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Design Languages >> Verilog-AMS >> Phase noise simulation using a verilog A model
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Message started by iVenky on Jun 17^th, 2017, 5:51pm

Title: Phase noise simulation using a verilog A model
Post by iVenky on Jun 17^th, 2017, 5:51pm

Hi,

I have an ideal current source for the VCO. The thermal noise of the current source was modeled in a verilog A model using the white_noise() function. When I run pss/pnoise, I observe that phase noise of the VCO is not considering the effect of noise due to this verilogA model. Any suggestions?

I tried verifying the white_noise() verilog A model separately by running a transient noise simulation and it works.

Title: Re: Phase noise simulation using a verilog A model
Post by subtr on Jun 17^th, 2017, 9:42pm

I expect that your noise is a transient parameter which the simulator even does not recognize as noise. The PSS basically wants to find periodic steady state which might even be hindered by the noise added. I don't think PSS runs a transient noise analysis. I believe PSS gives the sensitivity function which the pnoise can use to find the spectrum. Your noise is in time domain. pnoise is an AC analysis which might not even see your verilogA being there. Probably this is the reason why you see only device noise and not the model noise.
The solution is to do a tran noise analysis and take FFT of the crossing points to get the phase noise spectrum through matlab. This will take the effect of your verilogA into consideration because measurement is done on the transient data.

Title: Re: Phase noise simulation using a verilog A model
Post by Ken Kundert on Jun 17^th, 2017, 10:09pm

My suggestion is, if you want help, you should give the model. We cannot help you if you give us no information.

-Ken