User`s guide

13
-
14 Monte Carlo and Sensitivity/Worst-Case Analyses
Savin
g
the schematic
Before editing the models for the Rbreak resistors, save the
schematic.
To save the schematic
1
From the File menu, select Save As.
2
In the File Name text box, type
psensor.sch.
3
Click OK.
Definin
g
tolerances for the resistor models
Assign device (DEV) and lot (LOT) tolerances to the model
parameters for resistors R1, R2, R3, and R4 using the model
editor.
To assi
g
n 2% device and 10% lot tolerances to
the resistance multiplier for R1
1
Select R1.
2
From the Edit menu, select Model.
The Edit Model dialog box appears with these choices:
• Change Model Reference, which lets you change the
model association for the symbol instance; if you had a
model named MyModel, you could change R1 to
reference MyModel.
• Edit Instance Model (Text), which starts the model
editor and loads a copy of the model definition; for this
tutorial, this means the PSpice command syntax for the
.MODEL Rbreak definition.
• Edit Instance Model (Parts), which starts the Parts
utility and loads the device information for the
corresponding model; this selection lets you change the
behavioral properties of the device, but not device and
lot tolerances.
3
Click Edit Instance Model (Text).
Schematics searches the libraries for the Rbreak model
definition, makes a copy to create an instance model, and
The model editor lets you
chan
g
e the .MODEL or
.SUBCKT syntax for a model
definition. To find out more about
the model editor, see
Using the
Model Editor on page 4-29.