I am working on a direct conversion mixer and I need to plot NF at a fixed baseband frequency as a function of swept LO frequency. Does anyone know how QPSS and QPNOISE analyses should be setup?

I have tried to setup LO frequency as a swept design variable for QPSS analysis and performed a single point QPNOISE analysis but that does not produce correct results. Is there anything I have to do out of the ordinary when setting up the analysis?

Thank you in advance.
R. Zakai

Since this a narrow band direct conversion mixer, the beat frequency for PSS analysis is too small practically. QPSS analysis is better suited to handle these types of circuits. My understanding is when beat frequency for PSS analysis is less than 1/10 of the LO frequency, QPSS is more practical solution.

R. Zakai

Just to close on this issue, QPSS analaysis is the only thing to do here, there is a beat, it is equal to the LO frequency and since it varies as LO frequency is swept, PSS analysis does not work. QPSS is easy to setup, I originally has problems due to a scripqting error elsewhere.
Rehan