RF-Input Divisional Load-Modulated Balanced Amplifier With Extended Back-Off Range

This article presents a novel structure for the recently reported divisional load-modulated balanced amplifier (DLMBA). Compared with the previously reported DLMBA architecture with dual inputs, the proposed work developed a single radio frequency (RF) input DLMBA, which makes this framework more practical. As part of our approach, the Doherty PA (DPA) branch, which is used as the main PA, is modified in order to extend the range of the output back-off of the entire circuit. A detailed explanation of the new structure and an in-depth analysis are presented. The results demonstrate that the output-power back-off (OBO) range of the RF-input DLMBA can be extended beyond 15 dB. For the purpose of validation, an RF-input DLMBA has been designed and implemented using four GaN transistors. A fabricated RF-input DLMBA is capable of delivering an output power of between 43.3 and 44.4 dBm and a drain efficiency (DE) of between 60% and 66.8% at saturation in the frequency range of 2.3–2.7 GHz. In addition, the DE ranges from 46.3% to 54.7% at 6 dB OBO state, from 47% to 54.3% at 10 dB OBO state, and more than 40% at 16 dB OBO state. Furthermore, a modulation signal test has been provided. As a result of the excitation of a 20-MHz 5G new radio (NR) signal with a peak-to-average power ratio (PAPR) of 10.4 dB, the fabricated prototype has demonstrated an adjacent channel power ratios (ACPRs) better than −47.1 dBc after digital predistortion (DPD).