Challenges Facing Front Ends for 3G and 4G Multimode Handsets

WiMAX/LTE and Emerging Technologies n NOVEMBER 2008 how well it all works and how seamless designers have made it appear. Similar to the jet analogy, engineers may know how these complex handsets, and the highly integrated systems they contain, function, but that knowledge doesn’t preclude us from feeling a sense of awe when watching someone use their handset to check e-mail, download a video, or take a picture. There are also many parallels to the technical achievements and boundaries being pushed in the crop of current third-generation (3G) and future fourth-generation (4G) multimode phones under development. This article examines some of the drivers that are pushing designers to seek new and groundbreaking solutions for a key system in these mobile devices—the RF front end. “RF front end” has become the industry-standard term for the radio frequency components functionally located between the wireless transceiver and the antenna, required to both transmit and receive the radio signal. More specifically, the entire cellular front end system is comprised of power and low noise amplifiers; filtering, such as receive filters and duplexers; RF A s consumers, we are used to the continual productivity enhancements derived from having ever-increasing, computer-like handsets at our disposal. For those of us lucky enough to have indepth RF industry knowledge, we know full well the complexity of a system that can deliver this near desk-like performance in the palm of your hand. Still, it helps to step back now and again to consider how such an intricate system actually works in order to appreciate the arduous nature of developing these state-of-the-art mobile devices. Much like the awe we experience watching a jumbo jet take off— we may know how the basic interaction of forces occur, enabling the jet to break the sound barrier or cruise at an altitude of 30,000 feet, yet we’re still fascinated with Challenges Facing Front Ends for 3G and 4G Multimode Handsets