App note: Using MCP6491 Op Amps for photodetection applications
This app note discusses how to detect the intensity, position, color
and presence of light:
This entry was posted in app notes and tagged AN1494.Low input bias operational amplifiers (op amps) are often required for a wide range of photodetection applications, in order to reduce current error and improve the accuracy of the output signal.
Comments
Reminds me of way older applications from National Semiconductor (now merged in TI), where the short-circuit current of the photodiode was better employed, wisely operating the op-amp in the best operational point for Vos (just adding a resistor).
See http://www.ti.com/lit/an/snoa624a/snoa624a.pdf on page 20; the original application note dates back to 1986 in the printed edition I have.
I used with success a similar approach in the ’90s, with a mature LMC6482 that can still sport an input current 50 times lower than the Microchip device (20 fA vs. 1 pA).