A winning combination

Working closely with systems design engineers, 2012 Test Engineer of the Year Brad Davis and his team performed essential design-verification testing on an innovative wireless “combo chip” targeted for some of the hottest-selling mobile devices.

Lawrence D. Maloney, Contributing Editor -- Test & Measurement World, 3/1/2012 12:06:00 AM

Test & Measurement World’s annual Test Engineer of the Year award honors the special contributions that test engineers make to the quality of electronics products and systems. In our November 2011 issue, we described the accomplishments of six outstanding test engineers and asked our readers to vote for the engineer they believed was most deserving of the 2012 Test Engineer of the Year award. The winner: Brad Davis of Broadcom. Davis received the award on January 31, 2012, during the Best in Test awards ceremony, held in conjunction with the 2012 DesignCon event in Santa Clara, CA. As part of his award, Davis has designated a computer lab in the Dominican Republic to receive a $10,000 grant, courtesy of National Instruments, the award sponsor. This article also appeared in the March 2012 issue of Test & Measurement World. See the PDF.

Scratch the surface of the economic recovery, and you’ll quickly see one of its biggest drivers: mobile communications. Consumers can’t seem to get enough of the latest smartphones, tablet computers, notebooks, and e-readers. “Wi-Fi enabled devices will grow from less than 1 billion units in 2010 to more than 3 billion in 2015,” according to Mark Hung of Gartner Research, in a report the company published last June.

Among the world’s leading semiconductor companies, California-based Broadcom is well positioned to tap what has become a global fascination with all things wireless. The firm describes itself as offering the world’s largest portfolio of SOC (system-on-a-chip) and software solutions for high-performance mobile devices, computing and networking equipment, and digital entertainment and broadband access. Its 2011 revenues topped $7 billion.

With engineers making up more than 75% of its 10,000 full-time employees, Broadcom in any given year churns out a steady stream of new products. In 2011, none of its launches was more notable than that of the new BCM4330 combo chip, winner of a 2012 CES Innovations and Design Engineering Award at the Consumer Electronics Show held in Las Vegas in January.

Designed to support smartphones, tablets, and other mobile devices, the chip integrates dual-band 802.11n Wi-Fi, Bluetooth 4.0, and FM radio capability on a single silicon die. It also supports Wi-Fi Direct and Bluetooth High Speed standards, which let mobile devices communicate directly without having to connect first to an access point.

“Combination chips have gained tremendous traction as more manufacturers add multiple wireless features to mobile phones and other handheld devices,” said Philip Solis, research director of ABI Research. “Broadcom already controls a significant share of the wireless connectivity market within the rapidly expanding Android market.”

Quality seals the deal

While innovative semiconductor technology may grab the headlines, it is the reliability of these new devices that wins business from blue-chip customers like Samsung and Apple. That’s why firms covet outstanding test engineers like Brad Davis, who manages Broadcom’s WLAN hardware team. With experience in wireless technology that dates back to his engineering education at the University of Calgary, the 32-year-old Davis heads a seven-person team that characterizes RF performance of Broadcom’s mobility chips, modules, and drivers, including the award-winning BCM4330 combo chip.

It is because of his success in managing the test flow and helping the BCM4330 get to market quickly that his co-workers nominated him to be the 2012 Test Engineer of the Year. Test & Measurement World’s readers agreed with his co-workers’ assessment of Davis’s work and voted him as the winner. Davis was presented the award at T&MW’s Best in Test ceremony held on January 31 in conjunction with the 2012 DesignCon event in Santa Clara, CA.

“The primary job of our team is to verify that the Wi-Fi system, both hardware and software, performs up to Broadcom’s standards,” explained Davis.

Typically, the system design team does preliminary performance tuning of a mobility chip module, then hands the chip off to Davis’s design-verification team for much more rigorous testing. This work involves exercising more chips, exercising chips produced from different process variations (split lots), and testing chips across voltage, temperature, and other environmental variations.

The team may work with a particular chip for a year or more, especially if it is a high-volume product like the BCM4330, which is produced by several contract manufacturers. “Chip packages from each fabricator must be qualified separately,” said Davis. “Our job is to spot issues, then go back to the design team for resolution. There’s a lot of back and forth.”

In addition, Davis’s test team supports companies that want to customize a Broadcom chip, such as by adding their own power amplifiers, switches, or filters. “For larger customers, we’ll even help optimize their designs, and then run their product through our test suite,” said Davis.

Tools of the trade

A bread-and-butter tool for the team is the LitePoint one-box tester, which tests key functions of an RF chip, such as transmitter modulation accuracy and spectral mask, as well as receiver sensitivity and performance in the presence of interference. “One-box testers give us a lot of coverage very quickly,” explained Davis, “and because their setup is so simple, it is much easier to add peripheral equipment.”

Peripheral test modules, sometimes paired with the one-box testers, address such parameters as current consumption, temperature, and voltage control. Load-pull devices can also be added to simulate the effects of connecting a chip to various antennas. Using Python, LabView, and other software tools, Davis himself writes much of the automation code for managing the lab’s test equipment and protocols, which increasingly includes more and more homegrown solutions.

“Test engineering in this field demands multiple skills,” observed John Ma, manager of DVT (design-verification testing) for Wi-Fi modules at Broadcom. “You need to understand RF, test hardware, and programing for test automation. Plus, you need to be sensitive to important business perspectives. Brad Davis is one of the rare individuals who possesses all of those skills. On top of that, he just loves testing as a job.”

