by Jérémie Bouchaud and Bernardo Knoblich, Wicht Technologie Consulting
Few MEMS components have created so much excitement, and then such disappointment in so short a time. Is this component finally in production? Will there be an interesting market? And for whom? We have been following RF MEMS switches since 2000 and have just updated our technical and market analysis. Although the market was just $6 million last year, it will increase to $210 million in 2011.
Up and down
One can detect the first traces of MEMS switches back to 1979 at IBM (by Kurt Peterson), while DARPA's interest in military radar in the mid-1990s first spurred significant R&D effort in this area. RF MEMS switches really came into the spotlight in the early 2000s, as the cell phone market was booming and a number of companies envisioned using RF MEMS switches in each mobile handset. What actually transpired can be perfectly fitted to the "hype curve of new technologies".
The hype curve was first proposed by analysts at Gartner as a way to place technologies in their particular stage of evolution. This curve follows a distinct trend. We abstract this principle to the case of RF switches (see figure above). Switches reached their peak visibility - also called the "Peak of Inflated Expectations" - in 2003, when Magfusion and Teravicta announced the first samples. Unfortunately, these two small start-ups could not process the demands for samples that suddenly poured in from around the world. A number of potential adopters did not receive their samples and were frustrated. Confusion also plagued the announced specifications. As a result, those who were fortunate enough to receive samples were unimpressed by the performance. This is represented by the "Trough of Disillusionment" phase.
Happily, it appears that RF MEMS switches has now left the latter and emerged shining into the "Slope of Enlightenment", an indicator that the industry and technology are both maturing. Start-ups like Teravicta have completely changed management and sales teams and now tend to adopt a more modest or realistic marketing approach. Good funding rounds were recently finalized, for example, at Teravicta and Wispry. Meanwhile switches from companies like Radant and MEMtronics have surpassed the 100 billion cycles mark, further quelling reliability doubts. In addition, major improvements in low-cost in situ packaging and CMOS integration have been achieved.
First commercial products implementing MEMS switches, i.e. Automated Test Equipment (ATE) systems from Advantest, started shipping at the end of 2005. And finally, there is encouraging news from Wispry and NXP, which plan ramp-up production of MEMS switches (more precisely switched capacitors) for cell phones.
The last level, the so-called "Plateau of Productivity", is expected to be conquered by 2010 when the benefits of RF MEMS switches are demonstrated and accepted throughout a number of applications in test, telecom and defense applications.
The final height of the plateau will depend on whether MEMS switches will make it into cell phones, or be implemented only in niche markets.
Can we buy them yet?
A handful companies have started commercialising RF MEMS switches.
Such devices are in small production at Teravicta, Radant (in the US only for the moment, due to export restrictions), Advantest and Matsushita.
Advantest has started serial implementation of proprietary MEMS switches in its ATE and production of these MEMS switches is captive. However, the company just founded a branch "Advantest Component, Inc." to make switches available to the free market.
Additional companies have started sampling switches for selected customers including WiSpry for mobile handset applications and MEMTronics and XCOM for high end applications e.g. in defense. Omron recently joined the pack and is expected to start serial production by mid-2008.
NXP is currently in the"industrialisation phase" of switched capacitors for cell phones and is focussing its efforts on process and manufacturability. Several foundries have also launched serial production of DC switches for automated distribution frames (ADF) for telecommunications including IMT and APM.
As of September 2007, we estimate that around 50,000 switches are being shipped every month and that all in all 500,000 to 600,000 switches have already shipped (not considering ADF DC switches produced for qualification phase).
The selling price varies according to the specifications and volumes. Teravicta ships its 7 GHz SPDT (single pole double through) for $ 35 and 26,5 GHz SPDT for $92 in small volumes. Teravicta also announced a new 5 GHz SPDT switch for $ 8 by the end of the year. At Radant, SPST (Single Pole Single Through) can be bought for $25 and the SPDT for $40 in 2000 unit quantities. Matsushita positions itself at the high end ($50 and more) so that the MEMS solution does not cannibalize its line of conventional EMR relays. Switches for ADF are already shipping at less than $1 due to the high demand even in the qualification phase.
