POWER AMPLIFIER AND COMMUNICATION APPARATUS

摘要

A power amplifier which amplifies signals with two frequency bands, and which is downsized and high in efficiency at a low output. The amplifier comprises an input terminal (501), a branching circuit (102) or the like connected to the input terminal (501) at the input thereof and having one input and a plurality of outputs, amplifying means (104, 106) connected to part of outputs of the branching circuit (102) or the like and operating at mutually different signal frequencies, a transmission line (108) connected to the remaining one output of the branching circuit (102), a synthesizing circuit (110) connected to respective outputs of the amplifying means and an output from the transmission line, a switch (109) provided between the transmission line and a synthesis output unit, and a control circuit (112) for controlling the conduction of the branching circuit (102) or the like, the conductions and amplifying operations of the amplifying means (104, 106), and the conduction of the switch (109).