Analysis and performance of drain bias “in-dependent” Class-J power amplifier

This paper presents a broadband high power-efficiency Class-J PA investigation as a function of drain bias voltage VDC. The Class-J PA mode concept for which high power-efficiencies are released for the wideband frequency spectrum has been so far investigated for fixed VDC. In this paper for the first time the Class-J approach has been investigated as a function of the supply drain voltage. The experimental results performed on a 4.8 mm AlGaN/GaN packaged power transistor by using a harmonic active load-pull system have shown almost constant efficiency as a function of the supply voltage. The load-pull measured results have also been validated through measurements on a broadband Class-J PA prototype. Here, high efficiencies of around 55–65% are delivered in the frequency range 1.8–2.7 GHz as well as for various drain supply voltages between 10 V and 40 V.