Patent ID: 6605999
Filing Date: 2003-08-12
Classification: H03F,H03G

Abstract:
A high-frequency power amplifier, comprising:an input terminal; an output terminal; a control terminal which receives a power control signal; an amplifying system which has multiple amplifying stages and is connected between said input terminal and said output terminal; and a bias circuit which is connected to said control terminal and adapted to supply a bias voltage, which has a nonlinear response to the power control signal received on said control terminal, to a first amplifying stage connected to said output terminal among said multiple amplifying stages, wherein said bias circuit includes: a voltage division circuit which divides the voltage of the power control signal and delivers a divided voltage to the control terminal of said first amplifying stage; a control transistor having its control electrode connected to the voltage division node of said voltage division circuit, its first electrode connected to the resistor on the lower voltage side relative to the voltage division node of said voltage division circuit, and its second electrode grounded; and a current sensing transistor having its control electrode connected to the control electrode of the transistor of said first amplifying stage and releasing from its first electrode a voltage signal indicative of the value of a sensed current.