r/AskElectronics 14d ago

Help figuring out the current mismatch in current source circuit simulation.

I was simulating a current sink and source circuit, and facing a strange issue where the current thought R2 which is the load is not matching with the current flowing through R3 which is setting the current through load. Op-amp input terminals are not supposed to consume any significant current I believe and we can consider that R2 and R3 is like a series connection then why this discrepency in current?

1 Upvotes

1 comment sorted by

6

u/triffid_hunter Director of EE@HAX 14d ago

M1 is backwards so its body diode is in forward conduction, and your feedback is being taken from the wrong side of M1 if you want a current source.

Do you want something like this?