User Guide

Performance analysis
49
Performance analysis
Performance analysis is an advanced feature in PSpice
that you can use to compare the characteristics of a family
of waveforms. Performance analysis uses the principle of
search commands introduced earlier in this chapter to
define functions that detect points on each curve in the
family.
After you define these functions, you can apply them to a
family of waveforms and produce traces that are a
function of the variable that changed within the family.
This example shows how to use performance analysis to
view the dependence of circuit characteristics on a swept
parameter. In this case, the small signal bandwidth and
gain of the clipper circuit are plotted against the swept
input resistance value.
To plot bandwidth vs. Rval using the performance analysis wizard
1 In Capture, open CLIPPER.OPJ.
2 From PSpice’s Trace menu, choose Performance
Analysis.
The Performance Analysis dialog box appears with
information about the currently loaded data and
performance analysis in general.
3 Click the Wizard button.
4 Click the Next> button.
5 In the Choose a Goal Function list, click Bandwidth,
then click the Next> button.
6 Click in the Name of Trace to search text box and type
V(Out).
7 Click in the db level down for bandwidth calc text box
and type
3.
8 Click the Next> button.
The wizard displays the gain trace for the first run
(R=100) and shows how the bandwidth is measured.
This is done to test the goal function.
At eac
h
step, t
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e wizar
d
provi
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es
information and guidelines.
Click , then double-click V(Out).
Pspug.book Page 49 Wednesday, November 11, 1998 1:14 PM