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Special Report ­
Information Technology

 April 1997


Power and the Gigahertz Chip

Virginia Tech electrical and computer engineers are a leading force in the effort to develop new techniques for providing power to the next generation microprocessor.

Pentium photoSpeeding up the Pentium ­ Many microprocessors today cannot operate at their top speeds because they can't get power fast enough. Power electronics issues could also be a major influence on the next generation 1.5 gigahertz chips. The Department's Virginia Power Electronics Center (VPEC) is taking a leadership role in defining and investigating these issues.

Computers went from 16 megahertz speeds in 1985 to today's 200 MHz capability through improvements in microprocessor technology. The next jump - to gigahertz speed - could come in part from power electronics advances, and the Department's Virginia Power Electronics Center (VPEC) is taking the lead in developing that technology.

VPEC, one of the world's largest university-based power electronics groups, has recently formed a consortium to develop the technology to provide power to the next generation of microprocessors. VPEC's Voltage Regulator Module (VRM) consortium includes five companies; Intel, International Rectifier (IR), Texas Instruments, National Semiconductor, and SGS Thomson.

"Improving the amount of information that can be put on chips and the speeds at which they operate, has come down to one issue," said Professor Fred Lee, director of VPEC, "and that is voltage. The lower the voltage, the better."

"The capacity of a chip is limited by its voltage," he explained. "There are millions of logic circuits in one chip, and the more densely they are packed, the more potential there is for hot electrons and impact ionization to degrade performance. If we lower the voltage, we also lower the possibility of such degradation, and we can pack more into that chip."

VPEC is working on techniques for reducing voltage and increasing the speed that chips can operate, according to Lee. Many of the newest chips operate at 3.3 volts and the target for the next generation of chip is less than half of that. "There is a limit to how low you can go," Lee said. "But the semiconductor companies are targeting chips running at 1.5 to 2 volts to operate at gigahertz speeds."

As the chip is operating at gigahertz rate, power must be transferred to the logic gates at the compatible rate. "The challenge for us in power electronics is to get the power to the chip fast enough. Intel had to slow down the clock rate of the Pentium because the chip can't get power fast enough...The chips today require 20 to 30 watts of power. Future chips will require 60 to 100 watts to power them. The demand for power will increase, and today we are limited by the speed at which we transfer power.

"We need to look at different ways of processing power than we do for today's chips. We need to define what the issues are, what the fundamental limitations are, how much improvement can be done with today's design, and how much can be done with more advanced technology," he continued.

"An effort like this, where we are jumping to a whole new technology requires groups with different expertise to come together to work on the problem. That is why we formed the VRM consortium. It's a partnership program and each group brings different know how."

The group plans to explore a number of issues, including the power system architecture, the power distribution, the voltage regulator module design, and Application Specific Integrated Circuit (ASIC) for control, components, and applications.

"As far as Intel is concerned, they are looking for us to help them define the power architecture for the future Pentium processor," Lee said. "The technology we develop, however, will be generic to any processor."

The Bradley Department of Electrical Engineering
Virginia Tech

Last Updated, June 10, 1997
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