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Cannot plot Phase Noise following PSS (Harmonic Balance) + Pnoise

nbyrne

Hi,

DFii version: IC6.1.7-64b.78

virtuoso -W: sub-version  IC6.1.7-64b.78

spectre -W: sub-version  14.1.0.627.isr8

I cannot seem to plot Phase Noise from the Main Form if I run PSS Harmonic Balance + Pnoise

It works fine if I use PSS Shooting + Pnoise, and using the timeaverage analysis for Noise Type in pnoise analysis,

but when I use PSS Harmonic Balance the noise type switches to 'sources' in pnoise analysis and the option isn't there to plot Phase Noise in the Main Form. Below is the form following PSS Harmonic Balance + Pnoise:

Thanks,

Niall.

  • Andrew Beckett

    Hi Niall,

    Your picture didn't upload - but I don't need to so it.

    This is a quirk as part of the major change in IC617 to ensure that phase noise really is phase noise. For many years when you've been asking to plot phase noise, you've actually been getting output noise in dBc - which may or may not actually be phase noise (for oscillators, they tend to have mostly PM output noise, so it's usually OK). We wanted to ensure it was really correct and unambiguous. The quirk happens because the simulator features had only been partly implemented by MMSIM14.1 ISR8, and the HB side hadn't been done.

    I would suggest that you move to using MMSIM15.1 (I'd also suggest moving to a later ISR of both rather than using the Base version of IC617). When you do that, it switches to "timeaverage" when in HB mode as well, and provided you pick one of the modes that includes "PM" you'll be able to plot phase noise.

    If you're stuck with the versions you've got, you can either use "modulated" noise type (which will do the older algorithms for AM/PM separation) or you can get the old phase noise (from your USB-only pnoise sweep) by bringing up the calculator, picking "Spectre RF Functions" category from the function panel, picking "pn" as the function, and then plotting that. 

    Regards,

    Andrew.

  • nbyrne
    Excellent thanks for the explanation Andrew..

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