Linear power amplifier with distortion detection

摘要

A power amplifier (10) suitable for satellite cellular communication systems provides highly efficient linear amplification of noise-like RF signals that have multiple carriers spread over a large instantaneous bandwidth. The amount of distortion present in the output is detected (14, 16, 18) and a feedback signal is provided to control the bias point of the active devices. As drive levels increase, the increased harmonic distortion power detected causes the power amplifier bias to increase thus reducing distortion. The control circuit (20) continually re-biases the power amplifier (12) for maximum efficiency for a predetermined level of distortion. The control circuit (20) may be adjusted to maximize efficiency while maintaining an allowable distortion level over the entire dynamic range of the devices.