Patent ID: 7227418

Claim:
A power amplifier with a plurality of heterojunction bipolar transistors, the power amplifier comprising: a plurality of amplifier heterojunction bipolar transistors connected in parallel to one another, each including an emitter terminal being grounded, a base terminal via which an input signal is received, and a collector terminal via which an amplified signal is outputted; and a plurality of capacitors for removing a DC component of the input signal, which are connected to the base terminals of the amplifier heterojunction bipolar transistors; and a power-supply-side circuit for connecting the base terminals of the amplifier heterojunction bipolar transistors to a power supply terminal; and a plurality of unidirectional elements one ends of which are connected to the base terminals of the amplifier heterojunction bipolar transistors with no resistive element therebetween and other ends of which are connected to a ground for allowing a current to pass in a predetermined direction.