Less accurate processors to cut power consumption?

Krishna Palem, professor of computing at Rice University, claims it's possible to create mobile processors that use significantly less power in exchange for a small loss of precision. Palem believes PCMOS (probabilistic complementary metal-oxide semi­conductor technology) chips can increase battery life of mobile devices like cell phones and MP3 players as much as tenfold without compromising the user's experience.

Every calculation done by a microchip depends on its transistors' registering either a 1 or a 0 as electrons flow through them in response to an applied voltage. But electron­s move constantly, producing electrical "noise." In order to overcome noise and ensure that their transistors register the correct values, most chips run at a relatively high voltage. Palem's idea is to lower the operating voltage of parts of a chip--specifically, the logic circuits that calculate the least significant bits, such as the 3 in the number 21,693. The resulting decrease in signal-to-noise ratio means those circuits would occasionally arrive at the wrong answer, but engineers can calculate the probability of getting the right answer for any specific voltage. "Relaxing the probability of correctness even a little bit can produce significant savings in energy," Palem says.

Within a few years, chips using such designs could boost battery life in mobile devices such as music players and cell phones. But in a decade or so, Palem's ideas could have a much larger impact. By then, silicon transistors will be so small that engineers won't be able to precisely control their behavior: the transistors will be inherently probabilistic. Palem's techniques could then become important to the continuation of Moore's Law, the exponential increase in transistor density--and thus in computing power--that has persisted for four decades.

More info at Technology Review.