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Measurements >> Phase Noise and Jitter Measurements >> phase noise calculation using spectre
https://designers-guide.org/forum/YaBB.pl?num=1210259151

Message started by patwarga on May 8^th, 2008, 8:05am

Title: phase noise calculation using spectre
Post by patwarga on May 8^th, 2008, 8:05am

hi,

i am trying to calculate the phase noise for a frequency divider that we have designed in cadence.
when i look for any tutorial on the web, all of them talk about phase noise of an oscillator.
i got one document on the designer's guide though - which talks about the phase noise model of a divider.
it says that one should do pss on the divider and then the pnoise analysis.
but i am confused about what values do i need to give to different parameters like beat frequency, output harmonics etc. while doing the pss analysis
my pss analysis terminates due to error saying that it doesn't converge..
all i am looking for the steps (actually the babysteps) to do the pss and pnoise analysis on the divider with information about the values to be given in different boxes
i am using cadence spectre for the project.
can anyone please help me?

thanks

Title: Re: phase noise calculation using spectre
Post by couragebo on May 27^th, 2008, 5:47am

You can try the following:
beat frequency: divider's nominal output frequency
output harmonics: you mean the max. harmonic order? try the N*16 or plus. (N is the division order)
don't forget the tsab: the stablization time, usually 3-10 periods of beat frequency is suffisant.

Title: Re: phase noise calculation using spectre
Post by Miconos on Jun 29^th, 2008, 12:42am

Agree with the above with one more thing:
Sometimes playing with Tstab by a fraction of the cycle time can help dramatically. you don't want to be near the edges of the squared signal.