Patent ID: 6750718
Filing Date: 2004-06-15
Classification: H03F

Abstract:
A radio-frequency amplifier for amplifying a radio-frequency signal, comprising:a radio-frequency transistor having a base; a reference voltage supply unit for supplying a first base bias from a reference voltage source to a base of the radio-frequency transistor via a first resistor; and a bias circuit unit for outputting a second base bias to the base of the radio-frequency transistor, wherein the bias circuit unit comprises a switching terminal that provides a signal that switches output of the second base bias on and off, the radio-frequency transistor operates at a constant voltage and the radio-frequency amplifier produces a first output power when the bias circuit unit outputs the second base bias, and the radio-frequency transistor operates at a constant current and the radio-frequency amplifier produces a second output power, lower than the first output power when the bias circuit unit does not output the second base bias.