User Guide

AC sweep analysis
39
5 Click OK to close the Simulation Settings dialog box.
6 From the PSpice menu, choose Run to start the
simulation.
PSpice performs the AC analysis.
To add markers for waveform analysis
1 From Capture’s PSpice menu, point to Markers, point
to Advanced, then choose db Magnitude of Voltage.
2 Place one Vdb marker on the Out net, then place
another on the Mid net.
3 From the File menu, choose Save to save the design.
AC sweep analysis results
PSpice displays the dB magnitude (20log10) of the voltage
at the marked nets, Out and Mid, in a Probe window as
shown in Figure 20 below. VDB(Mid) has a lowpass
response due to the diode capacitances to ground. The
output capacitance and load resistor act as a highpass
filter, so the overall response, illustrated by VDB(out), is a
bandpass response. Because AC is a linear analysis and
the input voltage was set to 1V, the output voltage is the
same as the gain (or attenuation) of the circuit.
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ote
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ou must
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profile for the AC Sweep/Noise analysis
in order to use advanced markers.
Pspug.book Page 39 Wednesday, November 11, 1998 1:14 PM