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SPECTRE PNOISE and JITTER calculations

RRThomas

Hello,

I am trying to find out the clk-clk jitter performance of my VCO and after reading the inputs from the forum & Jitter_AN.pdf,  I could set up the simulation.

But the jitter expression, (drplRFJc ?from 1000 ?to 750000000 ?k 1 ?multiplier 1 ?result "pnoise" ?unit "UI") works with a single corner , single Vtune simulation. It annotates the Jc value into the graph. It returns the value in calculator also.

But it fails ( no annotation, calculator also fails to return te jitter value)  when I do a corner simulation.

It also fails when I do a single corner, Vtune sweep. So, in short it seems the jitter calculation fails when I have a family of waves.

I thought I could use famMap function, but couldn't manage to do it.

Could you please help me to solve this issue ?

Best Regards,

Thomas

Parents

  • Thomas,

    I would suggest that you use the integration options on the direct plot form - set up what you want and then use the "add to outputs" to get the expression you need added to the ADE XL outputs.

    This is far more sensible than trying to do it yourself - there has been a lot of thought put into ensuring that the calculations are done correctly. Integrating a curve in dBc doesn't make a lot of sense - you'd need to integrate the original noise data rather than having been converted into log units (dBc) - but the direct plot functions do all this for you.

    I only have limited time this week, so can only give a brief response.

    Regards,

    Andrew.

Reply

  • Thomas,

    I would suggest that you use the integration options on the direct plot form - set up what you want and then use the "add to outputs" to get the expression you need added to the ADE XL outputs.

    This is far more sensible than trying to do it yourself - there has been a lot of thought put into ensuring that the calculations are done correctly. Integrating a curve in dBc doesn't make a lot of sense - you'd need to integrate the original noise data rather than having been converted into log units (dBc) - but the direct plot functions do all this for you.

    I only have limited time this week, so can only give a brief response.

    Regards,

    Andrew.

Children
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