
[:][()]
Error 470 .MC specification on name: dead-zone too large compared to ‘normal’ zone
Error 471 Directive error name
Error 472 .PLOT: SMITH chart available for AC only
Error 473 .SETBUS: node name does not exist
Error 474 .AC expecting DEC, LIN, OCT, LIST or DATA: name found
Error 475 .PART: Unknown flag: name
Error 476 .PART: Syntax error. Syntax is .PART SUBCKT|INST ()
Error 477 .SETBUS: node name does not exist
Error 478 .EXTRACT: such SST output .H extensions
Error 479 .HOOK: expects ‘MOD=’ statement
Error 480 .LOOP: unexpected string name
Error 481 .DEFWAVE name: expects .H extensions
1398
Eldo® User's Manual, 15.3

Error and Warning Messages
Errors Related to Models
Error
Number
Error 482
Error 483
Error 485
Error 486
Error 487
Error 488
Error 489
Error 490
Error 491
Error 492
Error 493
Error 494
Error 495
Error 496
Error 497
Error 498
Error 499
Error 500
Table A-4. Errors Related to Commands (cont.)
Description
name: expects an integer value
name: missing a ‘(’ bracket
.STEP: step windows must be separated
Two ports are required for getting RNEQ/NFMIN_MAG/GOPT/
GAMMA_OPT/GAMMA_OPT_MAG/PHI_OPT/NC
.SNF: error specifying SIDEBAND: name
.PARAMOPT name 3 or 4 values expected
.PLOT: (SMITH) or (SPECTRAL) incompatible with (VERSUS)
.PLOT: (VERSUS) must be followed by only one wave.
.PLOT: No wave found before (VERSUS)
.TVINCLUDE: syntax error in test vector name
.DATA: name: Unable to open file name
.EXTRACT: name: LABEL = expected
.EXTRACT: name: expects MEAS(label_name)
.SNF: name
name not allowed with FS
.PRINT/PLOT/PROBE/EXTRACT: bad number of tones specified
name: Parameter name cannot be found
.CORREL: Instance name cannot be found
Errors Related to Models
The following error messages are preceded by MODEL:
Table A-5. Errors Related to Models
Error Description
Number
Error 501 Not found in library
Error 502 Unknown in the libraries
Error 503 Undeclared model reference
Error 504 Is defined twice
Eldo® User's Manual, 15.3 1399

Error and Warning Messages
Errors Related to Models
Error
Number
Description
Table A-5. Errors Related to Models (cont.)
Error 505 Parameter unknown
Error 506 Model not yet defined
Error 507 Inconsistency in level specification. LEVEL: number
Error 508 Level not implemented
Error 509 R model not declared
Error 510 NSUB < NI. exited
Error 511 C model not declared
Error 512 G model not declared
Error 514 BIDIR type not allowed. Use ATOD or DTOA
Error 515 Default BIDIR Converter not found
Error 516 LEVEL already specified
Error 517 Parameter TOX must be greater than 0
Error 518 Parameter STRUCT must be +1 or -1
Error 519 Unacceptable parameter value
Error 520 MJSW must be less than 1.0
Error 521 N must be positive
Error 522 FC must be less than 1.0
Error 523 The following parameter must only be used when eldomos is active or level 12 or
13 are used
Error 524 Model Error
Error 526 Unable to alter the parameters of that model
Error 527 This model is used by Eldo-XL and cannot be replaced
Error 528 This model cannot be changed using .LIB in an interactive mode: Inconsistent
level or architecture
Error 529 The following parameter cannot be used with model MM9
Error 530 Unknown language type
Error 531 Double MC specification (via .MCMOD/.MODEL) for the parameter name
Error 532 Expects PWL(1) SYMMETRY NO SOURCE CARDS DATA
Error 533 Parameter COX cannot be specified for that model
Error 534 W model: missing declaration of parameter N
1400
Eldo® User's Manual, 15.3

Error
Number
Description
Table A-5. Errors Related to Models (cont.)
Error and Warning Messages
Errors Related to Macromodels
Error 535 W model: incorrect number of parameters
Error 536 parameter name already assigned
Error 537 vector size not consistent for parameter name
Error 538 Missing inout values for parameter name
Error 539 Size of vectors not consistent
Error 540 Missing call to MP_vect_array
Error 541 inconsistent dimension of the vector array
Error 542 Position already allocated
Error 543 PASSFAIL, DICHOTOMY or SEARCH expected after METHOD parameter
Error 544 DEVX specification cannot be applied on .MODEL parameters
Error 545 This level is not supported yet
Error 546 Missing convertor type (STD_LOGIC, BIT, ... )
Error 547 Missing language definition
Error 548 Crypted models can't be simulated by FS
Error 549 W model: Tabular model expected
Error 550 Instance-dependant MC variation are allowed on DEV specifications only
Error 551 Language specification expected
Error 552 Parameter name must be specified
Error 553 Double definition for parameter(s) name
Error 554 The thresholds must be in the range [0,1] for supply dependant converters
Error 556 MCMOD cannot be used on this type of MODEL. Use .PARAM with MC
variations instead
Error 557 An existing node name is expected for VLOREF or VHIREF. "name" found
Error 558 Value for name found in global bin (name) does not match that of local bin (name)
Errors Related to Macromodels
The following error messages are preceded by AMODEL :
Eldo® User's Manual, 15.3 1401

Error and Warning Messages
Errors Related to Subcircuits
Error
Number
Error 601
Error 602
Error 603
Error 604
Table A-6. Errors Related to Macromodels
Description
Attempt to redefine an Amodel while the previous definition is not completed
Definition not completed
Macromodel not found
Pins must be specified before Ports
Errors Related to Subcircuits
The following error messages are preceded by SUBCKT :
Error
Number
Error 701
Error 702
Error 703
Error 704
Error 705
Error 708
Error 709
Error 710
Error 711
Error 712
Error 713
Error 714
Error 715
Error 716
Description
Table A-7. Errors Related to Subcircuits
Not found in library name
Undeclared subcircuit reference
is defined twice
Cannot be declared before the previous one has finished
Incorrect number of nodes at line number, while instantiating instance name.
number node(s) are expected according to SUBCKT definition,
number node(s) are found at instantiation.
Recursive .SUBCKT calls are not allowed
Unable to connect the output to a power supply or another digital output
Error in declaration
Already obtained from another LIB file
Cannot define a parameter named ‘M’
An ‘IF’ statement is not properly closed
Unexpected keyword name
refering to non-existing hierarchical node nameA possible cause of this error is
that the hierarchical character ‘name’
has been used when referring to non-hierarchical names.
This subcircuit cannot be used from within a .SUBCKT which has been
declared as FASTSPICE (here name)
1402
Eldo® User's Manual, 15.3

Error and Warning Messages
Miscellaneous Errors
Error
Number
Error 717
Table A-7. Errors Related to Subcircuits (cont.)
Description
Multiple redefinition of ground node
Miscellaneous Errors
Miscellaneous error messages.
Error
Number
Error 901
Error 902
Error 903
Error 904
Error 905
Error 906
Error 907
Error 908
Error 909
Error 910
Error 911
Error 912
Error 913
Error 914
Error 915
Error 916
Error 917
Error 918
Error 919
Error 920
Error 921
Table A-8. Miscellaneous Errors
Description
number: Unknown signal type at line
name: Unknown parameter
name: Specification ignored
name: Unknown model type
name: Parameter not found
name: Unknown output format specified
name: Can not affect value
name: Parameter not yet set
name: Unknown specification
name: Model not yet defined
Diagram not supported at line
name: Unknown command or component at line
Decreasing time on input signal number name
Decreasing time on input signal assigned to object
CFAS: Call to get_param_value() allowed in ALLOCATE MODE only
CFAS: Call to get_param_value_b4() not allowed
Unable to read from file name
Cannot reallocate component table
Cannot reallocate input signal
Unable to parse expression name
name is not specified in ATOD model
Eldo® User's Manual, 15.3 1403

Error and Warning Messages
Miscellaneous Errors
Error
Number
Error 922
Error 923
Error 924
Error 925
Error 926
Error 927
Error 928
Error 929
Error 930
Error 931
Error 932
Error 933
Error 934
Error 935
Error 936
Error 937
Error 938
Error 939
Error 940
Error 941
Error 942
Error 943
Error 944
Error 945
Error 946
Error 947
Error 948
Error 949
Description
Table A-8. Miscellaneous Errors (cont.)
Description of DTOA name is missing
DTOA name is declared as ATOD
Description of ATOD name is missing
ATOD name is declared as DTOA
Error in expression name. I or V expected
Error calling `new_fas_fnc': name not found
BIDIR name is declared as ATOD or DTOA
MODPAR: Parameter name not known
MODPAR: Parameter name is missing
EVAL: Parameter name is missing
EVAL: Parameter name not known
Error in TRISE or TFALL or TCROSS specification
.NOISE output must be a node voltage (V(xx))
.PBOUND: parameter name not found
name Inconsistent behavioural instance: expects ENTITY(ARCHITECTURE)
.LIB: keyword 'KEY =' expected: name found
.MCMOD: expecting LOT or DEV keyword: name
name Unknown .PLOT/.PRINT specification
.CHECKSOA: Not compatible with name
name cannot be redefined in a .PARAM statement
.CHRSIM name: Unknown argument
.SCALE not implemented for (name)
Invalid model name on .MSELECT statement - nested .MSELECT not allowed
Wrong Model type for name on .MSELECT statement - mixing models type is
not allowed
.INCLUDE: keyword 'SECTION = ' expected: name found
.DEFAULT/.SCALE: Unrecognized parameter (name)
.DEFAULT: Parameters are missing
.DEFAULT not implemented for (name)
1404
Eldo® User's Manual, 15.3

Error and Warning Messages
Miscellaneous Errors
Error
Number
Error 950
Error 951
Error 952
Error 953
Error 954
Error 955
Error 956
Error 957
Error 958
Error 959
Error 960
Error 961
Error 962
Error 963
Error 964
Error 965
Error 966
Error 967
Error 968
Error 969
Error 970
Error 971
Error 972
Error 973
Error 974
Error 975
Error 976
Error 977
Description
Table A-8. Miscellaneous Errors (cont.)
Missing FPORT number name
.FFILE: expecting unit (Hz, KHz, MHz, GHz): name found
.FFILE: expecting format MA or RI: name found
Dummy model name name on .MSELECT statement is also defined on a
.MODEL statement
.PZ: expecting V(pin) or I(Vxx)
Missing state name to be displayed for device name
.TEMP: real value expected, name found
.FFILE: expecting S/Y/Z: name found
.ALTER inside .INCLUDE is not allowed
.PLOT (LOW, HIGH) values must be real: name found
.SETSOA: Unexpected keyword 'ELSE' found
.SETSOA: source line name: Error in nesting IF-ENDIF statement
PORT name has only one connection
name: Invalid expression for .EXTRACT DC
Port specification in PLOT/PRINT is larger than the number of declared
PORTS
Inconsistent number of pins for devices name
M factor is less than or equal to zero for device name
.LIB: .LIB KEY=name already exists
Instance already defined: name
Unknown MC specification name
Missing MC specification in name
name: Parameter name cannot start with a digit
FNS order must be an integer: name found
.LIB: Unable to find library or variant
LOTGROUP name not defined
FOUR output: .H extension expected on the wave name
Too many simulation are required ( > ELDO_LONGVAL)
.H extension on wave: only integer value expected: name found
Eldo® User's Manual, 15.3 1405

Error and Warning Messages
Miscellaneous Errors
Error
Number
Description
Table A-8. Miscellaneous Errors (cont.)
Error 978 name
Error 979 IBIS: name
Error 980 IBIS: bad value specified for parameter name
Error 981 value cannot be negative
Error 982 Optimization cannot work when command name is active
Error 983 a non FFT output name appears in a FOUR or FOURMODSST extract
Error 984 unmatched if/else/then statement at or near line name
Error 985 Unable to alter parameter name because it controls device instantiation
Error 986 Entity name affected by both MC and a non-MC change
Error 987 Unexpected input format: name
Error 988 .NET: name found while expecting keyword RIN or ROUT
Error 990 At least two values are needed
Error 991 File name does not exist
Error 992 .EXTRACT mode: wave name can not be found in file name
Error 993 Parameter name is not allowed
Error 994 Unable to create/alter PORT structure on elements name which have not been
instantiated with PORT information in the netlist
Error 995 Parameter name should not contain boolean operator
Error 996 Parameter name should not contain any special characters
Error 997 .EXTRACT: wave name is incompatible with extract analysis
Error 998 .CORREL: need at least 2 name to generate a correlation
Error 999 .DSPMOD: name
Error 1000 .DSP: Syntax error in waveform definition
Error 1001 Using a parameter both in OPTIMIZATION and STEP is not allowed
Error 1501 This circuit exhibits singularity, due to ...
Error 1502 .OPTION DSCGLOB: unexpected specification name
Error 1503 .OPTION parameter DSCGLOB disabled. Use now DSCGLOB = X or
DSCGLOB = GLOB
1406
Eldo® User's Manual, 15.3

Error and Warning Messages
Miscellaneous Errors
Error
Number
Error 1504
Error 1505
Error 1506
Error 1507
Error 1508
Error 1509
Error 1510
Error 1511
Error 1512
Error 1513
Error 1514
Error 1515
Error 1516
Error 1517
Error 1518
Error 1519
Error 1520
Error 1521
Error 1522
Error 1523
Error 1524
Error 1525
Description
Table A-8. Miscellaneous Errors (cont.)
COMMAND .STEP LIB: name This library is not referenced in the netlist.
Please check that it was first used within a .LIB command.
Model descriptions and parameter values are unchanged.
COMMAND name: Unexpected keyword
Problem in using ‘\\’ in name
Object name: A periodic source must be associated to PHNOISE
.VEC: name
.HVEC: name
.PARAM name: parameter cannot be defined both as a string and as a real value
.CHRSIM : only analog waves are authorized using .CHRSIM
.OPTIMIZE: constraint specification on measurement: name is not compatible
with name method
.PARAMOPT: name
.CORREL: wildcards in parameter name name are not allowed
.PARAMOPT: device or model name does not exist
.PARAMOPT: Multiple definition for element name
.JWDB_OPTION: A real value is expected after keyword name
.JWDB_OPTION: Invalid keyword name
Object name
Parameter name found in name name depends directly or undirectly on DEV
specification. This is not supported yet by Questa ADMS. Note that this
parameter value is needed by device name. In case the DEV parameters do not
affect any Questa ADMS instances nor any ELDO Y instances, then .option
ADMSMCDEVSEV=warning can be used to disable the check, and let the
simulation running
COMMAND .PARAMOPT: wildcards in parameter name name are not
allowed
COMMAND .RESTART: file name name not found.
COMMAND .EXTRACT or .MEAS: Unexpected FFT output name
COMMAND .STEP PARAM name: parameter of type real cannot be given a
string value
COMMAND .STEP PARAM name: parameter cannot be a parameter of type
string
Eldo® User's Manual, 15.3 1407

Error and Warning Messages
Errors Related to Eldo Premier
Error
Number
Description
Table A-8. Miscellaneous Errors (cont.)
Error 1526 COMMAND .LIN: incorrect scattering parameter mixed-mode: name
Error 1527 COMMAND .LIN: syntax error on line name
Error 1528 COMMAND .LIN: unknown keyword name
Error 1529 COMMAND "name": The number of harmonics is restricted to 10.
Error 1530 COMMAND .CHRSIM: wave name is empty
Error 1531
Error 1532
Error 1533
Error 1534
Error 1535
Error 1536
Error 1537
Error 3001 Unable to initialize simulation with name
Error 3002 OBJECT name: varying parameters can’t be used with this object
Error 3003 Unable to open format name
Error 3004 name should be an INTEGER
Error 3005 nesting error inside #BB directive
Error 3006 #BB directive must be at top level
Error 3007 Can’t find subckt name for macro simulation
Error 3008 Only commands are accepted here
Error 3009 COMMAND .CALL_TCL name
Error 3010 FBLOCK model is not available for HP 64bits version
Error 3011 COMMAND .PARAMOPT: no initial value given
Error 3012
Error 3316 .MC analysis: Outer cannot be specified when DATAFLOW is not set to 0
(LEGACY) and SAMPLING is not RAND.
Errors Related to Eldo Premier
The following error messages are related to Eldo Premier:
1408
Eldo® User's Manual, 15.3

Error and Warning Messages
Errors Related to Eldo Premier
Error Number
Error 101001
Error 101002
Error 101003
Error 1021000
Error 1021001
Error 1021003
Error 1021019
Error 1021020
Error 1021021
Error 1021027
Error 1021033
Error 1021034
Error 1021036
Error 1021037
Error 1021038
Error 1021039
Error 1021041
Error 1021044
Error 1021048
Error 1021054
Error 1021056
Error 1021058
Error 1021059
Error 1021060
Error 1021062
Error 1021063
Error 1021064
Error 1021065
Table A-9. Errors Related to Eldo Premier
Description
Address %p not handled by the alligned allocator
name:%d : internal error, hRef overflow (%d)
name:%d : internal error, invalid call(kind=%d)
Assertion condition (name) failed in name:%d
Aborting program at name:%d :name
DLL 'name' open error: name
Error: Plugin 'name' registration failed: error on shared library
Error: Plugin 'name' registration failed: can not execute rtp_register
function
Error: Plugin 'name' registration failed: can not extract arguments : 'name'
Can not open module 'name'
Invalid value for option 'name' value: name
Invalid value for option 'name' value: %ld
Invalid href value in name:%d
Overflow href value in name:%d
No href defined for name
Failed to execute command 'name'
Failed to init solver for name instance ``name''
Incompatible options name and name
Elaboration failed
Assertion condition (name) failed in name:%d\tname
Error setting limit: name
\tname
Could not find exported subckt name for 'name'
Could not find name: 'name'
Function name not implemented
Command .connect is currently not supported
Device not supported for name
Subckt name contains %d nets (i.e more than %d allowed): can not
generate matrix or use premier_matrix_size_limit option
Eldo® User's Manual, 15.3 1409

Error and Warning Messages
Errors Related to Eldo Premier
Error Number
Error 1021068
Error 1021069
Error 1021070
Error 1021074
Error 1021080
Error 1021083
Error 1021094
Error 1021101
Error 1021102
Error 1021104
Error 1021107
Error 1021108
Error 1021147
Error 1021174
Error 1021187
Error 1021192
Error 1021197
Table A-9. Errors Related to Eldo Premier (cont.)
Description
State allocation required name, only name are available
Stack allocation required name, only name are available
Script 'name' do not exists
Matrix of name is structurally singular because of net 'name'
DSPF error: duplicate ``I'' definition 'name'
Invalid hierarchical reference for net 'name'
In SUBCKT ``name'', name ``name'': character '.' is not supported by the
simulator
Option name not implemented
Could not restart from file: mismatch between netlist and saved data
hmin (=%e ns) : NR rejection after %d iterations at %e ns
hmin (=%e ns) : fpe rejection after %d iterations at %e ns
Transient stopped due to a rejection of hmin
Dangling node name is only connected to one or more current source(s).
Either fix the netlist or use RGNDI option to avoid convergence issue.
Aborting program: name
.RESTART: This version of the simulator can only restart from a file
saved during a transient simulation performed with the same version of
the simulator.
Device name type 'name' not handled by Eldo Premier
Resolution library directory appears to be corrupted, please rerun with
premier_force_gen option. See “Forcing Elaboration” on page 71.
1410
Eldo® User's Manual, 15.3

Error and Warning Messages
Warning Messages
Warning Messages
Warning messages are divided into the following groups:
• Global Warnings
• Warnings Related to Nodes
• Warnings Related to Objects
• Warnings Related to Commands
• Warnings Related to Models
• Warnings Related to Subcircuits
• Miscellaneous Warnings
• Warnings Related to Eldo Premier
Global Warnings
Global error messages.
Warning
Number
Warning 1
Warning 2
Warning 3
Warning 4
Warning 5
Warning 6
Warning 7
Warning 8
Warning 10
Warning 12
Warning 13
Warning 14
Description
Table A-10. Global Warnings
Mismatch between .iic and .cir files. .RESTART ignored
The restarting values for .RESTART DC are only usable when no DC analysis
is required. DC analysis omitted
Unusual simulation time
Due to parameter PTF, the integration scheme has been changed from Trapeze
to Backward Euler
unusual value for EPS name
VDS and VGS initializations are useless with Eldo
No output to display
Due to .OPTION SWITCH, the ANALOG specification is ignored
.RESTART: a catenated file
.OPTION EPSDIG ignored due to .OPTION ANALOG
.AC: Values for lower and upper frequencies are inverted
Required ‘raw’ directory does not exist in the current directory; .OPTION
sda=2 ignored
Eldo® User's Manual, 15.3 1411

Error and Warning Messages
Global Warnings
Warning
Number
Description
Table A-10. Global Warnings (cont.)
Warning 15 AC analysis: name
Warning 16 Digital description ignored in AC analysis
Warning 17 .OPTION TIMEDIV ignored due to .OPTION SIMUDIV
Warning 18 .OPTION EPS set to name
Warning 19 Results from a TRAN analysis are being used for a DC analysis
Warning 20 .OPTION GRAMP accepts only positive integer values below 20 .OPTION
GRAMP ignored
Warning 21 Character 'O' found just after a '.' in line name
Warning 22 Non invertible matrix
Warning 23 There are BJT elements in the design, LVLTIM is set to 2
Warning 24 .TOPCELL should appear before any .SUBCKT definition
Warning 25 Rounding errors may occur between the Digital Simulator and Eldo
Warning 26 NUMDGT value name not accepted: default value used
Warning 27 Probable syntax error in library name
Warning 28 Negative or zero value for name ignored
Warning 29 Such messages will not be displayed in future. Set .OPTION MSGNODE=0 to
receive all warnings
Warning 30 Unable to open file name
Warning 31 No transient analysis specified .RESTART ignored
Warning 32 No FOUR plot to display: FFT analysis removed
Warning 33 XL: VSW0 and VSW1 set to name
Warning 34 UIC specification ignored on .TRAN card in ADMS
Warning 35 Multi-platform MC cannot be used
Warning 36 Unable to open LIB file name
Warning 37 Multiple definition of parameter name
Warning 38 Command name is ignored
Warning 39 First line of the command file must be a comment
Warning 40 .OPTION parmhier: ‘local’ or ‘global’ expected
Warning 41 Signals will be displayed in the digital output file
Warning 43 overwriting MIN/MAX of parameter name
1412
Eldo® User's Manual, 15.3

