Patent ID: 7522001

Claim:
A power amplifier comprising: a first amplifying device having input and output terminals and which amplifies a radio frequency signal; a second amplifying device having an output terminal connected to the output terminal of the first amplifying device, and an input terminal; an emitter follower circuit which applies to the input terminal of the second amplifying device a voltage according to a reference voltage applied to a reference terminal; first and second resistors connected in series between the reference terminal and the input terminal of the first amplifying device; a first transistor having an emitter, a collector connected to the reference terminal, and a base to which a control voltage is applied; a third resistor connected between the emitter of the first transistor and a grounding point; and a current mirror circuit which draws a current proportional to current input from the collector of the first transistor from a connection point of the first resistor to the second resistor.