A 1.5 GHz GaN HEMT fifth-harmonic-peaking Class-EF power amplifier with 85% drain efficiency and 42 dBm output power

In this paper, we present the design and implementation of a new variant of Class-EF PA, the so-called fifth-harmonic-peaking Class-EF. It inherits soft-switching operation from the Class-E PA and low peak switch voltage from the Class-F PA. The new topology also allows operations at higher frequencies and permits deployment of large transistors. Further, by employing novel λ/8 open and shorted stub arrangements, the PA is able to facilitate better even harmonic suppression leading to improved PA efficiency. Measured peak drain efficiency of 85% and output power of 42 dBm were obtained at 1.5 GHz. Across a 300 MHz frequency range i.e. 20% bandwidth, the PA delivered output power >40 dBm with drain efficiency >65%.