Christmas Greetings,
In my application, I need to analyze 5nA-10nA currents from a photodiode. The thing is that the signal I need to measure is around 5kHz and providing a such large gain (Lets say need 1MOhm), I need rather fast, over-MHz grade, op amps. One thought to get more gain without sacrifying phase margins, method I have already tried is the following circuit:
The results I have got are quite promising... behaves like a normal transimpedance in simulation and in real life. So the big question here is that WHAT AM I MISSING HERE? I have tried to analyze this circuit with math, and in the end, is this circuit also decreasing my phase margin and Closed loop GBW? Must be.
However with tests, this is providing me much more gain and is stable. What do you guys think? What am I missing?
- Tianyu
