Patent ID: 7259615

Claim:
A bias voltage supply circuit supplying a direct current bias voltage to an input terminal of a radio-frequency amplification transistor amplifying a radio-frequency signal, comprising: a constant-voltage power supply generating a constant voltage higher than said bias voltage; a rectifier transistor connected between a supply point of said bias voltage connected to said input terminal of said radio-frequency amplification transistor via an inductor (L) which reduces a high frequency component, and a power supply voltage supply line, wherein a control terminal is kept at a constant voltage generated by a constant-voltage power supply; and a constant-current power supply connected between said supply point of the bias voltage and a reference voltage supply line to supply a constant current to said rectifier transistor; wherein a negative feedback transistor; controlled by electric potential of said supply point of the bias voltage and applying negative feedback to said rectifier transistor; is connected between said control terminal of the rectifier transistor and said reference voltage supply line.