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How to calculate each blocks' jitter in PLL

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incol

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I already know the whole PLL's jitter requirement is RMS 2pS, then how to determine the jitter of PFD / CP, VCO, etc, so that I can reach the jitter spec of PLL? Thank you!
 

You can't calculate jitter for individual blocks. Only device noise can be calculated.
 

So I should simulate each blocks' phase noise, then calculate the total phase noise and convert it to jitter,is it right? Thanks!
 

Yes. Correct.
 

That would get you into the ballpark, but the real world is a little more complicated than that. You might have an oscillator and an RF amplifier. You know your oscillator phase noise from PLL calculations, and the residual RF amplifier phase noise. But how do you add the two?

If they are uncorrelated they add one way, but if they were correlated (like with spikes coming from the power supply to both) they would add a different way.

Example, PNosc=-100 dBc/Hz at 10 KHz, and residual PNamp=-100 dBc/Hz at 10 KHz. If they were uncorrelated, the total phase noise would be -97, but if correlated it would be -94.
 

ok, thanks biff44.
Can we use transfer function to calculate each blocks' phase noises contribute to the output, then get the total phase noise?
And if the phase noises of each block are correlated, how to calculate it, thanks!
 

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