Abstract: A transisterized circuit may be driven with a low voltage without saturation of a direct current operating voltage point. The transisterized circuit includes a first transisterized circuit formed by a cascade connection of a first differential transisterized circuit and a first emitter follower circuit, a second transisterized circuit formed by a cascade connection of a second emitter follower circuit and a second differential transistor circuit, and an inversion circuit connected between said first transisterized circuit and said second transistor circuit.

Abstract: A burst optical signal receiver receives optical signals produced in a burst form from a predetermined subscribers. This burst optical signal receiver comprises an identifying circuit for comparing the input level of an input optical signal with a predetermined threshold value to identify the input level; a peak detector for detecting and holding the peak value of the input optical signal; a DC feedback circuit for acquiring the DC level of an output of the identifying circuit; and a circuit for producing the predetermined threshold value from the DC level from the DC feedback circuit and the peak value held in the peak detector and supplying the predetermined threshold value to the identifying circuit. The peak detector has a plurality of peak detection sections having different gains and operational dynamic ranges and causes those peak detection sections to operate in accordance with the input level of the input optical signal.