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How small is 'small signal' in Spectre PAC, PXF and PNoise? (Read 3674 times)
ppg
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How small is 'small signal' in Spectre PAC, PXF and PNoise?
Aug 02nd, 2011, 10:00am
 
Dear All,

How shall one define the domain of validity of Spectre PAC, PXF and PNoise for oscillators knowing that for oscillators "even small-input perturbations lead to, over time, large changes in phase and timing properties" (see IEEE CAD Vol26 June 2007 p1054 by T. Mei)?

For small input signals larger than small in the sense of PAC, PXF and PNoise what are analysis alternatives? Spectre QPAC, QPXF and QPNoise?

Thank you,
Best Regards,
ppg
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Ken Kundert
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Re: How small is 'small signal' in Spectre PAC, PXF and PNoise?
Reply #1 - Aug 2nd, 2011, 12:30pm
 
Small signals do not create distortion.

-Ken
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ppg
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Re: How small is 'small signal' in Spectre PAC, PXF and PNoise?
Reply #2 - Aug 2nd, 2011, 1:59pm
 
Hi Ken,

Yes, I agree.
Now what will be the best way to check for distortion using Spectre RF? Via the PAC specialized analyses ... like 'Compression Distortion Summary' or ... ? Please provide pointer to possible tutorial info on such type of Specialized Analyses. Thank you.

Does distortion includes situation where the small signal could alter the oscillation frequency  and result in large accumulated non periodic variations? Are such effects included in PAC Specialized Analysis?

Best Regards,
ppg.
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Ken Kundert
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Re: How small is 'small signal' in Spectre PAC, PXF and PNoise?
Reply #3 - Aug 2nd, 2011, 3:12pm
 
I'm afraid I have no personal experience with the PAC specialized analyses. However, if it were me I would try the distortion summary if I were interested in knowing the distortion of my circuit when it is operating well out of compression. They should be faster and more informative than the QP analyses.

-Ken
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