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Diffstbprobe

DaleStubbs

I am currently running virtuoso version 6.1.5 and was reading on sourcelink about the diffstbprobe. In the past I have used the cmdmprobe with mixed results. I have a few quesitons: 

1.Does the diffstbprobe work as in http://www.designers-guide.org/Analysis/diff.pdf.

2.Is this probe called in the same way as cmdmprobe using the ADE->analyzes->stb option? 

3. Is it possible to use this during a transient simulation? I thought it was possible to set "actimes" to a time to run stb sim, and "acnames" to stb. This does not appear to be working in 6.1.5. Am I allone in seeing this, or am I not setting it up correctly.

4. Is it possible to do it during a transient simulation, if the simulator is APS?

Thanks,

Dale

Parents
  • Andrew Beckett

    Dale,

    diffstbprobe is a newer way of measuring differential and common-mode stability when using spectre's stb analysis. It supersedes the old cmdmprobe component. It has the advantage of handling unbalanced loops - the old cmdmprobe didn't work properly if there was significant CM to DM or DM to CM leakage, but that's not an issue with the new component. Also, one additional benefit is that you can choose on the stb analysis form whether you are measuring common-mode or differential-mode stability, rather than having to alter a parameter on the instance of the measurement device itself.

    To answer your specific questions:

    1. I don't really understand the relevance of the link you gave - that's a general paper on testbenches for differential circuits, and doesn't mention measurement of stability using stb analysis
    2. You point at the new probe in the same way from the stb choose analysis form in ADE.
    3. I don't see why you should not be able to use stb analysis as an acnames/actimes option for tran analysis. I've done this myself several times in the past - if it doesn't work, check with customer support - maybe it was broken in a specific version (although I'm not aware of this).
    4. Yes. You probably need to ensure you're running a recent enough MMSIM version though (all should be OK with MMSIM10.1).

    Best Regards,

    Andrew.

  • FormerMember
    FormerMember in reply to Andrew Beckett

    Dear Sir,

    I am new in to the analog design, I started recently with the simulation of the fully differential amplifier. I used the Iprobe with the stability analyses and this method is working with me perfectly, however I am not of how to use it with the stability simulation of both the common mode and differential stability 

    I would like to kindly show you the setup I am going to use and please confirm me if it is wrong or if there is other better setup than I showed

    Thank you in advance

    Differential mode stability test Common mode stability test

  • Andrew Beckett
    in reply to FormerMember

    Those pictures are too small to see what you you're trying to illustrate.

Reply
  • Andrew Beckett
    in reply to FormerMember

    Those pictures are too small to see what you you're trying to illustrate.

Children
  • FormerMember
    FormerMember in reply to Andrew Beckett

    Sorry Sir I am new to the forum, hope I will improve my post next time

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