The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Measurements >> Phase Noise and Jitter Measurements >> Spectre .pnoise type sources vs pmjitter
https://designers-guide.org/forum/YaBB.pl?num=1517489117

Message started by deba on Feb 1^st, 2018, 4:45am

Title: Spectre .pnoise type sources vs pmjitter
Post by deba on Feb 1^st, 2018, 4:45am

Hi All,
In the buffer circuit, I want to analyse the phase noise due to device noise. There are two methods of doing it as discussed.
1) Noisetype as sources: In this case, the signal “out” is clipped using an ideal VCVS to remove AM noise. In pnoise, noisetype as sources is run on “out_clip”.
2) Noisetype as pmjitter: One can also run a pmjitter on “out” signal and convert the voltage noise to an equivalent dBc/Hz number using the following equation.
dBc=20 log_10⁡(((v_n √2)/slew_rate)*pi*f_o )

Here is the question. The sources dBc/Hz numbers are smaller compared to pmjitter numbers. Why?

On spectrum analyser what dBc/Hz numbers will be more realistic?

For driven circuits, how does one simulate realistic phase noise in dBc/Hz?

Thanks