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Team develops energy-efficient microchip: Could lead to longer-lasting, self-charging cellphones, more

February 4, 2008

Researchers at MIT and Texas Instruments have
unveiled a new chip design for portable electronics that can be up to
10 times more energy-efficient than present technology. The design
could lead to cell phones, implantable medical devices and sensors
that last far longer when running from a battery.

energy-chip-enlarged.jpg
From left, electrical engineering graduate students Yogesh Ramadass, Naveen Verma and Joyce Kwong, along with Professor Anantha Chandrakasan. This team has developed a microchip that can be up to 10 times more energy-efficient than present technology (Photo, Donna Coveney).

The innovative design will be presented Feb. 5 at the International
Solid-State Circuits Conference in San Francisco by Joyce Kwong, a
graduate student in MIT's Department of Electrical Engineering and
Computer Science (EECS).

Kwong carried out the project with MIT colleagues Anantha
Chandrakasan, the Joseph F. and Nancy P. Keithley Professor of
Electrical Engineering, and EECS graduate students Yogesh Ramadass
and Naveen Verma. Their Texas Instruments (TI) collaborators are
Markus Koesler, Korbinian Huber and Hans Moormann. The team
demonstrated the ultra-low-power design techniques on TI's MSP430, a
widely used microcontroller. The work was conducted at the MIT
Microsystems Technology Laboratories, which Chandrakasan directs.

The key to the improvement in energy efficiency was to find ways of
making the circuits on the chip work at a voltage level much lower
than usual, Chandrakasan explains. While most current chips operate
at around one volt, the new design works at just 0.3 volts.

Reducing the operating voltage, however, is not as simple as it might
sound, because existing microchips have been optimized for many years
to operate at the higher standard-voltage level. "Memory and logic
circuits have to be redesigned to operate at very low power supply
voltages," Chandrakasan says.

One key to the new design, he says, was to build a high-efficiency DC-
to-DC converter-which reduces the voltage to the lower level-right on
the same chip, reducing the number of separate components. The
redesigned memory and logic, along with the DC-to-DC converter, are
all integrated to realize a complete system-on-a-chip solution.

One of the biggest problems the team had to overcome was the
variability that occurs in typical chip manufacturing. At lower
voltage levels, variations and imperfections in the silicon chip
become more problematic. "Designing the chip to minimize its
vulnerability to such variations is a big part of our strategy,"
Chandrakasan says.

So far the new chip is a proof of concept. Commercial applications
could become available "in five years, maybe even sooner, in a number
of exciting areas," Chandrakasan says. For example, portable and
implantable medical devices, portable communications devices and
networking devices could be based on such chips, and thus have
greatly increased operating times. There may also be a variety of
military applications in the production of tiny, self-contained
sensor networks that could be dispersed in a battlefield.

In some applications, such as implantable medical devices, the goal
is to make the power requirements so low that they could be powered
by "ambient energy," Chandrakasan says-using the body's own heat or
movement to provide all the needed power. In addition, the technology
could be suitable for body area networks or wirelessly enabled body
sensor networks.

"Together, TI and MIT have pioneered many advances that lower power
in electronic devices, and we are proud to be part of this
revolutionary, world-class university research," said Dr. Dennis
Buss, chief scientist at Texas Instruments. “These design techniques
show great potential for TI future low-power integrated circuit
products and applications including wireless terminals, battery-
operated instrumentation, sensor networks and medical electronics."

The research was funded in part by a grant from the U.S. Defense
Advanced Research Projects Agency.

- David Chandler, MIT News Office


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