Photodiode Amplifier

[npatel]

hi all,

i am building a photodiode amplifier with an opamp in inverting mode. The opamp is powered with +/-5V. it has 95 megs of feedback resistor and a capacitor in parallel to prevent oscillations. Can anyone tell me what value of the capacitor should i use to get stable readings. Some literature suggests it to make it the same as the input capacitance of the photodiode. Also the output of the opamp is fed in to an A/D. Can anyone suggest a suitable sampling frequency for the A/D.

Thanks

 

[prateeksikka]

hi npatel!
according to nyquist theorem i guess which will apply here also ur sampling frequency should atleast be twice that of the signal frequency.
regarding the cap choice u really cant tell unless u see the circuit and test it with power use a variac or bank cap and see the position of min oscillations.thats it
prateek

 

[shiva garg1]

hello every boby nyquiest does say that sampling frequeny should be atleat twice.but practiaclly it should be 5 times.