Patent ID: 6750720
Filing Date: 2004-06-15
Classification: H03F

Abstract:
A high frequency amplifying device comprising:a high frequency amplifier that uses a first NPN bipolar transistor as an amplifying element, the collector terminal of said first NPN bipolar transistor being operatively connected to a collector bias terminal; and a constant voltage biasing circuit that supplies a base bias voltage to said high frequency amplifier; wherein said constant voltage biasing circuit includes: a second NPN bipolar transistor that forms a current mirror together with said first NPN bipolar transistor; a third NPN bipolar transistor that compensates a base current of said current mirror; a first and second PNP bipolar transistors forming a current mirror that uses a collector current of said third NPN bipolar transistor as a reference current, and determines a collector current of said second NPN bipolar transistor; and a first and second resistors that are operatively connected between the emitter terminals of said first and second PNP bipolar transistors and a power supply/voltage setting terminal.