The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Analog Design >> pnoise/jitter and pnoise/time average discrepancy with Cadence Spectre
https://designers-guide.org/forum/YaBB.pl?num=1581619188

Message started by threepwood on Feb 13^th, 2020, 10:39am

Title: pnoise/jitter and pnoise/time average discrepancy with Cadence Spectre
Post by threepwood on Feb 13^th, 2020, 10:39am

Hi everyone,
I try to get the jitter from a clock generator, but I also need the phase noise curve for other reasons:
- When I simulate my circuit with the pnoise/jitter method, I get a RMS Jitter in a given bandwidth of 594.386fs (Jee>RMS).
- And when I simulate with the pnoise/time average method, by calculating my Jitter from the Phase Noise curve, I get 269.2fs.

Assuming that the pnoise>PM>Phase Noise plot is the IEEE definition, say Single-Sideband-to-Carrier Ratio, so-called L(df), "L-script of df",
I compute the RMS jitter as follows in my calculator:
[1 / sqrt(2)*pi*f0] * sqrt{ INTEGRAL[ L(df).df ] }

Of course, here L(df) is converted in linear, L(df)=10^LdBc(df)/10

In your opinion what do I miss??

Thanks a lot in advance for your help!