how does PAC use PSS simulation results?

Hi Guys
I do not feel I understand PSS and PAC simulation very well. Are there some papers which explain PSS and PAC simulation theory in details?
For me, PSS is a time domain period simulation which address the large signal variation.
The question is how PAC coupled with PSS?
For example, a mixer with large LO signal is sumulation with PSS. It will give period output . Then you can apply a small input of RF, a PAC can be tell you the AC gain of the mixer. For example, gain VS LO amplitude. In this case, the PAC is a small signal, how does the PAC use the previous PSS simulation result? I know it should be like first run DC and then run AC analysis. However, how does the PAC simulation use PSS results?


Second, if I want to see the voltage gain VS RF frequency for a fixed LO amplitude. I will run the PSS, and then run PAC with RF frequency sweep in a narrow frequency range.
Again, how does the PAC in this time using PSS simulation results.


Thanks