Abstract
Research activities and future trends in the field of RF and microwave power amplifiers (PA) design are addressed. Design strategies for high efficiency PA, based on harmonic tuning approaches are focused and the effects of the harmonic terminations on the PA main features (output power, efficiency, linearity) are discussed. In particular, their practical implementation in the design of GaAs and GaN technology based PA is demonstrated through experimental validation. A special emphasis is devoted to the harmonic terminations effects on the device linearity behaviour, which is focused by means of a Volterra series approach. Finally, some "evergreen" design solutions recently re-discovered for 3GPP and next generation communication systems, as the Doherty and Envelope tracking approaches, are revisited.