AMPLIFIER AND POWER CONSUMPTION CONTROL METHOD

摘要

PROBLEM TO BE SOLVED: To provide a FET amplifier the power consumption of which can be reduced in response to a signal level without the need for a variable control provision of a gate-source voltage Vgs and for a constant current provision of a drain current Id. SOLUTION: A control circuit 38 decides a power supply voltage on the basis of level information denoting a signal input level to an amplifier employing a field effect transistor FET for an amplifier element and controls a switch section 42 depending on the result to change-over a drain-source voltage Vds that is the power supply voltage.