Improving the power evenness of power amplifiers using out-of-phase combining

This paper shows how the use of an out-of-phase combining structure can improve an amplifier´s power uniformity into arbitrary loads. By choosing the number of amplifiers and their output matching networks in the proposed way, specific power distributions in the gamma plane can be tailored. Two new figures of merit are introduced to be able to concisely describe this output power distribution. Several versions of the proposed out-of-phase combining structure are modelled and compared using these measures. The benefits of the proposed topology are further demonstrated by means of measurement results from a realized balanced amplifier using two power amplifiers.