Tlaloc wrote on Sep 10th, 2008, 8:02pm:
If I understand, then, what Kundert is saying is that the timedomain noise will only report the sampled noise power while the sources noise will also include the direct filtered noise at the output. Is this correct ?
Correct. But a sampling of tdnoise in Cadence Pnoise is impulse sampling.Tlaloc wrote on Sep 10th, 2008, 8:02pm:
If so, when is a timedomain noise sim worthwhile if it is only a subset of the total noise?
You can see noise at specific time.
For example, you can observe noise of Gilbert Cell Mixer over local signal period. Changing duty of local or changing local signal shape, e.g. sinusoidal, rectangular pulse, you can observe noise behaivior over one local period.
But here this is not same as real spectrum analyzer where short time interval FFT is used.
Many people think of tdnoise same as real spectrum analyzer. This is misunderstanding.Tlaloc wrote on Sep 10th, 2008, 8:02pm:
By the way, which assumption assumed an ergodic process?
I can't understand a meaning of your question.
Noise at inverter output under large signal drive is not ergodic.
On the other hand, noise at inverter output under no signal drive is ergodic.
See the following.http://www.designers-guide.org/Forum/YaBB.pl?num=1207830622http://www.designers-guide.org/Forum/YaBB.pl?num=1059089369http://www.designers-guide.org/Forum/YaBB.pl?num=1218622880