Error and Warning Messages
Global Warnings
Warning
Number
Warning 44
Warning 45
Warning 46
Warning 47
Warning 48
Warning 49
Warning 50
Warning 51
Warning 52
Warning 53
Warning 54
Warning 55
Warning 56
Warning 57
Warning 59
Warning 60
Warning 61
Warning 62
Warning 63
Warning 64
Warning 65
Warning 66
Warning 67
Description
Table A-10. Global Warnings (cont.)
.MP not implemented with SST analysis
DATA name
Double definition for parameter name
Unusual value given for name
Multiple .TEMP not allowed in ADMS: only last TEMP value will be used
This circuit exhibits singularity, due to name
name is ignored because of Mach
Using .OPTION RMV0, name zero-voltage sources would have been removed
from the database
Optimizer not active with Eldo-demo
Eldo Mach partition UI can’t be used in Eldo Mach Black-Box mode
Eldo Mach Black-Box mode disabled because of Eldo Mach partition UI
.OPTION name has been set to
Large flat netlist: Eldo switches to a mode where the order in which statements
appear is important. In particular, make sure that .MODEL are defined on top
of the netlist. However, you can use command .DISFLAT for restoring original
Eldo behavior.
JWDB cannot be disabled when running Questa ADMS
OPTION RGNDI specified. It is used at least on device name
Probably missing a .MODSST command. TRAN performed
Option [P/N]GATEDEF also activates option FLOATGATE0
OPTION name set
Command name Variant name ignored
Command name not supporetd in H_mode
Probably missing surrounding ' or {} at or near name Eldo will consider that as
an expression, which is may be not what is expected
Unexpected token name That token is ignored by the parser
In .ALTER: ".del lib name" is ignoredIt can't be use without libtype or key
name to identify which library must be removed. Keeping "name" in file name
at line number
Eldo® User's Manual, 15.3 1413

Error and Warning Messages
Global Warnings
Warning
Number
Warning 68
Warning 69
Warning 70
Warning 71
Warning 72
Warning 73
Warning 74
Warning 75
Warning 76
Warning 77
Warning 78
Warning 79
Warning 80
Warning 81
Warning 82
Warning 83
Warning 84
Description
Table A-10. Global Warnings (cont.)
Objects number mismatch while doing .restart: "name" objects to read while
"name" objects currently in memory. The object's states may not be fully
restored.
Objects mismatch while doing .restart:
reading object name "name" while expecting object "name". The object's
states may not be fully restored.
Command name appears in an if-endif section. This can lead to unexpected
behaviour. The if-endif sections should contain device instantiations only.
Unable to measure ISUB(name) in Whitebox Mode. Use blackbox instead.
Maximum number of messages reached. Subsequent messages will not be
displayed.
Maximum number of messages reached for message name. Subsequent
messages will not be displayed.
.option RGND used with Questa ADMS may not add, in some cases, a
grounded resistor on all HDL instance nodes
Z state not allowed when SST analysis is running. SST analysis disabled.
Default time specification used on device name, but .TRAN card appears later
in the design. Please, set .TRAN earlier to prevent any possible time
specification problem.
Voltage loop found, but accepted because containing only 0 voltage sources:
Unbalanced double quotes in line name. Strings defined in double quotes can
not be splitted into several lines. That can lead to an unexpected behavior.
Recursive inclusion of file name detected during name. Bypassing the last
inclusion and continuing the execution. For your information, the inclusion
stack is: name
The name name comes from name and is in name (accessed during .step lib
command). name will not be updated. However, if you want to force the update
of elements that doesn't come from the same libraries, use .option force_update
in the netlist.
The name name comes from name and is in name (accessed during .step lib
command). Updating of name forced. However, if you don't want to update
elements that doesn't come from the same libraries, remove .option
force_update from the netlist.
Option name found: no more warning displayed.
PORT related output name not supported on SSTAC.
Multithread required, but single processor machine. Option ignored.
1414
Eldo® User's Manual, 15.3

Error and Warning Messages
Warnings Related to Nodes
Warning
Number
Warning 85
Warning 86
Warning 87
Warning 88
Warning 89
Warning 90
Warning 91
Warning 92
Warning 93
Warning 100
Description
Table A-10. Global Warnings (cont.)
The characters 0 found at the beginning of node name which contains only
integer characters (such as in name) are removed. Use .option nodestr if this
should not be the case, i.e if those 0 should be considered as being actually part
of the node name.
Command line argument mthread / usethread has been removed. The
command line argument -use_proc is the only supported.
Some X or device instances connected in parallel have been merged into a
single instance. This may cause some unexpected warning or error messages.
See Eldo documentation for detail. To prevent this merging, please use .option
nocatmx .
Command name seen while COMPAT was already name. Ignored
No .ENDCOMPAT found in the design: section between .COMPAT and .END
is assumed to be in COMPAT mode.
name is not supported with name
Recursive file inclusion found: "name"
Multiple name not allowed in Questa ADMS in compat mode: only last name
values will be used
name has been deactivated due to name
This version of Eldo does not include name
Warnings Related to Nodes
The following warning messages are preceded by NODE :
Table A-11. Warnings Related to Nodes
Warning Description
Number
Warning 101 Significant node voltage variation, but of a lesser magnitude than VTH at time:
number
Warning 102 Number of iterations at time: number
Warning 103 Attempt to redefine .IC
Warning 104 Attempt to redefine .NODESET
Warning 105 Decreasing time on time-values associated to the .IC command
Warning 106 Global node already defined
Eldo® User's Manual, 15.3 1415

Error and Warning Messages
Warnings Related to Nodes
Warning
Number
Table A-11. Warnings Related to Nodes (cont.)
Description
Warning 107 Less than two connections
Warning 108 This node is a floating gate
Warning 109 This bulk node is not biased
Warning 110 Connected to capacitors only
Warning 111 Less than two connections. Line: number
Warning 112 Connected to grounded capacitors only. This node is removed from the netlist
Warning 113 Not connected to any element. This node is removed from the netlist
Warning 114 Second input signal ignored on that node
Warning 115 This is an ATOD and DTOA node
Warning 116 STRENGTH's CONFLICT on this node. Return to DIGITAL
Warning 117 Not connected to any power supply
Warning 118 No DC path to ground
Warning 119 VTH1 > VTH2 on A2D converter
Warning 120 VLO > VHI on D2A converter
Warning 121 Signals will be displayed in the digital output file
Warning 122 DC dangling node
Warning 123 A capacitor of more than 1F is attached to that node
Warning 124 Appears in .CONNECT only
Warning 125 Previous IC value superseded
Warning 126 Previous NODESET/GUESS value superseded
Warning 127 Possibly no DC path on that node
Warning 128 .CONNECT: node not found
Warning 129 has been replaced by a DSPF network
Warning 130 This node is already connected to a voltage source: D2A applied onto that node
will have no effect
Warning 131 This node is a floating gate for device name. Eldo connects gate of that device
name to node name
Warning 132 This node has been used by the DSPF process
Warning 133 This node is not found, thus cannot be displayed as SIGNAL
1416
Eldo® User's Manual, 15.3

Warning
Number
Table A-11. Warnings Related to Nodes (cont.)
Description
Error and Warning Messages
Warnings Related to Objects
Warning 134 Node not found in netlist, appeared only in [P/N]GATEDEF: connectivity of
floating [P/N]MOS might therefore be wrong
Warning 135 This node is in a RF partition and therefore should appear in a TMODSST or
FMODSST output specification rather than in a TRAN output specification
Warning 136 Node name is in a RF partition and therefore should not appear in a PLOT/
PROBE of type TRAN
Warning 137 This node is in a non-RF partition and therefore it should appear in a transient
related output specification (TRAN or FOUR), rather than in a MODSST
related output specification
Warning 138 This node is assumed to be global node 0
Warning 139 This node is connected to capacitors only: adding GMIN across those
capacitors for DC analysis
Warning 140 This bulk node is not forced
Warning 141 This node has not been found in the netlist
Warning 142 This node is connected to zero-voltage source only
Warning 143 This node is detected as a floating gate, but there are also some non-MOS-gate
connections on that node: option FLOATGATE ignored on that node
Warnings Related to Objects
The following warning messages are preceded by OBJECT :
Warning
Number
Warning 201
Warning 202
Warning 203
Warning 204
Warning 205
Warning 206
Warning 207
Warning 208
Table A-12. Warnings Related to Objects
Description
Cannot be parameterized
Must be a differential amplifier. AC analysis omitted
Object not in the linear domain. AC analysis omitted
Already defined
Unrecognized word: name
No parameter or model specified
Second L value ignored
Second W value ignored
Eldo® User's Manual, 15.3 1417

Error and Warning Messages
Warnings Related to Objects
Warning
Number
Warning 209
Warning 210
Warning 211
Warning 212
Warning 213
Warning 214
Warning 215
Warning 216
Warning 217
Warning 218
Warning 219
Warning 220
Warning 221
Warning 222
Warning 223
Warning 224
Warning 225
Warning 226
Warning 227
Warning 228
Warning 229
Warning 230
Warning 231
Warning 232
Warning 233
Warning 234
Table A-12. Warnings Related to Objects (cont.)
Description
Parameter ignored: name
Z0 set to 50 W
RON set to 1 kW
W is less than WMIN. W is set to WMIN
L is less than LMIN. L is set to LMIN
Value becomes negative
W undefined. Default value is taken: number
L undefined. Default value is taken: number
RS is negative or zero: value reset to
Improper value. Default value is taken (1.0×100). Value: number
Undeclared inductor
Default values used for time specification
Instability may occur because some of the root modules of the denominator
are greater than 1, (outside the unit z circle). Poles are dumped in the standard
output file
Instability may occur because the real parts of some of the denominator’s
root are greater than 1, (outside the unit z circle). Poles are dumped in the
standard output file
Last specification ignored
Parameter already used as an equivalent: name
CPIN already called on pin: name
VSTATUS already called on: name
Resistor value is 0: object not called: name
This resistor is not a RC line. Parameter(s) ignored: name
WEFF=W-2DW too small or negative. Default value RES used
LEFF=L-2DL ≤ 0.0. Default value RES is used
LEFF and WEFF ≤ 0.0. Default value CAP is used
DTOA converter: Rhigh is not specified, the default value of 1 mW is taken
DTOA converter: Rlow is not specified, the default value of 1 mW is taken
This element cannot be converted into its switch equivalent
1418
Eldo® User's Manual, 15.3

Error and Warning Messages
Warnings Related to Objects
Warning
Number
Warning 235
Warning 236
Warning 237
Warning 238
Warning 239
Warning 240
Warning 241
Warning 242
Warning 243
Warning 244
Warning 245
Warning 246
Warning 247
Warning 248
Warning 249
Warning 250
Warning 251
Warning 252
Warning 253
Warning 254
Warning 255
Warning 256
Warning 257
Warning 258
Warning 259
Warning 260
Table A-12. Warnings Related to Objects (cont.)
Description
Capacitance value is negative or zero
Node name PARAM:xxxx found: This might be confused with PARAM:xxx
The following dimension has an unusual value: name
.SIGBUS: VHI < VLO
VHI < VLO on .D2A
Object Warning
Unable to plot the capacitances of this device, only charges are available
Unable to plot the charges of this device, only capacitances are available
This object makes reference to the above node, which will be assumed to be
ground node 0
Level cannot be given on the instance
Self in short circuit: Object not created
Temperature given for TDEV device: TDEV ignored.
Capacitance value of more than 1F
There are several ports with that index
The first pin of that element is undefined: Object not created
The second pin of that element is undefined: Object not created
Old syntax: Please use Ixx or Vxx element with PORT specification
Self-connected objected not created.
Parameter PGATE is defined for JUNCAP model only
Differential lines are not supported, the reference plane will be replaced by
the ground
Size not consistent with LMIN/LMAX/WMIN/WMAX
Very small value specified.
Values are out of range for
May be diode instantiation was intended, but its name could not start by
‘DEL’, which is a prefix reserved for Eldo DELAY primitive.
May be CCCS instantiation was intended, but its name could not be started
by ‘/FNZ’, which is a prefix reserved for Eldo FNS/FNZ primitive.
May be SUBCKT instantiation was intended, but its name could not be
started by ‘XOR’, which is a prefix reserved for Eldo XOR primitive.
Eldo® User's Manual, 15.3 1419

Error and Warning Messages
Warnings Related to Objects
Warning
Number
Table A-12. Warnings Related to Objects (cont.)
Description
Warning 261 May be Current Source instantiation was intended but its name could not be
started by ‘INV’, which is a prefix reserved for Eldo INVERTOR primitive
Warning 262 Incorrect value for keyword ABS (1 or 0 expected). Using 0 as default
Warning 263 Ambiguity on parameter name
Warning 264 Object not yet created
Warning 265 W or L not specified on that device. Default setting relevant to that model
will be used
Warning 266 The timestep chosen for the simulation exceeds the delay
Warning 267 Very small resistors have been encountered. This may cause nonconvergence
problems
Warning 268 Only 3 pins specified: bulk node set at 0
Warning 269 Unsupported keyword
Warning 270 Multiple DC specification found: only last one considered
Warning 271 Multiple AC specification found: only last one considered
Warning 272 Multiple TRAN specification found: only last one considered
Warning 273 Missing IPORT specification
Warning 274 name already specified, and name now specified. name takes precedence
Warning 275 Negative resistor has been encountered. This may cause non-convergence
problems
Warning 276 Unusual large value inductance: Might be that DCFEED specification is
missing on the instance
Warning 277 Unusual large value capacitance: Might be that DCCUT specification is
missing on the instance
Warning 278 R value specified is negative or greater than the last time value. Period
parameter ignored
Warning 279 Multiple definition of parameter name: New specification 'name' overwrites
previous specification 'name'
Warning 280 Model level attached to that device is level %ld: i.e. a UDM or a GUDM
model
Warning 281 This source contains DC/TRAN and noise specifications. Only the noise
specification will be considered during a .noisetran analysis. To obtain a DC
offset, specify two voltage sources in series (or two current sources in
parallel) with one source containing the DC specification and the other
source containing the noise specification
1420
Eldo® User's Manual, 15.3

Error and Warning Messages
Warnings Related to Commands
Warning
Number
Warning 282
Warning 283
Warning 284
Warning 285
Warning 286
Warning 287
Warning 288
Warning 289
Table A-12. Warnings Related to Objects (cont.)
Description
LFSR type source. First TAP value must be largest of all TAP values
I(name,name) not supported for this type of devices: name ignored
Capacitance value is negative
LFSR type source. Seed (val) exceeds range of max TAP, reset to 2^2-1.
Warnings Related to Commands
The following warning messages are preceded by COMMAND :
Warning
Number
Warning 301
Warning 302
Warning 303
Warning 304
Warning 305
Warning 306
Warning 307
Warning 308
Warning 309
Warning 310
Warning 311
Warning 312
Warning 313
Warning 314
Description
Table A-13. Warnings Related to Commands
.AC: FREQ1 is set to 1Hz
.AC: FREQ2 is set to 1Hz
.IC name: Ignored
.NODESET name: Ignored
.SOLVE: R sweep must be between positive values
.SOLVE: No solution has been found
.SOLVE: No solution has been found in the given interval
.IC or .NODESET name: This value does not match the value specified in the input
signal. Zero-time value is: number
.CHRSIM: The input signal will force the simulation to end at V=number
.CHRSIM: The input signal will force the simulation to end at time = number
.OPTION name: Ignored
.OPTIMIZE name: Ignored
.WIDTH name: Ignored
.OPTFOUR: Obsolete statement ignored
Eldo® User's Manual, 15.3 1421

Error and Warning Messages
Warnings Related to Commands
Warning
Number
Warning 315
Warning 316
Warning 317
Warning 318
Warning 319
Warning 320
Warning 322
Warning 323
Warning 324
Warning 325
Warning 326
Warning 327
Warning 328
Warning 329
Warning 330
Warning 331
Warning 332
Warning 333
Warning 334
Warning 335
Warning 336
Warning 337
Warning 338
Warning 339
Warning 340
Warning 341
Warning 342
Warning 343
Table A-13. Warnings Related to Commands (cont.)
Description
.GLOBAL: Nodes specified in this card are considered as global nodes from the
introduction of the corresponding .GLOBAL card, NOT BEFORE
.ENDS: The name does not match the .SUBCKT name
name: Option unknown
.RAMP name: Specification unknown. .RAMP ignored
.PZ: Previous specification on name ignored
.STEP: Previous card superseded
.NOISE: Previous specification ignored
.DC: Previous values superseded
.RAMP: Previous values superseded
.TRAN: Previous values superseded
.OPTIMIZE/.EXTRACT: Node name is connected to ground
.TRAN: The parameter TMAX is not used
.AC: Previous values superseded
.TRAN: Specification ignored
.TRAN: UIC specification accepted
.SENS: Element name not found
.SENS: Node name not found
.PZ: Node name not found
.PZ: Element name not found
.TF: Node name not found: .TF ignored
.TF: Element name not found: .TF ignored
.FIX: Element name not found
.UNFIX: Element name not found
.NOISE: Element/object name not found
.MC: Element name not found
.MC: Node name not found
.STEP: Parameter name not found
.STEP: No MOS name found
1422
Eldo® User's Manual, 15.3

Error and Warning Messages
Warnings Related to Commands
Warning
Number
Warning 344
Warning 345
Warning 346
Warning 347
Warning 348
Warning 349
Warning 350
Warning 351
Warning 352
Warning 353
Warning 354
Warning 355
Warning 356
Warning 357
Warning 358
Warning 359
Warning 360
Warning 361
Warning 362
Warning 363
Warning 364
Warning 365
Warning 366
Warning 367
Warning 368
Warning 369
Warning 370
Warning 371
Table A-13. Warnings Related to Commands (cont.)
Description
.OPTFOUR: Voltage source name found
.OPTFOUR: Node name found
.PRINT or .PLOT: Node name undeclared
.PRINT or .PLOT: Element name undeclared
.DC: Unknown sweep source name
.AC: No output specified in AC analysis: use .PLOT or .PRINT statement
.MC: Specification ignored
.OPTIMIZE: Ignored
.NOISE: Must be used in AC analysis only. NOISE analysis omitted
.IC: Node name not found
.NODESET: Node name not found
.GUESS: Node name not found
.CONSO: Voltage source name not found
.PROBE: Too many nodes to display. This value can be overridden by .OPTION
LIMPROBE = value
.OPTIMIZE: New AC input name is ignored
.PARAM: “=” is missing in expression name
.OPTIMIZE: Unexpected expression: name
.EXTRACT: Unexpected expression: name
.OPTIMIZE: Bounds for name must be MIN MAX
.PLOT/.PRINT: Wave name will be plotted in .MEAS file
.OPTOMIZE: GAIN target is unusually high: name
.PLOTBUS: Bus name not defined
.ANALOG: name not found
.PRINT or .PLOT or .PROBE: name not found
.WCASE: name not known
.MC ignored: Neither LOT or DEV specification found
.SETSOA: Expecting D E or M: name found
.SETSOA: Specification name unknown
Eldo® User's Manual, 15.3 1423

Error and Warning Messages
Warnings Related to Commands
Warning
Number
Table A-13. Warnings Related to Commands (cont.)
Description
Warning 372 .SETSOA: Object name unknown
Warning 373 .SETSOA: Model name unknown
Warning 374 name analysis omitted because of the DCSWEEP analysis found
Warning 375 .SETSOA: Double specification on name
Warning 376 .LOOP: Object name undefined
Warning 377 .NOISETRAN is currently incompatible with name. Transient Noise Analysis is
therefore omitted. For example, when a netlist contains both .MC and
.NOISETRAN commands, the .NOISETRAN command is ignored.
Warning 378 EPS is possibly too large (name): The usual EPS value for Transient Noise is 1.0e-6
Warning 379 RELTOL is possibly too large (name): %e The usual RELTOL value for Transient
Noise is
Warning 380 VNTOL is possibly too large (name): %e The usual VNTOL value for Transient
Noise is
Warning 381 .PLOT/.PRINT: Wave name will not be plotted in .ASCII file
Warning 382 .OPTION name
Warning 392 .STEP PARAM name: Sweep already defined in the .DC command
Warning 393 .PROBE ISUB (name): No wild character allowed
Warning 394 .PZ ignored because of FNZ functions
Warning 395 .PROBE name: No nodes/objects found
Warning 396 ISUB(name) not accessible: name is a global node
Warning 397 ISUB: Node name not found
Warning 398 .PROBE: Missing keyword AC, DC or TRAN
Warning 399 Unable to display I(M/B/Jxx): name assumed
Warning 400 .TRAN: TSTART > TSTOP: TSTART set to 0
Warning 401 .STEP: INCR_SPEC > T2-T1
Warning 402 .NOISE: zero or negative argument
Warning 403 .AC: Frequency cannot be 0.0 or less: The value has been reset to 1.0
Warning 404 .MODDUP: element name not found
Warning 405 .MODDUP: cannot be used on element name
Warning 406 .LIB cannot find name
1424
Eldo® User's Manual, 15.3

Error and Warning Messages
Warnings Related to Commands
Warning
Number
Warning 407
Warning 408
Warning 409
Warning 410
Warning 411
Warning 412
Warning 413
Warning 414
Warning 415
Warning 416
Warning 417
Warning 418
Warning 419
Warning 420
Warning 421
Warning 422
Warning 423
Warning 424
Warning 425
Warning 426
Warning 427
Warning 428
Warning 429
Warning 430
Warning 431
Warning 432
Warning 433
Warning 434
Table A-13. Warnings Related to Commands (cont.)
Description
.SETSOA ignoring SOA on model name
.SETSOA ignoring SOA on object name
.TF analysis not performed: Bad operating point
The line is too long: It has been truncated
.OPTNOISE: previous command superseded
.OPTNOISE: ON/OFF expected: name found
.MC: Unknown specification name: LOT or DEV expected
.FOUR: Parameter TSTOP is ignored
.TRAN: Parameter TPRINT is set to: name
.OPTFOUR: Previous values superseded
.USE: DC value for source name has been changed
.GLOBAL: Some subcircuits are already defined, if these subcircuits make use of
nodes which will appear in .GLOBAL statements, results can be in error
.OPTFOUR: Using INTERPOLATE=0 may increase the number of points
computed by the simulator
Missing FPORT number name
LOT/DEV specification on parameter name ignored
.PZ: Specified device is not a ‘voltage-like' element
.OPTFOUR: TSTART > TSTOP: TSTART is ignored
.OPTFOUR: TSTART < 0: TSTART is ignored
.OPTFOUR: TSTOP < 0: TSTOP is ignored
.OPTFOUR: NBPT < 0: NBPT is ignored
.OPTFOUR: FS < 0: FS is ignored
.OPTFOUR: Fnormal < 0: Fnormal is ignored
.OPTFOUR: Fmin < 0: Fmin is ignored
.OPTFOUR: Fmax < 0: Fmax is ignored
.OPTFOUR: Fund < 0: Fund is ignored
name: Only Magnitude or DB of NOISE outputs are available
LOT/DEV specification is ignored on the non-primitive parameter name
The given value for VSW0 is superior to VSW1:The values will be interchanged
Eldo® User's Manual, 15.3 1425

