[time-nuts] Spice simulation of PSRR and phase noise

Attila Kinali attila at kinali.ch
Fri Oct 27 18:30:15 UTC 2017

Hoi Bruce,

On Mon, 23 Oct 2017 09:58:40 +1300 (NZDT)
Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:

> Since close in phase noise can result from up conversion of supply noise
> etc via circuit non linearities, using an AC analysis won't work.
> Only transient simulation or perhaps analytical modelling of the various
> non linearities will provide accurate estimates of upconverted PN.

Unfortunately, my understanding of transistors is far from being good.
Hence doing accurate analytical analysis is beyond me. Hence my reliance
on spice to do the "hard work." 

> If you use transient simulation techniques increasing the level of the
> various noise sources above the actual levels encountered in real circuits
> and then correcting the resultant PN back to the level that would be
> encountered in the actual circuit (using the results of analytical modelling)
> may be a useful way to reduce simulation time or at least overcome some of
> the challenges associated with accurately determining low level PN from a
> simulation.

This is a good idea, thanks!

> There are some in the LTSpice Yahoo group attempting this but they seem
> way out of touch with the amount of simulation data required. I've provided
> them with the appropriate formulae to extract PN from the the amplitude
> spectra. At the moment they appear bogged down with some somewhat trivial
> peripheral issues.

I tried to read the yahoo groups... but god! is the interface bad!
I only found a few mails from last August that go into that direction.
Is there anything else that might be interesting?

			Attila Kinali
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson

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