# REalizing a programmable precision current source

Discussion in 'The Projects Forum' started by raghava216, Jul 2, 2010.

1. ### raghava216 Thread Starter New Member

Jul 2, 2010
1
0
Hi all
I want to implement a precision current source with current in the range $\mu$A -mA.
I hav a DAQ module which has an inbuilt DAC. I want to connect the output of the DAC to a V to I converter and then the obtained current has to drive a wheatstone bridge circuit, which contains my sensor.
Pls suggest me whether this can be practically realized/not.
If yes, pls suggest me the op-amp to be used in that current range.

Regards,
Raghavan

2. ### Darren Holdstock Active Member

Feb 10, 2009
262
11
Perfectly possible, the op-amp just provides feedback stabilisation from a voltage sensed off a resistor in series with the driven load. The type of architecture needed depends upon the load reference (i.e. referred to ground, +V, floating etc?), so you need to post your bridge and sensor circuit.

The op-amp spec will also depend upon other factors not given - a figure for the accuracy, load reference (does it need to have rail-rail inputs/output?), voltage compliance needed, and output current range. But generally for accuracy at DC you'd choose an op-amp with high open-loop gain, a low offset figure and low input bias currents. A chopper-stabilised amplifier would be even better, though they're expensive and have compromises in other areas.