User Guide

The Active Filter Desi
g
n 6
-3
The Parameters
The three variable resistors—Rfc, Rbw, and Rgain—are
implemented as potentiometers. The potentiometer symbol has
an attribute called SET which describes the slider position—a
value between 0 and 1.
To optimize slider position, the optimization parameters afc,
aBW, and AGain are assigned to the SET attribute for the
symbols Rfc, Rbw, and Rgain, respectively.
The parameters are shown in the OPTPARAM symbol on the
schematic. Each parameter is set up to range from 0.1 to 0.9 with
an initial value for each set to 0.5 (each potentiometer’s center
point). The settings for aGain are shown below.
The Goals
The example circuit is set up with predefined goals which you
can view using the PSpice Optimizer.
To activate the PSpice Optimizer
1
From the Tools menu, select Run Optimizer.
To see the assi
g
nment for SET,
double-click on one of the
variable resistor symbols to brin
g
up its list of symbol attributes.
To display the Optimizer
Parameters dialo
g
box, double-
click the OPTPARAM symbol in
the schematic.