**Ken Kundert wrote on Aug 12**^{th}, 2019, 2:56pm:PNoise starts with a PXF analysis on the periodically time varying linear representation of the circuit about it periodic operating point, which is used to compute the transfer functions from every noise source to the output.

If I understand correctly, for PXF to come up with accurate noise transfer functions the underlying PSS needs to compute all events along the corresponding transfer paths accurately. If I recall correctly, ~10 time points per crossing would be good. I recently experienced this as a result of not being sufficiently careful in Verilog-A code; When I lower the number of time points per crossing from ~10 down to zero the noise results change in an intriguing way.

So now my question: what makes the PSS time resolution sufficiently accurate for PXF? (What is the theoretical background? What happens when the resolution is not enough?)