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Hi,
You could use the OPA365 for trans-impedance applications. On a single +5V supply, I would recommend making the OPA365 non-inverting (+) input as 2.5V, even though the device supports rail-to-rail inputs. This is required so that the photo diode connected on the inverting (-) input is reverse-biased to around 2.5V.
For suggesting a suitable part for trans-impedance application, I will need the below parameters from you:
1. What photodiode are you using or the photo-diode capacitance? Part number of the photo-diode would be helpful.
2. What is the trans-impedance gain (feedback resistor - Rf) you are trying to achieve and the targeted BW?
3. What is the worst-case input current you are trying to detect?
Best Regards,
Rohit
Rohit,
Thank you very much for your reply!
I want to implement this circuit in a spectroscopy system. The reason I grounded the anode of the PD and the amp non-inverting input is to offer a voltage ranged between 0~2.5V to an ADC.And use less parts.
And I wonder how should I get the bias 2.5V you mentioned? Using a reference or just a Schottky diode?
The PD is a InGaSn PD,with its capacity of 80pF and shunt impedance of 30MΩ. More specific parameters are attached below.
The frequence I am interested in is between 10-100 kHz.. DC accuracy is not care about. We usaully use a Rf between 10kΩ-1MΩ, accroding to the intensity of light. So the minimum pohotcurrent may be several hundreds of nA.