Hi
I am working on a (passive like) CMOS attenuator and my problem is that when I do the IIP3 with PSS and PAC analysis my third harmonic is not increasing by 3dB. It is much lower. Me and my thesis supervisor did the transient analysis and did the calculations, we know that the third harmonic is increasing by 3dB but the PSS and PAC is not showing so. And the circuit is correct and this is a common problem with another collegue who is making a mixer with passive blocks. Can anyone please help and explain what might be wrong because if I have to generate the IIP3 from a transient analysis from a scratch it takes forever. And yes I have tried everything (low power, checked the simulation setup and checked the fuctionality of the circuit, tried qpss) it's the same.