OPTICAL RECEPTION CIRCUIT

摘要

PURPOSE:To prevent erroneous reception caused by noise and to execute the first transmission to a receiving state at high speed by providing a filter circuit having a time constant switching function in a DC voltage circuit which impresses to an APD. CONSTITUTION:A titled circuit provides the voltage circuit 2 which applies a voltage to an avalanche photodiode(APD) 1 and receives light beam supplied to the APD 1 under the condition where the voltage is impressed by the voltage circuit 2 as an electrical signal. And the filter circuit 5 having the time constant switching function is provided between the output end of the voltage circuit 2 and the APD 1 and an electric field effect transistor FET which constitutes one of the time constant circuits is provided in the filter circuit 5, then the electric field effect transistor FET is controlled by a received signal so as to alter the connection resistance of the transistor FET. Thus a comparatively small capacity will serve the voltage circuit 2 and the first transition of the reception circuit is made to be at high speed.