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VCO: PSS and pnoise analysis and Numerical Errors

rsrk

Hello,

   I am Sivaramakrishna. My query is about the numerical/simulation errors in pnoise/pss analysis of VCO.

   I am designing a (CMOS LC-) VCO and Interesting I am getting different phase-noise for the same circuit with with same settings, such as initial conditions, and integration methods(it was suggested that I need to use *trap* integration method in-order to get correct results).

   Its varying around 1-to-2 dBc. I feel that this variation is significant as it is in log scale.

   The only way I can, at least to the best of my knowledge, see if the numerical/simulation noise is playing any role. Could someone shed light on it.

Thanks and Regards

Sivaramakrishna 

 

    

  • Hi Sivaramakrishna,

     If this is a strongly nonlinear circuit (e.g. ring oscillator), then pss-shooting is appropriate.  Otherwise, I would use hb (harmonic balance). 

    Please check out your setup - very important to get correct results.   In my blog:

    SpectreRF Tutorials and Appnotes... Shhhh... We Have a NEW Best Kept Secret!

    I mention the new SpectreRF design workshops, which include  Simulating Oscillators:   LC and Ring Oscillators.

    The workshops take you through step by step the best way to set up your oscillator to get accurate results.  There is also a design database in the hierarchy.  The setup instructions are in Appendix A of the MMSIM12.1.1 or 13.1 SpectreRF User Guide.

    best regards,

    Tawna

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