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FIG. 9.121
Plot resulting from the dc sweep of R L for the network of Fig. 9.120 before
defining the parameters to be displayed.
will look as if the values were 0 �, 1 �, 2 �, etc. Click OK, and select
the Run PSpice key to obtain the display of Fig. 9.121.
First note that there are no plots on the graph and that the graph
extends to 35 � rather than 30 � as desired. It did not respond with a plot
of power versus RL because we have not defined the plot of interest for
the computer. This is done by selecting the Add Trace key (the key in the
middle of the lower toolbar that looks like a red sawtooth waveform)
or Trace-Add Trace from the top menu bar. Either choice will result
in the Add Traces dialog box. The most important region of this dialog
box is the Trace Expression listing at the bottom. The desired trace can
be typed in directly, or the quantities of interest can be chosen from the
list of Simulation Output Variables and deposited in the Trace Expression
listing. Since we are interested in the power to RL for the chosen
range of values for RL, W(RL) is selected in the listing; it will then
appear as the Trace Expression. Click OK, and the plot of Fig. 9.122
will appear. Originally, the plot extended from 0 � to 35 �.Wereduced
the range to 0 � to 30 � by selecting Plot-Axis Settings-X Axis-User
Defined 0 to 30-OK.
Select the Toggle cursor key (which looks like a red curve passing
through the origin of a graph), and then left-click the mouse. A vertical
line and a horizonal line will appear, with the vertical line controlled by
the position of the cursor. Moving the cursor to the peak value will
result in A1 � 9.0010 as the x value and 100.000 W as the y value as
shown in the Probe Cursor box at the right of the screen. A second
cursor can be generated by a right click of the mouse, which was set at
RL � 30.001 � to result in a power of 71.005 W. Notice also that the
COMPUTER ANALYSIS ⏐⏐⏐ 365