Multi frequency AC analysis, how ?

[kavea]

Hi,
I'm wondering how to simulate a circuit at different frequencies with different amplitudes, for example at 1MHz with 1V, at 2MHz with 3V source etc. Since there are a lot of frequencies i can't change amplitude and frequency of a single tone voltage source manually. I need some kind of frequency dependent voltage source.. Does anyone know how to proceed in this case ? I use LTSpice and Ansoft Designer simulators

 

[erikl]

• You can superimpose (i.e. put in series) several ac voltage sources with different frequencies and voltages
• Or you can use an FM ac source and modulate it with a (lower) frequency spectrum
• You can sweep the frequency of an ac voltage source during an ac analysis (but only with constant voltage, and only analysing the current frequency)

 

[crutschow]

You can use the .step function to step the param F.
Then replace the numerical frequency value in the sine Voltage Source with "{F}".
Look at the help for for .step to see how it works.

 

[kavea]

And what about Harmonic Balance analysis ?

 

[crutschow]

And what about Harmonic Balance analysis ?

Ltspice does not do that.
Don't know about Ansoft Designer.

 

[Borber]

Single frequency and constant amplitude are parameters from time domain analysis.