A Broadband Doherty Power Amplifier With Hybrid Class-EFJ Mode

This paper proposes a method that employs novel hybrid continuous class-EFJ power amplifiers (PAs) as carrier PA to design a broadband high-efficiency Doherty power amplifier (DPA). Bandwidth characteristic of the proposed DPA is analyzed in detail. By proper selection of related parameter values, up to 78% fabrication bandwidth can be obtained. Post-harmonic tuning network is applied to improve the bandwidth and enhance the efficiency. Then, a closed design process is presented to design broadband DPA based on derived theories. For validation, a broadband DPA operating in 1.2-2.8 GHz is designed and fabricated. Measurements illustrate that the DPA can deliver saturated output power between 43.7 dBm and 44.1 dBm in 1.2-2.8 GHz, and the saturated drain efficiency from 60.5% to 74.2 % is achieved. Moreover, drain efficiency is 48.1%-57.6% at the 6 dB power back-off. Compared with conventional DPAs, the proposed DPA exhibits superior performance of bandwidth characteristics and power back-off efficiency over a wide bandwidth.