Dettmann, I. (Rohde & Schwarz GmbH & Co. KG, 81671 München, Germany)
Berroth, M. (Institute of Electrical and Optical Communications Engineering, Universität Stuttgart, 70569 Stuttgart, Germany)
This paper investigates the supply modulation concept to improve the efficiency of power amplifiers in back off. The modulator is a class AD modulator which has a high efficiency while keeping a large signal bandwidth. In an experimental setup the efficiency of a 5 W GaAs power amplifier can be improved from 28% to 40% at 7dB back off.