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Input referred noise in PNoise (Read 5379 times)
Tlaloc
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Input referred noise in PNoise
Sep 15th, 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?
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Frank Wiedmann
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Re: Input referred noise in PNoise
Reply #1 - Sep 16th, 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?
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Tlaloc
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Re: Input referred noise in PNoise
Reply #2 - Sep 16th, 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.
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Frank Wiedmann
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Re: Input referred noise in PNoise
Reply #3 - Sep 16th, 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.
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Tlaloc
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Re: Input referred noise in PNoise
Reply #4 - Sep 16th, 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.   Tongue  Thanks anyway for the help.
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