I know that simulating FFT analysis of current/voltage across a single element via LTSpice is quite straightforward. I have simulated the summation of three distinct currents in the time domain. I'd like to perform an FFT analysis of the summed signal in its current incarnation (just as it is). Can anyone suggest to me how to compute the FFT analysis of the summed signal?
Best Answer
When you open the FFT dialog, highlight I(L1), I(L2), I(L3). You may want to set other FFT parameters, such as window type.
When you click OK, you are given the option of Alt-double clicking.
Do so and enter the sum of the currents: I(L1)+I(L2)+I(L3)
You now have the FFT of the sum of your currents.
Your FFT plots will benefit (lower noise floor) by disabling data compression (.option plotwinsize=0)
and reducing the maximum time step in the .tran statement.