OPTICAL RECEPTION CIRCUIT

摘要

PURPOSE:To decrease the detection error in an optical input level even with the presence of power supply fluctuation by detecting an optical input level depending on a current flowing to a photodetector impressed with a generated reverse bias voltage. CONSTITUTION:An optical input level detection circuit (OPTDET) 9 detects an optical input level with a current from a photodetector 1 with reverse bias and outputs information to an optical input level monitoring circuit 10 and an excess optical input detection circuit 11. The excess optical input detection circuit 11 receives the output electric signal of the optical input level detection circuit 9 and detects an excess optical input and issues an alarm to a terminal RX HIGH ALM. Thus, even when temperature fluctuation is applied, the monitoring error of an optical input level is decreased.