User Guide

Chapter 12 Monte Carlo and sensitivity/worst-case analyses
302
bandwidth and the center frequency vary when 1%
resistors and 5% capacitors are used in the circuit.
Creating models for Monte Carlo analysis
To vary the resistors and capacitors in the filter circuit,
create models for these parts on which you can set device
tolerances for Monte Carlo analysis. The
BREAKOUT.OLB library contains generic devices for this
purpose. The resistors and capacitors in this schematic are
the Rbreak and Cbreak parts from BREAKOUT.OLB.
Using the Model Editor, modify the models for these parts
as follows:
.model RMOD RES(R=1 DEV=1%)
.model CMOD CAP(C=1 DEV=5%)
Setting up the analysis
To analyze the filter, set up both an AC analysis and a
Monte Carlo analysis. The AC analysis sweeps 50 points
per decade from 100 Hz to 1 MHz. The Monte Carlo
analysis is set to take 100 runs. The analysis type is AC and
the output variable is V(OUT).
Figure 81 Chebyshev filter.
Pspug.book Page 302 Wednesday, November 11, 1998 1:14 PM