I have a fan-out circuit suing a HMC547 (to select src or cap) connected via RFC to a HMC641 to mux out to 4 lines
The board has AC coupling caps on all the RF inputs but the RFCs are connected together DC coupled (oversight)
I am getting weird issues, on 90% of the circuits it works fine but on the last 10, we see weird insertion losses (that can change)
If I put a meter on the RFC to check a diode for instance, I can change the behavior.
I'm going to respin the boards, but do you think this DC coupling may be the issue I am dealing with?