Technology Overview: Designing for Mobility

By Katherine Bourzac

Apple’s iPad   Credit: Apple

DATA SHOT 22.3 % The growth rate in the number of Internet-connected mobile devices that’s expected every year through 2013, according to market research firm In-Stat.

Anticipating the ever-increasing computing demands of tomorrow's mobile devices, chip makers are rolling out compact designs for processors that boost performance while drawing less battery power.

Designing processors for mobile devices requires more than simply reproducing desktop computer architecture in a smaller device. The tinier transistors get, the more electricity they leak, a killer for battery-­powered devices. To address this problem, Intel has incorporated better insulating materials into its current generation of chips, and IBM's chips will soon have a honeycomb design with empty spaces--because a vacuum is the best insulator of all.

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Another strategy is to package multiple processing units on the same chip, a technology called multicore computing. Instead of, say, a single power-hungry two-gigahertz chip, two energy-efficient, one-gigahertz cores could deliver the same performance. But programming multicore processors effectively can be tricky (see "Multicore Processors Create Software Headaches").

Packaging specialized systems with a general-purpose core can also be a way to boost performance for specific mobile applications, such as handling multimedia. Apple used this approach for its iPad tablet computer, creating a custom chip called the A4 to power the device. Qualcomm, Intel, and IBM are each taking this idea a step further by working on designs for three-­dimensional chips with multiple layers of circuitry. These designs save energy by shortening the distance bits must travel between, for example, the processor and a memory chip (the longer the path electrons must travel, the more are lost to heat). Qualcomm expects to have such chips in products next year.