I do not have a good reference that covers cyclostationary noise analytically (actually there are the Gardner books on cyclostationary noise, but those are rather heavy). I have written something that presents cyclostationary noise from a more conceptual level (see Noise in mixers, oscillators, samplers, and logic: an introduction to cyclostationary noise). But fundamentally you cannot tell from the output whether a noise contribution to an output is cyclostationary because the underlying source is cyclostationary or the path from the source to the output periodically modulates the noise signal.

Have you approached Cadence and asked them for help?

-Ken

A spectrum analyzer effectively converts the signal of interest down to baseband and then passes it through a lowpass filter. Generally, we think of spot noise as the total power of a signal within a 1Hz bandwidth centered about the frequency of interest. In this case, the bandwidth of the lowpass filter will be 1Hz. Response time with a 1Hz filter is really slow, so the spectrum analyzer will allow you to specify the bandwidth of this filter. But lets assume that the BW of the spectrum analyzer is set to 1Hz.

Then if the modulation frequency is less than 1Hz, you will see the noise change on the screen at the modulation frequency. If instead, the modulation frequency is greater than 1Hz, as it usually is, then you will not see the noise change on the screen because it is changing too fast. Instead, you will see the time-average noise.

-Ken

For a spectrum analyzer to see the cyclostationary nature of noise it must be synchronized to the modulation signal. Without that synchronization, you will always see some form of averaging.

-Ken