User Guide

AC sweep analysis
233
circuits about their bias point value before PSpice runs
the linear (small-signal) analysis.
• Because AC sweep analysis is a linear analysis, it only
considers the gain and phase response of the circuit; it
does not limit voltages or currents.
The best way to use AC sweep analysis is to set the source
magnitude to one. This way, the measured output equals
the gain, relative to the input source, at that output.
Setting up an AC stimulus
To run an AC sweep analysis, you need to place and
connect one or more independent sources and then set the
AC magnitude and phase for each source.
To set up an AC stimulus
1 Place and connect one of these symbols in your
schematic:
2 Double-click the symbol instance to display the Parts
spreadsheet.
Table 2
For voltage input
Use this... When you are running...
VAC An AC sweep analysis only.
VSRC Multiple analysis types including AC
sweep.
Table 3
For current input
Use this... When you are running...
IAC An AC sweep analysis only.
ISRC Multiple analysis types including AC
sweep.
Note
Un
l
i
k
e DC sweep, t
h
e AC
Sweep/Noise dialog box not include an
input source option. Instead, each
independent source in your circuit contains
its own AC specification for magnitude and
phase.
I
f
you are p
l
anning to run a DC or transient
analysis in addition to an AC analysis, see
If you want to specify multiple
stimulus types on page 3-77
for
additional information and source symbols
that you can use.
Pspug.book Page 233 Wednesday, November 11, 1998 1:14 PM