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What is a photodiode ? Explain its working with a circuit diagram and draw its I-V characteristics. |
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Answer» Solution :PHOTODIODE `:` Photodiode is an optoelectronic device in which current carriers aregenerated by photons through photo excitation. Working `:` When visible light of ENERGY greater than FORBIDDEN energy gap is incident on a reversebiased p-n junctionphotodiode,ADDITIONAL electron -hole pairs are created in the depletion layer ( near the junction). These CHARGE carrierswill be separated by the junction field and made to flow across the junction, creating a reverse current across the junction. The valeu of reverse saturation current increases with the increase in the intensity of incident light. V-I characteristics of photodiode is shown in figure. It is found that reverse saturation current through the photodiode varies almost linearly with the light flux. Uses `:` (1) It is used in switching thelight ON and OFF . (2) It is used in demodulation in optical signals.  
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