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Simulators >> RF Simulators >> SpectreRF PLL phase noise simulation?
https://designers-guide.org/forum/YaBB.pl?num=1167909520

Message started by Visjnoe on Jan 4^th, 2007, 3:18am

Title: SpectreRF PLL phase noise simulation?
Post by Visjnoe on Jan 4^th, 2007, 3:18am

Dear all,

is it possible to use SpectreRF to simulate the closed-loop PLL phase noise performance at transistor level?
Just assuming that simulation time is no issue, has anyone experience on this?

Is it difficult to get convergence? I know for example that EldoRF has difficulty converging when a LC-VCO and a subsequent CML + asynchronous FF-style divider are combined, so I never even tried full PLL simulation with it...

Kind Regards

Peter

Title: Re: SpectreRF PLL phase noise simulation?
Post by Ken Kundert on Jan 4^th, 2007, 8:54am

As long as the PLL has a periodic solution (no deadzone in the PFD) it should work fine. I have seen that harmonic balance based simulators tend to have an inordinate amount of difficulty with frequency dividers, but SpectreRF does not because it uses shooting methods.

-Ken

Title: Re: SpectreRF PLL phase noise simulation?
Post by Visjnoe on Jan 4^th, 2007, 10:48am

Dear Ken,

thanks for your comment.

If I understood your comment right, you expect SpectreRF to converge as long as there's a periodic solution, which would indeed be an improvement over EldoRF.

Do you think that a reference input signal that is dithered with jitter poses problems for SpectreRF? The goal would be to verify the input CLK jitter attenuation using such a set-up.

Kind Regards

Peter

Title: Re: SpectreRF PLL phase noise simulation?
Post by Ken Kundert on Jan 4^th, 2007, 11:53am

Jitter would definitely be a problem if you were trying to use the PSS analysis, because the solution would not be periodic. Envelope following might work. Or you could explore the jitter attenuation by using PAC while phase modulating the input source (you could use the PM modulator in http://www.designers-guide.org/VerilogAMS/functional-blocks/modulators/modulators.va while driving the modulation input with a small-signal source (a DC voltage source with pacmag=1)).

-Ken