I have two adjacent photodiodes in photovoltaic mode, with two transimpedance amplifiers. Unfortunately, my MCU (nRF52840) is one meter away, and I expect a fair amount of noise to enter the system. For my application, the only relevant data is the difference in luminosity between these photodiodes.
It seems the right solution would be to perform true differential signaling for each photodiode, but I can't do it in my case for very specific reasons.
By routing each signal next to each other, I hope that most of the noise would affect both signals roughly equally. My goal is to reject common-mode noise, interference, and maximize the dynamic range at the MCU location.
I am considering the following solutions:
- directly route each signal to the nRF52840 ADC in differential mode
- use a differential opamp and use the nRF52840 ADC in single-ended mode
- use a fully differential amplifier to drive the nRF52840 ADC in differential mode
The first solution would be simple, but I am not sure to get enough dynamic range. I am not familiar with fully differential amplifiers and I am not sure about their usage with non single ended signals.
What solution would be the most appropriate? Can you think of a better alternative?