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Simulators >> RF Simulators >> Plotting PNoise Data -- Method Discrepancy
https://designers-guide.org/forum/YaBB.pl?num=1170729317

Message started by juputeow on Feb 5^th, 2007, 6:35pm

Title: Plotting PNoise Data -- Method Discrepancy
Post by juputeow on Feb 5^th, 2007, 6:35pm

When plotting the same set of phase noise simulation results these two methods give different answers:

- Going through Analog Design Env -> Results -> Direct Plot -> Main Form -> pnoise radio button -> phase noise - > Plot
Curve name turns out as "Phase Noise; dBc/Hz, Relative Harmonic = 1"

- Going through result browser -> schematic -> psf -> Run1 -> pnoise-pnoise -> out and taking dB20 of it.
Curve name turns out as "dB20(getData("out" ?result "pnoise-pnoise" ?resultsDir "/export/simulation/CELLNAME/spectre/schematic"))"

The two curves have the exact same shape, but they are offset by a few dB. The exact amount of offset changes from circuit to circuit [observed 0.7 to 5.5 dB] The simulation is only ran once, on the same station, so pointing to different data is not the problem. Can the two ways be implying different parameters? [e.g. something like one takes the full 20 pnoise sidebands into account, as desired, while the other doesn't, maybe??] I'm attaching a PDF of a sample case.

Thanks for bearing with the long post.

Title: Re: Plotting PNoise Data -- Method Discrepancy
Post by Ken Kundert on Feb 5^th, 2007, 8:11pm

The "phase noise" in the direct plot form is not really phase noise, it is L, the normalized noise, which is the noise divided by the signal amplitude. The noise you are pulling from the results browser it just the noise. So they should differ (in dB) by the amplitude of the carrier.

-Ken

Title: Re: Plotting PNoise Data -- Method Discrepancy
Post by juputeow on Feb 5^th, 2007, 8:26pm

Thank you very much for your quick reply, Ken.