RF MEMS switches are currently being shipped or are in development for a very wide spectrum of applications, from high-value niches such as satellites up to mobile phones. We distinguish four application fields: test equipment, telecom infrastructures, aerospace and defense and finally, mobile phones.
Test and instrumentation
Automated Test Equipment (ATE) for semiconductors: this was the first commercial application for RF MEMS switches. Implementation of MEMS is quick and easy since it meets technical requirements and conventional relays can be directly replaced with MEMS without changing the system. ATE market leader Advantest developed its own MEMS switch, which it started to implement in its own ATE systems at the end of 2005. Most major ATE system suppliers including Agilent, Advantest, Teradyne, Credence and Verigy are currently evaluating or have started replacing conventional relays with MEMS.
Manufacturers of RF instrumentation equipment, i.e. network analysers, spectrum analysers and oscilloscopes like Agilent, Rohde & Schwarz and Tektronix are evaluating MEMS switches and would implement them "better yesterday than tomorrow". However, power handling issues must be solved prior to implementation in RF instruments since hot switching is required, contrary to ATE. Serial implementation is expected in 2009.
Automated Distribution Frames:
Although this application has often been neglected, MEMS switches will start to deploy for wireline telecom switching matrices early in 2008. These switches are no longer classified as RF (as they operate in MHz range) but we include these devices in our analysis because each can be considered to transmit a signal. Production is ramping up at foundries like IMT, APM and tMt. Simpler Networks is a key player in this area and signed an agreement with Alcatel-Lucent at the end of 2006. Worth mentioning are also Telepath Networks, Norcada and MEMScap, which owns key IP in this area.
RF MEMS switches are also under development for base stations in the 0.5 to 6 GHz range. RF MEMS is a real enabler for reconfigurable architectures due to high linearity properties. Additional switch applications in telecom infrastructure are currently being explored and include microwave infrastructure (at 20 to 60 GHz) and even RFID readers.
Aerospace & defense: more than a niche
Defense applications have historically driven the development of RF MEMS switches in the US and still does. We estimate that the US Department of Defense invested over $30 million in RF MEMS in 2006, mostly for switches. The volume application will be phased array antennas for communication and radar, e.g. for missiles, helicopters, aircrafts, drones, ships and so forth. A particular effort is also dedicated to switches and tunable capacitors for agile filters used in tactical radio. It comes as no surprise that the US leads in this field.
The pioneers, Raytheon and Rockwell, now play the role of system integrators, leaving most of the work on switches to start-ups Radant, MEMTronics or XCOM. In Europe, since ITAR issues bar access to these US-sourced components, system companies like EADS, BAE Systems and Thales have started to develop their own switches. In Asia, the major effort in the aerospace sector is performed by Mitsubishi.
Outside defense, NASA and ESA are sponsoring research for satellite communication payload. EADS and Thales are currently cooperating for the development of MEMS based reflect array antenna for internet access in civilian aircrafts (EC project RETINA).
Automotive: not mid-term
We do not see any opportunity for RF MEMS switches in the automotive sector by 2012, contrary to other recent market reports. In this case, the competitive technology is not at the component but at the system level. For automotive radar, RF MEMS switches are very promising for the beam steering approach investigated in the European project MIPA. Our interviews with the automotive industry show however that a digital beam forming approach offers more promise, since digital processing can make it cheaper. In this context, RF MEMS is irrelevant since a short switching time of some nanoseconds is required for digital beam forming systems .
In a similar fashion, we do not believe in the success of automotive roof antennas. The reason is the presence of 3G+ systems that could provide the same service for lower costs. Terrestrial infrastructure (base stations) are considerably cheaper than satellites.
Will RF MEMS hit cell phones?
