Loop controller for a feedforward amplifier minimizing the measured power signal

Adaptively controlled feedforward amplifiers are discussed in a large number of publications over the past years. Especially for the control of the distortion cancellation loop it was inevitable to implement a baseband-controller if the use of a pilot carrier should have been avoided. A significant deterioration of the costs of a feedforward amplifier can be achieved by using power sensors to balance all loops. This paper introduces a loop controller, which tunes the loops of a feedforward amplifier based on the power measurement of two signals within the circuit. The structure of this controller is discussed and measurement results for a 40 W GSM2+ (EDGE) power amplifier are presented.