Error and Warning Messages
Warnings Related to Commands
Warning
Number
Warning 435
Warning 436
Warning 437
Warning 438
Warning 439
Warning 440
Warning 441
Warning 442
Warning 443
Warning 444
Warning 445
Warning 446
Warning 447
Warning 448
Warning 449
Warning 450
Warning 451
Warning 452
Warning 453
Warning 454
Warning 455
Warning 456
Warning 457
Warning 458
Table A-13. Warnings Related to Commands (cont.)
Description
DEFAD/DEFAS/DEFPD/DEFPS overwritten by .OPTION XA for MOS models
BERKELEY/BSIMxx/EKV and MM9
.EXTRACT: Unable to open file name
.PLOT/.PRINT: wave name will be plotted as
.TRAN: last Tstep ignored.
.SETBUS: last Time point ignored
name ignored with Eldo Mach
.STEP: increment must be positive: name used
.PARAM name
.MEAS name is ignored. This is because specification name is not supported
.STEP: Compared to Eldo 5.4, the semantic of the .STEP ... LIN has changed: LIN
stands for ‘number of runs’. Rather use keyword INCR if ‘increment value’ is
meant
.TVINCLUDE: name
.PLOT: name statement removed. It appears more than once.
.STEP LIB: name. This library is not referenced in the netlist. Please check that it
was first used within a .LIB command. Model descriptions and parameter values are
unchanged.
Host name is already defined. Statement ignored.
EXTRACT MODE: name
Can't update correlation coefficient depending of parameter name
.CORREL ignored, no Monte-Carlo analysis found.
.DSP name
.PLOT: unexpected output name. Missing .STEP or .TEMP card for using that type
of output
.PLOTBUS: limited to 53 bits: name not plotted
.SIGBUS: Only first values specified for bus name will be taken for .SST analysis
.STEP: no SST analysis found, keyword (AUTOINCR) ignored
.MC: VARY was already specified. VARY overwritten
1426
Eldo® User's Manual, 15.3

Error and Warning Messages
Warnings Related to Commands
Warning
Number
Warning 459
Warning 460
Warning 461
Warning 462
Warning 463
Warning 464
Warning 465
Warning 466
Warning 467
Warning 468
Warning 469
Warning 470
Warning 471
Warning 472
Warning 473
Warning 474
Warning 475
Warning 476
Warning 477
Warning 478
Warning 479
Warning 480
Warning 481
Warning 482
Warning 483
Table A-13. Warnings Related to Commands (cont.)
Description
.EXTRACT DC: DCTRAN assumed since both transient and ac analysis found in
the netlist
.DSPMOD: Model name is ignored (not used by any .DSP command)
.DSP: Element name is ignored (not used inside the netlist)
.VEC: name
DSPF command was processed. to disable parsing these commands use .option
SPF_PROCESSCOMMANDS=0
.AGEMODEL: Parameter name is ignored. It is not related to reliability analysis
DSPF plot of node name limited to %d components. Use .option
MAX_DSPF_PLOT to override this limit
.AGE: name
.HVEC: name
.DCMISMATCH: name not found
STRESS FILE LOADING: name
.DCMISMATCH: no output available nor compatible extract found
.SENSPARAM: instance name does not exist
.SENSPARAM: subckt name does not exist
.BIND: subckt instance name does not exist
.BIND: subckt definition name does not exist
.DSPF_INCLUDE: dspf file not specified
.OPTFOUR: TSTART > .TRAN TSTOP ! FFT analysis ignored
.MC: measurement name not found, ignored
.PRINTFILE: xaxis STEPname has been set to: %e ns
.DISCARD: subckt name does not exist
.DISCARD: subckt instance name does not exist
.OPTIMIZE: parameter name has been deprecated and will be removed from future
releases
.OPTIMIZE: parameter name ignored
.OPTIMIZE: name scale cannot be applied to measurement (UBOUND or
LBOUND is

Error and Warning Messages
Warnings Related to Models
Warning
Number
Warning 484
Warning 485
Warning 486
Warning 487
Warning 488
Warning 489
Warning 490
Warning 491
Warning 492
Warning 493
Warning 494
Warning 495
Warning 496
Warning 497
Warning 498
Warning 499
Warning 500
Table A-13. Warnings Related to Commands (cont.)
Description
.DSPF_INCLUDE: instance name appears in several DSPF files. First occurrence
used
"name": on bus name. No transient analysis specified, this command is ignored
.DSPF_INCLUDE: unknown argument name
.DISCARD: deviceinstance name does not exist
.MSELECT: Model name is not defined
.IGNORE_DSPF/SELECT_DSPF: name with wildcards should be enclosed in
double quotes ""
.INCLUDE/LIB : unknown keyword name : Ignored
.PROBE/PLOT/PRINT : unknown keyword name : Ignored
.PLOT : keyword (name) has been ignored. It is not compatible with the required
analysis
.DEFAULT : keyword (name) is ignored on active devices
.SCALE : unknown keyword name. Keyword EXCEPT expected. The list of
models or element is ignored
.DCMISMATCH: extract name is incompatible with dcmismatch requirements
.PROBE: keywords MASK and EXCEPT can not be applied to generic probe of
type VX, IX or ISUB
.SCALE: No match found for (name)
.PRINT or .PLOT: quantity name can not be extracted according to port
specifications
.SCALE : Unexpected keyword (name) for this scale type: Ignored
.PLOT/.PROBE: no dcsweep analysis found in the netlist. DC plot ignored
Warnings Related to Models
The following warning messages are preceded by MODEL :
Warning
Number
Warning 501
Description
Table A-14. Warnings Related to Models
No parameter specified. Default values are used
1428
Eldo® User's Manual, 15.3

Warning
Number
Table A-14. Warnings Related to Models (cont.)
Description
Error and Warning Messages
Warnings Related to Models
Warning 502 GOFF less than zero
Warning 503 Access resistors for this model are created as objects
Warning 504 Unable to match reverse and forward region. BV = number
Warning 505 Reset parameter
Warning 508 LAMBDA value is high and may cause problems of convergence
Warning 509 KB1 is set to number
Warning 510 Parameter XQC ignored
Warning 512 IBV set to number milliAmps. IBV has been increased in order to create a
continuous diode current representation in the breakdown region.
Warning 513 Parameter CF1 set to the default value: number
Warning 514 Parameter CF3 set to the default value: number
Warning 515 Parameters specific to BSIM appear and LEVEL is neither 8 or 11
Warning 516 LOT and DEV cannot be applied on R|L|C parameters
Warning 517 Parameter MJSW must be less than 1.0. Default is used
Warning 518 Parameter MJ must be less than 1.0. Default is used
Warning 519 LOT specification is less than or equal to zero
Warning 520 DEV specification is less than or equal to zero
Warning 521 The following parameter has an unusual value:
Warning 522 DMUT parameter appears in a non-ST model
Warning 523 SUBSN=1 is not allowed on a lateral PNP
Warning 524 VTH1 > VTH2
Warning 525 VLO > VHI
Warning 526 Model Warning
Warning 527 Parameter AF has an unusual value
Warning 528 Parameter KF has an unusual value
Warning 529 Only one threshold is allowed for BIT A2D models: The average value has
been taken
Warning 530 MCMOD cannot be applied on the model parameter: It can only be applied to a
nominal value: MCMOD ignored
Warning 531 Sinwave function: Theta factor is negative
Eldo® User's Manual, 15.3 1429

Error and Warning Messages
Warnings Related to Models
Table A-14. Warnings Related to Models (cont.)
Warning Description
Number
Warning 532 COX is ignored because TOX is given
Warning 533 The model parameters (DW/RSH) that are specific to RC WIRE have been
ignored
Warning 534 Double definition for parameter(s)
Warning 535 Level 21 is now replaced by Level name. For future versions make sure to use
that level
Warning 536 The model parameter RHO is needed for ST model
Warning 537 name, parameter ignored
Warning 538
Warning 539 Very small value for TNOM, this can cause simulation errors
Warning 540 This model has no equivalent on TI Spice: it will be mapped to Eldo model %s
Warning 541 VHI and VLO are equal
Warning 542 VHI and VLO are inverted
Warning 543 VHI, VLO parameters specifications are ignored because VHIREF, VLOREF
are given
Warning 544 VTH, VTH1, VTH2 parameters specifications are ignored because VHIREF,
VLOREF are given
Warning 545 VLO, VHI, parameters specifications are ignored on A2D model
Warning 546 %s undefined. Default value is taken
Warning 547 %s is not expected for BIT A2D models. Using %s value (%e) for VTH
Warning 548 VTH is already defined, %s is not expected for BIT A2D models. Ignoring
parameter
Warning 549 VTH, VTH1, VTH2 parameters specifications are ignored on D2A model
Warning 550 Model level switched to %s because of presence of parameter %s
Warning 551 Second model definition ignored
Warning 552 %s has not been specified. This node will be grounded
Warning 553 VTHREL, VTH1REL, VTH2REL parameters specifications are ignored
because VHIREF, VLOREF are not given
Warning 554 Level reset to %d
1430
Eldo® User's Manual, 15.3

Warnings Related to Subcircuits
The following warning messages are preceded by SUBCKT :
Error and Warning Messages
Warnings Related to Subcircuits
Table A-15. Warnings Related to Subcircuits
Warning Description
Number
Warning 701 Unused parameter: name
Warning 702 name: Cannot be updated with .LIB in interactive mode
Warning 703 SUBCKT name cannot be that of a keyword
Warning 704 This pin name appears more than once on definition
Warning 705 The header of this SUBCKT contains node names defined as global
Warning 706 In subckt %s, the parameter %s is already specified during instantiation: local
affectation ignored
Warning 707 is not used. Associated ".part" command line is ignored
Warning 708 parameter %s exists and is set in both current subckt environment and in subckt
%s. Value will be taken from current subckt environment %s
Warning 709 parameter %s exists and is set in both current subckt environment and in subckt
%s. Value will be taken from subckt %s
Warning 710 parameter %s exists and is set in both current subckt environment and at top.
Value will be taken from top level
Warning 711 parameter %s exists and is set in both current subckt environment and at top.
Value will be taken from current subckt environment %s
Warning 712 Associated ".part" has no effect. This subckt is not used
Warning 713 The header of this SUBCKT contains node names defined as global. Such
nodes will be connected to the parent nodes which are passed by the X
instance. If this is not the expected behaviour, i.e if it is expected that these
nodes are connected to the global nodes, then use .OPTION
DSCGLOB=GLOB
Warning 714 Second definition ignored
Miscellaneous Warnings
Miscellaneous error messages.
Eldo® User's Manual, 15.3 1431

Error and Warning Messages
Miscellaneous Warnings
Table A-16. Miscellaneous Warnings
Warning Description
Number
Warning 901 Last time ignored on input signal at line: number
Warning 902 name: Model parameter ignored
Warning 903 Too many nodes to plot (>8)
Warning 904 Previous value of name superseded
Warning 905 VSAT is set to: number
Warning 906 VSATM is set to: number
Warning 907 Parameter not used: name
Warning 908 name: This parameter cannot be assigned
Warning 909 name: Unknown parameter
Warning 910 Unable to measure ISUB(name): Multiple connections
Warning 911 PORT name has only one connection
Warning 912 IBIS: name
Warning 913 IBIS: parameter name ignored
Warning 914 IBIS: parameter name not in the interval [0,1] is ignored
Warning 915 Probably missing a path to ground from object name
Warning 916 Unable to parse expression name
Warning 917 SWEEP specification on TRAN/DC/AC ignored when .STEP are used: these
two syntaxes are not compatible
Warning 918 The check for instance duplicates has been disabled (netlist too large). Use
.OPTION CHECKDUPL to override this limit.
Warning 919 .OPTION ACCOUT=1 can not be applied to FOUR(name).
Warning 920 Instances name, * not created because M is 0*
Warning 921 MC variation on name
Warning 922 .OPTION MEASDGT: value must be between 0 and 18
Warning 923 .OPTION MEASLINE: value can't be less than zero
Warning 924 Parameter %s is not a primitive. Unable to apply sensitivity
Warning 925 Character % ignored in expression
Warning 926
.MEAS on %s: Using voltage-dependant value on %s. This is not allowed:
value assumed to be 0.0
1432
Eldo® User's Manual, 15.3

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Warning 927
Warning 928
Warning 929
Warning 930
Warning 931
Warning 932
Warning 933
Warning 934
Warning 935
Warning 936
Warning 937
Warning 938
Warning 939
Warning 940
Warning 941
Warning 942
Warning 943
Warning 944
Table A-16. Miscellaneous Warnings (cont.)
Description
No IPROBE named %s found
.PARAMOPT %s : %s has already been defined using (xinit=%s, xmin=%s,
xmax=%s, xincr=%s)
.PARAMOPT %s : %s is now defined with (xinit=%s, xmin=%s, xmax=%s,
xincr=%s)
OBJECT "%s": TABLE not supported in NOISETRAN analysis. Table
values ignored
Command %s: %s expected. Command ignored
LOCATION_MAP File: %s doesn't exists or is not a file
Environment variable MGC_LOCATION_MAP = %s doesn't exists or is not
a file
Unable to find the mgc_location_map file. That may lead to errors during the
parse
If it is expected to accept Hierarchical characters in node name, it is still
possible to use .option dotnode
COMMAND .SNF: duplicate SNF found with label %s. The values of the
previous SNF will be overwritten by the current one. If this is not expected,
please change the label of one of these SNF
COMMAND .OPTION %s is ignored on %s side
In mgc_location_map, %s: No such directory. Soft name %s not loaded: Eldo
might not be able to load some libraries
Inductor/"voltage source" loop found. Voltage loop made of 0 voltage
sources only can be accepted using .OPTION LOOPV0. Voltage loop may
lead to singular matrix during simulation
Unable to find a model on device %s which satisfies binning conditions
(lmin, lmax, ...) and model name (current model name is %s)
Because it would give negative value, small-channel noise contribution
disabled on device %s
%s cannot be executed when design contains "%s" descriptions
The netlist contains both a .variation block and some montecarlo variation
specifications given on .param, device or model parameters. Only the
.variation block is used, the other variation specifications are ignored
Eldo® User's Manual, 15.3 1433

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Warning 945 Both the size of device %s and binned parameters of its model are affected by
MC variation. This situation cannot be handled. Use .option
"mc_ignore_binning" to ignore montecarlo variation on binning parameter
(lmin/lmax...)
Warning 946 Unable to evaluate GET_E(%s) on instance %s. That parameter has to be
defined either on the instance or in the model card of that instance
Warning 947 COMMAND "%s": previous values superseded
Warning 948 COMMAND .SAVE : Saving DC data requested but No DC analysis has
been actually performed
Warning 949 COMMAND "%s": Parameter %s ignored
Warning 950 COMMAND "%s": only top level parameters are elaborated in %s mode.
That may lead to errors during the parse of if-endif statements
Warning 951 COMMAND "%s": Saving time lower than HMIN. Set Eldo option 'HMIN'
to a lower value if needed
Warning 952 %d threads have been requested but Eldo detects only %d processors. Using
more threads than the number of processors of the computer might greatly
slow down the simulation
Warning 953 The number of requested threads (%d) is too high compared to the detected
number of processors. Eldo will use %d threads
Warning 954 Negative number of threads has been specified. Eldo will run in monothread
Warning 955 COMMAND .SETSOA: Error in the expression %s
Warning 959 COMMAND "%s": Unable to parse expression %s
Warning 962 OBJECT "%s": %s is negative, value is clipped to 0.0
Warning 963 COMMAND .NOISETRAN inside Premier parameter %s has been %s
Warning 1001 .NOISETRAN ignored: Only single TRAN analysis is allowed
Warning 1002 .NOISE ignored because the output node is not defined
Warning 1003 .SWITCH: Element name not found
Warning 1004 .MCMOD: Parameter name not known
Warning 1005 .MCMOD: Element name not known
Warning 1006 COMMAND name removed from the include file
Warning 1007 .SAVE and .RESTART used on the same file: .SAVE ignored
Warning 1008 COMMAND name found in include file
1434
Eldo® User's Manual, 15.3

Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Error and Warning Messages
Miscellaneous Warnings
Warning 1009 .OPTION: Incorrect range for name
Warning 1010 .PRINT or .PLOT: AC-like output name for non-AC analysis
Warning 1011 .PRINT or .PLOT: Unexpected AC output name
Warning 1012 .PLOT element name is not declared
Warning 1013 .PROBE/.SAVE element name is not declared
Warning 1014 .VIEW element name is not declared
Warning 1015 Element name is not found
Warning 1016 .SOLVE: Previous specifications superseded
Warning 1017 AC input sources used in connection with FPORT
Warning 1018 Digital gates are not handled in DCSWEEP
Warning 1019 .WC and .MC cannot be used together: .WC ignored
Warning 1020 .PZ analysis might give unexpected results because several AC sources are
found in the circuit
Warning 1021 .PRINT or .PLOT: Unexpected AC output name for SST
Warning 1022 .PRINT or .PLOT: Only V() or I() is allowed for SST type
Warning 1023 .TDEV: Object name not found
Warning 1024 .PLOT element name not declared
Warning 1025 .PRINT or .PLOT: Unexpected FFT output name
Warning 1026 .PRINT/.PLOT/.PROBE: Missing declaration .FOUR LABEL=name
Warning 1027 .PRINT or .PLOT SSTNOISE: Expected SSTNOISE output, and not name
Warning 1028 .MEAS: Element name not declared
Warning 1029 .EXTRACT: Element name not declared
Warning 1030 .PRINT: Smith chart expects non-AC wave names
Warning 1031 .SSTPROBE name: second node assumed to be 0
Warning 1032 .PRINT/PLOT/PROBE/EXTRACT: bad number of tones specified
Warning 1033 .PLOT: name. wave type is incompatible with extract type
Warning 1034 name: Group-Delay specifications ignored in SST analysis
Warning 1035 .PRINT or .PLOT: Only WOPT() is allowed for OPT type
Warning 1036 SUBCKT name will be simulated as top level
Eldo® User's Manual, 15.3 1435

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Warning 1037
Warning 1038
Warning 1039
Warning 1040
Warning 1041
Warning 1042
Warning 1043
Warning 1044
Warning 1045
Warning 1046
Warning 1047
Warning 1048
Warning 1049
Warning 1050
Warning 1051
Warning 1052
Warning 1053
Warning 1054
Warning 1055
Table A-16. Miscellaneous Warnings (cont.)
Description
Standard Eldo Mach commands ignored in Eldo Mach Black-Box mode
Command .EXTRACT OPMODE on name: name is not a valid keyword.
COMMAND .STEP: keyword (AUTOINCR) is ignored. It can only be
applied on .STEP PARAM syntax.
COMMAND .MC: keyword OUTER is disabled. No multi-run analysis has
been specified.
COMMAND .PRINT or .PLOT SSTJITTER: Expected SSTJITTER output,
and not name
COMMAND .PRINT or .PLOT SSTSTABIL: Expected SSTSTABIL output,
and not name
COMMAND .PRINT or .PLOT: output name will be written as real/
imaginary parts in files which do not support complex format.
COMMAND .EXTRACT or .MEAS: Unexpected name output
COMMAND .PRINTFILE: Element name not declared
COMMAND .DSPF_INCLUDE: file name. An extra X has been added on
name. That rule of adding an extra X will now be used by default in that file
for all subsequent *|NET instructions.
BUS name is of size 0: Could be declaration of that bus is missing.
.OPTION name: list of values are limited to 10 elements.
COMMAND .OPTWIND name is incompatible with options defined as a list
of values. Only first value is kept.
COMMAND name:Node name not found
COMMAND name:Device name not found
Object name: Eldo will simulate as if CTYPE = 1 had been set on that
instance... This is because C value seems not to be dependant on the pin bias,
or pins are connected to power supply or ground, and in such situations,
CTYPE = 1 mode is usually more appropriate.. However, in case this tuning
is here not appropriate, just set CTYPE = 0 on the device, or use .OPTION
NOAUTOCTYPE in order to disable this setup.
COMMAND .EXTRACT: name is ignored.
COMMAND .FOUR: name removed
COMMAND .MC: incorrect value for PRINT_EXTRACT. name found
while only NOMINAL, NOMLAST, ALL and numbers are allowed
1436
Eldo® User's Manual, 15.3

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Warning 1056
Warning 1057
Warning 1058
Warning 1059
Warning 1060
Warning 1061
Warning 1062
Warning 1063
Warning 1064
Warning 1065
Warning 1066
Warning 1067
Warning 1068
Warning 1069
Warning 1070
Warning 1071
Warning 1072
Warning 1073
Table A-16. Miscellaneous Warnings (cont.)
Description
COMMAND .MC: Several .MC commands found in the netlist. Only last one
will be used.
COMMAND .PUNCH: unimplemented analyze type (name) requested.
Command ignored
COMMAND name: SNF output required but no .SNF card has been given.
Please check that the .SNF and .PLOT SNF commands are labelled correctly.
COMMAND .OPTIMIZE: Type of design objective name is incompatible
with method
D2A/A2D command ignored using ADMS.
The SUBCKT(S) listed above will not be changed by the STEP command,
they will remain the same for the entire stepping process. Therefore, results
might not be as expected... Suggest to use .ALTER command in .cir file
instead.
COMMAND .AGE: TSTART/TSTOP specifications are ignored because of
TWINDOW.
COMMAND .EXTRACT/.MEAS name: Unable to find any .DATA
associated with current analysis. Command ignored.
COMMAND .EXTRACT/.MEAS name: Unable to find an item named name
in .DATA name. Command ignored.
COMMAND .EXTRACT/.MEAS name: Complex measurements are not
compatible with optimization. Command ignored.
COMMAND .EXTRACT/.MEAS name: Unable to find a .DATA named
name. Command ignored.
COMMAND .EXTRACT/.MEAS name: in name some points are outside the
simulation interval. They will be ignored by the fitting command.
COMMAND .EXTRACT/.MEAS name: in name some points are not
correctly ordered, or not unique for a given X value. Fitting command
ignored.
COMMAND .EXTRACT/.MEAS name: in name some points can't be
simulated. Fitting command ignored.
COMMAND .PLOT/.PRINT/.PROBE: wave name contains some errors.
This command is ignored.
COMMAND .PLOT/.PRINT/.PROBE: Unexpected character 'name' found
COMMAND .PRINTFILE: xaxis START value for file name has been set to:
COMMAND .PRINTFILE: xaxis STOP value for file name has been set to:
Eldo® User's Manual, 15.3 1437

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Warning 1074
Warning 1075
Warning 1076
Warning 1077
Warning 1078
Warning 1079
Warning 1080
Warning 1081
Warning 1082
Warning 1083
Warning 1084
Warning 1085
Warning 1086
Warning 1087
Warning 1088
Warning 1089
Warning 1090
Warning 1091
Warning 1092
Table A-16. Miscellaneous Warnings (cont.)
Description
In corner name of library name .BIND commands can't be processed by the
STEP command.They will be ignored during the stepping process, therefore
results might not be as expected. Suggest to use .ALTER command instead.
COMMAND .RAMP: syntax error in command declaration:
dc voltage reset to initial transient source value for source name
COMMAND .PLOTBUS: incorrect BASE value: name. Default value will be
used.
COMMAND .PLOTBUS: BIN, DEC, OCT or HEX is expected after
keyword BASE. Default value will be used.
COMMAND .PLOTBUS: UNSIGNED or 2COMP is expected after keyword
RADIX. Default value will be used.
COMMAND .PLOTBUS: display keywords BASE and RADIX are mutually
exclusive. Priority is given to RADIX.
COMMAND .PLOTBUS: display keywords BASE and RADIX are ignored.
They do not apply on analog buses.
COMMAND .USE_TCL: NATIVE_TCL or EZWAVE_UDF is expected
after keyword MODE. Default value will be used.
COMMAND .TRAN is ignored when .MODSST is set.
COMMAND .OBJECTIVE: unsupported analysis: name.
COMMAND .PRINTFILE: file name cannot support more than name
analysis.
COMMAND .SIGBUS: Last value for bus name is not consistent with
periodic definition. It should be equal to first value.
COMMAND .OPTION: name has been deprecated and will be removed from
future releases.
COMMAND .ADMS_RESTART: argument evaluates to 0.0analog
simulation start will not be delayed
COMMAND .OPTIMIZE: .STEP command containing parameter name
specified in OUTER_PARAM contains other parameters. OUTER_PARAM
will affect them all.
COMMAND .SCALE: Unable to find a device or model parameter to scale
COMMAND .OPTFOUR: FMIN/FMAX specifications can not be applied on
RF signals
COMMAND .BIND cannot be used for FS Black Box Instances name.
1438
Eldo® User's Manual, 15.3

Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Error and Warning Messages
Miscellaneous Warnings
Warning 1093 COMMAND .LIMIT: complex output is not allowed inside name. Statement
ignored.
Warning 1094 COMMAND .MEAS: duplicate measurement name name
Warning 1095 COMMAND .MODEL name: parameter name has been deprecated and will
be removed from future releases.
Warning 1096 COMMAND .MODEL name: parameter name ignored.
Warning 1097 COMMAND .extract or .meas name contains symbols which are not handled
in extract-mode. This command is ignored.
Warning 1098 COMMAND .FOUR: name removed. Node name is unknown.
Warning 1099 COMMAND .FOUR: name removed. Device name is unknown.
Warning 1263 Ambiguity on parameter %s. Value used is %e. value defined by SST is %e
Warning 1400 EXTRACT MODE: File %s has been sampled at frequency %e Hz. Extracted
values might be inaccurate
Warning 1401 COMMAND .PRINTFILE: The command is ignored because file %s can not
be opened
Warning 1402 COMMAND .PLOT FOURMODSST: %s will represent the first harmonic of
the signal
Warning 1403 COMMAND .PLOT CONTOUR: unable to plot the contour. Extract %s can
not be used, it must define a vector of values (using VECT or CATVEC)
Warning 1404 COMMAND .PLOT CONTOUR: unable to plot the contour. The vectors of
values of CATVEC extracts don't have the same size
Warning 1405 COMMAND .AGE: parameter %s is assumed to be a user defined parameter
Warning 1406 OBJECT "%s": ambiguity found: using parameter %s instead of model %s
Warning 1407 OBJECT "%s": ambiguity found: using model %s instead of parameter %s
Warning 1408 OBJECT "%s": The following parameter(s) has(ve) multiple definitions : %s
Warning 1409 COMMAND .AGE: a non-numerical character was found in TAGE=%s
specification. It is ignored, thus if a unit was meant consider using TUNIT
keyword
Warning 1410 COMMAND .PROBE: %s is used as default analysis for command(s) not
specifying it
Warning 1411 EXTRACT MODE: wave %s can not be found in file %s. Maybe a .plot or
.probe command should be added in the original netlist before running the
eldo -extract command
Eldo® User's Manual, 15.3 1439

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Warning 1412 COMMAND .OBJECTIVE %s:
MONIT_VAL=ERRMEAN|ERRMIN|ERRMAX has no meaning with
GOAL=MINIMIZE|MAXIMIZE. This statement is ignored
Warning 1413 COMMAND .DATA %s: Wrong number of column in file %s at line %ld
Warning 1414 COMMAND .DATA %s: Wrong number of lines in file %s
Warning 1415 .OPTION TEMP_UNIT: Incorrect unit %s. KELVIN or CELSIUS is
expected
Warning 1416 COMMAND .MC OUTER does not apply on .TEMP command. Consider
using .STEP TEMP LIST if an inner sweep of temperature is required
Warning 1417 COMMAND .MC: keyword OUTER is disabled. It can't be applied with
.AGE analysis
Warning 1418 Not enough points were stored to compute FFT
Warning 1419 Unable to compute a correct FFT since FFT stop time has not been reached
Warning 1420 COMMAND .STEP LIB %s. Variant %s not found. Model descriptions and
parameter values are unchanged
Warning 1421 COMMAND .STEP LIB %s. Nothing to update. Model descriptions and
parameter values are unchanged
Warning 1422 COMMAND "%s": Unexpected keyword %s
Warning 1423 COMMAND "%s": INITFILE is missing
Warning 1424 COMMAND "%s": DEFAULTINIT=NO is set but no replacement file has
been specified. Simulation may fail
Warning 1425 COMMAND "%s": Ignored: Only active with .tran, .ac or .dc sweep analyses
Warning 1426 COMMAND "%s": unable to detect any multiple run commands compatible
with distributed simulations. This command is ignored
Warning 1427 COMMAND "%s": Ignored: Only one license is allowed and is already in use
Warning 1428 COMMAND "%s": Ignored: Cannot distribute jobs (no active hosts)
Warning 1429 COMMAND "%s": Ignored: Cannot distribute jobs (there must be at least 3
runs)
Warning 1430 COMMAND "%s": Unknown keyword: %s. TRISE or TFALL is expected
Warning 1431 COMMAND ".OPTION %s": Option is ignored. Syntax is: MIXEDSTEP =
[LOCKED | FREE]
Warning 1432 COMMAND ".OPTION %s": Unknown option or unexpected parameter
type. .OPTION %s Ignored
1440
Eldo® User's Manual, 15.3

Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Error and Warning Messages
Miscellaneous Warnings
Warning 1433 COMMAND "%s": This command is interpreted as .PROBE
Warning 1434 COMMAND "%s": Analysis disabled. MODEL %s is crypted. Accessing its
parameters is not possible unless:
1/ command .SETKEY is crypted with the .MODEL
2/ command .USEKEY must be given in the netlist using the encrypted
models
Warning 1435 New definition of .FOUR %s ignored
Warning 1436 COMMAND ".USE_VERILOG": This command has been deprecated inside
Questa ADMS. ai file is ignored and the work library loaded instead
Warning 1437 COMMAND "%s": Quantity %s has been replaced by %s
Warning 1438 COMMAND .EXTRACT/.MEAS %s: Unable to find measurement %s.
Command ignored
Warning 1439 Parameter %s found in %s %s depends directly or undirectly on DEV
specification. This is not supported yet by Questa ADMS
Warning 1440 .OPTION %s: unknown specification %s ignored
Warning 1441 .OPTION %s is ignored. It is only active when PSF_VERSION=2
Warning 1442 COMMAND "%s": The type of analysis must be specified when RF analysis
are used. Command ignored
Warning 1443 COMMAND "%s": Unable to code %s in base %ld
Warning 1444 COMMAND "%s": labeled "%s". The expression "%s" contains a SNF card
that was not found
Warning 1445 COMMAND .OPTIMIZE: OUTER specification is ignored since the netlist
contains no .STEP commands
Warning 1446 COMMAND .EXTRACT/.MEAS %s: Fitting waveforms requires to have
either .option OUT_STEP, TIMESMP or FREQSMP. Fitting command
ignored
Warning 1447 Unable to release %s license, feature "%s"
Warning 1448 COMMAND "%s": No .extract or .meas labeled %s was found. This
command is ignored
Warning 1449 COMMAND .FILTER: keyword %s has already been defined. First value is
kept
Warning 1450 OBJECT "%s": W/L parameters specified, a model should have been
assigned to this device. As a value has been set, these parameters are ignored
for computation of the effective resistor value
Eldo® User's Manual, 15.3 1441

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Warning 1451 DSP MODEL %s is evaluated by EZwave engine. Thus output values of
.DSP instances using this model - such as DSPR(), DSPI(), DSPM(), DSPP()
and DSPDB() - will be identical to what is calculated in EZwave
Warning 1452 DSP MODEL %s: parameter TSTART is set to %e according to .TRAN
command
Warning 1453 DSP MODEL %s: parameter NBPT is set to %ld according to TSTART,
TSTOP and FS
Warning 1454 DSP MODEL %s: parameter TSTOP is set to %e according to .TRAN
command
Warning 1455 DSP MODEL %s: parameter %s is set to %e
Warning 1456 DSP MODEL %s: parameter INTERPOLATE is set to 1. INTERPOLATE=0
can only be specified with fixed time step
Warning 1457 DSP MODEL %s: TSTART > .TRAN TSTOP ! DSP analyse ignored
Warning 1458 COMMAND .DSP %s: Parameters related to the DSP function are ignored.
.DSPMODEL has precedence
Warning 1459 Goal value for objective %s is set to 0.0
Warning 1460 Command %s overwritten: last specification taken
Warning 1461 COMMAND .PROBE: It is not allowed to specify subckt instance
informations for .probe VN (even when using wildcards)
Warning 1462 COMMAND .FFILE: Only one command is allowed. Previous values are
replaced
Warning 1463 The parameter %s is not defined in the .model %s or is unknown. No
variation can be done on that parameter. Parameter ignored
Warning 1464 The parameter %s is not defined on the instance %s or is unknown. No
variation can be done on that parameter. Parameter ignored
Warning 1465 Below is the list of variation that will be ignored: %s
Warning 1466 Threshold value for extract %s has been set to %e
Warning 1467 COMMAND .DSP: Input waveform %s of element %s can not be found.
Command ignored
Warning 1468 Noise factor %s will not be considered by the DEX analysis. Its deviation is
equal to 0.0
Warning 1469 COMMAND .DEX: the analysis is disabled because there is no active factors
Warning 1470 COMMAND .PROBE %s is not supported
1442
Eldo® User's Manual, 15.3

Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Error and Warning Messages
Miscellaneous Warnings
Warning 1471 COMMAND .PARAMDEX %s: It is not possible to define the settings of a
parameter as a fraction of the range value (using the RNG argument) when
this parameter has a non-uniform distribution
Warning 1472 EXTRACT MODE: %s command has been detected in the netlist. This
command is ignored. This can cause unexpected results if some extracts use
the swept parameter(s)
Warning 1473 COMMAND .PROBE %s: The default analysis for .SST results is set to
FSST. If TSST results are required, the type of analysis must be explicitly
given
Warning 1474 COMMAND .PROBE %s: The default analysis for .MODSST results is set to
FMODSST. If TMODSST results are required, the type of analysis must be
explicitly given
Warning 1475 More than %ld points are required for %s analysis. Output database might be
very large
Warning 1476 License message from Provider: %s -- Feature: %s
Warning 1477 COMMAND .PARAMDEX: wildcards in parameter %s are not allowed.
This definition is ignored
Warning 1478 The initial value of parameter %s set for optimization is ignored because this
parameter is used in a STEP command
Warning 1479 Some %s commands are declared for %s analysis. They are ignored because
this analysis is not enabled
Warning 1480 COMMAND .SETSOA: Model %s not found in subckt %s
Warning 1481 COMMAND .SETSOA: Subckt %s not found: command ignored. If you
specified an instance name instead of a subckt name try with keyword "inst="
instead of "subckt="
Warning 1482 COMMAND .PLOT: complex waveforms can not be plotted using
(VERSUS) keyword. They will be represented using their magnitude
Warning 1483 COMMAND .DEX: the analysis is disabled because there must be at least 2
factors
Warning 1484 AC analysis will not be performed during transient because of the commands
ordering: AC command must appear before .TRAN for that
Warning 1485 COMMAND .PARAMDEX: %s is ignored. It defines a DEV-like variation
while the model parameter has LOT specifications
Warning 1486 COMMAND .PARAMDEX: %s is ignored. It defines a LOT-like variation
while the model parameter has DEV specifications
Eldo® User's Manual, 15.3 1443

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Warning 1487 COMMAND .PRINTFILE: xaxis START and STOP values%s are lower
than TSTART given on .TRAN command. The command is ignored
Warning 1488 COMMAND %s: Unexpected argument %s inside %s
Warning 1489 Model level %d does not support UDRM. The .AGE command is disabled
Warning 1490 Model level %d does not support UDRM while model level %d does. The
.AGE command is disabled to avoid incorrect results
Warning 1491 COMMAND .OPTION OPSELDO_ALTER is only active when SQP
method is used
Warning 1492 COMMAND %s: keywords MASK and EXCEPT can only be applied to
generic output specifications or to output specifications which contain
wildcards
Warning 1493 COMMAND "%s": Command is ignored because the requested analysis is
not compatible with the analysis defined on .defwave %s
Warning 1494 COMMAND .EXTRACT %s XTHRES/XUP/XDOWN threshold parameter
expected a scalar instead of a waveform. DC value of the waveform is used.
Use XYCOND if you want to detect intersection of 2 waveforms
Warning 1495 COMMAND %s : %s expected after keyword %s. default is %s
Warning 1496 COMMAND .AGE: Unable to update parameter %s
Warning 1497 COMMAND .AGE: Analysis disabled. Accessing crypted parameters is not
allowed unless:
1/ command .SETKEY is crypted with the .PARAM
2/ command .USEKEY must be given in the netlist using the encrypted
models
Warning 1498 W() can only reference one wave name or one wave expression. So, writing
W(xx,yy) is not allowed
Warning 1499 COMMAND %s is ignored: complex waveforms are not supported
Warning 1500
Warning 1501 No DSPF on node %s because at least one object of a different hierarchy level
is connected to it using full pathname
Warning 1502 No DSPF on node %s
Warning 1503 DSPF command %s. Probably missing a *|NET instruction
Warning 1504 DSPF: Cannot find object %s
Warning 1505 DSPF: %s
1444
Eldo® User's Manual, 15.3

Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Error and Warning Messages
Miscellaneous Warnings
Warning 1506 %sDSPF: node %s was not found in instance %s. Therefore, no DSPF added
on that node
Warning 1507 DSPF: node %s was not found. Therefore, no DSPF added on that node
Warning 1508 DSPF: Syntax error at line %ld (no pin %s) or object %s can not be handled
Warning 1509 DSPF: No DSPF added on node %s
Warning 1510 DSPF: Node %s is still connected ! This might indicate a problem in DSPF
since this node should be replaced by a network
Warning 1511 DSPF: No inductor %s found for K %s
Warning 1512 DSPF: Unable to open include file %s
Warning 1513 DSPF: subckt %s unknown PORT %s. DSPF ignored on that SUBCKT
Warning 1514 DSPF: subckt %s: unconsistent number of pins. %ld pins found in DSPF, %ld
expected. DSPF ignored on that SUBCKT
Warning 1515 DSPF: subckt %s not defined in pre-layout
Warning 1516 DSPF: nesting error at line %ld
Warning 1517 DSPF: syntax error at line %ld
Warning 1518 DSPF: instructions at line %d ignored
Warning 1519 DSPF: Unable to find DSPF file %s
Warning 1520
Warning 1521 EXTRACT MODE: Any new binary data will be written to %s to avoid a
conflict with an input file
Warning 1522 Missing index extension on %s
Warning 1523 Device %s: mismatch in parameter %s != %s. First value taken
Warning 1524 Device %s: mismatch in parameter with respect to nominal values on %s.
Nominal values taken
Warning 1525 %s statement ignored on %s when DEV parameter on .DSPF_INCLUDE is
of type DSPF
Warning 1526 COMMAND %s: Unknown output type: %s. Following specifications are
ignored
Warning 1527 COMMAND %s: Unknown analysis type: %s. This command is ignored
Warning 1528 COMMAND .AGE: Unable to access parameter %s
Warning 1529 COMMAND .AGE: Unable to access parameter %s in subckt %s. The update
of parameters for this subckt has not been enabled in the initialization method
Eldo® User's Manual, 15.3 1445

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Table A-16. Miscellaneous Warnings (cont.)
Description
Warning 1530 COMMAND .MPRUN: host %s is ignored. It does not exist or it does not
allow remote connections
Warning 1531 COMMAND %s: Unable to parse expression %s
Warning 1532 COMMAND "%s": Incorrect output syntax for device %s
Warning 1533 .OPTION %s: Incorrect value %s. INDEX or XAXIS is expected
Warning 1534 COMMAND .MPRUN: FLAT method is disabled. It can only be used with
.alter
Warning 1535 %s output is not available
Warning 1536 COMMAND %s: No output specified. Default output %s is used
Warning 1537 COMMAND %s: More than one %s value specified. Previous value for %s
superseded by the last value specified
Warning 1538 COMMAND %s: Stress vector element is out-of-range. Command is ignored
Warning 1539 COMMAND .MC: PRINT_EXTRACT keyword is disabled when NONOM
or ALL is used. All extract values are printed by default
Warning 1540 COMMAND .EXTRACT: MC extract type can only be used with Monte-
Carlo statistical functions such as MCAVG, MCMIN, etc. Command is
ignored
Warning 1541 COMMAND .PRINTFILE: analysis set to %s
Warning 1542 COMMAND .AGE MODE=BLOCKLOAD: stress values have been loaded
for all devices affected by the reliability analysis. Since no new stress values
need to be calculated, MODE=LOAD is assumed
Warning 1543 COMMAND .DSPF_INCLUDE %s: No X instance found in the circuit
matching instance specification specified on the command
Warning 1544 COMMAND .RESTART: %s specification is not available inside Questa
ADMS
Warning 1545 COMMAND %s: SWEEP type indicates that the following output
specifications are measurement results. %s is not a known .EXTRACT or
.MEAS label
Warning 1546 COMMAND .MPRUN: This command is ignored since it has already been
specified
Warning 1547 DSPF: line %ld, device %s: no pin named %s found in pin list of SUBCKT
%s
Warning 1548 Unable to print/plot/extract lv9( ) when .op_display is used with vth_mask=0
and vtmod=1 or 2
1446
Eldo® User's Manual, 15.3

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Warning 1549
Warning 1550
Warning 1551
Warning 1552
Warning 1553
Warning 1554
Warning 1555
Warning 1557
Warning 1601
Warning 1602
Warning 1603
Warning 1604
Warning 1605
Warning 1606
Warning 1607
Warning 1608
Warning 1609
Warning 1610
Warning 1611
Warning 1612
Warning 1613
Warning 1614
Warning 1615
Warning 1616
Table A-16. Miscellaneous Warnings (cont.)
Description
COMMAND .AGE: API function %s is used outside its context. This
statement is ignored. This function should be called in %s only
COMMAND .FOUR: node %s is in a RF partition and therefore requires an
harmonic specification
COMMAND .DEFINE_GROUP %s: No %s named %s found in the design
COMMAND .DSPF_INCLUDE: file %s, on node %s: Swapping %s. That
rule will now be used by default for node and device names
COMMAND .DEFINE_GROUP %s: No subckt, instance or device match the
patterns. This command is ignored
COMMAND .ENDCOMPAT: This command is ignored as compat mode
was turned on using .option compat|compnet or -compat|-compnet. It should
be used with .COMPAT only
DSPF: component %s: node %s not found ( node declaration missing in *|S
statement ?)
.MC analysis: OUTER specified on MC command; only a simplified MC
output can be generated in that mode.
Eldo® User's Manual, 15.3 1447

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Warning 1617
Warning 1618
Warning 1619
Warning 1620
Warning 1621
Warning 1622
Warning 1623
Warning 1624
Warning 1625
Warning 1626
Warning 1627
Warning 1628
Warning 1629
Warning 1630
Warning 1631
Warning 1632
Warning 1633
Warning 1634
Warning 1635
Warning 1636
Warning 1637
Warning 1638
Warning 1639
Warning 1640
Warning 1641
Warning 1642
Warning 1643
Warning 1644
Warning 1645
Table A-16. Miscellaneous Warnings (cont.)
Description
1448
Eldo® User's Manual, 15.3

Error and Warning Messages
Miscellaneous Warnings
Warning
Number
Warning 1646
Warning 1647
Warning 1648
Warning 1649
Warning 1650
Warning 1651
Warning 1652
Warning 1653
Warning 1654
Warning 1655
Warning 1656
Warning 1657
Warning 1658
Warning 1659
Warning 1660
Warning 1661
Warning 1662
Warning 1663
Warning 1664
Warning 1665
Warning 1666
Warning 1667
Warning 1668
Warning 1669
Warning 1670
Warning 1671
Warning 1672
Warning 1673
Table A-16. Miscellaneous Warnings (cont.)
Description
Eldo® User's Manual, 15.3 1449

Error and Warning Messages
Warnings Related to Eldo Premier
Warning
Number
Warning 1838
Table A-16. Miscellaneous Warnings (cont.)
Description
Some waveforms are identical due to circuit connectivity. In order to save
disk space, only one is saved in the output file. Please use .option
force_wave_aliases if you prefer to duplicate waveforms in the output file.
The complete list of discarded waveforms is available in the .chi file.
Warnings Related to Eldo Premier
The following warning messages are related to Eldo Premier:
Table A-17. Warnings Related to Eldo Premier
Warning Description
Number
Warning 1021002 Can not create file 'name'
Warning 1021015 Convergence problem for DC simulation : name
Warning 1021016 Reducing time step from %lf to %lf
Warning 1021017 Convergence problem for TRAN iteration : name
Warning 1021022 Net 'name' removed from netlist because it is not connected to any device.
Warning 1021035 Unknown Option line (ignored) 'name'
Warning 1021040 OBJECT 'name' (name): Empty sub-circuit not created
Warning 1021047 NODE 'name': Connected with only %i element.
Warning 1021049 NET 'name': Not connected to any element. This net was removed from
the netlist.
Warning 1021050 OBJECT 'name': Not connected to parent subckt. This object has been
removed from the netlist.
Warning 1021072 PORT 'name': Not connected to any element. This port was removed from
the netlist.
Warning 1021075 PIN NAME 'name' could not be resolved
Warning 1021077 NET 'name': remove parasitic devices connected to this net
Warning 1021081 DSPF: invalid hierarchical name ``name name'' in ``I'' definition
Warning 1021082 NET 'name' could not be found in pathname dictionary
Warning 1021090 Net name not solved in structurally singular matrix of name
Warning 1021091 'name': is not supported
1450
Eldo® User's Manual, 15.3

Warning
Number
Warning 1021092
Warning 1021093
Warning 1021100
Warning 1021105
Warning 1021106
Warning 1021114
Warning 1021115
Warning 1021116
Warning 1021119
Warning 1021120
Warning 1021121
Warning 1021122
Warning 1021138
Warning 1021148
Warning 1021149
Warning 1021150
Warning 1021156
Warning 1021157
Warning 1021158
Warning 1021161
Warning 1021162
Error and Warning Messages
Warnings Related to Eldo Premier
Table A-17. Warnings Related to Eldo Premier (cont.)
Description
SUBCKT 'name': duplicate object 'name'
NETLIST is empty
DEVICE 'name': no path to active device. This device was removed from
the netlist.
The maximun number of iterations (itl4) was reached
The norme diverged
Eldo is not supposed to request simulation value at this point
The net 'name' is a floating gate
The net 'name' is connected to the ground
NODE 'name' has less than two connections
The net 'name' is no longer a floating gate (forward biased diode detected)
The net 'name' is disconnected from the ground (forward biased diode
detected)
run-time option 'name' : No instance 'name' found.
DC CPU time %lf msec, which is over limit %d sec, processed killed
No DSPF added on node name
DSPF: Duplicate ``I'' definition for ``name name'' with different nodes
``name'' and ``name'': definition with node ``name'' is ignored
DSPF: Inconsistency inside SUBCKT name. The ``I'' statement ``name
name'' should refer to the NET ``name'' whose hierarchical name is
``name.name'' while it refers here to node ``name''. This could indicate an
inconsistency in the DSPF file. Anyway, Eldo proceeds according to the
DSPF statement.
DSPF: node name was not found in instance name. Therefore, no DSPF
added on that node.
DSPF: node specified by ``NET'' directive ``name'' does not exist.
However, a node was found by converting ``name'' to ``name''. Therefore,
the same character conversion will be performed for all nodes of this
``NET'' section.
DSPF: Character sequence ``%c%c'' needed to be translated to ``%c''
(instead of ``%c%c'') to resolve hierarchical name ``name''. Therefore,
this translation rule will be applied for all hierarchical names.
.REDUCE: CC reduction not implemented in name
.REDUCE: RONLY reduction not implemented in name
Eldo® User's Manual, 15.3 1451

