PURPOSE: To eliminate satisfactorily the in-phase component over a wide range of bands by inverting one of both signal currents and injecting the other signal current to an emitter electrode of a base earthed amplifier transistor directly or via a resistance.

CONSTITUTION: The collector current of a differential amplifier transistor (TR) 4 is injected to an emitter electrode of a base earthed amplifier TR17 via current mirrors 7∼10 which inverts the current. While the collector current of a differential amplifier TR5 is injected to said emitter electrode of the TR17 via a resistance 16. Therefore the in-phase components contained in the collector currents of the TRs 4 and 5 are offset, and only the differential component is obtained from the collector of the TR17.