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Gyroscopes take MEMS to consumer devices

Posted: 16 Jan 2007 ?? ?Print Version ?Bookmark and Share

Keywords:MEMS? gyroscope? gyros? accelerometer? InvenSense?

Gyroscopes may soon give accelerometers a run for their money as the MEMS of choice in a new breed of consumer gadgets, thanks to the advent of low-cost gyros from a MEMS startup. The development adds impetus to the expectation that MEMS are on the verge of winning sockets in handsets and other consumer products for motion-sensing applications.

InvenSense Inc., a fabless vendor of motion-sensing MEMS, announced in late November volume manufacturing of a family of integrated dual-axis gyroscopes with a target price of less than $2 per unit, or less than $1 per axis. The price point is important, say analysts, because such devicesnow primarily used in automotive appsgenerally cost closer to $10 per axis. At less than $1, gyroscopes for consumer applications could augment or even supplant MEMS accelerometers, which remain less expensive but are considered less sophisticated.

Cellphones are "going to be an interesting bit of battleground" for MEMS, said Marlene Bourne, president and principal analyst at Bourne Research LLC, a MEMS-focused market research firm. "Is that going to be the domain of gyros or accelerometers?"

Target devices
Motion sensing in cellular handsets was one promising application area cited by MEMS company executives who took part in a panel at last November's Electronica show in Munich, Germany. They also argued that portable computers and gaming devices are prime candidates for incorporating motion sensing. The prevailing wisdom is that midrange handsets will be a big market for MEMS starting this year or perhaps in 2008.

"The great hope for a lot of MEMS-based motion detectors has been to put these into consumer devices," said Robert Lineback, an analyst with IC Insights Inc. "The trick has been to get the price down."

Analyst Bourne said MEMS are seen as providing motion-sensing capability in handsets for features like keyless dialing, scrolling through address books by tilting the phone, and pedometer functions. Gyroscopes could pique handset makers' interest at the InvenSense price point, she said. But she noted that the price of tri-axis accelerometers is still falling much faster than that of gyroscopes.

The average selling price (ASP) of a tri-axis accelerometer is about $2 at current shipment levels, she said. By 2008, it is possible that volumes will be sufficient to drive the ASP below $1, but only if tri-axis accelerometers are integrated into more than just a few handset models.

Generally speaking, accelerometers sense linear movement. A tri-axis accelerometer, such as the Analog Devices Inc. ADXL330, incorporated into the controller for Nintendo's Wii game console, senses linear motion on three planes. Accelerometers are marketed by companies including Freescale Semiconductor, STMicroelectronics, Bosch Sensortec and Honeywell.

A gyroscope, by contrast, is designed to sense rate of rotation around an axis independent of gravity or linear motion. According to InvenSense, unlike accelerometers, gyroscopes measure yaw or pitch. The company said gyroscopes are valuable for applications such as handsets and gaming, digital video and still-camera image stabilization, 3D remote controls, and an "air mouse" (which controls an on-screen cursor when waved through the air).

For now, InvenSense executives maintain that the two device classes are best used together. "We are excited about the fact that accelerometers are going into consumer devices such as Wii and Sony's Playstation 3," said Steven Nasiri, founder and CEO of InvenSense. "We are filling in the missing halfthe equally important gyroscope."

Trumping accelerometers
But late this year, InvenSense hopes to bring to market a single-chip, six-axis inertial-measurement unit that will enable next-generation consumer products with advanced motion-sensing capabilities. Though cost will remain critical, such a product could trump accelerometers for many applications.

At this point, augmenting a tri-axis accelerometer with InvenSense's dual-axis gyroscope would be expensive and require a larger footprint, but it would theoretically offer a much fuller motion-sensing capability. "When you combine the gyro with an accelerometer, you get a sensor that can give you rotation and linear motion," Nasiri said. "It's going to give you a lot better performance and responsiveness."

InvenSense said its family of integrated dual-axis gyroscopes is being shipped to OEMs in Japan, Taiwan and the U.S. It said its gyroscopes have been designed into such high-volume consumer applications as cameras and 3D remote controllers.

- Dylan McGrath
EE Times

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