A Bandwidth Enhanced Outphasing Power Amplifier

This letter introduces a new wideband output combiner for outphasing power amplifier. The conventional two non-commensurate transmission lines are replaced with two reconfigurable T-type networks loaded with shunt varactors. In virtual of the proposed architecture, the bandwidth limitation that happens in the conventional combiner is greatly reduced. To provide reactance compensation in a large operational bandwidth, the post-matching strategy is further employed. For demonstration, an OPA prototype based on the proposed method is implemented using two 10 W GaN HEMT transistors. A minimum of 67% drain efficiency is maintained at saturation from 2.4 GHz to 2.8 GHz. At 6 dB back-off power, over 57% drain efficiency is obtained in the same frequency band.