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Simulators >> RF Simulators >> Input referred noise in PNoise
https://designers-guide.org/forum/YaBB.pl?num=1221531834

Message started by Tlaloc on Sep 15^th, 2008, 7:23pm

Title: Input referred noise in PNoise
Post by Tlaloc on Sep 15^th, 2008, 7:23pm

When I run a PNoise sim with sources and specify an voltage input on a vsource instance, I am able to look at the input referred noise. Then, when I change the sim to tdnoise, the input referred noise is not saved. I made no changes to the schematic nor to any of the settings (other than the frequency range of the pnoise sim). Why is this?

Title: Re: Input referred noise in PNoise
Post by Frank Wiedmann on Sep 16^th, 2008, 12:15am

If I remember correctly, the noise summary was not available for tdnoise in earlier versions of SpectreRF. Are you using a recent version?

Title: Re: Input referred noise in PNoise
Post by Tlaloc on Sep 16^th, 2008, 7:42am

I am using spectre version 6.2.0.420. The noise summary seems to work correctly. I am having trouble retrieving the waveform for the input referred noise when running tdnoise.

Title: Re: Input referred noise in PNoise
Post by Frank Wiedmann on Sep 16^th, 2008, 8:03am

Ok, so I misunderstood your problem. I usually do not look at input referred noise but rather at the noise at the output (and where it comes from, of course). The only other suggestion I have is to use the Results Browser and see if you can find something there.

Title: Re: Input referred noise in PNoise
Post by Tlaloc on Sep 16^th, 2008, 8:13am

Unfortunately, I've already tried that. The "in" net does not appear in the browser. I am trying to get the noise of an integrator, so looking at the output noise open-loop is meaningless since the noise has been multiplied by the loop gain. I've tried closing the loop as was suggested by Kundert in delta-sigma.pdf, but the results are just not making sense. :P Thanks anyway for the help.