From 5G To 6G: Investigation on Efficiency Improvement of Millimeter Wave Power Amplifier

As wireless communication systems transition from 5G to 6G, developing millimeter-wave power amplifiers (PAs) that combine high efficiency and excellent linearity has become a key challenge in current research. However, challenges such as high peak-to-average power ratios (PAPR), wideband operation, and thermal constraints significantly hinder conventional PA architectures. This review systematically examines recent advances in millimeter-wave PA development for 5G/6G systems. Two primary avenues are highlighted. First, architectural innovations include broadband matching networks, Doherty/outphasing topologies, digital predistortion (DPD), envelope tracking (ET), and their hybrid implementations. Second, material technologies involve GaN/CMOS process optimization, thermal management, and advanced packaging. By analyzing the current research, we explore the fundamental trade-offs between efficiency, linearity, bandwidth, and integration density. We also outline future directions such as higher-frequency operation, intelligent adaptive design, and novel semiconductor materials for next-generation communication systems. The insights provided herein offer valuable guidance for the development of high-performance PAs tailored to future 6G communication systems.