Less sucky power amplifiers will double smartphone battery life

While you'd think that improving smartphone battery life would mean slight tweaks to different components while adding bigger and fancier batteries, smartphones use 60% of their power to drive signal power amplifiers that are only 30% efficient. This ginormous battery suck is about to get fixed.

Power amplifiers in both cell phones and cellular base stations are terribly, horribly inefficient. The world spends $36 billion on base station electricity every year, and 65% of that energy is completely wasted. And since lot of it ends up turning into heat inside the aforementioned terrible horrible power amplifiers, base stations also need to have air conditioning systems running all the time, adding another 10% or so to the energy bill. Yuck.

The reason that such hardware inefficiency has persisted for so long is inherent in the way that cell phone antennae operate. When actively transmitting, an antenna is at full power, and that's where you want it to be. When not actively transmitting, you want the antenna to be in as low of a power state as possible. The issue is that switching back and forth between low and high power causes significant signal distortion, so to minimize those power jumps, "low power standby mode" is actually not very low power at all, and all of it is being wasted. The more data you're trying to send, the worse this problem gets, since the more the antenna needs to switch.

An MIT spinoff company called Eta Devices has developed a new type of power amplifier that uses an "electronic gearbox" of sorts to rapidly switch voltages, intelligently selecting the precise amount of power necessary to maintain antenna performance while minimizing power consumption. By doing this 20,000,000 times every second in what's called "asymmetric multilevel outphasing," Eta's power amplifier chips are as much as 100% more efficient than existing designs. That's huge.

Commercialization of this tech will start as early next year, but the first place it's going to show up is in base stations, since that's where the savings in energy (and consequently money) will be most significant. A chip-scale version, which is currently in development, could "double the battery life of smartphones," but we'll have to wait just a little longer to get our hands on that.

Eta Devices, via Tech Review

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