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Noise analysis on dynamic comparator

minci

 Hi,there

I am using  cadence IC5141 usr6 and MMSIM72.

I want to know the noise performance of my circuit,a dynmic comparator contains a pre-amp followed by latch.

I select noise analysis in ADE,sweep the frequecny from 1 to 10G,output noise I choose voltage,and select Pos.&Neg. differential output respectively.Then I am confusing about Input noise.Since my input is differential also and there is only one selection,I dont know how to do and just select one vdc source out of two.

The result is so weried,the input-referred noise is so big that is 1.3e+13.

I believe I have made some falses but I dont know where.And I try to find the simulation method in spectre manual but only to find nothing valuable about noise analysis.

I wonder whether noise analysis could be used for dynamic comparator,or just for linear op-amp? If not,how to simulate the noise of dynamic comparator where there are some switches during its operation?

 

Best regards

urian

 

  • in reply to ydawjee

    I get result more close to transient noise if I use the gain measured with PAC (sampled) and use this to calculate input referred noise. I get 2.9mVRms with transient noise while 2.65mVrms with PAC/PNoise analysis. When I follow the setup direction provided in ADC verification workshop tutorial for Pnoise, I get 4.5mVrms.

    Another interesting thing to see is that when I change the reltol, vabstol and iabstol the noise changes aswell. As we tighten these the result changes (both pnoise and pac). So using constant gain (vin*threshold) as suggested depending on this observation would be wrong.

    I think either tutorial provided in the workshop is missing some explanation . It would be great if you please provide me with correct steps or get the setup verified on your end. 

  • in reply to ydawjee

    I had a very quick look at the tutorial in its current form and I'm not really sure why this double period is used (it's not obvious to me), nor why the results you get don't match. It would need me (or somebody) to look at it closely and work through the tutorial again to check, and realistically I don't have time to do that at the moment (I've just been on vacation for a week and have a lot of catch up to do this coming week with the day job). A little reminder - I answer questions here in my spare time, and it's not part of my role at Cadence to respond here...

    So please contact customer support - that's the right channel to ask these kind of clarification/accuracy questions (it may be a mistake has been introduced in the tutorial, or maybe there's a good reason that needs clarification in the instructions).

    Thanks,

    Andrew.

  • in reply to Andrew Beckett

    Thanks a lot for your time. I will contact cadance customer support to check with them.

  • in reply to Andrew Beckett

    Hi Andrew,

    I dont have a key for get online support. I would have to request it through my professor. Is there anyother way to contact customer support?

    BR,

    Yunus

  • in reply to ydawjee

    Hi Yunus,

    For Universities, that's how you do it (unless part of Europractice, in which case you can log a support request with Europractice). You need to go through your University contact:

    I believe the details are covered here: https://www.cadence.com/en_US/home/company/cadence-academic-network.html (at least they used to be, I didn't check thoroughly).

    Andrew.

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