MIT spin-out developing technology that could make smartphones more power efficient

1 Nov 2012

Anything that drains power is the bane of the smartphone user, and much of the battery life of these devices is wasted on inefficient cellular technology. But new technology being developed by MIT spin-out Eta Devices could solve this problem for base stations and mobile devices.

Power amplifiers, which turn electricity into radio signals, are an incredibly inefficient piece of technology, consuming large amounts of power not only when sending out signals but even when in standby. This is because a sudden jump in power can produce distorted signals, and so the power used in standby mode cannot be reduced.

“It means you are pulling a lot of energy just to keep the thing on,” explained Joel Dawson to the MIT Technology Review. “With high data rate communication, you wind up needing far more standby power than signal power. This is why the phone is warm.”

So, when you notice your smartphone heating up when watching videos on YouTube, this is a sure sign that the power amplifiers inside are killing your battery.

A possible power solution

Along with fellow MIT electrical engineering professor David Perreault, Dawson is the co-founder of Eta Devices, a start-up that may have found a solution to this power problem. Their power amplifier design uses a technology they call asymmetric multilevel outphasing. Basically, this amplifier chooses the most efficient voltage that can be sent across the transistor at a rate of 20m times per second.

Expected to launch at Mobile World Congress in February, Eta Devices is initially targeting this product at cellular base stations, particularly those in the developing world, which are powered by diesel-sucking generators that eat up US$15bn-worth of fuel per year.

Globally, these base stations consume about 1pc of all electricity produced worldwide per year, and most of this is wasted on power amplifiers. Eta Devices’ technology could not only reduce base station energy use by half, it could also reduce costs such as air-conditioning required to cool down the current inefficient amplifiers.

If this breakthrough technology can be scaled down for a smartphone, battery life could be doubled. Recent smartphones contain a number of power amplifiers for various modes and frequencies available globally (for example, the iPhone 5 contains five of them) and these use about 60pc of the smartphone’s power. Eta Devices hopes to develop a single power amplifier based on its design that supports all wireless communications standards, such as CDMA, GSM and 4G/LTE.

Low battery image via Shutterstock

Elaine Burke is the editor of Silicon Republic