Linearized power amplifier

摘要

A linearized power amplifier is provided which comprises a non-linear radio frequency (RF) power amplifier, a linearization circuit such as a Cartesian Feedback circuit, an RF feedback circuit; an IF feedback circuit; or a feedforward circuit, and a dynamic bias modulation circuit for modulating an operating voltage of the amplifier. The dynamic bias modulation means includes an envelope determining circuit, signal processing circuits in which predetermined data or a simplified transfer function determined from measured characteristics of the amplifier is stored and used to produce power bias and/or base or gate bias signals, and driver circuits for modulating the power supply voltage and/or base or gate bias voltage of the RF amplifier in response to the bias signals. The dynamic bias modulation may be used with a BJT-based, and FET-based or any other type of RF power amplifier. With the right combination of power supply and base or gate bias modulation the efficiency of the RF amplifier can be maximised for a given output power, and the combination of linearization means and high level power supply and/or base or gate bias modulation gives the benefits of improved spectral control and intermodulation distortion reduction coupled with high efficiency.