npatel Posted May 18, 2005 Report Share Posted May 18, 2005 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 Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted May 19, 2005 Report Share Posted May 19, 2005 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 itprateek Quote Link to comment Share on other sites More sharing options...
shiva garg Posted May 19, 2005 Report Share Posted May 19, 2005 hello every boby nyquiest does say that sampling frequeny should be atleat twice.but practiaclly it should be 5 times. Quote Link to comment Share on other sites More sharing options...
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