PSS simulation

 Hi,

I'm trying to run pss and pnoise simulations on a switched capacitor circuit. The only periodic voltage source in the circuit is a clock but the problem is that switching and sampling doesn't happen on the clock. It clocks a logic that produces waveforms which control sampling and switching in the circuit. When I run the pss, although I specify the beat frequency to be the frequency of the actual sampling signal it seems that the simulator still detects the clock stimuli (which is pwlf source) and I have the feeling it periodizes the analysis with repect to the clock, not to the actual sampling waveform.

Is there anyway to trick the simulator not to take the clock but the logic signal that acrually does the sampling? I can not remove the logic block that's being clocked or substitute the sampling signal with a voltage source.

Thanks