Hello all. I'm attempting to design a TIA for a balanced detector circuit. Unfortunately the detectors share a ground with other components, so I can't use the normal approach of taking the difference current from a common node and amplifying it directly. Because achieving low noise is important, I would like to reduce the number of devices and resistive elements. Because the configuration of the detectors is fixed, ie both cathodes tied to a common ground, my thinking was that I could use two TIAs, one for each detector, then use a differential amplifier to take the difference between the resulting voltages.
I would bias the detectors by placing a bias voltage on the non-inverting inputs of the TIAs with the detectors connected to the inverting inputs. I've only found one commercial solution with differential current inputs, but the form factor isn't appropriate for our application. Is there a way to differentially amplify the current with a single device while simultaneously biasing both detectors? Thanks for any advice that you can provide.
D. B. Cole