Technique could offer dramatic laptop battery power savings

A new form of radio chip that could be used in mobile phones and Wi-Fi and Bluetooth devices can cut the power needed to broadcast and receive wireless data by a factor of 10.

Developed at the University of Rochester in New York by Hui Wu, a professor of electrical and computer engineering, the chipset uses a technique called injection locked frequency divider (ILFD) to cut the amount of power used for radio data transfer by up to 90 per cent.

For two radio users to communicate they must be on exactly the same frequency. The phone therefore needs to maintain a very accurate and stable clock, which is generated by a special circuit called a phase-locked loop. But this consumes a dramatic portion of the battery life on wireless devices.

Professor Wu's ILFD method uses less power than conventional digital methods because the tiny 'ones' and 'zeroes' that comprise digital information waste energy.

An ILFD device, on the other hand, does not use the brute-force approach of counting each pulse, but employs an analogue method that requires less power.

ILFD technology has been considered before but has limitations in matching frequencies correctly. Professor Wu claims to have overcome this by increasing the number of transistors on the chipset to allow for more accurate frequency matching.

The researchers have designed and fabricated several prototype chips which successfully demonstrated the concepts.

Professor Wu is also working on other power-saving aspects of chip design that he hopes can be used to stretch the battery life of wireless devices even further.