Mobile phones have always been a lucrative, yet difficult to hit, market for RF MEMS ICs. Jeff Hilbert, president and CEO of WiSpry believes for the industry to be successful here RF MEMS must be able to offer an added benefit to the mobile phone that no other technology can offer, and only for a small increase in price. Nevertheless, RF MEMS IC manufacturers are confident that they can bring the price of RF MEMS ICs down with improved manufacturing methods and thus open up large mobile phone applications. Rick Thompson, manager of advanced technologies for BAE Systems mentioned impedance matching as a viable application, where the MEMS IC, acting as a switch, would cut in to match a low or lost signal to the phone in low-signal areas until a stronger signal is acquired, then shut down.
One major (though not well-publicized) application for RF MEMS in terms of large unit volume sales is as switches for automatic test equipment (ATE) test heads. Companies like TeraVicta Technologies Inc. work with the major ATE system manufacturers to provide them with millions of RF MEMS switches.
TIMING AND MICROPHONE DEVICES EMERGING
The time has come for the MEMS oscillator. A flurry of announcements late last year, first by SiTime, followed by Discera, has revved up interest in the use of CMOS MEMS oscillators as timing circuits to replace the venerable quartz crystal oscillator. Both expect to ship volume quantities by next year. A third company, Silicon Clocks, is mum about its MEMS oscillator design but is expected to join the market soon. All three companies are typical of the fabless design houses that create the IC design, then have an outside foundry house produce it using a CMOS process that handles most of the chip’s processing steps. Wicht Technologie Consulting predicts that by 2012, the MEMS oscillator market will reach $200 million, up from a very small market this year (see Fig. 3).
SiTime is using a Bosch licensed process to produce its product. It is working with the Silicon Valley Technology Center (SVTC), a business unit of Cypress Semiconductor, to achieve a “lab to fab” capability as promoted by SVTC, for its product’s production. Recently, Discera signed a very broad agreement with Vectron, a major quartz crystal manufacturer, which involves all aspects of the design, development and manufacture of Discera’s MEMS timing ICs.
Another MEMS entry into mass-market applications is the microphone, spearheaded by Akustica’s announcement early this year of the first integrated CMOS MEMS IC. Knowles Acoustics also produces SiSonic MEMS microphones. However, unlike Akustica’s single-chip approach, they use a silicon microphone together with an ASIC. The newest entry in this market is Infineon Technologies with a miniature MEMS microphone it unveiled at Electronica (see Fig. 4). All of these microphones are aiming to replace the decades-old electret condenser microphone (ECM).
The key element in all of these aforementioned mass-market applications will be to make MEMS sensors more attractive. This requires bringing down costs and achieving higher levels of integration, and functionality, which in turn means the use of standardized packaging, testing and manufacturing approaches. In the meantime, MEMS IC manufacturers continue to refine and advance their product offerings in their traditional markets like the automotive sector, focusing on smarter air-bag sensors and tire-pressure monitoring systems (TPMSs).