SIGNAL DEMODULATION CIRCUIT AND OPTICAL SIGNAL RECEIVER USING IT

摘要

PROBLEM TO BE SOLVED: To provide a signal demodulation circuit which efficiently prevents the malfunction of output due to input noise in an optical signal receiver and is high in the noise tolerance of output malfunction by high sensitivity and to prevent the malfunction of an output terminal due to a disturbance light noise. SOLUTION: The optical signal receiver for converting a received optical signal to an electric signal and then demodulating it by the signal demodulation circuit a circuit block for signal detection consisting of a low-pass filter LPF for setting the center value of an input signal at a detection level and a comparing integration circuits COMP1 and C2 for integrating the difference signal of the input signal and the detection level, a low-pass filter LPF1 for detecting the average of the input noise and a circuit for processing long period noise for setting the detection level for setting the average of a lower limit peak hold PHLD for detecting the lower limit value of the input noise and the input noise based on the difference signal of the lower limit value in connection with the lower limit value of the input noise.