Power Amplifiers and Distributed Amplifiers

This chapter begins with a theoretical discussion of the unwanted frequency components generated by amplifiers with a non‐linear power transfer response, and in particular on the influence of third‐order distortion products. This is followed by a discussion of the principal methods used to linearize the performance of a power amplifier. The chapter includes a discussion of the basic principles of distributed amplifiers. It discusses two particularly significant developments, namely the use of gallium nitride to replace gallium arsenide, both in discrete and monolithic applications, and the use of advanced packaging techniques to improve the thermal management of high power devices. Load matching networks for power amplifiers differ from source matching networks in that there is not a conjugate impedance match at the output. The chapter concludes with a short review of the developments in materials and packaging that are influencing the advancement of RF and microwave power amplifier devices.