Sun February 24, 2013 By: Mrinal

What is the reason to operate photodiode in reverse bias?

Expert Reply
Sun February 24, 2013
The photodiode is reverse biased for operating in the photoconductive mode. As the photodiode is in reverse bias the width of the depletion layer increases. This reduces the junction capacitance and thereby the response time. In effect, the reverse bias causes faster response times for the photodiode. The photocurrent is linearly proportional to the illuminance.   
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