Energy Efficiency: Better Batteries or Better Chip Design

When portable devices and energy efficiency butt heads, the focus is usually on better batteries. However, researchers at MIT and Texas Instruments have taken a different approach, focusing instead on new chip designs.

According to MIT's Anantha Chandrakasan, Joyce Kwong, Yogesh Ramadass, and Naveen Verma, and TI's Markus Koesler, Korbinian Huber, and Hans Moormann, the key to energy efficiency is to find ways of making the circuits on the chip work at a voltage level much lower than usual. To that end, the design they came up with works at just 0.3 volts, compared to most current microcontrollers that operate at around 1 volt.

Memory and logic circuits do have to be redesigned to operate at very low power supply voltages, of course. And one key to the new design, says Chandrakasan, is to build a high-efficiency DC-to-DC converter that 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.

The researchers add that one of the biggest problems they 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. The team has demonstrated the ultra-low-power design techniques on TI's MSP430 microcontroller.

Commercial applications may be five years away, but perhaps sooner. 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" 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.

-- Jonathan Erickson
jerickson@ddj.com

Posted by Jon Erickson at 12:05 PM  Permalink