I am currently tasked with improving the design of an electrometer unit. It was NOT designed by an electrical, and there are some questionable design practices. My question is concerning the first amplification stage. A much simplified schematic follows:
In this schematic, R1 and C1 are set from a network of relays (not shown). R2 is constant, and in all cases much much less than R1. My question is, what is the purpose of R2? I have never seen this type of feedback loop. It seems to me that this is just going to make the opamp have to work a lot harder to maintain stability. I'm tempted to just remove R2 outright.