Research on power amplifiers at Chalmers is targeting the need for increased bandwidth and higher energy efficiency in mobile communication transmitters. During 2014 the researchers demonstrated GaN MMIC power amplifier based on a new modified Doherty topology (patented by Ericsson) to obtain a record >35% average efficiency and 5.8–8.8 GHz bandwidth.

A wide range of important point-to-point radio link frequency bands can thereby be served while eliminating the thermal problems caused by the inefficient solutions presently used. For narrowband applications the researchers also derived a new technique to integrate the measured non-ideal characteristics of high frequency transistors directly into the fundamental amplifier design equations (patented by Ericsson). It has already allowed demonstration of state-of-the-art Doherty and outphasing results up to 3.5 GHz, and will form the basis for our ongoing research on advanced millimetre wave MIMO transmitters for next generation (5G) mobile and radar systems.

The research is conducted in close collaboration with the Communication Systems Group at the Department of Signals and Systems at Chalmers.

Caption: Wideband 5.8 – 8.8 GHz GaN MMIC power amplifier with record efficiency for point-to-point radio link applications.