Book Description

Radio frequency (RF) power amplifiers (PA) are the most power consuming components of a mobile communications unit. They are used to convert the DC power from the battery into RF power delivered to the antenna. In a cell phone it becomes very important to use highly efficient power amplifiers, such as Class C and Class E PAs, to increase the talk time which is directly proportional to the battery life. On the other hand these RF PAs are inherently nonlinear and will produce spectral regrowth and other undesirable effects. Therefore, to exploit their high efficiency, it is desirable to employ linearization techniques to linearize the overall response of these nonlinear amplifiers. Linear model matching and nonlinear multiplicative feedback linearization techniques are investigated in this work to compensate for PA onlinearities. The application of these techniques resulted in controller architectures that deliver excellent linearity performance of the compensated Class E and Class C PA models, making them very suitable in Wideband Code-Division Multiple-Access (W-CDMA) and Code-Division Multiple Access 2000 (CDMA2000) systems for transmission of multiple signals at high data rates, assuring that intermodulation distortion and spectral regrowth are minimized at the output of the power amplifier. Moreover, their high efficiency provides a significant extension of the battery lifetime.