Mixer IIP3 simulation in Cadence

Hi Everyone,

I am simulating a single balance mixer in Cadence using QPSS. When plotting the IIP3, I don't obtain a 3:1 slope as expected, but a slope much lower. This issue is mentioned in the following thread but there are no further comments on it: https://www.edaboard.com/thread25014.html
Has anyone had s imilar issue and knows the causes? I suspect it has to do with the PORT sources but I'm still not sure what it could be...

Thanks in advance!

How about running the simulation at a lower RF power level?