Patent ID: 7378909

Claim:
A radio-frequency power amplifier apparatus comprising: N amplifiers sequentially connected in series, an input signal being input to a first amplifier, and an output signal being output from an Nth amplifier; an (N−1)th power source voltage control regulator which supplies an (N−1)th adjustable power source voltage to an (N−1)th amplifier in accordance with an (N−1)th control signal; and an Nth power source voltage control regulator which supplies an Nth adjustable power source voltage to the Nth amplifier in accordance with an Nth control signal, wherein, when the output signal is equal to or higher than a predetermined value that is larger than a value in which a linearity between the output signal and the Nth control signal can not be maintained, the Nth control signal is identical to the (N−1)th control signal, wherein, when the output signal is lower than the predetermined value, the Nth control signal is fixed to set the Nth adjustable power source voltage at a fixed voltage, and wherein a first power source voltage of the first amplifier is fixed.