A 2-W GaN-based three-level class-D power amplifier with tunable back-off efficiency

This paper presents a voltage-mode three-level class-D gallium nitride (GaN) power amplifier (PA) for the 700MHz band. The PA achieves a drain efficiency of 68.7%, at a maximum output power of 2.1 W and a drain efficiency of 71.6% at 9-dB power back-off. The optimum power back-off is easily changed from 3 to 12 dB by tuning the supply voltage to the IC without degrading the peak efficiency. The PA consists of a single monolithic microwave integrated circuit (MMIC) without a power combiner. This is, to our best knowledge, the simplest architecture offering high back-off efficiency.