PSS determines the period of the small-signal analyses

[anhnha]

Here is a description about PSS analysis in Cadence:

PSS is a large-signal analysis and determines the period of the small-signal analyses. PSS requires that multiple periodic stimuli be coperiodic.


Can anyone explain the bold part?

 

[BigBoss]

I think you used more than one stimuli ( sources,ports etc. ) that have no minimum common frequency.
When you use PSS, the stimulis should have at least common beat freqeuency which is at the same time biggest searching period.

 

[anhnha]

Thanks. Sorry for the confusion. Those statements are from Cadence tutorial. Here is the page: **broken link removed**
I have read some articles about PSS analysis and here is my understanding relating to fundamental frequency.

Take an example of an circuit including two sources, source1 900MHz and source2 10MHz; the fundamental frequency is the largest common one of the two, therefore, f_fund = 10MHz.
And could you explain how PSS determines the period of the small-signal analyses. I am new to the software and I am trying to use it.