Researchers tied to the Massachusetts Institute of Technology say they’ve figured out how to double smartphone battery life, and the breakthrough has nothing to do with the battery itself.
Eta Devices, a spinout from MIT, claim that the power amplifiers in today’s smartphones are woefully inefficient, wasting as much as 65 percent of their energy. But as MIT’s Technology Review reports, the company is working on a smartphone chip that solves the efficiency problem.
When your phone transmits data, the power amplifier’s transistors switch from standby mode to a high-power output signal mode. The problem is that big spikes in power can cause signal distortion. To prevent this, existing technologies set standby power at a higher level, thereby reducing the size of any sudden jumps. This of course burns more energy, which could be one reason why your phone runs warm while streaming video or handling large file transfers.
Eta’s solution is a technology called “asymmetric multilevel outphasing.” It picks the appropriate level of voltage to minimize power consumption, and can send different voltages across a transistor at over 20 million times per second. The technology is in lab stages now, but in time Eta hopes its chip will lead to a single power amplifier for all modes and frequencies of mobile broadband. (Apple’s iPhone 5 uses five amplifiers, as seen in iFixit’s teardown.)
I’m always interested in hearing about these advances, because the fact that many smartphones can barely make it through a day of substantial use is a major source of frustration. Despite how far smartphones have come in the last few years, battery technology remains largely unchanged. If you want a phone that will never struggle to last a day, even under the heaviest workloads, your only option is a phone with a humongous battery, which demands a tradeoff in thinness and lightness.
Eta’s technology isn’t the only breakthrough we’ve heard about in recent years. In November 2011, engineers at Northwestern University talked up an electrode for lithium-ion batteries that would apparently allow for a week’s worth of capacity and 15-minute recharge times. And in March 2010, researchers at Stanford University developed a lithium-sulfur battery that could last four times as long as modern lithium-ion packs. Of course, there’s always talk of more far-out concepts, like kinetic charging and human-powered gadgets.
Still, commercial viability is never talked about much when researchers tout their latest breakthroughs. If you’re lucky, as with the Northwestern research, you’ll get some vague prognostication of market readiness within a half-decade. There’s no word on when Eta’s power amplifier will be ready for the market, but I figure the more breakthroughs we hear about, the more likely that one of them will eventually save us from battery headaches for good.