User Guide

Chapter 1 Things you need to know
4
AC sweep and noise
These AC analyses evaluate circuit performance in
response to a small-signal alternating current source.
Table 2
summarizes what PSpice calculates for each AC
analysis type.
Note To run a noise analysis, you must also run an AC sweep analysis.
Table 2
AC analysis types
For this AC analysis... PSpice computes this...
AC sweep Small-signal response of the circuit
(linearized around the bias point) when
sweeping one or more sources over a
range of frequencies. Outputs include
voltages and currents with magnitude
and phase; you can use this information
to obtain Bode plots.
Noise For each frequency specified in the AC
analysis:
•
Propagated noise contributions at an
output net from every noise
generator in the circuit.
•
RMS sum of the noise contributions
at the output.
•
Equivalent input noise.
Pspug.book Page 4 Wednesday, November 11, 1998 1:14 PM