PURPOSE: To use a circuit even in a high frequency area without restrictions on band due to an operational amplifier by not using the operational amplifier to constitute the circuit.

CONSTITUTION: The voltage to the ground of an input terminal 1 of a bias circuit 6 is 0V, and the bias circuit 6 gives the bias voltage which flows an idle current to transistors TRs 4 and 5. When a current flows from the input terminal 1, the collector current of the TR 5 is increased or reduced in proportion to increase or reduction of the input current, and the collector current of the TR 4 is reduced or increased contrarily. The voltage drop of load resistors 2 and 3 is changed by the change of respective collector currents. This voltage change is outputted to an output terminal 11 through two emitter follower circuits consisting of TRs 7 and 9 and level shift circuits 9 and 10.