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https://designers-guide.org/forum/YaBB.pl Simulators >> RF Simulators >> Switched capacitor circuit noise simulation https://designers-guide.org/forum/YaBB.pl?num=1286566916 Message started by lunren on Oct 8th, 2010, 12:41pm |
Title: Switched capacitor circuit noise simulation Post by lunren on Oct 8th, 2010, 12:41pm Hi All, I have a switched capacitor circuit which has three clock phases, ph1 and ph2 work at 25MHz and ph3 works at 50MHz. Clock is 3.3V pulse. I am wondering if there is a way to use SpectreRF to run the pnoise or qpnoise? My knowledge about pnoise is that PSS only works for the circuit which has only one tone; qpnoise is that QPSS only works for sinusoidal tone. Thanks, |
Title: Re: Switched capacitor circuit noise simulation Post by lunren on Oct 8th, 2010, 1:59pm I made the simulator to run with some tricks. Now I have another question. The clock in the circuit is 25MHz, but the circuit output is still at 50MHz, should I put 12.5Mhz or 25MHz in the Stop of pnoise form? Thanks, |
Title: Re: Switched capacitor circuit noise simulation Post by pancho_hideboo on Oct 8th, 2010, 10:55pm I can't find out any measurement issue in your post. Your question is no more than very easy usage of very specific vendor's simulator. lunren wrote on Oct 8th, 2010, 12:41pm:
lunren wrote on Oct 8th, 2010, 12:41pm:
PSS is an expansion by single frequency basis while QPSS is an expansion by multiple frequency bases which have no common divisor frequency each other. lunren wrote on Oct 8th, 2010, 12:41pm:
In your case, fundamental frequency of PSS is 25MHz. And you can adopt PSS/Pnoise without any problem. In your case, you can't use QPSS/QPnoise since 25MHz and 50MHz have common divisor frequency of 25MHz. lunren wrote on Oct 8th, 2010, 1:59pm:
Show me the reason why you want to include 12.5MHz as frequency for Pnoise analysis. Generally I don't recommend to include fundamental frequency of master large signal steady state analysis as analysis frequency for slave small signal noise analysis. See the followings. http://www.designers-guide.org/Forum/YaBB.pl?num=1258339986/7#7 http://www.designers-guide.org/Forum/YaBB.pl?num=1258339986/13#13 http://www.designers-guide.org/Forum/YaBB.pl?num=1218622880/3#3 |
Title: Re: Switched capacitor circuit noise simulation Post by lunren on Oct 11th, 2010, 12:47pm pancho_hideboo wrote on Oct 8th, 2010, 10:55pm:
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Title: Re: Switched capacitor circuit noise simulation Post by pancho_hideboo on Oct 12th, 2010, 4:51am lunren wrote on Oct 11th, 2010, 12:47pm:
lunren wrote on Oct 11th, 2010, 12:47pm:
There is no concept of "beat frequency" in both PSS and QPSS of Cadence Spectre. See the followings. http://www.designers-guide.org/Forum/YaBB.pl?num=1232036048/4#4 http://www.designers-guide.org/Forum/YaBB.pl?num=1268969030/7#7 lunren wrote on Oct 11th, 2010, 12:47pm:
Other medium signals also can be pulse waveform. However from practical point of view, if you use pulse wave as medium signal, convergence of QPSS of Cadence Spectre is very very very bad. This is very true especially for Shooting-Newton-QPSS. lunren wrote on Oct 11th, 2010, 12:47pm:
And it has to be "fundamental_frequency/2" not "beat_frequency/2". The followings are general notes for you. - Always describe correct tool's name and vendor's name which you use as tool or simulator. - Don't do multiple posts which are same content. - Don't request source code or behavioral model without any efforts. - There are many simulators which have analyses called as PSS, PAC and Pnoise. - Describe in detail and correctly with using correct terminologies. - Warnigns are different from Errors. - ADS is not name of simulator. - There is no tool which name is Cadence. - Don't use Direct Plot of Cadence ADE blindly without knowing definition. - All gains in Direct Plot of Cadence ADE are "right", "true" and "practical" voltage gain. - Don't mix up Simulation with Post Processing. They are completely different phase. - MATLAB are different from Simulink. - Learn measurements using actual instruments. Not "EDA Tool Play |
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