Patent ID: 6661290
Filing Date: 2003-12-09
Classification: H03F

Abstract:
A high-frequency power amplifier comprising:a plurality of high-frequency amplifier sections, each being composed of bipolar transistors; a plurality of capacitors each corresponding to one of said high-frequency power amplifier sections, one end of each capacitor being connected to bases of the bipolar transistors of the corresponding high-frequency power amplifier section, and the other end thereof being connected to a high-frequency signal source: and a plurality of bias circuits each corresponding to one of said high-frequency power amplifier sections, applying a bias voltage to the bases of the bipolar transistors of the corresponding high-frequency power amplifier section, wherein each bias circuit is located close to the corresponding one of said high-frequency power amplifier sections, and includes a bias voltage lowering section lowering the bias voltage in response to an increase in temperature of the bipolar transistors, wherein each of said bias circuits includes a ballast resistor and a voltage generating circuit generating a voltage and supplying the generated voltage to the bases of the bipolar transistors as said bias voltage, wherein said voltage generating circuit includes a first diode, of which a cathode is grounded, a second diode, of which a cathode is connected to the first diode and an anode is connected to a control power supply via a control resistor, and a bipolar transistor, of which a collector is connected to a bias power supply, a base is connected to the anode of said second diode, and an emitter is connected to said ballast resistor, and wherein said first diode is located close to the bipolar transistors of the corresponding high-frequency amplifier section.