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I want to use a photodiode to measure light intensity, but I am not sure if the photodiode should be used in photoconductive or photovoltaic mode.

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From my understanding the photovoltaic configuration will have a leakage current proportional to light intensity and the photoconductive configuration will produce a current proportional to the light intensity. Both seem like the would work for my application.

Will either configuration work? and is there a benefit to using one over the other?

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Right, except for photovoltaic it's not leakage current... just photocurrent. The biased version will give a little more dark current. The big advantage of biasing the photodiode is that you reduce it's capacitance. (typical numbers might be by a factor of 4 or 5. at 10V) And this makes the detector faster. Which is almost always a good thing. Oh one final disadvantage to the bias case is that any noise on the bias voltage appears on the output. (so filter the bias supply.)

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Photovoltaic will give you near zero dark current and very high linearity over a wide current range. Photoconductive can't do that.

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