Eta Devices

Eta Devices is developing a high efficiency power amplifier for cell phones and cell base stations that will improve battery life and reduce base station energy usage

See article:  http://www.technologyreview.com/news/506491/efficiency-breakthrough-promises-smartphones-that-use-half-the-power/

This company is a spinout of the 2008 project, A New Architecture for Highly Efficient, Broadband RF Tranceivers.