Going back to this discussion adding another tidbit:
If you run an .AC analysis, and then do a View > FFT, LTspice will gladly perform an (inverse) FFT on the frequency-domain output from the .AC sweep.? The output will be saved in an *.imp file, where it is the waveform as a function of time.? It's likely that it is not particularly useful to most users.? But LTspice gladly complies.
So there is another way to get an *.imp file, without doing an FFT on the output of an FFT.
Andy
