LIGHT RECEPTION CIRCUIT AND LIGHT TRANSMISSION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a light reception circuit with wide light reception dynamic range. SOLUTION: Current signals detected by a photodetector 10 are converted to voltage signals by a pre-amplifier circuit 20 and the output of the pre-amplifier circuit 20 is inputted to a reception light level conversion circuit 100. The reception light level conversion circuit 100 is provided with a function for amplifying the output signals of the pre-amplifier circuit 20 in the case that the output signals of the pre-amplifier circuit 20 is lower than a prescribed level and is provided with the function for amplifying and also level-shifting the output signals of the pre-amplifier circuit 20 in the case of the output signals of the pre-amplifier circuit 20 is higher than the prescribed level. The output of the reception light level conversion circuit 100 is amplified by a main amplifier circuit 30 and the main amplifier circuit 30 is bipolar-operated by the output of the reception light level conversion circuit 100 in the case of the output signals of the pre-amplifier circuit 20 are higher than the prescribed level. The output signals of the main amplifier circuit 30 are waveform-shaped by a comparator circuit 40 based on a prescribed threshold value.