OPTICAL SIGNAL RECEPTION CIRCUIT

摘要

PURPOSE:To reproduce a signal up to a limit amplitude at which the signal is compared and discriminated with respect to a noise by giving a DC bias to a reception signal from a photodetector to apply waveform shaping. CONSTITUTION:A DC bias voltage is given to a bias circuit BC1 to a voltage signal obtained across a load resistor R1 and the result is fed to a waveform shaping circuit FW1. Then the reception signal within the operating region of the detector is boosted for the level. A reference voltage is set higher by the share of the DC bias to the reception signal level when the optical signal is 'nil', then the minimum reception level corresponding to the limit of transmission distance is decided by the difference between the reception signal level when the optical signal is 'nil' and the preset reference voltage and the signal is reproduced up to the limit amplitude compared and discriminated for the reception signal to a noise.