Collecting light power: voltaic or conductive?

摘要

Photovoltaic versus photoconductive terminology for photo-detecting circuits has always been confusing for me. My research shows that others share my confusion. In photoconductive mode, a photodetector has a consistent voltage impressed across the anode and cathode of the diode. The constant voltage can range from approximately OV (less than 20 mV) to hundreds of negative volts. Higher negative voltages across the photodetector decrease the diode's parasitic capacitance, which in turn increases the system's frequency response. At a given reverse bias voltage, the magnitude of the parasitic capacitance remains constant.