| 摘要 |
A signal is sampled at a stage following a first amplifier circuit ( 12, 14, 16 ) and preceding a second amplifier circuit ( 20, 22 ), and the presence or absence of a signal is detected by a detector circuit ( 30 ). When the presence of a signal is detected, a gate bias circuit ( 32 ) switches a gate bias for FETs in the second amplifier circuit ( 20, 22 ) 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.
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