eldo_user

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