A 7GHz High Efficiency GaN Doherty Power Amplifier Module for 5G massive MIMO Base-Stations

This paper presents the design and characterization of a 7GHz high efficiency Gallium Nitride (GaN) Doherty Power Amplifier (DPA) module for 5G massive MIMO base-stations. It is challenging to adopt the design method used in 3-4GHz DPA module with multi-chip configuration for 7GHz, because of the effect of bond wires and parasitic. Systematic numerical calculation based on the design method for 3-4GHz DPA modules showed that, although the design space, in which proper Doherty operation can be realized, is substantially reduced in 7GHz compared to 3.5GHz case, some limited design space can be found even for 7GHz with multi-chip configuration. By using this space, GaN DPA module prototype was designed and fabricated with effective area of 76mm2, operating in the frequency range of 6.8-7.1GHz. Measurements showed that the DPA module has the highest efficiency and gain ever reported among GaN DPAs in 6-8GHz band with saturation output power over 40dBm.