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dB
were set in the Property Editor box rather than by selecting the components
from the screen. Note the need for the two resistors in series
with the inductors since inductors cannot be considered ideal elements.
The small value of the resistive elements, however, will have no effect
on the results obtained.
In the Simulation Settings dialog box, AC Sweep wasagain selected
with a Start Frequency of 100 Hz and an End Frequency of 10 MHz
(be sure to enter this value as 10MEGHZ) to ensure that the full-range
effect is provided. We can then use the axis controls to close in on the
desired plot. The Points/Decade remains at 10k, although with this
range of frequencies it may take a few seconds to simulate. Once the
SCHEMATIC1 appears, Trace-Add Trace-V(RL:1)-OK will result in
the plot of Fig. 23.96. Quite obviously there is a reject-band around
200 kHz and a pass-band around 600 kHz. Isn’t it interesting that up to
10 kHz we have another pass-band as the inductor L p provides an
almost direct path of low impedance from input to output. At frequencies
approaching 10 MHz, there is a continous stop-band due to the
open-circuit equivalence of the L p inductor. Using the cursor option, we
can place the left-click cursor on the minimum point of the graph by
using the Cursor Trough key pad (the second pad to the right of the
Toggle cursor pad). The right click can be used to identify the frequency
of the maximum point on the curve near 600 kHz. The results
appearing in the Probe Cursor box clearly support our theoretical calculations
of 200 kHz for the band-stop minimum (A1 � 200.02 kHz
with a magnitude of essentially 0 V) and 600 kHz for the pass-band
maximum (A2 � 603.115 kHz with a magnitude of 1 V).
FIG. 23.96
Magnitude plot versus frequency for the voltage across R L of the network of
Fig. 23.95.
COMPUTER ANALYSIS ⏐⏐⏐ 1083