rfmems wrote on Apr 13th, 2008, 7:29am:
From the calculations above, we can see that the integrated phase noise should actually integrate time-average phase noise for all the frequencies.
This is your misunderstanding point. If signal is averaged over time, you can not get jitter information.rfmems wrote on Apr 12th, 2008, 4:17am:
I agree this is not physical because of the impulse function, more realistic is to do sample and hold.rfmems wrote on Apr 13th, 2008, 7:29am:
However, people keep doing very often. I think this is at least not rigorous. And I don't see a reason it can be done in that way.
I can't understand why you think it is not rigorous.
Assume an operation of sampling oscilloscope(digitizing oscilloscope) which shows jitter statistics.
Here an average calculation is done over frames not times. So there is no time window which causes Sinc spectrum such as Sample & Hold you are thinking.
For specific time=t0 in 0<=t0<T=1/fout, PSD(t0, freq) is calculated by frame average power not time average power.
Here time=t0 is just one point, it has no width.
Again(4 times), sampling is done at t0+n*T,(T=1/fout, 0<=t0<T, -infinity<n<+infinity).
Even though Vout(time=t0) is captured by S/H which has finite width time window,
we can compensate S/H characteristics in frame average(Ensemble Average
So it is rigorous.