Error and Warning Messages
Warnings Related to Eldo Premier
Warning
Number
Warning 1021163
Warning 1021164
Warning 1021165
Warning 1021166
Warning 1021168
Warning 1021172
Warning 1021178
Warning 1021179
Warning 1021180
Warning 1021182
Warning 1021185
Warning 1021186
Warning 1021191
Warning 1021199
Table A-17. Warnings Related to Eldo Premier (cont.)
Description
Default reduction network type set to RC (TICER)
.REDUCE TICER: PORTMERGE not implemented in name
Due to the reduction process some outputs may not be available. Options
REDUCE_KEEP_NODE=nodename and
REDUCE_KEEP_INSTANCE=instance_name may be used to enforce
the availability of some specified node voltages or branch currents
respectively. Alternately, the global REDUCE_KEEP_OUTPUTS=YES
option may be used to enforce the availability of all required outputs. This
option may however hamper more strongly the reduction process.
DSPF: device kind '%c' is not supported (yet) in DSPF file. Therefore,
device ``name'' is not added.
NET ``name'' could not be exported (limitation of current
implementation)
OBJECT ``name'': parameter KR is not supported with h_mode
reltol=%g vntol=%g abstol=%g. This setting gives higher accuracy than
default tuning, but the simulation time may increase.
Newton: No convergence at time %gns ; try to pass over...
DSPF: subckt name not defined in pre-layout.
NODE ``name'': has been replaced by a DSPF network
SUBCKT 'name': duplicate object 'name' (from DSPF)
DSPF: port ``name'' appears in several ``|I'' interfaces. Only the first one is
taken into account.
Resistor name with small value is removed. Therefore, I(name) will not
be computed
Multi-threading mode disable : name
1452
Eldo® User's Manual, 15.3

Appendix B
Troubleshooting
Most users of any product will from time to time experience problems in its use. This appendix
is intended to provide an easy to use quick reference from which such problems can be
identified and corrected.
Common Netlist Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1453
Tips for Troubleshooting and/or Improving Convergence and Performance . . . . . . . . 1454
Tips for Troubleshooting Performance Bottlenecks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1454
Troubleshooting File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1455
Common Netlist Errors
There are a number of common errors to look out for when producing an input netlist:
• First Line of a File Not the Title.
The first line of a netlist must be the title of the circuit. If part of the circuit description is
found on the first line, it will be ignored. If the first line is a blank, this will be taken as
the title line.
• Correct Usage of the Simulator Accuracy (eps, vntol, reltol).
The simulator accuracy parameters are the most important Eldo parameters—they must
be correctly initialized.
Tip
For more details refer to the Speed and Accuracy chapter.
• Correct Units on Devices.
It is very important to make sure that all the components in the netlist have correct units;
one mistake can have a large effect. An example of this is specifying units of farads
instead of picofarads.
• Missing Model.
Make sure that model definitions are available to the simulator, either directly in the
netlist, or in a referenced library.
• Missing Voltage Sources.
Independent voltage sources defined to have a voltage of 0V may be removed by Eldo
to simplify calculations. If you wish to use a voltage source as a current probe, avoid
Eldo® User's Manual, 15.3 1453

Troubleshooting
Tips for Troubleshooting and/or Improving Convergence and Performance
defining its voltage as 0V, but instead, define its voltage value to be very small.
Moreover, currents through components may be measured directly, therefore, the use of
voltage sources as current probes is not necessary.
• Correct Model Name Syntax.
The first character of a model name cannot be a number. This causes the compilation of
the netlist to be interrupted, and an error message to be displayed.
• Unknown Model Parameter.
When defining model parameter values, care must be taken to ensure that the parameter
is spelt correctly and that it is indeed a legal parameter of the device.
• Ground (0) Node.
A 0 node (ground) must always be present in the input netlist.
Note
Eldo does not recognize GND as GROUND!
• Reserved Keywords.
Some keywords should not be specified in a .PARAM command. If they are then errors
will be generated. See .PARAM in the Eldo Reference Manual.
Tips for Troubleshooting and/or Improving
Convergence and Performance
This topic collects together a number of techniques for improving convergence and/or
simulation performance.
• Operating Point Calculation.
See “Improving DC Convergence” on page 211 and “DC Convergence
Troubleshooting” on page 213.
• Saving, Using, and Restarting Simulations.
See “Improving DC Convergence” on page 211.
Tips for Troubleshooting Performance
Bottlenecks
To help you understand why a circuit does not behave as expected, or takes more time than
expected to simulate, a set of diagnostics are available.
See “Diagnosing Convergence and Performance Issues” on page 377.
1454
Eldo® User's Manual, 15.3

Troubleshooting File
Troubleshooting
Troubleshooting File
If an unexpected problem is detected by Eldo (for example, a message that reports an “Error
Code”) the simulation will terminate, and one of the following files will be generated in the
output directory:
• eldo-stacktrace.vstf
• eldo-stacktrace.dump
Include the eldo-stacktrace file along with the model causing the error when submitting your
Service Request to Mentor support. For more information on Service Requests, please refer to
the section Tracking Service Requests, DRs, and ERs of the AMS Release Notes.
Eldo® User's Manual, 15.3 1455

Troubleshooting
Troubleshooting File
1456
Eldo® User's Manual, 15.3

Appendix C
Eldo Interactive Mode
Eldo interactive mode is a way of invoking Eldo and sending commands to it interactively
instead of sending the commands in the netlist. Some other AMS tools, such as ICanalyst, make
use of Eldo in the interactive mode, although this is transparent to the user. Eldo interactive
mode is not supported by Questa ADMS.
Invoking Eldo Interactive Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1457
Reading Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1459
Resetting Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1461
Change Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1463
Controlling Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1466
Invoking Eldo Interactive Mode
To invoke Eldo interactive mode, from the command line run eldo with the -inter argument:
eldo cir_file_name -inter
where cir_file_name is the name of the .cir control file to be simulated. Default extension is .cir.
When working in Eldo interactive mode, a prompt will appear:
eldo>
Some help information is available, at the eldo> prompt. Type:
help
help
help all
to see the list of available commands
for more information about a particular command
to obtain the complete help listing
When working in Eldo interactive mode, type your command after the eldo> prompt. For
continuation lines, type the backslash character (\) at the end of a line.
Commands can be read from a file specified via either of the following:
• .eil file_name in the input file
• -eil file_name at invocation of Eldo
Eldo® User's Manual, 15.3 1457

Eldo Interactive Mode
Invoking Eldo Interactive Mode
The eldo> prompt appears before the first simulation, unless:
• option DOSIMCIR is specified
• -DOSIMCIR used at invocation of Eldo
To control simulation, use the following commands:
QUIT
LOAD
RUN
GO
CONT
NEXT
To check netlist elements, use the following commands:
DISPLAY
LIST
To handle simulation information, use the following commands:
STATUS
PRINT
DELETE
RESET
OPTRESET
To handle breakpoints, use the following commands:
STOP IF (expression)
STATUS BREAK n
DELETE |ALL
To alter simulation conditions, use the following Eldo/SPICE commands:
.TRAN
.DC
.AC
.OP
.STEP
.TEMP
.ALTER
.NOISETRAN
To change stimuli, re-instantiate the device with new values:
Vxx n1 n2
To change element/model parameters, or parameters, use:
SET
1458
Eldo® User's Manual, 15.3

Eldo Interactive Mode
Reading Information
Use the command, eilout file_name, to redirect the outputs generated by specific Eldo
interactive commands to the specified file. Errors are still displayed on the terminal window.
Use the command, eilout stdout, to switch back to the default mode, where information is sent
to the terminal window.
Reading Information
This section describes the commands used to read information.
STATUS
STATUS [BREAK]
STATUS ANAL
STATUS AC
STATUS TRAN
STATUS DC
STATUS MC
STATUS PZ
STATUS EXTRACT
STATUS PLOT
STATUS PROBE
STATUS PRINT
STATUS PARAM
STATUS INPUT
STATUS SAVE
STATUS RESTART
STATUS MCMOD
STATUS MCPARAM
STATUS STAT
STATUS OPTION
shows breakpoints
shows status of the current simulation
shows the AC simulation command and stimuli
shows the TRAN simulation command
shows the DC simulation command
shows the MC simulation command
shows the PZ simulation command
shows the expressions to extract
shows the .PLOT commands typed
shows the .PROBE commands typed
shows the .PRINT commands typed
shows the parameters (.PARAM)
shows the input stimuli
shows the .SAVE commands issued
shows the .RESTART commands issued
shows the MC specifications on models
shows the MC specifications on parameters
shows the statistics at runtime
shows all the options set inside Eldo
PRINT
The PRINT command can be issued to display:
• Voltage or current (like plot command)
Eldo® User's Manual, 15.3 1459

Eldo Interactive Mode
Reading Information
• Values from the extract-command language
• EXTRACT indexwhere index is the key returned by STATUS EXTRACT
• Values of Device/Models/Parameters; syntax is:
PRINT E ([,W/L/AD/AS/PD/PS/NRD/NRS/AREA])
PRINT M (,)
PRINT P ()
• OPTION
Examples:
PRINT V(S)
PRINT V(S) + V(SS)
PRINT TPD(E,S)
PRINT OPTIM 2
Note
Note that the extract information issued through a PRINT command works only if the
corresponding .EXTRACT command had been specified before running the simulation, or if
Eldo is able to extract the information from the binary output file (.PLOT available, and
general-purpose extraction language used).
DISPLAY E string[*]
The DISPLAY E string* command can be used to display the connectivity information,
parameter names and values, if any, for each element selected by the string.
The following commands are also available to list netlist elements. Wildcards are supported in
the name specification.
Command
LIST []
[.]LSDEV []
LSDEVPAR
LSDEVMOD
[.]LSMOD []
Table C-1. Netlist Element Commands
Description
Returns the list of all elements which have a name
matching specified name. For example:
eldo> LIST string*
Lists all elements whose name begins with string.
Returns the list of all elements which have a name
matching specified name.
Returns the list of all parameters of specified element.
Returns the model of the specified element.
Returns the list of all models which have a name matching
specifed name.
1460
Eldo® User's Manual, 15.3

Command
[.]LSMODEV
LSMODPAR
[.]LSSUB
[.]LSSUBDEV
LSSUBPAR
LSPAR []
.LPTOP
[.]LDEVNODE
.LNODEDEV
[.]TRACEI
[]
Resetting Features
Table C-1. Netlist Element Commands (cont.)
Description
This section describes the commands used to reset several features.
Eldo Interactive Mode
Resetting Features
Returns the list of all elements which have a model
matching specifed name.
Returns the list of all parameters of the specified model.
Returns the list of all the subckt which have a name
matching specifed name.
Returns the list of all the instances of the specified subckt.
Returns the list of all the parameters of the specified
subckt.
Returns the list of all parameters which have a name
matching specified name.
Returns the list of top level parameters.
Returns the list of devices connected to the specified
node.
Returns the list of nodes connected to the specified
device.A device name must be specfified as an argument.
For example, with the device:
M1 A B C D NMOS w=10u l = 3u
eldo> .lnodedev M1
will return:
M1.1 A
M1.2 B
M1.3 C
M1.4 D
Returns the list of current contributions on the specified
node. The optional value is a threshold value. For
example, under the eldo> prompt, you can specify:
eldo> tracei s 1.0e-8
IX(M4.1) = -2.1725E-05
IX(M9.1) = 2.1725E-05
The two contributions are not dumped because they fall
below the threshold 1.0e-08. This tracei command returns
current contributions on the specified node (s in this
example): 1.0e-8 is a threshold, optional.
Eldo® User's Manual, 15.3 1461

Eldo Interactive Mode
Resetting Features
RESET
RESET [PRINT|PLOT|PROBE|IC|NODESET|GUESS|EXTRACT]
Used to remove a set of commands.
RESET FILES
Rewind output files .cou and .chi.
The options available in Eldo interactive mode are listed in the tables below.
DC Control Options
GMIN NMAXSIZE ITL1 GRAMP
NETSIZE VMIN VMAX
Accuracy Control Options
ITOL EPS VNTOL RELTOL
RELERR PIVREL PIVTOL ABSTOL
FLXTOL
MAXORD
Time-Step Control Options
ZOOMTIME STEP STARTSMP FREQSMP
OUT_RESOL TRTOL HMIN ITL3
ITL4 FT DCLOG LVLTIM
LVLCNV DVDT RELVAR ABSVAR
SAMPLE HMAX SPICDC NOSPICDC
Options which can be set, but not reset:
SPIOUT NEWTON OSR TRAP
GEAR BE PROBEOP NOLAT
NWLAT ANALOG BBDEBUG NOSIZECHK
QTRUNC UNBOUND LCAPOP
1462
Eldo® User's Manual, 15.3

Eldo Interactive Mode
Change Features
Change Features
Some Eldo commands are available from interactive mode.
.TRAN .AC .DC .OP .STEP .TEMP
.PLOT .PRINT .PROBE .PLOTBUS .PRINTBUS .PROBEBUS
.EXTRACT .OPTION
.MEAS .FOUR .OPTFOUR
.NODESET .IC .GUESS
.SAVE .RESTART .USE .LIB
You can change the stimuli in interactive mode. The complete line must be re-entered with new
stimuli. For example:
V1 1 2 PWL (0 0 20n 0 30n 5)
Eldo interactive checks the component name, and applies the new stimuli.
BUS
BUS
Define a bus. The BUS command defines a bus with several different nodes by grouping them
together.
Name of the new bus
Ignored (kept for Lsim compatibility)
List of nodes composing the bus (msb...lsb).
Example:
bus foo x A[0] A[1] A[2] A[3] clk reset
bus foo x A[0:3] clk reset
bus ADD x A0 A1 A2 A3 A4 A5
[.]CHMOD
CHMOD
Replace the model by the model for all the devices using (can
be used for M, Q, D, J models).
DELETE
DELETE BREAK index
DELETE BREAK ALL
DELETE index
Eldo® User's Manual, 15.3 1463

Eldo Interactive Mode
Change Features
DELETE is used to remove breakpoints used to stop Eldo at run time. The third syntax is used
to remove the command corresponding to the index returned by the command STATUS .
DISABLE
DISABLE BREAK index
DISABLE BREAK ALL
DISABLE is used to remove breakpoints used to stop Eldo at run time. Breakpoints can be
enabled back using command ENABLE.
ENABLE
ENABLE BREAK index
ENABLE BREAK ALL
ENABLE is used to re-activate breakpoints used to stop Eldo at run time, whenever these
breakpoints have been disabled by DISABLE.
FORCE
FORCE =
Force the node node_name to value after RISE_TIME or FALL_TIME depending on current
value (see further information below). Used to impose a voltage on a node. If multiple FORCE
are applied on the same node, the last command is used. If an input signal was applied on the
node it will be ignored. The voltage imposed by FORCE can be removed using RELEASE.
HIGH
HIGH
Force the node node_name to HIGHVOLTAGE after RISE_TIME (see further information
below).
LOW
LOW
Force the node node_name to LOWVOLTAGE after FALL_TIME (see further information
below).
Tip
The previous three commands contain the parameters, HIGHVOLTAGE, LOWVOLTAGE,
RISE_TIME and FALL_TIME. These parameters can be set using the .OPTION command.
For more information, see Miscellaneous Simulation Control Options in the Eldo Reference
Manual.
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Eldo® User's Manual, 15.3

Eldo Interactive Mode
Change Features
PWL
PWL t1 v1 [t2 v2] ...
Force a PWL on the specified node during transient simulation. tn are times
relative to the current time. vn are the source values at tn.
RELEASE
RELEASE ...
Release force on node. If a signal is present on node , and if no FORCE command
had been applied on the node, then the signal is disabled (node will be computed by Eldo as any
other node).
SET
SET E ( [,W/L/AD/AS/PD/PS/NRD/NRS/]) [=]
SET M (,) [=]
SET P () [=]
The SET command is used to change device geometries or models parameters. The
parameter_name can be specified as a string parameter.
SETBUS
SETBUS [[:]]
Set a value on a bus. The SETBUS command sets a value on the specified bus. Values may be
specified as binary, octal, hexadecimal, or decimal. The bus bit accepts the standard digital
values 1, 0, X and Z.
The command automatically sets all signals in a bus if the subscripted values are omitted. The
default bit order is the European style D 0 ...D N-1 . Therefore, for a hierarchical base name that
defines an 8-bit bus, the command:
setbus Xcircuit.port[0:7] b00001111
is equivalent to:
setbus Xcircuit.port b00001111
To use the American style D N-1 ...D 0 bit order, you must specify the range of bits explicitly:
setbus Xcircuit.port[7:0] b00001111
The SETBUS command ignores the most significant portion of values that are wider than the
specified bus. Therefore, if you set a value of hexadecimal 8F to a 12 bit bus, the bus receives
the value 0F.
Eldo® User's Manual, 15.3 1465

Eldo Interactive Mode
Controlling Execution
Note
This SETBUS syntax is different to the Eldo .SETBUS syntax used in the netlist .cir file.
See .SETBUS and .SIGBUS in the Eldo Reference Manual. However, if you want to use the
netlist syntax in interactive mode, specify the Eldo interactive command:eldo>LSIM OFF
TRANSITION
TRANSITION TT VALUE [DELAY]
TT
VALUE
DELAY
Transition Time
Value of the signal after the transition
Time delay before the transition starts
Overwrite the signal which was on node by a PWL:
Vxx 0 PWL (
)
Controlling Execution
This section describes the commands used to control execution.
LOAD
This command stops the current simulation, and Eldo loads the file . Extension .cir
is assumed.
SAVESIM
Eldo creates three files:
1. filename.eilThis file contains all the commands typed since the loading of the circuit
file; it is possible to re-execute this set of functions by:
-i circuit -eil filename.eil
2. filename.chiThis file contains the ASCII output.
3. filename.couThis file is the binary output file readable by graphic-postprocessors.
Note
A .pz file might be created if a .pz card exists.
The files circuit.cou and circuit.chi are then reset.
1466
Eldo® User's Manual, 15.3

STOP IF
Eldo Interactive Mode
Controlling Execution
Set breakpoints in interactive mode. can refer to the SWEEP value, and/or any
valid plot command.
The argument, soadetected, can be specified to specify a breakpoint on a safe operating area
(SOA).
Examples:
STOP IF (SWEEP > 1n)
STOP IF ((SWEEP > 10n) && (V(S) > 2.5))
stop if(soadetected(mysoa))
Eldo will stop the first time the .SOA labeled mysoa is violated. Wildcards are allowed in
soadetected.
STOP SIMU
Stop the current simulation; Eldo is then ready to run a new simulation.
RUN
Restart the simulation.
RUN FOR
RUN UNTIL
Run until the sweep value has changed of
Run until the sweep value reaches
Note
can be a parameter, this must be specified on the .PARAM command in the netlist.
NEXT [SIMU]
NEXT
NEXT SIMU
Eldo will stop at the next sweep value.
Eldo will stop after the next simulation if .TEMP or
.STEP command are found.
CONT
CONT
Forces Eldo to continue the simulation(s) until
breakpoints are encountered, or the requested number
of simulation is completed.
Eldo® User's Manual, 15.3 1467

Eldo Interactive Mode
Controlling Execution
QUIT
QUIT
QUIT SIMU
Quit the application.
Stop current analysis.
VIEW , UNVIEW
Used for adding or removing signals whenever EZwave is connected to Eldo, running in
interactive mode.
Examples:
view V(VDA)
view I(*)
1468
Eldo® User's Manual, 15.3

Appendix D
Eldo Conversion Utilities
This appendix describes some conversion utilities available with Eldo.
Utility to Convert .chi to .cir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1470
Utility to Convert VCD to Test Vectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1471
Utility to Convert a Waveform Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1473
Eldo® User's Manual, 15.3 1469

Eldo Conversion Utilities
Utility to Convert .chi to .cir
Utility to Convert .chi to .cir
A standalone utility chi2cir converts an Eldo ASCII output (.chi) file into a netlist (.cir) file. The
resulting netlist file is independent of any libraries (no .LIB/.INCLUDE required), and all
information required for another simulation is inside the netlist file (providing that there were
no commands such as .NOTRC preventing the writing of the circuit description in the .chi file).
Usage
chi2cir [chifile cirfile]
Arguments
• chifile
Input filename, the Eldo ASCII output (.chi) file.
• cirfile
Output filename for the resulting netlist (.cir) file.
If no options are specified, the utility will prompt you for filenames.
Description
This utility could be useful to exchange testcases between user’s avoiding library dependence
and would also simplify the creation of different tests on the same circuit.
Once the circuit has been run once (to generate the .chi file), run this chi2cir utility to generate a
testcase from this .chi output to modify some parameters/options to re-run other simulations.
• The chi2cir utility does not handle references to Verilog-A model files or S-parameters
files.
• No provision is made for .ALTER statements for multiple simulation runs, only the first
simulation is taken into account.
Examples
chi2cir trigger.chi my_trigger1.cir
Once the original trigger.cir circuit had been run once (to generate the .chi file), running the
chi2cir utility on the trigger.chi ASCII output file generates a testcase file my_trigger1.cir.
Some parameters/options can then be modified in this testcase to re-run other simulations.
1470
Eldo® User's Manual, 15.3

Eldo Conversion Utilities
Utility to Convert VCD to Test Vectors
Utility to Convert VCD to Test Vectors
A standalone utility vcd2tv can be used to convert VCD (Value Change Dump) stimuli into test
vectors. It is a simple format converter, and can be used independently for any simulator.
Output is in the test vector format. This utility can also be used to convert EVCD (extended
VCD) files. Note when converting from EVCD format: inout statements are converted to input
statements.
Usage
vcd2tv -i vcd_input_file [-io io_input_file] [-o tv_output_file]
[-hier] [-end_time conversion_end_time] [-case]
Arguments
• -i vcd_input_file
Input filename. Name of the VCD file to convert.
• -io output_file
Input/output filename. Name of the file containing the I/O definition (input or output).
• -o tv_output_file
Output filename. Name of the test vector file (.tv) to generate.
• -hier
When specified hierarchical node names are also converted. If not specified, only the top
level is converted.
• -end_time conversion_end_time
Conversion time limit (if not specified conversion is done until the end of the VCD file).
• -case
Enables the case sensitive treatment of signal names.
If this is not enabled, and the utility detects two signals with the same name except for the
case, a warning will be generated suggesting to enable case-sensitivity with the -case
argument. For example:
*** Warning:the following signals are merged because their names
differ only by the case. Please use -case option to enable case
sensitivity.
CLK
clk
Description
The ADiT Fast-SPICE simulator supports VCD directly because it internally converts it to test
vector format, transparently using the vcd2tv converter. Eldo is not able to read VCD, which is
why this utility is useful. It can be used for any simulator which can read test vectors but not
VCD.
Eldo® User's Manual, 15.3 1471

