eldo_user

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