Variable operating currents are generated in relation to input signal power and output signal power and achieving both low noise and low power consumption. Emitter follower circuits are attached to output terminals of a frequency divider for generating a local signal. By adjusting the currents flowing through the emitter follower circuits, the amounts of currents flowing into mixers is adjusted. When the amounts of currents of local signals flowing into the mixers increases, the effect of noise suppression is expected. The amounts of the currents flowing through the emitter follower circuits is changed depending on the amplification factor of variable amplifiers.