Eldo Conversion Utilities
Utility to Convert VCD to Test Vectors
After converting a VCD file, use the generated test vector file by specifying the .TVINCLUDE
command in the Eldo Reference Manual.
Examples
vcd2tv -i testcase2.vcd -io testcase2_ports.csv
Converts the VCD values into test vectors, using the I/O definition provided in the .csv file,
storing the test vectors in the generated file vcd2tv.tv.
1472
Eldo® User's Manual, 15.3

Eldo Conversion Utilities
Utility to Convert a Waveform Database
Utility to Convert a Waveform Database
A standalone utility ffcv can be used to convert a waveform database from one format to one, or
several, other formats.
Usage
ffcv [-i] input_database output_format_modifier [output_database]
[-cvt_start xstart] [-cvt_stop xstop] [-cvt_tsample xvalue]
[-cvt_progress] [-cvt_stat] [-cvt_duplicate_rule]
[-cvt_mode SEQUENTIAL | GROUP | FULL]
[-cvt_group_size val]
[-cvt_untyped VOLTAGE | CURRENT]
[-cvt_trise val] [-cvt_tfall val]
[-tabular_comment string]
[-tabular_separator string]
[-cvt_numdgt value]
[-cvt_selection_list filename]
Arguments
• [-i] input_database
Input filename with known extension. Name of the waveform database file to convert.
Note
Split FSDB files of the following extensions are allowed: .fsdb.X or
.fsdb0.x; .X.fsdb or .X.fsdb0; .fsdb_X or .fsdb0_X.
• output_format_modifier
Specification of the output format to generate. Can be one of the following:
Table D-1. ffcv Output Format Modifier
output_format_modifier Output Format
-cou
Binary COU file
-cou_ascii
Raw ASCII representation of a COU file
-comment
Commented ASCII representation of a COU file
-compat
Binary compatible file
-compat_ascii
ASCII compatible file
-csdf
CSDF file
-fsdb
FSDB file, compatible version is v5.2 (release
2014.12) on Linux only
-wdb
Joint Waveform Database file (Eldo default)
-stimuli
SPICE representation of voltage waveforms
Eldo® User's Manual, 15.3 1473

Eldo Conversion Utilities
Utility to Convert a Waveform Database
Table D-1. ffcv Output Format Modifier (cont.)
output_format_modifier Output Format
-tabular
Tabulated representation of waveforms
-wdf WDF file, compatible version is v2007.1
• output_database
Output filename. Name of the waveform database file to write converted format to. By
default the root name of the input file is used with the output format modifier extension.
General Purpose Arguments
• -cvt_start xstart
Conversion start point (time or frequency) in database.
• -cvt_stop xstop
Conversion end point (time or frequency) in database.
• -cvt_tsample xvalue
Time or frequency interval to sample output data.
• -cvt_progress
Displays the conversion progression, in percent.
• -cvt_duplicate_rule FIRST | MAX | MIN | LAST | ALL
Selects which value must be written to the output database when the input database contains
multiple values at the same X. Default is set to ALL if the input database uses a compatible
format, and MAX for other formats.
Format-Specific Arguments
• -cvt_mode SEQUENTIAL | GROUP | FULL
Applies to FSDB format only. Selects the method used to convert the input database into the
target format(s). This option is format dependent: it can be ignored if the input (or output)
format does not support one or the other method. Default is set to FULL.
FULL
All waveforms are loaded in a single pass reading. This method is faster than the
sequential method, but it requires more memory. Default.
GROUP
Waveforms are loaded in groupings of 200. This is an intermediate conversion mode
between FULL and SEQUENTIAL. To modify the grouping size specify argument
-cvt_group_size.
SEQUENTIAL
Waveforms are loaded one after another. This method is often slower because it uses
multiple-pass reading. However, it usually requires less memory.
1474
Eldo® User's Manual, 15.3

Eldo Conversion Utilities
Utility to Convert a Waveform Database
• -cvt_group_size value
Applies to FSDB format only. Specifies the number of waveforms to load simultaneously in
-cvt_mode GROUP mode.
• -cvt_stat
Applies to FSDB format only. Displays statistical information about file content. For
example:
Statistical information about data read so far :
------------------------------------------------
simulator version: ELDO 15.1 (64 bits)
number of unsupported waveforms: 0
number of waveforms: 5
analog: 5
digital: 0
bus: 0 (for a total of 0 bits)
number of aliases: 0
number of files: 1
number of nodes in the hierarchy: 1
• -cvt_selection_list filename
Applies to FSDB format only. Provides a list of waveforms to extract from the input file,
one waveform name per line. Wildcards are not supported. Waveform names are casesensitive.
They follow FSDB syntax, the hierarchy comes before the signal name, for
example:
/top/x1/V(input)
The hierarchy separator can be specified inside the file using syntax:
#hierarchy_separator
where character is the hierarchical separator (default is /).
Example conversion notes:
Conversion note: 4 signal references have been identified in file
my.list.txt
Conversion note: 2 waveforms matching selection list were loaded
from FSDB file.
• -cvt_untyped VOLTAGE | CURRENT
Applies to WDB and STIMULI output only. Defines the default type which must be
assigned to untyped waveforms such as VHDL-AMS real signals.
• -cvt_trise value
Applies to STIMULI output only. Specifies the rise time applied to edges encountered while
converting digital-like waveforms, such as VHDL-AMS real signals, into analog waveforms
(default is 1.0e-12 seconds).
Eldo® User's Manual, 15.3 1475

Eldo Conversion Utilities
Utility to Convert a Waveform Database
• -cvt_tfall value
Applies to STIMULI output only. Specifies the fall time applied to edges encountered while
converting digital-like waveforms, such as VHDL-AMS real signals, into analog waveforms
(default is 1.0e-12 seconds).
• -tabular_comment string
Applies to TABULAR output only. Defines the comment character for tabular output
format.
• -tabular_separator string
Applies to TABULAR output only. Defines the column separator for tabular output format.
For example to remove the comment char and use a comma as the separator, specify the
command:
ffcv -tabular -tabular_comment """" -tabular_separator "", ""
• -cvt_numdgt value
Applies to TABULAR output only. Specifies the number of significant digits printed for
numerical values.
Description
See also:
• Index File Format in the EZwave User’s and Reference Manual
• dataset merge in the EZwave User’s and Reference Manual
1476
Eldo® User's Manual, 15.3

Appendix E
STMicroelectronics Models
Describes how to use the STMicroelectronics models inside Eldo, which is called Eldo-ST
mode.
How to Invoke Eldo-ST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1477
What Does Eldo-ST Mode Change?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1478
How to Invoke Eldo-ST
Eldo-ST mode is invoked either on the command line or by specifying an option. The .OPTION
takes precedence. Use to enable STMicroelectronics device models.
• Command line:
eldo -stver ... cir_file_name
• Option (must be specified before the .MODEL cards):
.OPTION STVER
You can disable the Eldo-ST mode either on the command line or by specifying an option. The
.OPTION takes precedence.
• Command line:
eldo -nostver ... cir_file_name
• Option (must be specified before the .MODEL cards):
.OPTION NOSTVER
Instead of these global settings, you can enable individual ST-models by adding the following
in the .MODEL card:
MODTYPE=STVER
This takes precedence over any STVER or NOSTVER global setting (in the command line, as
an option, or in the Eldo initialization file eldo.ini).
When MODTYPE=STVER is used, some additional options can also be specified that are set
by default when the global Eldo-ST mode is set:
• .option WL
Eldo® User's Manual, 15.3 1477

STMicroelectronics Models
What Does Eldo-ST Mode Change?
Reverses the order of MOS length and width specification for rare cases where only
values are specified without keywords W= and L=.
• .option ERRDEVDUPLI
Forces Eldo to stop the simulation and generate an error if there are duplicate instance
names. Default.
• .option STPROBEOP
Forces Eldo to generate the operating point file named probeop# instead of
.op#.
What Does Eldo-ST Mode Change?
When Eldo-ST is invoked, model levels are automatically changed to use Eldo-ST in exactly
the same way as ST-SPICE.
You can use standard Eldo levels in Eldo-ST by adding the following in the .MODEL card:
MODTYPE=ELDO
Specially tuned device models have been developed for use when simulating
STMicroelectronics designs. These STMicroelectronics models are available within the
standard version of Eldo.
A special version of Eldo is also available which has been developed for use within the
STMicroelectronics design kit. This version is identical to the standard version in every respect
except that the STMicroelectronics device models occupy different levels within the lists of
available device models.
Option OPTYP
When Eldo-ST is invoked, an additional control of Operating Point information is available.
• .OPTION OPTYP=2
Can be specified only when either the -stver argument or the STVER option are set.
Used to print the reduced operating point information for the MOSFET models (see the
SPICE documentation for more details). Otherwise equivalent to optyp=1. This can be
used with UDM and BSIM4 models.
Table E-1 lists the character string displayed in the Operating Point table for the different optyp
values. Elements on the same line are synonymous: that is, the same value is printed if optyp
changes.
1478
Eldo® User's Manual, 15.3

STMicroelectronics Models
What Does Eldo-ST Mode Change?
optyp=1 (Default)
or optyp=3
Table E-1. Operating Point—optyp values
When -stver argument
or STVER option is set
ID ID ID
IS
IB
VGS VGS VGS
VDS VDS VDS
VBS VBS VBS
VTH VTH VTH
VDSAT VSS VSS
When -stver argument or
STVER option is set and optyp=2
GM -Gsg gm
GDS
Gds
GMB Gdd+ Gdg + Gds gmbs
Ibd
Ibd
Ibs
Ibs
Gdd
Gdg
Gss
Gsd
Gbd
Gbs
RON
1/max(1e30,Gds)
An explanation of some of these parameters is provided below:
Ibd
Ibs
VTH
VSS or VDSAT
Bulk-drain current through the parasitic BD diode.
Bulk-source current through the parasitic BS diode.
Internal threshold OP dependent; see the Eldo Device Equations
Manual for how it is computed.
Saturation voltage at DCOP.
Eldo® User's Manual, 15.3 1479

STMicroelectronics Models
What Does Eldo-ST Mode Change?
Gxy
Cxy
Isub
Derivative of static current on node x with respect to Vy; x and y
can be one of D, G, S, B.
Derivative of charge on node x with respect to Vy; x and y can
be one of D, G, S, B.
Subthreshold current component.
As shown in Table E-1, with the -st argument or STVER option set and optyp not set or not 2,
then Eldo reports multiple Gxy terms, where Gxy stands for derivative of current on pin x with
respect to voltage on pin y. For example, Gds is the derivative of the current on the Drain with
respect to the voltage on the Source. In all other cases, just three conductances values are
reported:
• GM is the derivative of IDS with respect to VGS.
• GDS is the derivative of IDS with respect to VDS.
• GMBS is the derivative of IDS with respect to VBS.
In the OP table for BSIM3v3, Eldo also displays VBI and PHI:
PHI
VBI
Surface potential at strong inversion.
Built-in voltage for the PN junction between the substrate and
the source.
Table E-2. Operating Point—optyp values—Dynamic Part for Charge Control
Model
optyp=1
(Default)
optyp=3
When -st argument or
STVER option is set
Cdd Cddb Cdd
Cdg Cdgb Cdg
Cds Cdsb Cds
Cdb Cdb Cdb+CJDB
Cgd Cgdb Cgd Cgd+CVGD
Cgg Cggb Cgg
Cgs Cgsb Cgs Cgs+CVGS
Cgb Cgb Cgb+CVGB
Csd
Csd
Csg
Csg
When -st argument or
STVER option is set and
optyp=2
1480
Eldo® User's Manual, 15.3

Css
Css
Csb Csb Csb+CJSB
Cbd Cdbd Cbd
Cbg Cbgb Cbg
Cbs Cbsb Cbs
Cbb
Cbb
Option PROBEOP
STMicroelectronics Models
What Does Eldo-ST Mode Change?
Table E-2. Operating Point—optyp values—Dynamic Part for Charge Control
Model (cont.)
optyp=1
(Default)
optyp=3
When running Eldo-ST mode, with the -stver flag or option STVER set, option PROBEOP is
set by default and the generated file is named probeopX, where X is the index of the run. Specify
option NOPROBEOP to disable the creation of the probeopX file in Eldo-ST mode.
Option NODUPINSTERR
When -st argument or
STVER option is set
When -st argument or
STVER option is set and
optyp=2
When running Eldo-ST mode, with the -stver flag or option STVER set, option
NODUPINSTERR changes ERROR 838 into WARNING 204. This option is ignored if not
specified with the stver argument/option.
Eldo® User's Manual, 15.3 1481

STMicroelectronics Models
What Does Eldo-ST Mode Change?
1482
Eldo® User's Manual, 15.3

Index
— Symbols —
! comment delimiter, 104
.AC
Examples, 1272, 1275, 1278, 1281, 1291,
1306
.ADDLIB
.SUBCKT, 127
.ALTER
Altering netlist data, 298
Examples, 300
.CHECKSOA
Safe Operating Area (SOA) Checks, 341
.cir file, 95
.cir File Structure Overview, 97
.DATA
Sweeping parameters, 296
.DC, 205
.DCMISMATCH, 269
.DEFPLOTDIG, 316
.DEX, 274
.DSPF_INCLUDE
Post-layout simulation, 394
.EXTRACT
Extract functions, 324
Extract outputs, 324
Extracting information, 321
Extraction Mode, 327
Monte Carlo analysis (.MC), 465, 468
Plot and print quantities, 323
.HIZ
High Impedance Node Checks, 349
.IP_protect, 146
.LIB
.SUBCKT, 127
Interactive mode, 137
.LSTB, 229
Example, 1299
.MC, 265
Examples, 1291
Index
.MODEL
Examples, 1278, 1281, 1284, 1287, 1291,
1294
.MPRUN, 156
.NOISE, 239
Examples, 1278
.NOISETRAN, 241, 244
.OP, 208
.OPTNOISE, 239
.PARAM
Examples, 1287
Parameter values, 291
.PLOT
.AC, 225
.TRAN, 218, 259, 268
Dynamic plot, 47, 318
Examples, 1272, 1275, 1278, 1281, 1284,
1287, 1291, 1295
.POWER_ANALYSIS, 279
.PRINT
.AC, 225
.TRAN, 218, 259, 268
.PZ, 230
.RAMP
DC Operating Point Calculation, 212
.REDUCE
Reduction, 404
.SAVE
DC Operating Point Calculation, 215
End of Simulation Results, 221
.SENS, 270
Examples, 1294
.SENS TRAN, 272
.SENSAC, 272
.SENSPARAM, 273
.SETSOA
Safe Operating Area (SOA) Checks, 341
.STEP
Nested sweeps, 295
Sweeping parameters, 292
Eldo® User's Manual, 15.3
1483

Sweeping parameters examples, 292
.SUBCKT
.PRINT, 310
Examples, 1281
.TEMPNODE, 282
.TF, 237
.TRAN
Examples, 1275, 1284, 1287, 1298, 1303,
1305, 1307
.USE
DC Operating Point Calculation, 215
.USE_TCL, 1139
.WCASE, 267
*comment delimiter, 103
// comment delimiter, 103
— Numerics —
4th Order Butterworth Filter Tutorial, 1274
5th Order Elliptic SC Low Pass Filter Example,
1303
— A —
ABS (Absolute value) function, 109
AC Analysis (.AC)
.LSTB, 229
.PZ, 230
.TF, 237
4th Order Butterworth Filter Example,
1275
Active RC Band Pass Filter Example, 1306
Adaptive example, 226
Band Pass Filter Example, 1278
Description, 224
during Transient analysis, 226
Examples, 1281, 1295
Parallel LCR Example, 1272
Results, 225
Save and Restart, 227
AC Sensitivity Analysis (.SENSAC)
Description, 272
Results, 273
Accuracy
EPS Parameter, 1453
VNTOL parameter, 1453
ACOS (Arc cosine of value) function, 109
ACOSH (Arc hyperbolic cosine of value)
function, 109
Active RC Band Pass Filter Example, 1306
Admittance parameters, 683
Aging and Reliability Analysis (Eldo UDRM)
Description, 277
Aging and Reliability Simulation, 713
Altering Netlist Data, 298
Amodel Error Messages, 1401
Arithm etic Functions&Operators
PWL(), 110
Arithmetic Functions&Operators
ABS(VAL), 109
ACOS(VAL), 109
ACOSH(VAL), 109
ASIN(VAL), 109
ASINH(VAL), 109
ATAN(VAL), 109
ATANH(VAL), 109
BITOF(a, b), 109
CEIL(VAL), 109
COMPL EX(a,b), 112
CONJ(), 112
COS(VAL), 109
COSH(VAL), 109
DB(VAL), 109
DDT(VAL), 109, 110
DERIV(VAL), 109
DMAX(VAL1, ..., VALn), 110
DMIN(VAL1, ..., VALn), 110
EXP(VAL), 109
IDT(VAL), 110
IMAG(), 112
INT(VAL), 110
INTEG(VAL), 110, 112
LIMIT(a, b, c), 110
LOG(VAL), 110
LOG10(VAL), 110
MAGNITUDE(), 112
MAX(VAL1, ..., VALn), 110
MIN(VAL1, ..., VALn), 110
MOD(x,y), 110
ONGRID(), 110
POW(VAL1, VAL2), 110
PWL_CTE(), 110
1484 Eldo® User's Manual, 15.3

PWL_LIN(), 111
PWR(VAL1, VAL2), 110
REAL(), 112
ROUND(VAL), 111
SELECT(), 111
SGN(VAL), 111
SIGMA(), 111
SIGN(VAL), 111
SIGN(VAL1, VAL2), 111
SIN(VAL), 111
SINH(VAL), 111
SMABS(val,eps), 111
SMMAX(a,b,eps), 111
SMMIN(a,b,eps), 111
SMSGN(val,eps), 111
SMSIGN(val,eps), 111
SQRT(VAL), 111
STOSMITH(), 112
STRCASECMP(str1,str2), 112
STRCMP(str1,str2), 111
STRMATCH(str,pat), 111
STRNCASECMP(str1,str2,n), 112
STRNCMP(str1,str2,n), 112
TAN(VAL), 112
TANH(VAL), 112
TRUNC(VAL), 112
VALUEOF(), 112
YTOSMITH(), 112
ZTOSMITH(), 112
Arithmetic Functions&Operators in Eldo
Arithmetic Functions, 109
Arithmetic operators, 116
Bitwise operators, 117
Boolean operators, 116
-compat flag, 114, 177
Expressions, 118
ASINH (Arc hyperbolic sine of value)
function, 109
ATAN (Arc tangent of value) function, 109
ATANH (Arc hyperbolic tangent of value)
function, 109
— B —
Band Pass Filter Tutorial, 1277
Bipolar Amplifier Tutorial, 1293
BITOF function, 109
Bitwise operators, 117
Boolean operators, 116
Bootstrap
Statistical analysis, 470
— C —
Calculation of Transfer Function (.TF), 237
Capacitors
Floating&Grounded Information, 363
Cascaded Inverter Circuit, 32
Case-Sensitivity, 105
CEIL (Value rounded up to integer) function,
109
Charge Control in MOS Models Example,
1304
Check Safe Operating Area Analysis
.CHECKSOA, 278, 279
.SETSOA, 278, 279
Chi File Output, 363
backward compatibility, 365
Convergence Information, 364
Floating&Grounded Capacit ors
Information, 363
Locating messages, 368
Matrix Information, 366
Newton Block Information, 364
Node&Element Information, 363
Simulation time, 365
System information, 363
chi2cir utility, 1470
Circuit file, 95
Circuit Title, 98
CITIfile Data Format, 708
CKDCPATH option, 174
Classification of Error Messages, 369
Colpitts Oscillator Tutorial, 1283
Command
Error Messages, 1392
Warning Messages, 1421
Command Description
.NOISETRAN, 244
.TEMP, 287
Command Line operation
-extract, 327
Comment Lines in Eldo, 103
Common Netlist Errors, 1453
Eldo® User's Manual, 15.3
1485

-compat flag
Arithmetic Functions&Operators in Eldo,
114, 177
Compatibility
HSPICE, 162
Spectre, 179
COMPEXUP option, 174
COMPLEX (Complex number) function, 112
Complex Modifiers, 314
Component Names in Eldo, 99
Compound Waveforms, 315
CONJ (Conjugate of complex number)
function, 112
Continuation Lines in Eldo, 103
Control Language, 95
Convergence
DC, 211
improving, 211
troubleshooting, 213
Convergence Information in Eldo, 364
COS (Cosine of value) function, 109
COSH (Hyperbolic cosine of value) function,
109
Current simulation time
TIME variable, 119
— D —
DB (Value in decibels) function, 109
DC Analysis (.DC)
.DC, 205
.OP, 208
convergence, 211
convergence troubleshooting, 213
differences with .OP, 210
during Transient analysis, 207
improving convergence, 211
Results, 206
Save and Restart, 215
DC Mismatch Analysis (.DCMISMATCH)
Description, 269
Results, 269
DC Operating Point, 211
DC Operating Point Calculation (.OP)
.SAVE and .RESTART, 215
.SAVE and .USE, 215
DC Sensitivity Analysis (.SENS)
Description, 270
Results, 271
DDT (Derivative of value) function, 109
Defining Waveforms, 336
Examples, 337
Deleting a Library, 136
DERIV (Derivative of value) function, 109
Design of Experiments, 274, 556
Design of Experiments Analysis (.DEX)
Description, 274
Results, 275
Device Libraries, 127, 132
.ADDLIB, 132
.INCLUDE, 132
.LIB, 132
.SCOPE, 133
Deleting a library, 136
Library variant management, 134
Nesting, 135
Search path priorities, 133
Search rules and naming conventions, 136
DEX, 274, 557
Directives, 121
Distribution
gaussian, 433
LIMIT, 548
uniform, 431
User-defined, 435
DMAX (Maximum value) function, 110
DMIN (Minimum value) function, 110
Documentation Syntax Conventions, 39
DSCGLOB option, 127
DSP Functions
Post-Processing Library (PPL), 1215
DSPF Backannotation, 392
DSPF Backannotation Examples, 396
Dynamic Plot
Simulation Connection Manager, 318
Dynamic plot
Simulation Connection Manager, 47
Dynamically Adding Voltage/Current Plots,
318
— E —
Effects of Error Messages, 369
Eldo
1486 Eldo® User's Manual, 15.3

