Here's how the Wii-mote become a reality....
Wii Have a Winner! - Thanks to MPD’s ADXL330 Team
By Howard Wisniowski, marketing program manager
July 5, 2007
An intriguing fact about engineers is that their biggest ideas are quite often their smallest. A perfect example is the phenomenal ADXL330 iMEMS® accelerometer conceived and developed by a team of engineers at ADI’s Micromachined Products Division (MPD). At only two square millimeters, it can sense three axes of motion (up and down, side to side, and front to back) and has caused six months of mass hysteria at electronics retailers everywhere as a key component in Nintendo’s “Wii-mote” controller.
For all its newfound success, however, the development of the ADXL330 was years in the making. Through a progression of iMEMS technology advances, the genes of this small marvel can be traced back nearly two decades to when the vision of Steve Sherman, senior design engineer, was coupled with the unwavering support of Ray Stata, co-founder and chairman. Steve's early patents and papers continue to be a source of inspiration and are cited by engineers worldwide. The design of the ADXL330 was no exception.
The need for a low-g 3-axis accelerometer was identified in 2003 when the late Dave Zawadzki, MPD product marketing manager, began focusing MPD’s attention on consumer product applications. By November 2004, a broad cross-functional team was formed and the Trident’s (aka ADXL330) development activities were officially kicked off with a PSD1 (Product Start Document) and put on a fast track. Headed up by senior design engineer, Dave Hollocher, the sensor, circuit, and test/trim “sub-teams” that included Jack Memishian, Mike Judy, Sam Zhang, Mark Dube, and Kevin Chau went to work bringing together their skills in both circuit and mechanical structure design. Here are some insights into the Trident project by those who made it happen.
Jack Memishian, ADI Fellow ’80, and a true disciple of the mantra “never follow!” commented, “The team was hard at work on the 3-axis accelerometer well before I got involved. I came up with a way to use a single sensor for all three axes along with the additional benefits of low voltage operation and small size. I always push for a radical approach and Dave always pushes back toward the more reasonable.”
As Dave Hollocher described the interaction, “It’s always an exercise in creative conflict. Jack and I always have different views but eventually find the common ground. In this case, we were able to show the team how they could get outputs from three axes on a single MEMS sensor structure. This was indeed radical and had never been done before.”
Jerry Fishman presenting the ADXL330 team with a Hardball Award the 2007 GTC. Left to right: Jack Memishian, Dave Hollocher, Jerry Fishman, Sam Zhang, Mack Lund, and Mike Judy. Not pictured: Kevin Chau and Prakash Moparthi.
Sam Zhang, MEMS design engineer, and Mike Judy, ADI Fellow ‘03, began modeling several sensor structures so the design team could work with the 3-axis MEMS sensor even before they saw one. According to Sam, “The models cut months off the development time by predicting behavior under a variety of conditions and design specifications. The result was an optimized and more robust sensor design.”
While the circuit and sensor design issues were being resolved, the layout function was busy optimizing the die topography. According to Mark Dube, layout engineer, “Dave, Jack, and I worked at it until we reduced die size over 40 percent and were able to increase the number of die per wafer from 2700 to 4000. It was painful, but in the end, it was a beautiful thing.”
Less than four short months after project kickoff, the team taped out the first silicon and passed the PSD2 phase gate. With a record turn time in fab, the team soon had a working first silicon by March 2005. “When the ADXL330 worked on the bench like it did in simulation, we were all breathing a huge sigh of relief,” added Dave. “It’s always difficult to predict how long something will take when it is completely new and no one has done it before. Even with the best models, you’ll often discover something is missing, but you just don’t know what it is. You must rely on your experience and just keep at it until you understand the problem and find the solution.”
The ADXL330 was the first product to utilize the third generation of iMEMS Wafer Fab Processes (iMEMS3). Initially designed to enhance the performance of ADI’s precision gyro products, this process was well suited to provide the additional features needed for Z-axis sensing. “We worked to reduce leakage and noise for the gyro and in doing so, came up with a solution that provided a Z-sensing capability,” recalls Bruce Wachtmann, the technical lead on the team. “While we had characterized the processes and passed reliability testing for the gyro, upon reexamination, we determined it would also be a good fit for ADXL330.”
As the target project launch date was closing in, the test and trim team was busy with its own set of challenges. As Rob O’Reilly, test engineering manager, likes to tell it, “We had to invent a new way to trim the Z-axis. There were no Z-axis testing models yet, so we resorted to physical measurement which meant we needed to shake the wafers. Since there was no equipment for that, we made a shake machine out of existing equipment that was never intended to be a shake machine.” As it turned out, the new test and trim equipment was released at the same time the ADXL330 went into production. It should be noted that Rob and his team, which included Huy Tang, Wei Chen, John Grandbois, Nick Pizzi, Rick Lueth, Frank Haskins, Eric Butler, Dave Lucas, and Qui Nguyen were recognized at the 2006 ADI Quality Fest and won top honors.
In addition to the Trim Platform, the production ramp was also on a remarkable timetable. According Craig Core, MPD wafer fab manager, “In order to meet the product run demands, we had to ramp up the wafer fab two times and die capping ten times. A significant addition of new equipment was involved and we got it all up and running in six months. We upheld our reputation as the little fab that could.”
The Trident team successfully released the ADXL330, MPD’s first three-axis accelerometer, in March 2006. The following May at the Electronics Entertainment Expo (E3) in Los Angeles, ADI issued a joint press release with Nintendo announcing that the ADXL330 had been designed into a motion-enabled controller for Nintendo’s new “Wii” game system to be released in November 2006. In the press release, Nintendo senior management stated, “We selected the ADXL330 because its accuracy, small size, and extremely low power consumption were critical to the Wii Console’s design objectives and key for a wireless controller that will revolutionize the gaming industry.”
Ultimately, the Trident team achieved their objectives for consumer product applications: a small die size and a single beam structure for the most efficient use of die area; low voltage operation; and the industry’s lowest power consumption, requiring less than half of the power of typical competitive parts.
Postscript: As reported in the 6/11/2007 issue of Fortune
While game consoles typically attract youngish males with an antisocial streak, the Wii is bringing people of all demographics together: in nursing homes, for Wii bowling leagues, on cruise ships, at coed (!) Wii-themed parties and, of course, in lines - as hordes of consumers clamor to buy the impossible-to-find $250 machine. Nintendo is churning out over a million units a month and still can't meet demand.
The Core Team
Low-g Design Team (Sensor and Circuit Design, Product Engineering)
Mike Judy, Sam Zhang, Jack Memishian, Dave Hollocher, Kevin Chau, Prakash Moparthi
Trim z-shake Development Team
Rob O'Reilly, Nick Pizzi, Rick Lueth, Frank Haskins, Eric Butler, Dave Lucas, Qui Nguyen
iMEMS3 Team
Susan Alie, Dan Davis, Rob Maher, Stewart Sellars, John Sledziewski, Bruce Wachtmann, Craig Core
Others
Laurie Stuart - New Product Coordinator
Mark Dube – Layout
John Grandbois – Trim
John O’Connor – Test
Carolyn Pipitone – Reliability
Frank McNally – Yield and FMU team leader
Gail Edwards – Characterization
Harvey Weinberg – Product Applications
OC Wambu – CAD
Mack Lund – Product Marketing
Dave Zawadzki – Product Marketing
Christophe Lemaire – Customer Marketing
Wei Chen – Characterization
Kevin (Katsuhiko) – ADKK Sales Team
Iku Nagai – ADKK Sales Team


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