Patent ID: 8457565

Claim:
A power amplifier circuit, comprising: a constant envelope signal generation circuit for converting an input signal having envelope variation into a first constant envelope signal and a second constant envelope signal which have the same amplitude and different phases so as to output the first constant envelope signal and the second constant envelope signal; a first amplifier for amplifying the first constant envelope signal so as to output a first amplified signal; a second amplifier for amplifying the second constant envelope signal so as to output a second amplified signal; and an output adder for outputting an amplified output signal having envelope variation based on the first amplified signal and the second amplified signal, wherein the constant envelope signal generation circuit includes: a fundamental signal generation circuit for generating a first fundamental signal and a second fundamental signal having the same amplitude and predetermined phase relationships with the input signal, and a third fundamental signal having constant phase relationships with the first fundamental signal and the second fundamental signal, from the input signal having envelope variation; a converted signal generation circuit for generating a first converted signal which has an amplitude Y satisfying Y 2 =A 2 −X 2 , where X denotes the amplitude of the first fundamental signal and the second fundamental signal, and A denotes any constant amplitude larger than X, and which is advanced in phase with respect to the first fundamental signal by π/2, and a second converted signal which has the amplitude Y and is delayed in phase with respect to the second fundamental signal by π/2, based on the third fundamental signal; a first adder for performing vector addition of the first fundamental signal and the first converted signal; and a second adder for performing vector addition of the second fundamental signal and the second converted signal, wherein the first constant envelope signal is output based on a signal output from the first adder, and the second constant envelope signal is output based on a signal output from the second adder.