A review of GaN HEMT broadband power amplifiers

The unique material properties of GaN, wide bandgap, high thermal conductivity, high breakdown voltage, high electron mobility and the device properties of GaN HEMT (High Electron Mobility Transistor) namely low parasitic capacitance, low turn on resistance and high cut off frequencies make it a good choice to use in a power amplifier. During this era of wire- less communication with complex modulation schemes having high peak to average power ratio, maintaining the efficiency and linearity of power amplifier is a tough task. In this paper an extensive review of GaN HEMT based power amplifier is presented. First of all, GaN technology is described and compared with other semiconductor technologies. The different classes of power amplifier like class B, C, D, E, F and J with GaN is discussed. Efficiency and linearity enhancement techniques like envelope tracking, Doherty power amplifier and digital pre-distortion used in applications with high PAPR waveforms is described. The advantages of GaN MMIC (Microwave Monolithic Integrated Circuit) are reviewed. Finally different thermal management solutions used for GaN power amplifier to cope with its self heating phenomenon are explained. (C) 2020 Elsevier GmbH. All rights reserved.