For nearly two decades now, micro-electromechanical systems (MEMS)-based devices like acceleration sensors have been effectively serving the automotive world in airbag systems. During that period the technology has made impressive gains to pervade other commercial sectors such as inkjet printers, blood pressure monitors and digital light processor video projection systems. Plus, its use in areas such as biomedical and environmental applications is gaining momentum. With these advances, the communications space is now eager to exploit the RF benefits of MEMS technology.

This was apparent at the recent IEEE Microwave Theory and Techniques Society (MTT-S) convention in Fort Worth, Texas, wherein several technical sessions, workshops and panel discussion were devoted to RF MEMS and the challenges of integrating the technology with conventional IC process flows while meeting the cost constraints. In addition, several makers demonstrated products that were ready for production, especially switches, filters, ultraminiature resonators and high-performance passive components.

While the design and development activity has certainly mushroomed in the last few years, only a handful of players have taken their respective RF MEMS devices to production. Consequently, the RF MEMS market is insignificant today as compared to the overall MEMS revenues, which reached $5.3 billion last year, according to market research firm In-Stat/MDR. In fact, the MEMS industry as a whole witnessed a 35.7 percent growth in 2003 over the previous year, driven collectively by all these emerging applications. Nevertheless, In-Stat/MDR's senior research analyst Marlene Bourne predicts that the RF MEMS section of the market will see about 18 percent compound annual growth rate (CAGR) for the next few years. At this rate, the analyst expects the RF MEMS share to cross the $100 million mark by 2008. During that period, the overall MEMS revenues will almost double to reach $10 billion by 2008.

As a result, with the ongoing progress in performance and reliability, deployment of RF MEMS devices like switches, filters, passives and resonators as building blocks for integrated RF front-end and other subsystems are gaining ground. As this decades-old technology now begins to produce ultraminiature RF circuits for low-loss switching, filtering or frequency generation with high degree of reliability, the system designers have begun to focus on the challenges of IC integration. With RF functions like switches, oscillators, and filters moving toward the production phase, integrating these with other circuits on a common substrate to form a module is the intermediate step toward full integration on a silicon chip as the ultimate goal.

Since designers have just begun to test the waters, only a handful of developers have taken their respective RF MEMS devices (switches, duplexers, filters etc) to full production only recently. And only a noted few have lately readied prototypes of integrated RF front-end modules and subsystems using their RF MEMS parts and combining them with power amplifiers and other passives in a single package. Agilent Technologies, Intel, IBM, and XCom Wireless, among others, are key drivers of this integrated trend. Agilent, for instance, has taken its MEMS-based film bulk acoustic resonator (FBAR) filters and duplexers to production, as well as developing RF front-end modules incorporating its RF MEMS devices and other circuitry. It hopes to take these modules into production soon. Likewise, Intel is planning to use MEMS in the wireless arena to improve the performance of RF systems. And IBM has readied MEMS resonators and filters that promise to replace these passives in wireless applications sooner than you think. Similarly, XCom Wireless is addressing packaging issues for an integrated subsystem for joint tactical radio system using its production-ready phase shifters, switches and filters.

Given the rate of progress and adoption, single chip MEMS driven RF front-ends, transceivers or any other subsystem are years away. While integration issues will definitely be resolved with time, cost will play a crucial role in bringing single-chip RF MEMS solutions to the mainstream applications.