Is it possible to graph R and X of a circuit?
Such as looking into a filter, instead of amplitude
and phase, could I graph R and X.
If yes, how?
Thanks, Mike
Yes... OK, there are many ways you could do this. Here's just one.
I'm assuming you will do an AC analysis, to get the response versus
frequency. Excite the circuit with a current source, say I1. It's
convenient to set it to AC 1 amp, zero phase, but not necessary. Have
that current flowing INTO the circuit. Then the voltage at the input
divided by the current will be a complex quantity equal to the net
impedance. If you made the current = 1A, you don't even have to
divide by it, but there's an advantage to do so... The real part of
that will be resistance, and the imaginary part will be reactance.
Let's say you labeled the input node "in" Then to start, plot V(in).
The default is a dB plot. Now right-click on the label at the top. A
box will come up; change the plotted quantity to re(V(in)/I(I1)), and
"ok" that. Now put your cursor over the plot, and right click.
Select "manual limits". Set the left vertical axis to linear. You
should now have a plot of the real part of the input impedance,
displayed in ohms. But wait! If you change the plotted quantity back
to just V(in)/I(I1), it will plot the real part (resistance) on the
left axis, and the imaginary part (reactance) on the right axis.
Dat help any?
Cheers,
Tom