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Simulators >> Circuit Simulators >> When do I need to resample for an FFT in Spectre
https://designers-guide.org/forum/YaBB.pl?num=1165851956

Message started by makelo on Dec 11^th, 2006, 7:45am

Title: When do I need to resample for an FFT in Spectre
Post by makelo on Dec 11^th, 2006, 7:45am

I have noticed that some of the transient simulation results from spectre have a varied time step. When I use the PSD function in the waveform calculator does it autmatically resample the signal or do I need to do that manually to get a pure tone in my FFT results? If resampling is required, is it best to export to MATLAB or is there and easier way?

Thanks,
Makelo

Title: Re: When do I need to resample for an FFT in Spect
Post by Andrew Beckett on Dec 12^th, 2006, 2:10pm

Both psd and dft in the calculator will re-sample the waveform, because it is the norm for spectre to write out with an uneven timestep - the default is that it writes out any timestep actually simulated.

You can also use the transient option strobeperiod to set a time interval for spectre to place a timestep at, and also to write out the results. This leads to a higher accuracy FFT, since you're minimising the interpolation error if you can arrange the strobeperiod to coincide with the FFT sampling interval.

There are various posts on this in these forums - you should be able to search for strobeperiod to find more info on this.

Regards,

Andrew.