Power Amplifier

Catchwords such as Software Defined Radio, (SDR) suggest that the development of hardware components appears to be on the decline. However, if you analyze implementations of this SDR, you can see that the complexity of the necessary analog circuit components has even increased. In particular, the need for amplification of the emitted radio frequency power is constantly increasing. The new digital modulation methods such as WLAN, Edge, UMTS and 5G also require a highly linear transmission behavior of these power amplifiers. The increasing use of radio modules in mobile devices places the greatest demands on the efficiency of power amplifiers in order to maximize transmission times on the one hand and to use as little material as possible for cooling purposes on the other. This chapter first covers the fundamentals of developing a PA, including output impedance matching. Furthermore, the classical operating modes A, B, and C, which are solely determined by the bias point setting, are introduced in detail. Subsequently, a variety of concepts for improving efficiency are presented. Following that, combined amplifiers are introduced. Finally, a detailed discussion on linearization techniques is provided.