Eta Devices, a spinout from the Massachusetts Institute of Technology, has commercialized a power amplifier for base stations that uses envelope tracking to adjust voltage as needed and reduce overall power needs. The company is also developing a complementary chip for smartphones.
Eta Devices' new chip.
Conventional RF amplifiers use fixed supply voltage, but envelope tracking technology continuously adjusts the voltage supplied to a power amplifier as needed, resulting in more efficient operations. Eta claims its specific approach, called Asymmetric Multilevel Outphasing (AMO), will lead to significantly reduced power consumption and smaller cabinets for base stations. When used in handsets, envelope tracking increases battery life and enables multiband communications at a fraction of the cost and footprint of existing approaches, making it possible "to use a single LTE handset model all over the world," Eta said.
Last last year, Eta announced availability of its power amplifier for mobile base stations, which it said "exploits the extreme performance capabilities of GaN switching power amplifiers, advanced supply modulation and digital pre-distortion algorithms" to deliver 70 percent drain efficiency for LTE.
According to Mattias Astrom, Eta's cofounder and CEO, "By deploying our solution, base station efficiency is doubled compared to current state-of-the-art technology, which saves a tremendous amount of power."
He claims broad use of the company's base station solution would result in a reduction of greenhouse gas emissions equivalent to taking more than 7 million cars off the road and would also save mobile operators $18 billion per year in utility costs.
The company is far from alone in developing and commercializing envelope tracking technology. For example, during the 2013 Mobile World Congress, Qualcomm (NASDAQ:QCOM) showed off its RF360 front end solution, which, among other things, includes the first commercial envelope power tracker for 3G and LTE mobile devices. Qualcomm's envelope tracking technology is already available in 10 handsets, including the Samsung Galaxy Note 3 and Nexus 5.
Eta Devices is taking a different tack from the usual approach to envelope tracking, said MIT Technology Review. While envelope tracking generally requires a large capacitor, Eta is using a smaller capacitor that is more efficient at dealing with fast, abrupt voltage changes. Though the energy changes result in more signal noise, Eta believes it can address the issue via advanced digital signal processing.
Low-power base station company Vanu, which makes equipment based upon software-defined radio technology and also has MIT roots, is testing Eta's base station module. "We think this can give us a 'green' benefit as well as an operating cost advantage," David Bither, director of platform engineering at Vanu, told MIT Technology Review.
Eta is based in Cambridge, Mass., and has an R&D office in Stockholm. The firm is funded by $6 million from Analog Devices cofounder Ray Stata and his venture capital firm, Stata Venture Partners.
- see this MIT Technology Review article
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