noise simulation of the mixer

Hi there,

I have a question about the noise simulation, from the Cadence tutorial, there are three ways to simulate the mixers NF: PNOISE with a DC input at RF port, the PSP following a PSS and QPNOISE following QPSS. I am wondering which one is more accurate? Even from the tutorial, I can see that the simulation results from the former two are different.

Thanks

nxing