I'm trying to use one DAC to control multiple N-channel MOSFETs each with identical loads. The objective is for all MOSFETs to output the same amount of current with respect to each other and have a linear relationship to the DAC's output voltage.
I researched voltage controlled current source circuits and simulated the attached circuit I found. It looks like the circuit is doing exactly what's needed but the op amp input voltage is reduced to a range between 0 to 110 mV instead of a wider range (see attachment for op amp input voltage vs MOSFET output current graph).
The sense resistor (R3) is set to 1 Ohm. If it's increased, the input voltage range changes but the maximum current that can be sunk from the MOSFET gets reduced (not wanted).
How can I get a wider input voltage range for such a circuit (0V to 3V for example)?
Is there another circuit that I should look into instead of this one?