Technology developments driving an evolution of cellular phone power amplifiers to integrated RF front-end modules

Millions of cellular phone power amplifiers (PAs) are produced every day worldwide using a great diversity of technologies. This is true both for the active devices, where various silicon as well as GaAs transistors are used, and for the PA architecture, in which MMIC, module, and discrete solutions compete. This paper gives an overview of the various technological and architectural choices and discusses their influence on the PA performance, notably the power efficiency and linearity. It sketches the future of PA development toward more functional integration, which may be obtained by two paths: integration on chip and added functionality in modules