I'm needing to sense small currents (.02 - .6 mA) accurately.
I've been looking for transducers that are designed for this sort of thing, but I haven't been turning anything up in that low range.
I have also considered simply measuring and amplifying the voltage across a resistor. I can get some .1% tolerance 50 ohm resistors from digikey for not so much, but then when I think about amplification, I realize that my feed back resistor networks are going to suffer from considerably worse tolerances given the available resistor tolerances that I see.
I would like to have the entire system accurate to 1uA if possible.
It occurs to me that the I could use some fine variable resistors to tune the circuit in, but then I'm not sure what standard I might measure against?
Any suggestions appreciated.