BURST SIGNAL DETECTION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To allow a burst signal detection circuit for detecting the arrival of a burst signal to accurately detect the burst signal against DC level fluctuation and to detect a burst signal with high precision even when an arrived burst signal is a very weak optical signal. SOLUTION: This burst signal detection circuit is provided with a DC fluctuation elimination circuit 12 that detects a bottom level of an input signal and eliminates DC level fluctuation of the input signal on the basis of this bottom level and with an amplitude identification circuit 15 that detects presence of a burst signal on the basis of an output signal of the DC fluctuation elimination circuit 12. The amplitude identification circuit 15 has an amplitude detection circuit 16 that detects the maximum amplitude of the output signal of the DC fluctuation elimination circuit 12, an identification level control circuit 17 that controls the identification level of the output signal, and a comparator 15A that compares an output level from the amplitude detection circuit 16 with the identification level to provide an output of a detection signal denoting the presence of the burst signal.