PURPOSE: To reduce the power consumption and to execute the operation at a high speed by biasing a second transistor by a constant-current source and impedance, and obtaining the constant-current source brought to temperature compensation.

CONSTITUTION: The base of a pull-down side transistor Q5 is connected to the middle point of a circuit consisting of a constant-current source IBIAS and impedance Z being in series thereto, and one end of this circuit and the other end are connected to a power source V1 (GND) side, and a power source V2 (VE) side, respectively. In such a state, by the constant-current source IBIAS and the impedance Z, the transistor Q5 is biased. Accordingly, the constant- current source brought to temperature compensation is obtained easily. In such a way, the variation of static current of the transistor Q5 can be suppressed, the power consumption can be reduced and the operation can be executed at a high speed.