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stb analysis outputs

DKaraca

Hi,

I have a question about the stb analysis outputs in cadence.

I believe the way stb analysis works in spectre is based on Kundert's paper on small signal stability with double injection method: https://kenkundert.com/docs/cd2001-01.pdf

Unfortunately, the only output of this analysis (in the result browser) is the loopgain, although there must be much more information generated in order to arrive to this result.

If I could access the ABCD parameters mentioned in the 5th page of the original paper, I could use this information for several other purposes in our design & verification work.

I wonder if this is possible, or can be made possible?

Thanks in advance!

Tool versions I'm using:

cadence_ic: 6.1.7.500.23

cadence_spectre: 19.10.292

  • There is no option to output this data. I've not seen any requests for it before, but feel free to contact customer support to request that such a feature be added. You'll almost certainly need to provide a reason as to why it would be useful - i.e. what you're planning to do with the results - to justify the effort needed to output the additional data.

    Kind Regards,

    Andrew.

  • in reply to Andrew Beckett

    Dear DKaraca,

    In response to your comment:

    DKaraca said:
    Unfortunately, the only output of this analysis (in the result browser) is the loopgain, although there must be much more information generated in order to arrive to this result.

    and just to add to Andrew's comment...

    In the outside possibility you were not aware of it, the loop phase, gain and phase margins for a stability analysis are also available and may be added as outputs. The following link details how to include them as outputs.

    https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1O0V000009EThbUAG&pageName=ArticleContent

    Hopefully, the combination of these will provide your needs in lieu of the ABCD parameters. The only other reason I could think of why you might want the ABCD parameters was if you wanted a means to more readily explore the forward and reverse feedback path contributions (i.e., what the authors refer to as the normal and reverse  retum ratio contributions to the true return ratio).

    Shawn

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