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February - 2003 - issue > Cover Feature
Big Daddy Baliga Power Saver
Venkat Ramana
Thursday, January 30, 2003
HAVE YOU TURNED ON YOUR COMPUTER TODAY? Maybe turned on your air conditioning or started your car? If you have done any of these, then you have probably used a power switch invented by Dr. B. Jayant “Jay” Baliga, Distinguished University Professor of Electrical Engineering and director of the Power Semiconductor Research Center at North Carolina State University.

His invention is the Insulated Gate Bipolar Transistor (IGBT), a device that saves energy and controls power flow in commercial and industrial power systems. It is used in everything electronic, including Japan’s Bullet train, air conditioners, electric cars, lighting systems and many industrial and household appliances. The device increases efficiency resulting in the reduction of fossil fuel use and environmental pollution. Recently, this device has been used to make compact, portable defibrillators for saving the lives of cardiac arrest victims. The American Medical Association projects that this development will save 100,000 lives yearly in the United States alone. “I find this use more fulfilling and satisfying than the fact that my invention is a billion dollar industry today,” says the big daddy of inventions.

In 1999, Baliga joined an elite society, whose members include Thomas Alva Edison, Percy L. Spencer, who developed radar and the microwave oven, and James Fergason, inventor of the liquid crystal display. Baliga’s 100th patent—Methods of Forming Silicon Carbide Semiconductor Devices Having Buried Silicon Carbide Conduction Barrier Layers Therein—was issued on September 7, 1999, and gives him the legal recognition for inventing an electric switch that could significantly improve the energy efficiency of household appliances, electric trains and cars, air conditioning units and other large machines. “I patent the structure, which is very hard to disguise and copy, and not the process or so on, which are easily open to copying. My lawyer is proud of his 100 percent success rate in patent grants,” laughs Baliga.

A member of the prestigious National Academy of Engineering, Baliga was recently named one of the “new candidates for hero status” by Glenn Zorpette in a special issue of Scientific American magazine entitled “The Solid State Century,” commemorating the invention of the transistor. He joined an august roll of seven honorees that includes Nobel prize winners Shockley, Baird, and the Intel founders. He predicts that U.S. Patent No. 5,950,076, like many of the others he’s earned, will deliver lower costs to consumers, as many of his past inventions always did.

He laid the groundwork for this technological advancement 20 years ago, when he derived an equation that describes the fundamental relationship between the electrical properties of semiconductor materials and the performance of power devices. The equation, now commonly known as Baliga’s Figure of Merit, (there are only three Figures of Merit recognized worldwide) predicted that power devices made from siliconcarbide materials would be 1,000 times more efficient than commercially available silicon-based power devices.

The bearded inventor began his career in GE Labs, where he spent the better part of his youth, delving into the mysterious depths of transistor science. “I took a long sabbatical, went to Palo Alto and worked on some research, wrote books, travelled Europe,” reminisces Baliga.

Following this stint, Baliga formed an advisory company, “Giant (a take-off on his name, Jayant) Inc., to work with companies to bring his inventions to the market. “I found this frustrating, as I had to watch company bureaucracy from the sidelines, and my inventions took their own time to come to market. It was a short step to forming my own company,” recalls Baliga. His current company, Silicon Semiconductor, based in the Research Triangle Park, is a satisfying attempt at “inventing, bringing those inventions to market, and seeing success.”

The power amplifier is one of the most significant transmission components for a wireless base station. The power amplifier increases the strength of the radio signal prior to transmission in order for it to transmit across the desired distance. If a base station is underpowered, its coverage area will be reduced. This will result in the network operator needing to deploy additional cellsite equipment and driving network costs higher. If, on the other hand, the power amplifier does transmit sufficient power for the desired coverage area, but does so at the cost of signal integrity, the resulting transmissions will degrade and the effective capacity of the base station will be reduced.

Baliga’s SLMOSFET technology addresses the performance of the base station’s power amplifier. By increasing linearity and efficiency, SLMOSFET allows its power amplifier customers to improve both the base station coverage area and capacity. Another day, another invention.

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