Patent ID: 7715812

Claim:
An RF power amplifier comprising: a first power amplifier that amplifies a first RF transmission input signal of GSM850 and GSM900; and a second power amplifier that amplifies a second RF transmission input signal of DCS1800, PCS1900, and WCDMA1900, wherein the first power amplifier is constituted by a first multi-stage amplifier including at least a first input side amplifier and a first output side amplifier, the second power amplifier is constituted by a second multi-stage amplifier including at least a second input side amplifier and a second output side amplifier, when the second power amplifier amplifies the second RF transmission input signal of WCDMA1900, a gain of the second input side amplifier of the second multi-stage amplifier is set to a low gain in response to a mode signal of a predetermined signal, and when the second power amplifier amplifies the second RF transmission input signal of DCS1800 or PCS1900, the gain of the second input side amplifier of the second multi-stage amplifier is set to a gain higher than the low gain in response to a change of the mode signal to a signal different from the predetermined signal.