For the most part, ABI Research remains bullish on MEMS for mobile phones, which will certainly benefit RF MEMS. The company predicts that MEMS will take off in mobile phones in 2008. It forecasts five major application areas: RF filters, adaptive tuning circuits, resonators and oscillators, audio microphones, and motion sensors.
ABI also notes companies to watch. For instance, WiSpry is developing MEMS-based RF capacitors, tunable filters, duplexers, and RF switches that will enable the adaptive RF front end needed for multiband handsets of the future. ABI additionally casts a light on XCom Wireless, where the primary focus is on making agile and tunable mobile-phone front ends with features much like those of software-defined radio (SDR) circuits.
Not all RF MEMS switches may make much sense for mobile phones, according to some analysts. In many cases, conventional technologies, while not at MEMS level in terms of performance, are good enough as long as they can enable the production of lower-cost phones. RF MEMS switches can be used in mobile phones for impedance matching networks, filter banks, and mode/band switching, especially for converting future single-pole, six-throw (SP6T) phones to single-pole, eight-throw (SP8T) switches.
Also, switched capacitors can be used for impedance matching. Here, a single power amplifier can be employed instead of the usual three or four, saving space and costs. The most obvious advantages are a high degree of linearity, besides the inherent low-power, high-isolation, and low-insertion-loss characteristics of RF MEMS devices. Wicht Technologie Consulting predicts some market growth for RF MEMS in the next two years, along with growth in other application sectors (see the figure). Still, it tempers this prognostication due to the hype surrounding the technology. As a result, there’s lots of skepticism regarding when RF MEMS will take off.
The core problem with using RF MEMS for mobile phones is cost. Front-end circuit manufacturers for cell phones may not be ready to pay $1 or less for an RF MEMS switch.
Jeff Hilbert, president and CEO of WiSpry, believes that the mobile-phone market for RF MEMS may not be very large, at least for now. “RF MEMS could offer benefits to mobile-phone users that no other approaches are capable of, so long as the price increase is a small one,” he says.
Considering the consumer’s ferocious appetite for fancier and more advanced cell phones, his outlook may be an understatement.
Market research firm Yole Développement also is cautiously optimistic. It believes that the large-scale introduction of RF MEMS ICs into the market may not happen before 2010.
Despite some pessimism, nearly everyone agrees that RF MEMS will lay the foundation for present and future communications systems in the home/ground mobile and space spheres, such as handsets, basestations, and satellites. Moreover, they will enable the development of ubiquitous wireless connectivity. Many industry experts caution that RF MEMS technology should not be underestimated and that its potential for growth is enormous.
“There’s no doubt that RF MEMS technology will be successful in the market,” says Roger Grace of Roger Grace Associates, a MEMS marketing and technology company. “The question is when.” He projects that successful commercialization of RF MEMS for mass-market applications won’t occur until 2010.
“The elusive high-volume ‘killer’ applications associated with mobile handsets, whose numbers are reported to be in the $1 billion-plus range for 2007, are still beyond the reach of existing RF MEMS solutions,” says Grace. “This is mainly because of a high price and the inability of RF MEMS IC manufacturers to cost-effectively satisfy the value-added needs of handset manufacturers.”
He also notes that existing pin-diode solutions are proving quite satisfactory in mobile phones.