Hello everyone,

I'm working on a project with a sensor which has an analog circuit to convert output current signal of photodiode to voltage like attached in the file. I'm not so specialized in analog circuit but I really want to understand how this circuit can convert from current to voltage. Can you explain in detail how does it work (the sub-component linear amplifier and non-inverter amplifier)?

Here is the only information written in the report about this circuit but I can't understand well:
- The linear amplifier part is an analog low-pass filter with a cutoff frequency equal to 106kHz. Considering the high gain given by the resistance of 150kOhm, the linear amplifier aims at preventing signal from oscillations.

Thank you for your explanation.

P/S I also attach the paper of the sensor.

 

hi,
This link may help.
https://en.wikipedia.org/wiki/Transimpedance_amplifier
E

 

hi,
This link may help.
https://en.wikipedia.org/wiki/Transimpedance_amplifier
E

Thank you so much, but how about the "Non-inverter amplifier" part? What is the role of that part in the circuit?

 

hi,
It amplifies the low level signal output from the Trans/amp, by a factor of 1+ (100k/4k7)= ~ 22 times.
The non inverting mode means that the output signal from the trans/amp is not inverted

E

 

Simply DC gain.

Both amplifiers are linear. The first is a "current-to-voltage" converter, where 1 uA of photodiode current produces an output of 0.15 V. The second is a DC coupled gain stage with a gain of 22.3. These values are based on my guess of the resistor values in the schematic. If there are decimal points in the resistor values, I can't see them.

ak