OrCAD/PSpice Question

Oct 22, 2003 4 Replies

What is the best way to get input and output impedance of a two-port network using OrCAD/PSpice?



I was just curious if there was a more direct way than what I've been doing-- exciting the input with a 1Vac signal and dividing that by the input current. Seems to me they should have a "special button" for getting the impedances directly...??



Thanks,



Jason


What can be more direct than that?

The AC source (call it VIN) has unity value, thus the following applies...

Y = REAL(-I(VIN)) + j*IMAG(-I(VIN))

(PSpice uses R=REAL and IM=IMAG, but I made macros that are more readable.)

Another useful macro that I made is:

CAP = IMAG(-I(VIN))/(2*pi*Frequency)

I also have macros for resolving capacitors with series losses if anyone is interested (like MOS capacitors).

...Jim Thompson

[snip]
[snip]

Make that IMG=IMAG

...Jim Thompson

hmm, perhaps I'm just spoiled by other software packages. I figured it would be such a common need that someone might have built in a way to "automatically" do it.. Thanks.

Jason

One can simply id a source to tell the simulator to automatically calculate V/I and plot impedance. I am aware of at least one simulator that does this:-)

Kevin Aylward snipped-for-privacy@anasoft.co.uk

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a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design.

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