Advanced Imaging


Advanced Imaging Magazine

Updated: January 12th, 2011 09:49 AM CDT

New PCMOS Microchip Uses 30 Times Less Power


In the first real-world test of a revolutionary type of computing that thrives on random errors, scientists have created a microchip that uses 30 times less electricity while running seven times faster than today's best technology. The U.S.-Singapore team developing the technology, dubbed PCMOS, revealed the results at the International Solid-State Circuits Conference (ISSCC) in San Francisco last month.

Conceived by Prof. Krishna Palem of Rice University (Houston, Texas), PCMOS piggybacks on the CMOS technology that chipmakers already use. That means chipmakers won't have to buy new equipment to support PCMOS, or "probabilistic" CMOS. Although PCMOS runs on standard silicon, it breaks with computing's past by abandoning the set of mathematical rulesóBoolean logicóthat thus far have been used in all digital computers. PCMOS instead uses probabilistic logic, a new form of logic developed by Palem and his doctoral student, Lakshmi Chakrapani.

"A significant achievement here is the validation of Rice's probabilistic analog to Boolean logic using PCMOS," said Shekhar Borkar, an Intel Fellow and director of Intel's Microprocessor Technology Lab. "Coupled with the significant energy and speed advantages that PCMOS offers, this logic will prove extremely important because basic physics dictates that future transistor-based logic will need probabilistic methods."

Silicon transistors become increasingly noisy as they get smaller, but engineers have historically dealt with this by boosting the operating voltage to overpower the noise and ensure accurate calculations. Chips with more and smaller transistors are consequently more power-hungry.

"PCMOS is fundamentally different," Palem said. "We lower the voltage dramatically and deal with the resulting computational errors by embracing the errors and uncertainties through probabilistic logic."

PCMOS was jointly validated by Rice and Nanyang Technological University (NTU) in Singapore via a joint institute that Palem founded in 2007, the Institute for Sustainable Nanoelectronics (ISNE). Directed by Palem, ISNE is based at NTU, where the first prototype PCMOS chips were manufactured last year in collaboration with Professor Yeo Kiat Seng and his team.

The prototypes were application-specific integrated circuits, or ASICs, that were designed solely for encryption. Unlike the general-purpose microprocessors that power PCs and laptops, ASICs are designed for a specific purpose, and they are embedded by the millions each year in a growing constellation of products like automobiles, cell phones, MRI scanners and electronic toys.

The Rice-NTU team plans to follow its proof-of-concept work on encryption with proof-of-concept tests on microchips for cell phones, graphics cards and medical implants.

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