My requirement is to measure currents in the range 10uA to 100mA (resolution = 10uA). I also have a NIDAQ(6105) with a resolution of 100uV (appx) to log the voltage data automatically. I am planning to use LTC6100 so that I can amplify the current more so that the DAQ can log the data. The LTC6100 requires a minimum sense voltage of 300uV to work. However, the value of the sense resistor seems to be a real problem. For 100mA currents, the voltage drop is just too large. Is this is the best way to do it?
You may have to consider connecting several shunt resistors to cover all required ranges .. see attached picture ..
Switching can be done with, for example, MOSFETS, as they have channel resistance Rds(ON) well below 0.1Ω ..