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Differce between IC5 & IC6 in pnoise simulation(jitter)

I'm currently designing a dynamic comparator and would like to get the input refered noise by jitter in the pnoise simulation.

Previously, the way we used to estimate the input referred noise of the dynamic comparator is by applying a small input difference(~100uV), and using jitter to observe the output difference cross the threshold value(10mV). Within the range of 10mV, the gain of the latch stage in the two-stage dynamic comparator is linear. Thus we can divide the output noise by this gain(10m/100u) to get the input referred noise.

However, the IC6 setup window is quite different from IC5, the input-referred noise I get this time by jitter is around milli vol level, since the same circuit was verified with a hundred micro vol input referred noise by such a method in IC5.
I also estimate this circuit on IC6 by choosing the noise type as timeaverage, which comes out hundred micro vol input-referred noise, which is just the same as our prior our work.

My setup of IC5&IC6 is shown below, do I mix something up which led to such a big difference in my simulation results?

And this is my pnoise simulation setup.

ShawnLogan over 2 years ago

Dear HsuiMin,

HsiuMin said:
However, the IC6 setup window is quite different from IC5, the input-referred noise I get this time by jitter is around milli vol level, since the same circuit was verified with a hundred micro vol input referred noise by such a method in IC5.
I also estimate this circuit on IC6 by choosing the noise type as timeaverage, which comes out hundred micro vol input-referred noise, which is just the same as our prior our work.

As Andrew Beckett mentioned in his initial response to your initial post, there have been many changes in the manner in which IC5 and IC6 compute jitter. Your methodology differs a bit from that recommended by Cadence. I recently responded to a question regarding a methodology to compute the input referred noise of a dynamic comparator in the Forum post at URL:

https://community.cadence.com/cadence_technology_forums/f/custom-ic-design/47380/how-can-i-get-the-input-referred-noise-of-dynamic-comparator-by-pnoise

In that post, I refer to a recent Cadence Application Note that describes estimating the input referred noise using both a transient noise and pss/pnoise simulation. Please see pages 10 to 22 at URL:

https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1O0V000009ESBAUA4&pageName=ArticleContent

Finally, using a timeaverage jitter measurement in IC6 does not sound appropriate for your application. Hence, if its result is "the same as our prior our work", I would consider re-examining your prior methodology. For a few words on the difference between a jitter measurement using timeaverage and a measurement of sampled jitter, please refer to Tawna Wilsey's comments in the Forum post at URL:

https://community.cadence.com/cadence_technology_forums/f/rf-design/50967/timeaverage-and-sample-jitter

I know this is not an exact answer to your quandary, but I wanted to at least provide some reference material HsuiMin,

Shawn
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