Analysis and Design of RF-Input Asymmetric Divisional LMBA With Extremely Extended Back-Off Range

A novel power amplifier (PA) architecture named the RF-input asymmetric DLMBA (RF-input ADLMBA) is presented and analyzed in this work. A detailed explanation of the structure and an in-depth analysis are presented. The effects of varying current ratios among carrier amplifier carrier PA (CPA), peaking amplifier peaking PA (PPA), and balanced amplifier (BA) pairs on the high-efficiency output back-off (OBO) range of this novel structure are examined. In addition, the role of different power divider allocation ratios in the OBO range has also been examined. According to the results, it is possible to extend the OBO range of the radio frequency (RF) input ADLMBA to more than 20 dB by using a reasonable power allocation strategy. Two different RF-input ADLMBAs have been designed and implemented using four GaN transistors for validation purposes. RF-input ADLMBAs fabricated in this study can deliver an output power of between 42.8 and 44.7 dBm and a drain efficiency (DE) of between 56% and 62.8% at saturation in the frequency range of 2.352.65 GHz. In addition, DE ranges from 42% to 46.7% at 10-dB OBO state, and from 44% to 53% at 20-dB OBO state. A modulation signal test is also included. After 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 demonstrated adjacent channel power ratios (ACPRs) better than –49 dBc after digital predistortion (DPD).