Question

Can we measure the frequency response from SPICE transient analysis? If yes,
how? If no, why?

Answer 1

Yes, we can find the Frequency response using the transient analysis.
Conside a the following signal to be the input.
x(t) = sin(2*pi*t) for 10sec then for next 10 sec x(t) = sin(2*pi*2*t), then for next ten 10 sec x(t) = sin(2*pi*3*t) and so on....This kind of signal is called chirp signal.
Now performing the transient analysis, we get at the output the time domain signal for the chirp signal at input.
Now to build a frequency response we only need to know what is the Magnitude gain at all the frequencies and the phase shift at all the frequencies.
So observing the signal's amplitude for the first 10 sec, we can find the gain and phase at 1Hz, then observing the amplitude and phase foe next 10 seconds we get amplitude and phase at 2Hz and so on we can find the Magnitude and phase at all the frequencies.

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