High-frequency amplifier circuit

A signal is sampled at a stage following a first amplifier circuit and preceding a second amplifier circuit, and the presence or absence of a signal is detected by a detector circuit. When the presence of a signal is detected, a gate bias circuit switches a gate bias for FETs in the second amplifier circuit to a normal operating voltage value, and when the signal is no longer detected, the gate bias is switched to a voltage value that reduces power consumption, after a mask time has elapsed. In a distortion feedback-type high-frequency amplifier circuit, a means for cutting off a circuit portion for the adjustment of each of a distortion extracting circuit and an inverse distortion adding circuit is achieved by switching FET gate voltage so as to put the corresponding amplifier in a virtually cutoff condition.