Lehmann, Thomas; Knöchel, Reinhard (Institute of Electrical and Information engineering, Microwave Research Laboratory, University of Kiel, Kaiserstrasse 2, 24143 Kiel)
A switched sequential amplifier (SSA) with 50% relative bandwidth is presented. It utilizes switched Lange couplers as power splitters and combiners, but requires two additional phase shifters. The proposed SSA concept is based on the "balanced" amplifier scheme and can be used with off the shelf amplifiers. The average PAE can be doubled if using type A amplifiers. An average PAE of 50% is feasible when using type B amplifiers. The circuit can be operated at envelope speed for digitally modulated signals. The paper presents the circuit concept, theoretical considerations for possible efficiency enhancements and experimental results for a practically realized SSA.