32-bit and 64-bit modes, 42
An Introduction, 29
chi2cir utility, 1470
convert .chi to .cir, 1470
Efficient Usage, 1243
Encryption, 139
fast launch script, 46
Getting Started, 31
Initialization file, 51
Input and Output Files, 35
Multi-Threading, 42
Netlist Setup, 95
Running from the Command Line, 41
Running of, 31, 41
Simulation Connection Manager, 47, 318
Speed and Accuracy, 1243
Syntax, 103
Temperature Handling, 287
Utilities, 1470
Eldo Premier, 61
Automatic Activation, 64
Classic DC Solution, 66
Enabling, 64
Error Messages, 1408
Example, 62
Matrix-like circuits, 67
Netlist Support, 74
Output, 69
Overview, 61
RAM disk storage, 68
Supported Com mands, 74
Supported Models, 89
Supported Options, 78
Target Applications, 62
Temporary Files, 69
Transient Noise Analysis, 90
Unsupported Devices and Features, 93
Warning Messages, 1450
Eldo UDRM
Aging and reliability analysis, 277
eldo.ini, 51
Electrothermal Simulation
.TEMPNODE, 282
Element and Source Definitions, 99
Encryption, 139
.IP_protect, 146
Encrypted libraries, 144
Encrypting a protected library, 144, 146
Errors and Warnings, 154
Semi-Transparent, 147
End Statement, 102
Environment Variables, 108
EPS option, 1253, 1453
Error and Warning Messages, 1379
Error Messages, 1380
Classification, 369
Classification of, 369
Effects, 369
Global, 1380
Miscellaneous, 1403
Related to Amodels, 1401
Related to Commands, 1392
Related to Eldo Premier, 1408
Related to Models, 1399
Related to Nodes, 1384
Related to Objects, 1385
Related to Subcircuits, 1402
Examples
.ALTER, 300
.EXTRACT, 329
5th Order Elliptic SC Low Pass Filter, 1303
Active RC Band Pass Filter, 1306
Cascade of Inverters, 32
Charge Control in MOS Models, 1304
DSPF backannotation, 396
Eldo Premier, 62
IBIS models, 790
Loop Stability Analysis, 1299
Monte Carlo analysis (.MC), 526
Optimization (.OPTIMIZE), 664
Overshoot Extraction, 1301
Post-layout simulation, 396
Post-Processing Library, 1137
Safe Operating Area (SOA), 345, 350
Safe Operating Area (SOA) Checks, 343
SC—Schmitt Trigger, 1298
Second Order Delta Sigma Modulator,
1307
Sweeping Parameters, 292
Transient Noise Analysis, 260
Eldo® User's Manual, 15.3
1487

Two-Stage Operational Amplifier, 1309
EXP (Exponent of value) function, 109
Experiment Design, 556
Expressions in Eldo, 118
-extract
Running from the command line, 327
Extract Examples, 329
Extract Functions, 324
Extract Outputs, 324
Extracting Information, 321
Examples, 329
Extract functions, 324
Extract outputs, 324
Plot and print quantities, 323
Extraction Mode, 327
Extraction Plot and Print Quantities, 323
EZwave, 370
Displaying Eldo simulation data, 372
Graph windows, 371
— F —
ffcv utility, 1473
FLOOR (Value rounded down to integer)
function, 110
FNS Model, 235
Frequency Limit
for Pole-Zero Post-processing, 234
Functions&Operators
see Arithmetic Functions&Operators
— G —
Gaussian distribution, 433
Getting Started
with Eldo, 31
Global
Error Messages, 1380
Warning Messages, 1411
— H —
HACC option, 1251
Hand Selection
in Pole-Zero Post-processing, 234
Hierarchical Nodes
Monitoring of, 309
High Impedance Node Checks, 349
High Voltage Cascade Tutorial, 1286
How to Run Eldo, 31, 41
HSPICE Compatibility, 162
— I —
IBIS Models, 728
Algorithmic Model Interface (AMI), 787
Buffers, 752
Component, 765
Device standards, 732
Electrical board description, 777
File types and structures, 729
Golden parser, 731
Introduction, 728
Package, 773
Support in Eldo, 749
Supported keywords and sub-parameters,
780
Syntax, 751
Tutorials, 790
IDT (Integral of value) function, 110
IEM, 1260
IMAG (Imaginary part of complex number)
function, 112
Impedance parameters, 683
Initialization file, 51
Input and Output Files for Eldo, 35
Instances
Merging in parallel, 158
INT (Integer of value) function, 110
INTEG (Integral of value) function, 110
Interactive Mode, 58, 1457
Internal Pin Values
Plotting, 314
Interruption of a Simulation, 222
Invoking Eldo, 41
— J —
JWDB, 36, 359, 370
Incremental saving, 354
— K —
Keywords, reserved, 104
— L —
Library Nesting, 135
Library Variant Management, 134
LIMIT distribution, 548
1488 Eldo® User's Manual, 15.3

LIMIT function, 110
Limiting Output Information, 352, 353
Limiting the Size of Transient Output Files,
353
Local and Global Variations, 442
Location Maps, 53
LOG (Neperian log of value) function, 110
LOG10 (Decimal log of value) function, 110
Loop Stability Analysis (.LSTB)
Example, 1299
Loop Stability Analysis Example, 1299
Low Pass Filter Tutorial, 1280
— M —
MAGNITUDE (Magnitude of complex
number) function, 112
Matrix Information in Eldo, 366
MAX (Maximum value) function, 110
MCCONV Extract Function
Monte Carlo analysis (.MC), 514, 518
Merging Instances in Parallel, 158
MIN (Minimum value) function, 110
Miscellaneous
Error Messages, 1403
Warning Messages, 1431
MOD (Modulo value) function, 110
Model
Error Messages, 1399
Names in Eldo, 98
Warning Messages, 1428
Model Definitions, 98
Models
STMicroelectronics, 1477
Monitoring of Hierarchical Nodes, 309
Monte Carlo Analysis (.MC), 409
Bootstrap, 470
Command, 421
Description, 265
DEV, DEVX or LOT, 447
Distribution Function, 431
Examples, 526, 1291
Extracting, 465, 468
Global sensitivity analysis, 471
Graphical Output, 509
Introduction, 411
Local and global variations, 442
Results, 266, 463
Run-length control, 514, 518
Sampling plan methods, 451
Sensitivity analysis, 520
Sharing distributions, 429
Specifying, 421
Statistical parameter naming conventions,
536
Statistical Parameters, 427
Statistical Variations, 423
Tolerance setting, 447
Monte Carlo Basic Tutorial, 1290
MOS Instances
TSMC libraries, 156
MOS instances, 156
Multiple Runs, 156
Multiplication (M) Factor, 127
Multi-Threading, 42
— N —
Nested Output Requests, 310
Nested Sweeps, 295
Netlist file, 95
Netlist Setup, 95
Case-sensitivity, 105
Circuit title, 98
Comment lines, 103
Component names, 99
Conditional statements, 121
Continuation lines, 103
Device libraries, 132
Directives, 121
Element and source definitions, 99
End statement, 102
Environment variables, 108
Expressions, 118
Model definitions, 98
Node Name conventions, 99
Numerical values, 107
Parameter names, 104
Reserved keywords, 104
Simulator commands and options, 100
String parameters, 104
Subcircuit definitions and calls, 99
Subcircuits and device libraries, 127
Netlist setup, 33
Eldo® User's Manual, 15.3
1489

Netlist Termination (.END), 102
Newton Block Information in Eldo, 364
NOBSLASHCONT option, 174
Nodal
Error Messages, 1384
Warning Messages, 1415
Node and Element Information in Eldo, 363
Node Names
inside Subcircuits, 127
Nodes
Node Name conventions, 99
Node Names inside Subcircuits, 100
Noise
in subcircuits, 127
Noise Analysis (.NOISE)
.NOISETRAN, 241
Description, 239
Results, 239
Transient, 241
— O —
Object
Error Messages, 1385
Warning Messages, 1417
ONGRID function, 110
Operating Point
Calculation of, 211
Operating Point Analysis, 208
Results, 208
Operator Precedence, 115
Operators, 115
Optimization (.OPTIMIZE), 587
Commands, 589
Description, 276
Design objectives, 603
Design Variables, 594
Examples, 664
Introduction, 589
Methods, 622
Monitoring design objectives, 653
Multiple-run, 632
Options, 591
Output, 639
Output file, 642
plotting, 641
Post-analysis, 639
Results, 277, 639
Status codes, 656
Sweep simulations, 633
Types of problems, 629
Option PARHIER
Parameter scoping, 291
Output
Tabular listing, 317
Output Commands, 306
Output Files, 358
Output Types, 306
Output Variables, 320
Overshoot Extraction Example, 1301
Overview
.cir file structure, 97
— P —
Parallel LCR Circuit Tutorial, 1272
Parameter Extraction, 683
Parameter Names in Eldo, 104
Parameter Scoping Rules, 291
Parameter Values
.PARAM, 291
Parasitic Network Types, 394
Plotting
Analog Signal as a Digital Bus, 315
Dynamic plot, 318
Example Safe Operating Area (SOA)
Checks, 343
Optimization (.OPTIMIZE), 641
Output Variables, 320
Safe Operating Area limits, 341
Plotting Extractions, 309
Plotting Internal Pin Values, 314
Plotting Output Variables, 309
Plotting Templates, 309
Plotting, Printing and Probing, 308
Pole Zero Analysis, 230
Pole-Zero
Cancellation by Threshold, 234
Numerical Issues, 236
Post-processor, 360
Dialogue of, 231
Post-Layout Simulation, 389
.DSPF_INCLUDE, 394
Commands, 394
1490 Eldo® User's Manual, 15.3

DSPF backannotation, 392
Examples, 396
Options, 395
Parasitic network types, 394
Reduction, 403
Post-Processing Library (PPL), 1137
Accessing waves, 1233
DSP functions, 1215
Examples, 1137
Usage, 1139
User defined functions, 1139
Waveform functions, 1150
Waveforms inside user defined functions,
1142
Post-processors
Pole-Zero, 360
POW (Power) function, 110
Power Analysis (.POWER_ANALYSIS)
Description, 279
PPL (Post-Processing Library),seePost-
Processing Library (PPL)
PWL function, 110
PWL_CTE function, 110
PWL_LIN function, 111
PWR (Power) function, 110
— R —
Ramping, 212
REAL (Real part of complex number) function,
112
Reduction, 403
Reduction (.REDUCE), 404
Commands, 406
Options, 406
Reliability Simulation, 713
RELTOL option, 1264
Results, 305
RF Analyses, 283
ROUND (Value rounded to integer) function,
111
Running
32-bit and 64-bit modes, 42
Eldo from the Command Line, 41
fast launch scrip, 46
Multi-Threading, 42
Simulation Connection Manager, 47, 318
— S —
S, Y, Z Parameter Extraction, 683
output file specification (.FFILE), 688
Source Syntax, 684, 685
Safe Operating Area (SOA) Checks, 341
Examples, 345, 350
Modifying the SOA identifier format, 343
Plotting, 341
Safe Operating Area Examples, 345, 350
SC Low Pass Filter Tutorial, 1295
Scattering parameters, 683
SC—Schmitt Trigger Example, 1298
Second Order Delta Sigma Modulator
Example, 1307
SELECT function, 111
Select Index
in Pole-Zero Post-processing, 234
Sens itivity Analysis of Parameters
(.SENSPARAM)
Results, 273
Sensitivity Analysis
Interpreting, 521
Monte Carlo Analysis (.MC), 520
Sensitivity Analysis (.SENS)
Examples, 1294
Sensitivity Analysis of Parameters
(.SENSPARAM)
Description, 273
Set
Circuit Temperature (.TEMP), 287
SGN (Signum) function, 111
SIGMA (Sum of values) function, 111
SIGN (Signum) function, 111
Signal Monitoring Specifications, 313
Simul ation
Counters, 365
Simulation
Accuracy
RELTOL, 1264
VNTOL, 1264
Altering netlist data, 298
Counters
Convergence Information, 366
Grounded Capacitors Information, 366
Matrix Information, 366
Eldo® User's Manual, 15.3
1491

Newton Block Information, 366
Node&Element Information, 366
Files created, 308
Interruption, 222
Limiting output information, 352, 353
Limiting size transient output files, 353
Multi-Threading, 42
Output, 305
Output commands, 306
Output files, 358
Output types, 306
Plotting, printing and probing, 308
Reruns, 298
Restart, 215
Results, 33, 305
Running, 33
Save, 215
Types of Waveforms, 309
Using previous run results, 302
Simulation Connection Manager, 47, 318
Simulation Time
Chi file output, 365
Simulator Commands and Options, 100
SIN (Sine of value) function, 111
SINH (Hyperbolic sine of value) function, 111
SMABS (Absolute valu e) function, 111
SMMAX (Maximum value) function, 111
SMMIN (Minimum value) function, 111
S-Model, 692
Applications, 696
FBLOCK, 699
Implementation, 695
Syntax, 699
SMSGN (Signum) function, 111
SMSIGN (Signum) function, 111
SOA
Safe Operating Area analysis, 278, 279
Spectre Compatibility, 179
Speed and Accuracy, 1243
SQRT (Square root of value) function, 111
stacktrace file, 1455
States
Plotting, 313
Statistical and Sensitivity Related Analyses,
265
AC sensitivity analysis (.SENSAC), 272
DC Mismatch analysis (.DCMISMATCH),
269
DC sensitivity analysis (.SENS), 270
Design of experiments analysis (.DEX),
274
Monte Carlo analysis (.MC), 265
Sensitivity analysis of parameters
(.SENSPARAM), 273
Transient sensitivity analysis (.SENS
TRAN), 272
Worst Case analysis (.WCASE), 267
Statistical Experimental Design and Analysis,
556
Statistical Parameters, 427
Parameter naming conventions, 536
Statistical Variations, 423
Statistics File, 57
Content, 386
STMicroelectronics
Models, 1477
STOSMITH (Smith) function, 112
STRCASECMP (String compare, ignoring
case) function, 112
STRCMP (String compare) function, 111
String Parameters in Eldo, 104
STRMATCH (String match) function, 111
STRNCASECMP (String compare, ignoring
case) function, 112
STRNCMP (String compare) function, 112
Subcircuit
Error Messages, 1402
Warning Messages, 1431
Subcircuit Definitions and Calls, 99
Subcircuits, 127
Access of Nodes, 127
Access of Nodes from within, 100
Multiplication (M) factor, 127
Nodes, 127
Noise, 127
Sweeping Parameters
.DATA, 296
.STEP, 292, 295
.STEP examples, 292
Switch
1492 Eldo® User's Manual, 15.3

Noise Model, 1373
Syntax
Errors, 369
General aspects
Comment lines, 103
Component names, 99
Continuation lines, 103
Model names, 98
Node name conventions, 99
Parameter names, 104
Reserved keywords, 104
String parameters, 104
Values, 107
of Eldo, 103
System Information
Chi file output, 363
— T —
T Parameter, 288
Tabular Listing Output, 317
TAN (Tangent of value) function, 112
TANH (Hyperbolic tangent of value) function,
112
Tcl,seePost-Processing Library (PPL)
TEMP Variable, 289
TEMPER Variable, 289
Temperature
.TEMP, 287
Handling in Eldo, 287
TEMP Parameter, 289
TEMPER Parameter, 289
TMOD Parameter, 288
TNOM Parameter, 287
TParameter, 288
TICER Reduction, 403
TIME Variable, 119
TMOD Parameter, 288
TNOM option, 287
Tolerance Setting
DEV, DEVX or LOT, 447
Touchstone Data Format, 705
Transfer Function, 237
Transient Analysis (.TRAN)
Description, 217
Examples, 1275, 1284, 1287, 1295, 1298,
1303, 1305, 1307
Results, 218
Save and Restart, 219
Transient Noise Analysis
in Eldo Premier, 90
Transient Noise Analysis (.NOISETRAN)
Algorithms, 245
Applications, 243
Description, 241
Example, 260
Multiple noisy runs, 243
Parameters, 244
Performance and accuracy, 245, 257
Results, 259
Time domain noise sources, 246
Transient Sensitivity Analysis (.SENS TRAN)
Description, 272
Results, 272
Troubleshooting, 1453
stacktrace file, 1455
TRUNC (Truncated value) function, 112
TSMC Libraries, 156
Tutorials, 1269
1—Parallel LCR Circuit, 1272
2—4th Order Butterworth Filter, 1274
3—Band Pass Filter, 1277
4—Low Pass Filter, 1280
5—Colpitts Oscillator, 1283
6—High Voltage Cascade, 1286
7—Monte Carlo Basic, 1290
8—Bipolar Amplifier, 1293
9—SC Low Pass Filter, 1295
IBIS models, 790
— U —
UDRM, 713
Aging and reliability analysis, 277
Uniform distribution, 431
User-defined distribution, 435
Utilities, 1469
— V —
VALUEOF (Returns the current value of an
extract) function, 112
Values in Eldo, 107
vcd2tv utility, 1471
VNTOL, 1264
Eldo® User's Manual, 15.3
1493

Correct usage, 1453
— W —
Warning Messages, 369, 1411
Global, 1411
Miscellaneous, 1432
Related to Commands, 1421
Related to Eldo Premier, 1450
Related to Models, 1428
Related to Nodes, 1415
Related to Objects, 1417
Related to Subcircuits, 1431
Warnings
Messages, 369
Waveform Definition Using a Tcl Function
.TCL_WAVE, 1140
Waveform Functions
Post-Processing Library (PPL), 1150
Waveform types, 309
Waveforms
Defining, 336
Examples defining waveforms, 337
X-axis, 316
WINTEG (Integral of waveform) function, 112
Worst Case Analysis (.MC)
Description, 267
Worst Case Analysis (.WCASE)
Results, 268
— X —
XBLOCK
Syntax, 710
X-Model
XBLOCK, 710
— Y —
YTOSMITH (Smith) function, 112
— Z —
ZTOSMITH (Smith) function, 112
1494 Eldo® User's Manual, 15.3

Third-Party Information
This section provides information on open source and third-party software that may be included in the Eldo product.
•
© 2005-2009 Jim Idle, Temporal Wave LLC
http:www.temporal-wave.com
http:www.linkedin.com/in/jimidle
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
conditions are met:
1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products derived from this software without specific
prior written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
• /legal/intel_source_code.pdf.
•
© 1996 by AT&T
Permission to use, copy, modify, and distribute this software for any purpose without fee is hereby granted, provided that
this entire notice is included in all copies of any software which is or includes a copy or modification of this software and
in all copies of the supporting documentation for such software.
THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED WARRANTY. IN
PARTICULAR, NEITHER THE AUTHORS NOR AT&T MAKE ANY REPRESENTATION OR WARRANTY OF
ANY KIND CONCERNING THE MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY
PARTICULAR PURPOSE.
© 1996, 1997 Silicon Graphics Computer Systems, Inc.
Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted
without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this
permission notice appear in supporting documentation. Silicon Graphics makes no representations about the suitability of
this software for any purpose. It is provided "as is" without express or implied warranty.
© 1994 Hewlett-Packard Company
Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted
without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this
permission notice appear in supporting documentation. Hewlett-Packard Company makes no representations about the
suitability of this software for any purpose. It is provided "as is" without express or implied warranty.
© 1997 Moscow Center for SPARC Technology

Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted
without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this
permission notice appear in supporting documentation. Moscow Center for SPARC Technology makes no
representations about the suitability of this software for any purpose. It is provided "as is" without express or implied
warranty.
•
© 2004-2007 The Trustees of Indiana University and Indiana University Research and Technology Corporation. All
rights reserved.
© 2004-2005 The University of Tennessee and The University of Tennessee Research Foundation. All rights reserved.
© 2004-2007 High Performance Computing Center Stuttgart, University of Stuttgart. All rights reserved.
© 2004-2005 The Regents of the University of California. All rights reserved.
and renamed for hwloc:
© 2009 INRIA. All rights reserved.
© 2009 Université Bordeaux 1
© 2010 Cisco Systems, Inc. All rights reserved.
See COPYING in top-level directory.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
conditions are met:
- Redistributions of source code must retain the above copyright notice, this list of conditions and the following
disclaimer.
- Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
disclaimer listed in this license in the documentation and/or other materials provided with the distribution.
- Neither the name of the copyright holders nor the names of its contributors may be used to endorse or promote products
derived from this software without specific prior written permission.
The copyright holders provide no reassurances that the source code provided does not infringe any patent, copyright, or
any other intellectual property rights of third parties. The copyright holders disclaim any liability to any recipient for
claims brought against recipient by any third party for infringement of that parties intellectual property rights.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
© 2009 CNRS
© 2009 INRIA. All rights reserved.
© 2009 Université Bordeaux 1
© 2009 Cisco Systems, Inc. All rights reserved.
See COPYING in top-level directory.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
conditions are met:
1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided with the distribution.

