Hello.

I am simulating a basic Gilbert downconverter, using PSS, PAC and PNoise. When I change the resistive load to be a first-order RC filtering load, I find that the simulated in-band gain drops and the simulated in-band noise figure increases. And there is no problem with the first-order filtering function and the filtering corner in the simulation results. How to explain this phenomena, or is there any possible problem with the simulation settings for this case?

Thank you.

There is no problem when using sole resistive load. After adding the parallel capacitors without any other modification, the performance degrades as mentioned earlier.