Novel transmission line combiner for highly efficient outphasing rf power amplifiers

A novel transmission line (TL) combiner is proposed having the same functionality as a Chireix-combiner with respect to its load impedance and combiner efficiency, but without the need of additional parallel compensating elements, which are necessary to improve the power backoff efficiency in highly efficient outphasing RF power amplifiers. Thus the design complexity is reduced and an alternative approach to Chireix-combiners becomes available. A detailed mathematical analysis of this TL-combiner is presented and design equations are derived. Its different physical operation and performance is demonstrated by a design example.