Patent ID: 7123095

Claim:
A high frequency power amplifier circuit, comprising: an output power detection circuit for receiving a signal from a power amplifier circuit for amplifying a high frequency signal to thereby detect output power of the power amplifier circuit; a differential amplifier circuit for comparing a detection signal delivered from the output power detection circuit with a signal designating an output level to thereby output a signal according to a potential difference therebetween; and a bias control circuit for providing the power amplifier circuit with a bias based on an output of the differential amplifier circuit, wherein the output power detection circuit is configured such that the signal from the input terminal or the output terminal of an output transistor of the power amplifier circuit is impressed on the input terminal thereof, comprising: a detection transistor connected to a resistor between the output terminal and a power source voltage terminal; and an operational power source voltage fed to the power source voltage terminal is set so as to be less in variation than an operational power source voltage fed to a power source voltage terminal of the power amplifier circuit.