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Phase noise plot

Jithin

Hi,

I have been doing a  Pnoise analysis . Unfortunately I was unable to plot the phase noise response.
My design was  setup was described below.
My apparatus was a PLL with a fixed divider ratio of 20 and output frequency of 500Mz
In PSS analysis I have set the beat frequency as reference frequency ie 25 MHz and given tstab as 5u which is far enough.

In Pnoise tab I have put "output node as VCO output" ie 500MHz node and "Input source kept as none".

And also I have given "noise type as Sources" 

Even though the PSS analysis had been converged and done the Pnoise analysis, I haven't got any Phase noise Plot.

Is there any problem in my setup for Pnoisw analysis.Please guide me to overcome this problem.

Thanking you in advance .

With regards,
Jithin

Parents

  • Jithin,

    On the pnoise choose analysis form, did you tell it to do  a relative sweep and set the relative harmonic to 20 (since you want to do a sweep of the VCO frequency, which will be the 20th harmonic of the input frequency)? Then set the start and stop frequency to be an appropriate offset from the carrier that you want to measure the output noise in dBc over. So for example, 10Hz to 10MHz - or whatever. It will then do the sweep from 500MHz+10Hz to 500MHz+10MHz.

    I did something similar with a divider, and I was able to plot the phase noise (using the Results->Direct Plot->Main Form).

    If this doesn't work, I suggest you give full details of your setup - or better still, log a Case with customer support.

    Regards,

    Andrew.

Reply

  • Jithin,

    On the pnoise choose analysis form, did you tell it to do  a relative sweep and set the relative harmonic to 20 (since you want to do a sweep of the VCO frequency, which will be the 20th harmonic of the input frequency)? Then set the start and stop frequency to be an appropriate offset from the carrier that you want to measure the output noise in dBc over. So for example, 10Hz to 10MHz - or whatever. It will then do the sweep from 500MHz+10Hz to 500MHz+10MHz.

    I did something similar with a divider, and I was able to plot the phase noise (using the Results->Direct Plot->Main Form).

    If this doesn't work, I suggest you give full details of your setup - or better still, log a Case with customer support.

    Regards,

    Andrew.

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