PURPOSE: To avoid deterioration of trailing characteristics even with large sized transistor, by connecting a rapid discharge path which is temporarily operative, to the base circuit of an output emitter follower transistor (TR).

CONSTITUTION: A discharge path DIS consisting of diodes D3, D4 is connected between the base N2 of an output emitter follower TRQ4 and the collector N4 of a TRQ2. Thus, when an input VIN changes from H to L, since the TRQ2 is conductive, the charge at a point N2 is quickly discharged in the path of N2-D3-D4-N4- Q2-VEE to speed up the trailing of the output N3. When N3=0volt, the diodes D3, D4 are not conductive to stop discharging. Then, the circuit DIS is operative only when the output N2 is switched by H-L, and no output waveform is distorted through normal operation.