Question 14.16: Use PSpice to generate the gain and phase Bode plots of V in......
Use PSpice to generate the gain and phase Bode plots of V in the circuit of Fig. 14.55.
The circuit treated in Example 14.15 is first-order while the one in this example is second-order. Since we are interested in Bode plots, we use decade frequency sweep for 300 < f < 3,000 Hz with 50 points per decade. We select this range because we know that the resonant frequency of the circuit is within the range. Recall that
ω_{o} = \frac{1}{\sqrt{LC}} = 5 krad/s     or    f_{o} = \frac{ω}{2π} = 795.8 Hz
After drawing the circuit as in Fig. 14.55, we select Analysis/Setup/AC Sweep, DCLICK Decade, enter 50 in the Total Pts box, 300 as the Start Freq, and 3,000 in the End Freq box. Upon saving the file, we simulate it by selecting Analysis/Simulate. This will automatically bring up the PSpice A/D window and display V(C1 : 1) if there are no errors. Since we are interested in the Bode plot, we select Trace/Add in the PSpice A/D menu and type dB(V(C1 : 1)) in the Trace Command box. The result is the Bode magnitude plot in Fig. 14.56(a). For the phase plot, we select Trace/Add in the PSpice A/D menu and type VP(C1 : 1) in the Trace Command box. The result is the Bode phase plot of Fig. 14.56(b). Notice that the plots confirm the resonant frequency of 795.8 Hz.
