Optimal combiner design for outphasing RF amplification systems

Different kinds of RF power combiner are studied. Wilkinson and hybrid combiner show very good linearity but low power efficiency. Chireix combiner using stubs at the input shows good efficiency and bad linearity of system. This paper shows that an unmatched chireix combiner without stub used at the output of class-B amplifiers can be optimized in transmission line length in order to obtain the same good linearity of a matched Wilkinson combiner but better efficiency. Analytical, ADS simulation and experimental work are presented to support this work. Excellent agreement between simulations and measurements is obtained in all cases considered.