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Sampled HB noise analysis: Output noise to Edge phase noise conversion

ArpanT

Hello,

I have a very simple test case as below. In a Vsource sinusoidal element, flat phase noise of -160dBc/Hz is specified. It is converted to differential waveform of 2V pk and phase noise is measured at zero crossing of Vip-Vim. I have done comparison between time-average and sampled phase noise. Both time average and edge phase noise have same results of -160dBc/Hz but their output noise is 2E-16 and 8E-16 respectively. 

As we can see that time average phase noise can be easily calculated with 10*log10(Pnoise/Psignal) = 10*log10 (2E-16/(2*2/2)) = -160dBc/Hz and it matches calculation. But this formula is not valid for edge phase noise.

I understand that time-average and sample phase noise will be different as sampled phase noise is jitter based measurement. I have gone through similar threads and discussion forum. There are many links specified there, but unfortunately those are no longer available. Whatever is available does not solve my doubt.

My question is from "output noise waveform of sampled noise analysis", how do I calculate "edge phase noise"?

  • Sampled noise analysis gives you the power of both sidebands combined. Also, half of the noise power at the zero crossing comes from the 100% correlation between the sidebands of pure phase noise: they add like voltages, not like powers. Both factors of 2 together give the 4x higher value of sampled noise power density that you observed. The fact that you get the same phase noise result in both cases shows that Virtuoso takes both effects into account when it calculates edge phase noise.

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