User`s guide

Usin
g
the Model Editor 4
-35
Example: Editin
g
a Q2N2222
Instance Model
Suppose you have a schematic named my.sch 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.
Startin
g
the model editor
To start the model editor, you need to:
1
Select Q6 on your schematic.
2
From the Edit menu, select Model.
3
Click Edit Instance Model (Text).
The model editor automatically creates a copy of the Q2N2222
base model definition and changes the name to Q2N2222-X.
The model editor also displays the PSpice syntax for the copied
model in the edit area.
Editin
g
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).