User Guide

Chapter 4 Creating and editing models
114
Example: editing a Q2N2222 instance model
Suppose you have a design named MY.OPJ that contains
several instances of a Q2N2222 bipolar transistor.
Suppose also that you are interested in the effect of base
resistance variation on one specific device: Q6. To do this,
you need to do the following:
• Define a tolerance (in this example, 5%) on the Rb
model parameter.
• Set up and run a Monte Carlo analysis.
The following example demonstrates how to set up the
instance model for Q6.
Starting the Model Editor
To start the Model Editor, you need to:
1 In the schematic page editor, select Q6 on the
schematic page.
2 From the Edit menu, choose PSpice Model.
The Model Editor automatically creates a copy of the
Q2N2222 base model definition.
3 In the Model Editor, from the View menu, choose
Model Text.
The Model Editor displays the PSpice syntax for the
copied model in the text editing area.
Editing the Q2N2222-X model instance
Text edits appropriate to this example are as follows:
•
Add the DEV 5% clause to the Rb statement (required).
•
Change the model name to Q2N2222-MC (optional, for
descriptive purposes only).
To
f
in
d
out more a
b
out PSpice comman
d
and netlist syntax, refer to the online
OrCAD PSpice A/D Reference
M
anual.
Pspug.book Page 114 Wednesday, November 11, 1998 1:14 PM