I'm trying to create a "precision" fully differential amplification stage, to measure uA on a 10R shunt, and mA on a 0.01R shunt. shunt resistance values are set at those values for burden voltage reasons. thus the voltage would be ~10uV/uA and ~10uV/mA.
my topology of my frontend is two sets of Shunt -> x10 differential amp -> PGA -> Muxed input of 24 bit ADC (LTC2442).
my question here pertains to the x10 stage amplifier. I've come up with the circuit shown, but it does have its downfalls, mainly requiring 2x 8$ resistor packages each. Cost is not the issue, I just feel that I might be overlooking a simpler solution. I might add a potentiometer to adjust the CMRR, but I'm hoping the resistors match closely enough.
My question is whether or not my design is a good implementation, any improvements to my design, or a solution requiring less matched precision resistor packages.
Pictured is a "clear" picture of what I'm considering using (NOT the one used). the one actually used has two packages of 4x 5K and 4x 1K resistors, as the 4 values need to match closely, but the ratio is software calibrated. VREF = 2.5v. SENSE flags are connected directly to shunts.