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Regarding PNOISE results obtained from Spectre-RF

sarfraz

Hi,
What sort of spectral density is obtained when we do Pnoise analysis in Spectre-RF.
Is it power spectral density of phase or is it power spectral density of voltage?

Best Regards
Sarfraz

Parents
  • Hi Sarfraz,

    It is power spectral density of voltage (or current, depending on how you have probed the output in the pnoise analysis). This can then easily be converted to phase noise (in dBc using the phaseNoise calculator function - use the direct plot form in ADE to do this easily).

    Strictly speaking this gives you output noise in dBc rather than phase noise, but for most oscillators the PM part is dominant and so it's the same as the phase noise. If you want true separation of the AM and PM parts of the noise, you can use noiseType=modulated (at the bottom of the pnoise form) to extract PM and AM parts (as well as being able to see the noise in both the lower and upper sideband).

    Regards,

    Andrew
Reply
  • Hi Sarfraz,

    It is power spectral density of voltage (or current, depending on how you have probed the output in the pnoise analysis). This can then easily be converted to phase noise (in dBc using the phaseNoise calculator function - use the direct plot form in ADE to do this easily).

    Strictly speaking this gives you output noise in dBc rather than phase noise, but for most oscillators the PM part is dominant and so it's the same as the phase noise. If you want true separation of the AM and PM parts of the noise, you can use noiseType=modulated (at the bottom of the pnoise form) to extract PM and AM parts (as well as being able to see the noise in both the lower and upper sideband).

    Regards,

    Andrew
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