Hi, when I read the Spectre reference for 'pnoise', there is the sentence of "The time-average of the noise at the output of the circuit is computed in the form of a spectral density versus frequency". I have some difficulty understanding what "time-average of the noise" means.

Also, is 'pnoise' the proper analysis to calculate period jitter of a ring oscillator? The analysis 'pss' is run ahead of 'pnoise', so I also have difficulty understanding what the periodic steady state within each cycle is for a ring oscillator (the settled high/low state or the threshold crossing state)?

Further, which simulator (and its associated analysis) can calculate the timing jitter for digital logic circuits resulting from device noise, like thermal, shot and flicker noise?

thanks for your time and help.