Hello,
I hope you can help me with this. I'm trying to design a circuit that allows me to measure currents as low as 1nA +/- 0.5nA up to 1A or 2A. I don't think using a single shunt resistor is a good idea, as if I use a value of 0.1Ω, when there is 1nA, I will get 0.1nV and I won't be able to amplify that with any op-amp. The lowest value I found among your op-amps for Vos = +-20uV (maximum) is far from 0.1nV, but I know it's possible to amplify voltages as small as 0.1nV; I just can't figure out how. Do you have any application notes that could help me design a circuit that allows me to measure currents between 1nA to 1A? Or any application note for signals in the order of nV with your op-amps or instrumentation amplifiers? I would be very grateful.
Regards.
