Hello,

I want to simulate the influence of the common mode voltage of my mixer. It is a standard gilbert cell, but the problem is, I cant simulate CMRR because of the periodic variing operation point of the switching transistors. Has somebody an idea, how I can simulate it ? I think I have to use pss analysis, but it is not clear for me. Thanks for response.

Can you describe, what setup at the ports (LO,IF,RF) I have to apply ? I use an rf frequency of 2.4 GHz and and lo frequency of 2.37 GHz. Do I sweep the rf frequency and which port contains the PAC magnitude ? It's not really clear for me. Thanks for response.

You keep the LO frequency constant and sweep the RF input frequency. The PAC sweep can be set up in one of two ways: either absolute input frequency or "relative" to the PSS fundamental. I find it easier to use an absolute input range.

The output will contain many sideband results from the different harmonics of the LO, but one of them will be the frequency conversion response that you are looking for. If this is a downconversion mixer then you are most likely interested in the -1 sideband response (RF to IF or BB).

I suggest running a PSS/PAC simulation in differential mode first to make sure the set up is correct and you are simulating the correct conversion gain. Then change the input to be common mode and repeat the simulation to measure the common mode gain.