Contents I. Introduction
High data-rate wireless communication is essential for future wireless communication systems. As the frequency spectrum becomes increasingly crowded due to civilian, commercial and military use, the wireless carriers have been forced in two directions. First, the spectrum which is currently in use must be utilized more efficiently. Secondly, radios which can operate at carrier frequencies in the tens of GHz (e.g. 5G cellular), where large swaths of unused bandwidth is available, must be deployed. Moving in either of these directions puts strain on the power amplifier (P A) which must be small and power efficient, as weight, size and battery life are a concern in handheld, man-pack, vehicular and airborne terminals.