3. The name of the author may not be used to endorse or promote products derived from this software without specific
prior written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
•
The terms under which the HICUM software is provided are as follows:
Software is distributed as is, completely without warranty or service support. The Model Owner and his team members
are not liable for the condition or performance of the software.
Michael Schroter (Model Owner) owns the copyright but shall not be liable for any infringement of copyright or other
proprietary rights brought by third parties against the users of the software.
The Model Owner hereby disclaims all implied warranties.
The Model Owner grants the users the right to modify, copy, and redistribute the software and documentation, both within
the user's organization and externally, subject to the following restrictions:
1. The users agree not to charge for the HICUM code itself but may charge for additions, extensions, or support.
2. In any product based on the software, the users agree to acknowledge the Model Owner that developed the software.
This acknowledgment shall appear in the product documentation.
3. The users agree to reproduce any copyright notice which appears on the software on any copy or modification of such
made available to others.
No part of this code may be reproduced or used in any form without written permission from the originator.
• /legal/gnu_lgpl_2.1.pdf. To obtain a copy of the KLU version 1.1.1
source code, send a request to request_sourcecode@mentor.com. This offer shall only be available for three years from
the date Mentor Graphics Corporation first distributed KLU version 1.1.1.
• /legal/gnu_lgpl_2.1.pdf. To obtain a copy of the AMD version 2.2.2
source code, send a request to request_sourcecode@mentor.com. This offer shall only be available for three years from
the date Mentor Graphics Corporation first distributed AMD version 2.2.2.
• /legal/gnu_lgpl_2.1.pdf. To obtain a copy of the COLAMD version
2.7.3 source code, send a request to request_sourcecode@mentor.com. This offer shall only be available for three years
from the date Mentor Graphics Corporation first distributed COLAMD version 2.7.3.
• /legal/gnu_lgpl_2.1.pdf. To obtain a copy of the BTF version 1.1.2
source code, send a request to request_sourcecode@mentor.com. This offer shall only be available for three years from
the date Mentor Graphics Corporation first distributed BTF version 1.1.2.
• /legal/gnu_lgpl_2.1.pdf. To obtain a copy of the UFconfig version
3.6.1 source code, send a request to request_sourcecode@mentor.com. This offer shall only be available for three years
from the date Mentor Graphics Corporation first distributed UFconfig version 3.6.1.
•
©1991, 1993 The Regents of the University of California. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
conditions are met:
1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided with the distribution.
4. Neither the name of the University nor the names of its contributors may be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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© 2002 Niels Provos provos@citi.umich.edu All rights reserved.
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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•
•
©2000-2008 Julian Seward. All rights reserved.
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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•
• /legal/gnu_lgpl_2.1.pdf. To obtain a copy of the CHOLMOD
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End-User License Agreement
The latest version of the End-User License Agreement is available on-line at:
www.mentor.com/eula
IMPORTANT INFORMATION
USE OF ALL SOFTWARE IS SUBJECT TO LICENSE RESTRICTIONS. CAREFULLY READ THIS LICENSE
AGREEMENT BEFORE USING THE PRODUCTS. USE OF SOFTWARE INDICATES CUSTOMER’S
COMPLETE AND UNCONDITIONAL ACCEPTANCE OF THE TERMS AND CONDITIONS SET FORTH IN
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END-USER LICENSE AGREEMENT (“Agreement”)
This is a legal agreement concerning the use of Software (as defined in Section 2) and hardware (collectively “Products”)
between the company acquiring the Products (“Customer”), and the Mentor Graphics entity that issued the corresponding
quotation or, if no quotation was issued, the applicable local Mentor Graphics entity (“Mentor Graphics”). Except for license
agreements related to the subject matter of this license agreement which are physically signed by Customer and an authorized
representative of Mentor Graphics, this Agreement and the applicable quotation contain the parties’ entire understanding
relating to the subject matter and supersede all prior or contemporaneous agreements. If Customer does not agree to these
terms and conditions, promptly return or, in the case of Software received electronically, certify destruction of Software and all
accompanying items within five days after receipt of Software and receive a full refund of any license fee paid.
1. ORDERS, FEES AND PAYMENT.
1.1. To the extent Customer (or if agreed by Mentor Graphics, Customer’s appointed third party buying agent) places and Mentor
Graphics accepts purchase orders pursuant to this Agreement (each an “Order”), each Order will constitute a contract between
Customer and Mentor Graphics, which shall be governed solely and exclusively by the terms and conditions of this Agreement,
any applicable addenda and the applicable quotation, whether or not those documents are referenced on the Order. Any additional
or conflicting terms and conditions appearing on an Order or presented in any electronic portal or automated order management
system, whether or not required to be electronically accepted, will not be effective unless agreed in writing and physically signed
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1.2. Amounts invoiced will be paid, in the currency specified on the applicable invoice, within 30 days from the date of such invoice.
Any past due invoices will be subject to the imposition of interest charges in the amount of one and one-half percent per month or
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other similar charges, which Mentor Graphics will state separately in the applicable invoice. Unless timely provided with a valid
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and clear of, and without reduction for, any withholding or other taxes; any such taxes imposed on payments by Customer
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payments on Customer’s behalf, Customer shall be liable for payment under Orders placed by such third party in the event of
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1.3. All Products are delivered FCA factory (Incoterms 2010), freight prepaid and invoiced to Customer, except Software delivered
electronically, which shall be deemed delivered when made available to Customer for download. Mentor Graphics retains a
security interest in all Products delivered under this Agreement, to secure payment of the purchase price of such Products, and
Customer agrees to sign any documents that Mentor Graphics determines to be necessary or convenient for use in filing or
perfecting such security interest. Mentor Graphics’ delivery of Software by electronic means is subject to Customer’s provision of
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2. GRANT OF LICENSE. The software installed, downloaded, or otherwise acquired by Customer under this Agreement, including any
updates, modifications, revisions, copies, documentation and design data (“Software”) are copyrighted, trade secret and confidential
information of Mentor Graphics or its licensors, who maintain exclusive title to all Software and retain all rights not expressly granted
by this Agreement. Mentor Graphics grants to Customer, subject to payment of applicable license fees, a nontransferable, nonexclusive
license to use Software solely: (a) in machine-readable, object-code form (except as provided in Subsection 5.2); (b) for Customer’s
internal business purposes; (c) for the term of the license; and (d) on the computer hardware and at the site authorized by Mentor
Graphics. A site is restricted to a one-half mile (800 meter) radius. Customer may have Software temporarily used by an employee for
telecommuting purposes from locations other than a Customer office, such as the employee’s residence, an airport or hotel, provided
that such employee’s primary place of employment is the site where the Software is authorized for use. Mentor Graphics’ standard
policies and programs, which vary depending on Software, license fees paid or services purchased, apply to the following: (a) relocation
of Software; (b) use of Software, which may be limited, for example, to execution of a single session by a single user on the authorized
hardware or for a restricted period of time (such limitations may be technically implemented through the use of authorization codes or
similar devices); and (c) support services provided, including eligibility to receive telephone support, updates, modifications, and
revisions. For the avoidance of doubt, if Customer provides any feedback or requests any change or enhancement to Products, whether
in the course of receiving support or consulting services, evaluating Products, performing beta testing or otherwise, any inventions,
product improvements, modifications or developments made by Mentor Graphics (at Mentor Graphics’ sole discretion) will be the
exclusive property of Mentor Graphics.

3. ESC SOFTWARE. If Customer purchases a license to use development or prototyping tools of Mentor Graphics’ Embedded Software
Channel (“ESC”), Mentor Graphics grants to Customer a nontransferable, nonexclusive license to reproduce and distribute executable
files created using ESC compilers, including the ESC run-time libraries distributed with ESC C and C++ compiler Software that are
linked into a composite program as an integral part of Customer’s compiled computer program, provided that Customer distributes
these files only in conjunction with Customer’s compiled computer program. Mentor Graphics does NOT grant Customer any right to
duplicate, incorporate or embed copies of Mentor Graphics’ real-time operating systems or other embedded software products into
Customer’s products or applications without first signing or otherwise agreeing to a separate agreement with Mentor Graphics for such
purpose.
4. BETA CODE.
4.1. Portions or all of certain Software may contain code for experimental testing and evaluation (which may be either alpha or beta,
collectively “Beta Code”), which may not be used without Mentor Graphics’ explicit authorization. Upon Mentor Graphics’
authorization, Mentor Graphics grants to Customer a temporary, nontransferable, nonexclusive license for experimental use to test
and evaluate the Beta Code without charge for a limited period of time specified by Mentor Graphics. Mentor Graphics may
choose, at its sole discretion, not to release Beta Code commercially in any form.
4.2. If Mentor Graphics authorizes Customer to use the Beta Code, Customer agrees to evaluate and test the Beta Code under normal
conditions as directed by Mentor Graphics. Customer will contact Mentor Graphics periodically during Customer’s use of the
Beta Code to discuss any malfunctions or suggested improvements. Upon completion of Customer’s evaluation and testing,
Customer will send to Mentor Graphics a written evaluation of the Beta Code, including its strengths, weaknesses and
recommended improvements.
4.3. Customer agrees to maintain Beta Code in confidence and shall restrict access to the Beta Code, including the methods and
concepts utilized therein, solely to those employees and Customer location(s) authorized by Mentor Graphics to perform beta
testing. Customer agrees that any written evaluations and all inventions, product improvements, modifications or developments
that Mentor Graphics conceived or made during or subsequent to this Agreement, including those based partly or wholly on
Customer’s feedback, will be the exclusive property of Mentor Graphics. Mentor Graphics will have exclusive rights, title and
interest in all such property. The provisions of this Subsection 4.3 shall survive termination of this Agreement.
5. RESTRICTIONS ON USE.
5.1. Customer may copy Software only as reasonably necessary to support the authorized use. Each copy must include all notices and
legends embedded in Software and affixed to its medium and container as received from Mentor Graphics. All copies shall remain
the property of Mentor Graphics or its licensors. Customer shall maintain a record of the number and primary location of all copies
of Software, including copies merged with other software, and shall make those records available to Mentor Graphics upon
request. Customer shall not make Products available in any form to any person other than Customer’s employees and on-site
contractors, excluding Mentor Graphics competitors, whose job performance requires access and who are under obligations of
confidentiality. Customer shall take appropriate action to protect the confidentiality of Products and ensure that any person
permitted access does not disclose or use Products except as permitted by this Agreement. Customer shall give Mentor Graphics
written notice of any unauthorized disclosure or use of the Products as soon as Customer becomes aware of such unauthorized
disclosure or use. Except as otherwise permitted for purposes of interoperability as specified by applicable and mandatory local
law, Customer shall not reverse-assemble, reverse-compile, reverse-engineer or in any way derive any source code from Software.
Log files, data files, rule files and script files generated by or for the Software (collectively “Files”), including without limitation
files containing Standard Verification Rule Format (“SVRF”) and Tcl Verification Format (“TVF”) which are Mentor Graphics’
trade secret and proprietary syntaxes for expressing process rules, constitute or include confidential information of Mentor
Graphics. Customer may share Files with third parties, excluding Mentor Graphics competitors, provided that the confidentiality
of such Files is protected by written agreement at least as well as Customer protects other information of a similar nature or
importance, but in any case with at least reasonable care. Customer may use Files containing SVRF or TVF only with Mentor
Graphics products. Under no circumstances shall Customer use Products or Files or allow their use for the purpose of developing,
enhancing or marketing any product that is in any way competitive with Products, or disclose to any third party the results of, or
information pertaining to, any benchmark.
5.2. If any Software or portions thereof are provided in source code form, Customer will use the source code only to correct software
errors and enhance or modify the Software for the authorized use. Customer shall not disclose or permit disclosure of source code,
in whole or in part, including any of its methods or concepts, to anyone except Customer’s employees or on-site contractors,
excluding Mentor Graphics competitors, with a need to know. Customer shall not copy or compile source code in any manner
except to support this authorized use.
5.3. Customer may not assign this Agreement or the rights and duties under it, or relocate, sublicense, or otherwise transfer the
Products, whether by operation of law or otherwise (“Attempted Transfer”), without Mentor Graphics’ prior written consent and
payment of Mentor Graphics’ then-current applicable relocation and/or transfer fees. Any Attempted Transfer without Mentor
Graphics’ prior written consent shall be a material breach of this Agreement and may, at Mentor Graphics’ option, result in the
immediate termination of the Agreement and/or the licenses granted under this Agreement. The terms of this Agreement,
including without limitation the licensing and assignment provisions, shall be binding upon Customer’s permitted successors in
interest and assigns.
5.4. The provisions of this Section 5 shall survive the termination of this Agreement.
6. SUPPORT SERVICES. To the extent Customer purchases support services, Mentor Graphics will provide Customer with updates and
technical support for the Products, at the Customer site(s) for which support is purchased, in accordance with Mentor Graphics’ then
current End-User Support Terms located at http://supportnet.mentor.com/supportterms.
7. LIMITED WARRANTY.

7.1. Mentor Graphics warrants that during the warranty period its standard, generally supported Products, when properly installed, will
substantially conform to the functional specifications set forth in the applicable user manual. Mentor Graphics does not warrant
that Products will meet Customer’s requirements or that operation of Products will be uninterrupted or error free. The warranty
period is 90 days starting on the 15th day after delivery or upon installation, whichever first occurs. Customer must notify Mentor
Graphics in writing of any nonconformity within the warranty period. For the avoidance of doubt, this warranty applies only to the
initial shipment of Software under an Order and does not renew or reset, for example, with the delivery of (a) Software updates or
(b) authorization codes or alternate Software under a transaction involving Software re-mix. This warranty shall not be valid if
Products have been subject to misuse, unauthorized modification, improper installation or Customer is not in compliance with this
Agreement. MENTOR GRAPHICS’ ENTIRE LIABILITY AND CUSTOMER’S EXCLUSIVE REMEDY SHALL BE, AT
MENTOR GRAPHICS’ OPTION, EITHER (A) REFUND OF THE PRICE PAID UPON RETURN OF THE PRODUCTS TO
MENTOR GRAPHICS OR (B) MODIFICATION OR REPLACEMENT OF THE PRODUCTS THAT DO NOT MEET THIS
LIMITED WARRANTY. MENTOR GRAPHICS MAKES NO WARRANTIES WITH RESPECT TO: (A) SERVICES; (B)
PRODUCTS PROVIDED AT NO CHARGE; OR (C) BETA CODE; ALL OF WHICH ARE PROVIDED “AS IS.”
7.2. THE WARRANTIES SET FORTH IN THIS SECTION 7 ARE EXCLUSIVE. NEITHER MENTOR GRAPHICS NOR ITS
LICENSORS MAKE ANY OTHER WARRANTIES EXPRESS, IMPLIED OR STATUTORY, WITH RESPECT TO
PRODUCTS PROVIDED UNDER THIS AGREEMENT. MENTOR GRAPHICS AND ITS LICENSORS SPECIFICALLY
DISCLAIM ALL IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NON-INFRINGEMENT OF INTELLECTUAL PROPERTY.
8. LIMITATION OF LIABILITY. EXCEPT WHERE THIS EXCLUSION OR RESTRICTION OF LIABILITY WOULD BE VOID
OR INEFFECTIVE UNDER APPLICABLE LAW, IN NO EVENT SHALL MENTOR GRAPHICS OR ITS LICENSORS BE
LIABLE FOR INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES (INCLUDING LOST PROFITS OR
SAVINGS) WHETHER BASED ON CONTRACT, TORT OR ANY OTHER LEGAL THEORY, EVEN IF MENTOR GRAPHICS
OR ITS LICENSORS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. IN NO EVENT SHALL MENTOR
GRAPHICS’ OR ITS LICENSORS’ LIABILITY UNDER THIS AGREEMENT EXCEED THE AMOUNT RECEIVED FROM
CUSTOMER FOR THE HARDWARE, SOFTWARE LICENSE OR SERVICE GIVING RISE TO THE CLAIM. IN THE CASE
WHERE NO AMOUNT WAS PAID, MENTOR GRAPHICS AND ITS LICENSORS SHALL HAVE NO LIABILITY FOR ANY
DAMAGES WHATSOEVER. THE PROVISIONS OF THIS SECTION 8 SHALL SURVIVE THE TERMINATION OF THIS
AGREEMENT.
9. HAZARDOUS APPLICATIONS. CUSTOMER ACKNOWLEDGES IT IS SOLELY RESPONSIBLE FOR TESTING ITS
PRODUCTS USED IN APPLICATIONS WHERE THE FAILURE OR INACCURACY OF ITS PRODUCTS MIGHT RESULT IN
DEATH OR PERSONAL INJURY (“HAZARDOUS APPLICATIONS”). EXCEPT TO THE EXTENT THIS EXCLUSION OR
RESTRICTION OF LIABILITY WOULD BE VOID OR INEFFECTIVE UNDER APPLICABLE LAW, IN NO EVENT SHALL
MENTOR GRAPHICS OR ITS LICENSORS BE LIABLE FOR ANY DAMAGES RESULTING FROM OR IN CONNECTION
WITH THE USE OF MENTOR GRAPHICS PRODUCTS IN OR FOR HAZARDOUS APPLICATIONS. THE PROVISIONS OF
THIS SECTION 9 SHALL SURVIVE THE TERMINATION OF THIS AGREEMENT.
10. INDEMNIFICATION. CUSTOMER AGREES TO INDEMNIFY AND HOLD HARMLESS MENTOR GRAPHICS AND ITS
LICENSORS FROM ANY CLAIMS, LOSS, COST, DAMAGE, EXPENSE OR LIABILITY, INCLUDING ATTORNEYS’ FEES,
ARISING OUT OF OR IN CONNECTION WITH THE USE OF MENTOR GRAPHICS PRODUCTS IN OR FOR HAZARDOUS
APPLICATIONS. THE PROVISIONS OF THIS SECTION 10 SHALL SURVIVE THE TERMINATION OF THIS AGREEMENT.
11. INFRINGEMENT.
11.1. Mentor Graphics will defend or settle, at its option and expense, any action brought against Customer in the United States,
Canada, Japan, or member state of the European Union which alleges that any standard, generally supported Product acquired by
Customer hereunder infringes a patent or copyright or misappropriates a trade secret in such jurisdiction. Mentor Graphics will
pay costs and damages finally awarded against Customer that are attributable to such action. Customer understands and agrees that
as conditions to Mentor Graphics’ obligations under this section Customer must: (a) notify Mentor Graphics promptly in writing
of the action; (b) provide Mentor Graphics all reasonable information and assistance to settle or defend the action; and (c) grant
Mentor Graphics sole authority and control of the defense or settlement of the action.
11.2. If a claim is made under Subsection 11.1 Mentor Graphics may, at its option and expense: (a) replace or modify the Product so that
it becomes noninfringing; (b) procure for Customer the right to continue using the Product; or (c) require the return of the Product
and refund to Customer any purchase price or license fee paid, less a reasonable allowance for use.
11.3. Mentor Graphics has no liability to Customer if the action is based upon: (a) the combination of Software or hardware with any
product not furnished by Mentor Graphics; (b) the modification of the Product other than by Mentor Graphics; (c) the use of other
than a current unaltered release of Software; (d) the use of the Product as part of an infringing process; (e) a product that Customer
makes, uses, or sells; (f) any Beta Code or Product provided at no charge; (g) any software provided by Mentor Graphics’
licensors who do not provide such indemnification to Mentor Graphics’ customers; or (h) infringement by Customer that is
deemed willful. In the case of (h), Customer shall reimburse Mentor Graphics for its reasonable attorney fees and other costs
related to the action.
11.4. THIS SECTION 11 IS SUBJECT TO SECTION 8 ABOVE AND STATES THE ENTIRE LIABILITY OF MENTOR
GRAPHICS AND ITS LICENSORS, AND CUSTOMER’S SOLE AND EXCLUSIVE REMEDY, FOR DEFENSE,
SETTLEMENT AND DAMAGES, WITH RESPECT TO ANY ALLEGED PATENT OR COPYRIGHT INFRINGEMENT OR
TRADE SECRET MISAPPROPRIATION BY ANY PRODUCT PROVIDED UNDER THIS AGREEMENT.
12. TERMINATION AND EFFECT OF TERMINATION.
12.1. If a Software license was provided for limited term use, such license will automatically terminate at the end of the authorized term.
Mentor Graphics may terminate this Agreement and/or any license granted under this Agreement immediately upon written notice
if Customer: (a) exceeds the scope of the license or otherwise fails to comply with the licensing or confidentiality provisions of

this Agreement, or (b) becomes insolvent, files a bankruptcy petition, institutes proceedings for liquidation or winding up or enters
into an agreement to assign its assets for the benefit of creditors. For any other material breach of any provision of this Agreement,
Mentor Graphics may terminate this Agreement and/or any license granted under this Agreement upon 30 days written notice if
Customer fails to cure the breach within the 30 day notice period. Termination of this Agreement or any license granted hereunder
will not affect Customer’s obligation to pay for Products shipped or licenses granted prior to the termination, which amounts shall
be payable immediately upon the date of termination.
12.2. Upon termination of this Agreement, the rights and obligations of the parties shall cease except as expressly set forth in this
Agreement. Upon termination, Customer shall ensure that all use of the affected Products ceases, and shall return hardware and
either return to Mentor Graphics or destroy Software in Customer’s possession, including all copies and documentation, and
certify in writing to Mentor Graphics within ten business days of the termination date that Customer no longer possesses any of
the affected Products or copies of Software in any form.
13. EXPORT. The Products provided hereunder are subject to regulation by local laws and United States (“U.S.”) government agencies,
which prohibit export, re-export or diversion of certain products, information about the products, and direct or indirect products thereof,
to certain countries and certain persons. Customer agrees that it will not export or re-export Products in any manner without first
obtaining all necessary approval from appropriate local and U.S. government agencies. If Customer wishes to disclose any information
to Mentor Graphics that is subject to any U.S. or other applicable export restrictions, including without limitation the U.S. International
Traffic in Arms Regulations (ITAR) or special controls under the Export Administration Regulations (EAR), Customer will notify
Mentor Graphics personnel, in advance of each instance of disclosure, that such information is subject to such export restrictions.
14. U.S. GOVERNMENT LICENSE RIGHTS. Software was developed entirely at private expense. The parties agree that all Software is
commercial computer software within the meaning of the applicable acquisition regulations. Accordingly, pursuant to U.S. FAR 48
CFR 12.212 and DFAR 48 CFR 227.7202, use, duplication and disclosure of the Software by or for the U.S. government or a U.S.
government subcontractor is subject solely to the terms and conditions set forth in this Agreement, which shall supersede any
conflicting terms or conditions in any government order document, except for provisions which are contrary to applicable mandatory
federal laws.
15. THIRD PARTY BENEFICIARY. Mentor Graphics Corporation, Mentor Graphics (Ireland) Limited, Microsoft Corporation and
other licensors may be third party beneficiaries of this Agreement with the right to enforce the obligations set forth herein.
16. REVIEW OF LICENSE USAGE. Customer will monitor the access to and use of Software. With prior written notice and during
Customer’s normal business hours, Mentor Graphics may engage an internationally recognized accounting firm to review Customer’s
software monitoring system and records deemed relevant by the internationally recognized accounting firm to confirm Customer’s
compliance with the terms of this Agreement or U.S. or other local export laws. Such review may include FlexNet (or successor
product) report log files that Customer shall capture and provide at Mentor Graphics’ request. Customer shall make records available in
electronic format and shall fully cooperate with data gathering to support the license review. Mentor Graphics shall bear the expense of
any such review unless a material non-compliance is revealed. Mentor Graphics shall treat as confidential information all information
gained as a result of any request or review and shall only use or disclose such information as required by law or to enforce its rights
under this Agreement. The provisions of this Section 16 shall survive the termination of this Agreement.
17. CONTROLLING LAW, JURISDICTION AND DISPUTE RESOLUTION. The owners of certain Mentor Graphics intellectual
property licensed under this Agreement are located in Ireland and the U.S. To promote consistency around the world, disputes shall be
resolved as follows: excluding conflict of laws rules, this Agreement shall be governed by and construed under the laws of the State of
Oregon, U.S., if Customer is located in North or South America, and the laws of Ireland if Customer is located outside of North or
South America. All disputes arising out of or in relation to this Agreement shall be submitted to the exclusive jurisdiction of the courts
of Portland, Oregon when the laws of Oregon apply, or Dublin, Ireland when the laws of Ireland apply. Notwithstanding the foregoing,
all disputes in Asia arising out of or in relation to this Agreement shall be resolved by arbitration in Singapore before a single arbitrator
to be appointed by the chairman of the Singapore International Arbitration Centre (“SIAC”) to be conducted in the English language, in
accordance with the Arbitration Rules of the SIAC in effect at the time of the dispute, which rules are deemed to be incorporated by
reference in this section. Nothing in this section shall restrict Mentor Graphics’ right to bring an action (including for example a motion
for injunctive relief) against Customer in the jurisdiction where Customer’s place of business is located. The United Nations
Convention on Contracts for the International Sale of Goods does not apply to this Agreement.
18. SEVERABILITY. If any provision of this Agreement is held by a court of competent jurisdiction to be void, invalid, unenforceable or
illegal, such provision shall be severed from this Agreement and the remaining provisions will remain in full force and effect.
19. MISCELLANEOUS. This Agreement contains the parties’ entire understanding relating to its subject matter and supersedes all prior
or contemporaneous agreements. Some Software may contain code distributed under a third party license agreement that may provide
additional rights to Customer. Please see the applicable Software documentation for details. This Agreement may only be modified in
writing, signed by an authorized representative of each party. Waiver of terms or excuse of breach must be in writing and shall not
constitute subsequent consent, waiver or excuse.
Rev. 140201, Part No. 258976