OPTICAL RECEIVING CIRCUIT

PURPOSE: To obtain a large reception dynamic range by obtaining a large eye aperture at the reception of a high level optical signal. CONSTITUTION: An electric signal obtained by applying photoelectric conversion to an optical signal at a light receiving element 1 is inverted at a phase inversion circuit 10 before the electric signal is given to a variable gain amplifier circuit 3. The variable gain amplifier circuit 3 amplifies the electric signal so that the level of the inverted electric signal by the phase inversion circuit 10 is constant under the control of a gain control circuit 5 and gives the amplified signal to an identification circuit 4. The identification circuit 4 identifies a level of the received electric signal to be an L level when the level is an identification level Vth or over and identifies a level of the received electric signal to be an H level when the level is the identification level Vth or less respectively and identifies and recovers a digital signal.