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Simulators >> Circuit Simulators >> Want to plot impedance over frequency domain
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Message started by Mo on Jul 31^st, 2003, 1:19pm

Title: Want to plot impedance over frequency domain
Post by Mo on Jul 31^st, 2003, 1:19pm

I used smartspice to simulate a circuit. I am wondering how I can get a plot of impedance over the frequency domain.

Do I need to write any scripts in C++/Java/C simulate the circuit hundreds of times and pick each voltage and current to find the corresponding impedance? If so, how? I will really appreciate any ideas or advance. THanks

Mo

Title: Re: Want to plot impedance over frequency domain
Post by Mighty Mouse on Aug 1^st, 2003, 10:08am

Drive the port for which you want the impedance with 1 A current source and perform an AC analysis. Then plot the port voltage. The impedance is V/I, and I is 1, so the magnitude and phase of the voltage will be identical to the magnitude and phase of the port impedance.

- MM -

Title: Re: Want to plot impedance over frequency domain
Post by Mo on Aug 4^th, 2003, 7:09am

Thanks for your reply.
But the capacitance/resistance/inductance are dependent to the frequency. Can I still do it with ac analysis? To make it clear, the magitude of some of the resistance, capacitance and inductance are a function of frequency. Thanks.

Title: Re: Want to plot impedance over frequency domain
Post by Mighty Mouse on Aug 4^th, 2003, 2:56pm

Sure, just perform an AC analysis where you sweep the frequency. Try it, it is easy.

- MM -

Title: Re: Want to plot impedance over frequency domain
Post by Mo on Aug 5^th, 2003, 6:47am

mmmm......but i am not sure how to make the arbitrary value of resistance work....

say one of the resistance is (freq/x+y)...... How can I let the simulator know that freq is the frequency that it sweeps thru? sorrie, i am a newbie....thanks very much