Patent ID: 6297694
Filing Date: 2001-10-02
Classification: H03F,H04W

Abstract:
A high frequency power amplifier for a dual band system, comprising:first and second power amplifiers, each power amplifier comprising at least one power amplifying heterojunction bipolar transistor (HBT);first and second biasing circuits providing a bias for the first and second power amplifiers, respectively, each biasing circuit comprising an HBT; anda bias switching circuit for exclusive switching between the first and second biasing circuits in accordance with first and second signals input to the bias switching circuit, the bias switching circuit comprising:a first switching circuit comprising a first HBT for controlling output of the first signal to the second biasing circuit;a second switching circuit comprising a second HBT for controlling output of the first signal to the first biasing circuit; anda third switching circuit comprising a third HBT for controlling operation of the second switching circuit according to the second signal for controlling operation of the first switching circuit, for exclusive selection and operation of the first and second switching circuits wherein the first power amplifier and the first biasing circuit are integrated circuits integrated in a first semiconductor substrate, the second power amplifier and the second biasing circuit are integrated circuits integrated in a second semiconductor substrate, and the biasing circuit is an integrated circuit integrated with other circuits on one of the first and second semiconductor substrates.