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