The mechanical relay has been re-born at the GE Global Research Center where a group of researchers are advancing MEMS (Micro-Electro-Mechanical Systems) technology to create ultra-small switches that could have an ultra-large impact on system design that will drive mobile devices of the future. Prototype device testing shows that GE’s RF MEMS switch can help enable increased data transfer speeds, enhanced signal quality, longer battery life, and the advanced RF designs required of LTE-Advanced devices. Pictured is a die containing 400 ohmic MEMS switches, as viewed under a microscope, atop a U.S. dime. This device, made with GE’s Metal MEMS process, is capable of handling greater than 1kW in this tiny form factor. For mobile applications, the technology can be scaled down and miniaturized.
These metal switches, which are no bigger than the width of a human hair, can control the flow of electricity to an array of electrical systems from high-power devices that use kilowatts of power, to an ordinary light bulb. Future applications of the technology are far-reaching. Switches are used in everything from hand-held electronics, to industrial equipment to protection devices. What separates GE's MEMS switch from other MEMS technologies is the unique material set developed by GE researchers that allows the switch to operate for billions of cycles under extreme operating conditions, such as elevated temperature, while maintaining extremely low contact resistance.
"Our cross-disciplinary expertise in materials, device design, fabrication, packaging, electronics and system integration has allowed us to solve the fundamental challenges of switch miniaturization," said Chris Keimel, Process Development Engineer at GE Global Research. "We have developed a common device fabrication platform that allows us to pack hundreds of microscopic relays together on a single die for industrial power control or alternately, to create high-isolation, low-loss RF switches for next-generation RF communications products. We're guiding a transformational change in switch technology and I'm excited to see where it goes next."
LTE-Advanced, also known as "True 4G." has already been deployed in parts of Asia, and will soon set the benchmark for mobile communications worldwide. Most notably, it enables data download speeds that could, theoretically, top 3 gigabits/sec compared to 300 Mb/sec on 4G LTE. By utilizing a wider radio bandwidth, smarter transmission algorithms, and multiple-antennas, LTE-Advanced will enable stronger connections and signal quality. To make all of these upgrades possible, hardware must evolve and that's where GE's MEMS switch technology offers a distinct advantage.
As demonstrated in the lab, RF switches made with GE's proprietary metal MEMS process have the ability to meet the demanding requirements for both RF front-end modules and wireless infrastructure products for next-generation LTE-Advanced mobile networks. Some key advantages include: Ultra-high linearity – The amount of distortion introduced by RF components limits the effective bandwidth of the system. Ohmic contact RF switches made with GE's metal-MEMS process have shown improvements of 15 to 20dB in IIP3, when compared to SOI (silicon on insulator) switch technology. Insertion Loss The power lost when passing through the many switches in a handset affects signal level and battery life. GE has measured insertion loss <0.3db at 3Ghz. Isolation The ability to separate radio bands while maintaining signal integrity is increasingly important with carrier aggregation. GE has measured channel to channel isolation better less than 35dB at 3GHz. Miniature Size a single switch element measuring ~50um x 50um, allows high-throw-count switches in a very small die area, which directly impacts cost.
"The mobile and tablet market represents over 2 billion units annually, and those devices are increasingly of the all-in-one, or smartphone, variety." said Chris Giovanniello, VP Business Development, GE Ventures Licensing. "Advanced antenna and radio technologies will be required, and devices made with GE's revolutionary metal-MEMS process have the potential to deliver that increased performance at prices comparable to SOI, GaAs (gallium arsenide), or other semiconductor technologies. In addition, the modular unit-cell design can be scaled up to support higher-power applications including wireless infrastructure.
"We're proud to see our MEMS technology reaching maturity. At GE Global Research, we've spent the last decade developing this advanced switching technology and components that will be used in GE's mission-critical systems," noted Keimel. "Reinventing the switching component allows us to deliver breakthrough benefits to our systems that drive down the size, weight, power consumption, and cost of our systems while improving overall performance."
GE is also actively working with development partners to license the proprietary process and enable other low-cost manufacturing options which will allow for the technology to be adopted in numerous consumer and industrial applications.