User`s guide

DC Sweep 9
-7
Curve Families for DC Sweeps
Whenever a nested DC sweep is performed, the entire curve
family is displayed. That is, the nested DC sweep is treated as a
single Probe data section (or you can think of it as a single
PSpice A/D run).
For the circuit shown in Figure 9-3, you could set up a DC
sweep analysis with an outer sweep of the voltage source VD
and an inner sweep of the voltage source VG as listed in
Table 9-2
.
When the DC sweep analysis is run, add a current marker at the
drain pin of M1 and display the simulation result in Probe. The
result will look like Figure 9-4.
To add a load line for a resistor, add a trace that computes the
load line from the sweep voltage. Assume that the X axis
variable is the sweep voltage V_VD, which runs from 0 to 5
volts. The expression which will add a trace that is the load line
for a 50 kohm resistor is:
(5V-V_VD)/50K
This can be useful for determining the bias point for each
member of a curve family as shown in Figure 9-5.
Table 9-2
Curve Family Example Setup
Outer Sweep Nested Sweep
Swept Var Type Voltage Source Voltage Source
Sweep Type Linear Linear
Name VD VG
Start Value 0 0
End Value 5 2
Increment 0.1 0.5
Fi
g
ure 9-3
Curve Family
Example Schematic
Use Mark Current Into Pin in
MicroSim Schematics on the
Markers menu to add a current
marker.
V_VD is the hierarchical name
for VD created by netlistin
g
the
schematic. This is the name
used by Probe.