Cell phones have brought the most excitement for switches since coming to light in 2000 with the looming perspective of a billion unit market. A number of applications have been investigated including T/R switch, multiband filters and filter banks, and impedance matching networks, and so on. Infineon, Motorola/Freescale and ADI have abandoned the idea for several reasons, besides the well-known reliability and packaging difficulties:
- Extreme price pressure. Even if MEMS switches enable lower insertion loss and higher isolation, while these improvement are nice to have, in most cases no customer will be ready to spend a cent more.
- Alternative technologies kept improving! In particular, SoS CMOS switches from Peregrine offer excellent linearity and insertion loss. These devices have bridged a major part of the gap between MEMS and other technologies in term of performance, making the need for MEMS less obvious.
What's left for MEMS switches in cell phones? From all the possible cell phone applications mentioned above, WTC believes that impedance matching networks for the PA (Power Amplifier) or the antenna module offer the best (and only) prospects for RF MEMS switches -- or more precisely, switched capacitors -- in the next 5 years. NXP, RFMD and WiSpry are currently developing switches for this function. NXP plans to commercialise antenna matching circuits based on switched capacitors as early as 2009 or 2010. NXP leverages its PASSI process to integrate MEMS with other passive at a very low additional cost. A prototype will be presented for the first time at Semicon Europe in October.
RFMD is very strongly positioned in the PA business and plans to commercialise MEMS-based reconfigurable PAs, again by the end of the decade.
The RF MEMS switch market
All in all, the RF MEMS switch market reached a close-to-insignificant $6 million last year, mainly for ATE and automated distribution frames (see figure). We expect the total market to reach $210 million in 2011. The main applications will continue to be ATE. The figure for cell phone refers only to the additional cost of RF MEMS switches in antenna or PA modules (mainly packaging cost). If one considers the RF MEMS based modules which NXP or RFMD will ship, cell phone will dominate with more than $ 100 million in 2011.
In terms of the supply chain, who is best positioned on this emerging market? We have referenced more than 40 companies actively developing or manufacturing switches. Interesting is the prominent number of system companies with an own switch development effort, e.g. Raytheon, Rockwell, Thales, EADS, BAE Systems, for defense and aerospace, Advantest for test, and NXP, RFMD, NTT DoCoMo, LG and Samsung for cell phones. There are two reasons why system companies do this:
- The high impact of MEMS switches at system level (enabling new architecture), where system companies need a hands-on approach to understand the potential impact at this level.
- The limited availability of RF MEMS switches so far, especially at microwave frequencies as a result of ITAR restrictions. Therefore, system companies in Europe or Asia need to develop their own technology.
This high involvement of system companies at the MEMS component level should not be taken as a sign of a closed market. Most of these companies prefer to buy from the free market. In fact most defense and aerospace companies – even pioneers like Raytheon and Rockwell – will either:
- buy the switches from components from the start-ups such as Radant, MemTronics, XCOM…
- or transfer their design at MEMS foundries such as Tronics, IMT…
Also worthy of note, some system companies capitalize on their MEMS switch development – initially for their own needs – and commercialise them on the free market. This is the case for Advantest, the leading ATE company. Additional system companies are currently investigating this opportunity.
Returning to the hype curve, we see that RF MEMS switches have finally left the "Trough of disillusionment" for the much more enjoyable "slope of enlightenment".
There are interesting opportunity for suppliers of the following:
- Single components for test and instrumentation
- Modules with higher value, e.g. phase shifters or tunable filters for base station or defense and aerospace.
There are also great chances for module suppliers to cell phones. Since better performance is not sufficient per se, we believe that integration will be the key for success. Therefore, the best opportunities are for those organizations that can integrate MEMS into their existing module business, like RFMD or NXP. Start-ups in this field will probably have to licensee the technology or take the more risky route of developing their own modules.
Important lessons, alternative technologies also improve; new competing technologies emerge such as SoS FET or ferroelectric devices. Therefore MEMS switches need to continuously keep improving where they already are superior e.g. insertion loss, linearity… And last but not least, sometimes, the alternative is not at the component level but at the system level like shown in automotive radar and roof antennas.
 ARRRO at http://www. wtc-consult.de/arrro.