Patent ID: 7642859

Claim:
A power amplifier, comprising: an amplification circuit configured to receive signals in plural frequency bands, to amplify an input signal in each frequency band through a common active element common to the signals in plural frequency bands, and to output amplified signals in plural frequency bands, the amplification circuit including the common active element which simultaneously amplifies each of the received signals in the plural frequency bands; an input stage matching circuit, disposed on an input side of the common active element, to match impedances across the plural frequency bands between an output impedance of a first circuit, which supplies the signals in the plural frequency bands, and an input impedance of the common active element; and an output stage matching circuit, disposed on an output side of the common active element, to match impedances across the plural frequency bands between an input impedance of a second circuit, which receives the amplified signals in plural frequency bands outputted from the common active element, and an output impedance of the common active element.