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phase noise/vin vs. frequency

skylink

Hi all,

I have a Phase Interpolator to simulate in Periodic Steady-State (shooting). This circuit synthesizes a clock with digitally-controlled delay on its ouput based on input reference clocks.

I would like to simulate the output phase noise / input phase noise transfer function (this could be either the input reference clock or VDD for PSRR) in a Bode diagram (over frequency); could somebody explain to me the way to do that ? I I know how to do for a voltage output / voltage input transfer function using PXF analysis, or simulating the intrinsic phase noise using PNOISE, but not for outpout phase noise / input phase noise transfer function...

Thanks a lot in advance.

PS: I am using Spectre with ADE-XL.

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  • FormerMember
    FormerMember

    Dear skylink,

    A conventional pnoise analysis with the digital code held as a DC bus value will provide the output phase noise characteristic of a driven circuit. This is a methodology we have used. I do not know if you are using ideal quadrature clocks to drive the phase interpolator or if the clocks originate from other circuits that may contribute phase noise. If the latter is the case, you will need to do a second pnoise simulation of the input clocks to assess their phase noise.

    My guess is you will need to repeat the output phase noise simulation at a few selected phase steps to validate your assumption about which phase code provides the greatest phase noise degradation.

    Does this make sense?

  • in reply to FormerMember

    Hi ShawnLogan, thank you for your answer.

    As a matter of fact I am running a single phase control (a worst case); my question was more to get the transfer function from the input CLOCKs phase noise, or Vdd voltage noise =>to output phase noise.

    In the second case (VDD=>output phase noise) think my concern is more to find the correct formula to convert the output voltage spectral density (from a PXF simulation) to a phase noise L(df) and a RMS Jitter... I am a bit lost and not very good at maths... :-)

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  • in reply to FormerMember

    Hi ShawnLogan, thank you for your answer.

    As a matter of fact I am running a single phase control (a worst case); my question was more to get the transfer function from the input CLOCKs phase noise, or Vdd voltage noise =>to output phase noise.

    In the second case (VDD=>output phase noise) think my concern is more to find the correct formula to convert the output voltage spectral density (from a PXF simulation) to a phase noise L(df) and a RMS Jitter... I am a bit lost and not very good at maths... :-)

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