Patent ID: 6842074

Claim:
A base bias circuit which supplies a bias current to a base of a common-emitter bipolar transistor of an npn type for a power amplifier, wherein: the base bias circuit comprises first through third bipolar transistors of an npn type and first and second resistors integrated on a semiconductor substrate and a base bias current control terminal, the first resistor is inserted between the base bias current control terminal and the first bipolar transistor, the second resistor is inserted between a base of the second bipolar transistor and the first bipolar transistor, a base of the second bipolar transistor is connected to a collector of the third bipolar transistor, an emitter of the second bipolar transistor is connected to a base of the third bipolar transistor, an emitter of the third bipolar transistor is grounded, a collector of the first bipolar transistor is connected to a positive power supply, and an emitter of the first bipolar transistor is directly connected to the base of the bipolar transistor for the power amplifier.