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Plot Phase Noise of each sub-circuit from Calculator

Anjana Dissanayake

Hi All,

I am trying to analyze the phase noise of a VCO + Driver + Divider chain. I would like see how much phase noise is contributed by each sub-circuit. I can see the spot or integrated noise at each hierarchical element from noise summary but I would like to actually plot the full phase noise curve corresponding to the noise contributed by each individual sub-circuit. Is there a way to do this directly in VIVA or calculator instead of saving the noise contribution and manually formatting the data?

info: 

spectre: 21.1.0.132.isr1, IC: 6.1.8-64b

Thank you in advance,

Best regards,

AD

  • Andrew Beckett

    Perhaps you could just use the "multiple phase noise" checkbox at the top and then measure the noise (in hbnoise or pnoise) at the output of each stage. Given that all noise analyses essentially compute output-referred noise, what this does is run multiple simulations with the output at different places in the circuit, and then you can plot the phase noise at each point in the chain.

    If you don't want that and instead want the phase noise at the output coming from a particular block, then there's no direct way of doing that (you could perhaps use the approaches described in this thread  Print Noise summary and corresponding OCEAN noiseSummary - Custom IC Design - Cadence Technology Forums - Cadence Community  but I think you'd then need to scale the results by the magnitude of the carrier to convert to phase noise). Not sure how meaningful this would be though.

    Andrew

  • Anjana Dissanayake
    in reply to Andrew Beckett

    Hi Andrew,

    At the moment I am doing something similar where I set multiple pnoise tests in ADE-XL using the solution of a single PSS sim. In each test I am selecting only one sub circuit noise to be on while designating others as noiseless through options->analog. However this leads to a quite a long simulation time, hence I was wondering if there was a way to avoid this redundancy. 

    I will try play with the solution you posted. Thank you very much!

    Best regards,

    Anjana

  • Andrew Beckett
    in reply to Anjana Dissanayake

    I realised I forgot to upload the screenshot that I took pointing out the multiple noise

    :

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