Davis’s responsibilities also demand a great deal of coordination with those outside the design-verification team. On any given day, he can be consulting with a smartphone company, a fabricator, or a test and measurement vendor looking for input on capabilities needed to test next-generation chips. He also works hand in hand with other Broadcom test teams involved with software development and data analysis.

A never-ending race

The introduction BCM4330 in February 2011 strengthened Broadcom’s already strong position in the wireless combo chip category. The combo chip, shown here at the center of a reference board, integrates the capabilities of 802.11n WiFi, Bluetooth 4.0, and FM radio. Courtesy of Broadcom.

Meanwhile, the fast pace of technology places ever-changing demands on Davis and his team. The BCM4330, for example, uses the new HSIC (High-Speed Inter-Chip) digital interconnect bus, which ruled out the use of cabling in test setups. So, Broadcom had to design a test platform that could run the test software and also connect directly to the device under test. And because of the 4330’s tiny footprint of 25.51 mm² (28% smaller than its predecessor), debugging is tougher. Current consumption also is so low that it is difficult to find instruments that can measure the chip in real-time fashion.

Davis pointed out that each generation of chips supports more standards. “On the 4330, we had to test IEEE 802.11a/b/g. The next generation will add 802.11ac, and each new standard requires a whole new suite of tests, which can potentially drive up your test time. Product cycles keep getting shorter, and test doesn’t want to be the holdup.”

To make things even more complicated, the DVT team must constantly juggle its time and resources between a chip that is close to production and newer ones emerging from design, not to mention supporting legacy products.

Despite such pressures, the payoffs of being in the right place at the right time with the right product can be enormous. Sales of the iPhone 4S, one of the 4330’s early design wins, topped more than 4 million units during its first weekend of sales last October, the most ever for a phone launch, according to Apple.

Industry analysts were amazed that the 4330 began showing up in hot new products like the Apple iPhone 4S and the Samsung Galaxy S II as early as last fall, just a few months after its February 2011 launch. Chipworks, a Canadian reverse-engineering firm, noted that new chips usually don’t show up in consumer products until 12 to 18 months after public launch.

As Davis sees it, a key contribution that the test team makes to such timely product launches is its close cooperation with the systems design team. “In test, we need to hit key parameters on multiple chips very fast and then get our data back to the design team so that they can work on any problems.”

In most cases, said DVT manager Ma, Davis and his team delivered overnight turnaround of essential test results to systems design engineers. “Not only that, but Brad’s test results and reports are always solid and reliable, which gives him great credibility with the design team. His reports can go directly into the hands of customers, which closes the loop in a very timely fashion. He’s also a very good leader, and his team devoted a lot of extra effort on the 4330. The volume of test data that they provided to design every day was simply unprecedented.”

Added Michael Hurlston, senior VP and GM of Broadcom’s Wireless LAN line of business: “Brad Davis truly exemplifies Broadcom’s reputation of engineering the impossible. Since testing is considered such an important part of our overall product flow, we moved Brad from a design position to lead our verification group. In this role, he’s proven that he’s an invaluable engineer with the intelligence, agility, drive, and problem-solving skills that are required for success.”

The pressure of keeping up with the demands of the job does take its toll, and Davis admits that his team must constantly cope with the stress of being the “middle man” between serving the needs of contract manufacturers, customers, and Broadcom’s own design teams. “Something always needs to get out the door urgently,” said Davis.

Even so, he gets a lot of satisfaction from solving day-to day technical problems, which can be as simple as debugging a balky test station. Also very gratifying: formal sign-off milestones when his team can say: “We’ve tested this product thoroughly, and here’s the evidence to support it.”

Catching the wireless bug

The wireless world is clearly where Davis wants to be, and that’s been the case ever since the Calgary native chose the “hands-on” field of electrical engineering over computer science. At the University of Calgary, Davis focused his master’s thesis on sending wireless signals over optical links for broadband, high-speed data distribution.

“I started to get excited about wireless even as an undergrad,” recalled Davis. “I took a course on wireless communications and modulation standards, as well as an RF lab course where we did traditional RF measurements and basic RF design.”

It helped, too, that TR Labs, the Edmonton company that Davis worked with in his internship and master’s thesis work, focused on wireless communications. After completing his education, Davis got more wireless experience at two Calgary firms: Advanced Measurements, a test and control systems integrator, and SignalCraft Technologies, a contract design firm specializing in such technologies as GPS receivers and WiMAX.

“Brad is very ambitious and always eager to take on more than is asked of him,” said Mike King, who worked with Davis at Advanced Measurements and was a fellow student at the University of Calgary. “And he is very well rounded. At Advanced Measurements, he not only built test systems for clients, but also developed the software to run them.” King also recalled that, while at the university, Davis performed RF design and software development work on an autonomous robot.

Sunny future for wireless

Davis, who joined Broadcom in 2009, is already testing future generations of mobility chips, as Broadcom continues to unveil products that boast even greater capability. At the January CES event in Las Vegas, for example, the company introduced its first family of IEEE 802.11ac chips. This 5G Wi-Fi product improves wireless range in the home, allowing consumers to watch HD-quality video from more devices. The chips are also three times faster than equivalent 802.11n chips, a big advantage in downloading Web content or large video files.

Davis believes that the deployment of wireless is still in its infancy. “It’s only been in the last couple years that we’ve seen mobile wireless really take off from a data-transmission standpoint. Wireless is really changing the way consumers and business people run their lives.”

Over the next five years, Davis looks forward to solving the test challenges created by the steady march of technology, while helping Broadcom build and manage test infrastructure adaptable enough to handle the large volume of tests required in the semiconductor industry. Said Davis: “What really excites me is designing test systems that enable us to stay agile in the marketplace.” T&MW

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