User`s guide

2
-
22 Simulation Examples
AC Sweep Anal
y
sis Results
Probe displays the dB magnitude (20log10) of the voltage at the
marked nets, Out and Mid, as shown in Figure 2-19. 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.
Fi
g
ure 2-19
dB Magnitude Curves for “Gain” at Mid and Out
To displa
y
a Bode plot of the output volta
g
e,
includin
g
phase
1
In Schematics, from the Markers menu, select Mark
Advanced.
2
Place a Vphase marker on the output next to the Vdb
marker.
3
Delete the Vdb marker on Mid.
4
Activate the Probe window. The gain and phase plots both
appear on the same graph with the same scale.
5
Click the trace name VP(Out) to select it.
Note
Dependin
g
upon where the Vphase marker was
placed, the trace name may be different, such as
VP(Cout:2), VP(R4:1), or VP(R4:2).