Patent ID: 6960959

Claim:
A power amplifier, comprising: branch output means having an input terminal and a plurality of output terminals, a plurality of amplifying means which are connected to some of the output terminals of the branch output means and are operated at different signal frequencies from each other, bypass means connected to the other output terminals of the branch output means, a synthesis output unit which receives outputs of the plurality of amplifying means and an output from the bypass means as inputs and has an output terminal connected to an outside, switch means of switching presence and absence of conduction of the bypass means, and control means of controlling conduction of the branch output means, conduction and an amplifying operation of the plurality of amplifying means, and conduction of the switch means, wherein each of said amplifying means includes: a first matching circuit provided on a side of the branch input means, a second matching circuit provided on a side of the synthesis output unit, a transistor provided between the first matching circuit and the second matching circuit, and a DC bias supply circuit for an operation of the amplification of said transmitter, said second matching circuit of said amplifying means is configured so that impedance to the plurality of said amplifying means from said synthesis output unit is high impedance in all signal frequencies, in the case that said respective amplifying means connected to said second matching circuit does not perform amplification, and according to the signal frequency and necessary output power, the control means performs control so that an input to the branch output means is amplified and outputted to the synthesis output unit via any one of the plurality of amplifying means or the input is outputted to the synthesis output unit via the bypass means without amplification.