Design of Ultra-Wideband Power Amplifier Based on Extended Resistive Continuous Class B/J Mode

This brief presents the design of an ultra-wideband high-efficiency extended resistive continuous class B/J (ERCB/J) power amplifier (PA). Beyond an octave bandwidth, the conventional class B/J mode is inappropriate. Whereas the existing resistive-reactive class J modes present an overlapped impedance space at the expense of the efficiency and power degradation or voltage swing beyond 4
$V_{DD}$
. Therefore, this brief presents a novel ERCB/J mode to achieve overlapping impedance space promising high efficiency over a multi-octave bandwidth. A design scheme is presented to map loads of the proposed mode to frequencies in the targeted multi-octave band to design a feasible matching network. For the proof of concept, a PA has been designed based on ERCB/J using commercialized GaN HEMT. This PA operates from 0.5-3.25 GHz, exhibiting fractional bandwidth of 146.7%. The peak drain efficiency of 60-70.1% and peak output power of 39.1-41.75 dBm are obtained at saturation over the operating band. The PA has also been tested with a two-tone signal with 10 MHz spacing and a 10 MHz LTE signal.