Patent ID: 7215203

Claim:
A mobile communication apparatus having a power amplifier, the power amplifier comprising: an input terminal; an output terminal; a plurality of amplifying stages each of which has an amplification transistor and a bias circuit which forms a current mirror circuit with the amplification transistor; and a bias control circuit which receives a power control signal, generates bias signals different from each other and supplies the bias signals to each of the plurality of amplifying stages, wherein the plurality of amplifying stages are coupled in cascade between the input terminal and the output terminal, wherein the bias circuit includes a first transistor which has a control terminal, a first terminal and a second terminal, the control terminal being coupled to the second terminal and to an input terminal of the amplification transistor, and wherein the control terminal of the first transistor of each bias circuit receives one of the bias signals, wherein the amplification transistor are constituted by metal oxide semiconductor field effect transistor, and wherein the first transistors are constituted by metal oxide semiconductor field effect transistors.