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Jul 22nd, 2024, 4:36pm
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Plot an oscillator output spectrum (Read 144 times)
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Plot an oscillator output spectrum
Apr 22nd, 2021, 5:36pm

I have an oscillator running at fosc. My question is how to plot the spectrum of the time domain output of the oscillator. What I am specifically looking for is the relation between the simulation time (time domain data record), the number of FFT points, and fosc to correctly plot the spectrum.  Does the Coherent Sampling of a periodic waveform apply here? if so, how?

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Ken Kundert
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Silicon Valley
Re: Plot an oscillator output spectrum
Reply #1 - Apr 22nd, 2021, 7:54pm
You have two choices, you can perform an FFT after the simulation, in which case the FFT will not be synchronous with the oscillation. In this case the period of the FFT will not match that of the oscillator. You can reduce the artifacts of the period mismatch by simulating many cycles while applying windowing.

Or, you can use SpectreRF.  It computes the periodic steady state analysis, and so it directly computes the period.  It can compute the spectrum without the artifacts.

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