A highly efficient wideband asymmetric Doherty power amplifier with 10 dB output power back-off

In this paper, the design and optimisation of a 10 W wideband asymmetric Doherty power amplifier (ADPA) with 10 dB output power back-off (OBO) at 2.14 GHz is presented. The amplifier has been optimised to achieve wideband operation and high efficiency over the whole dynamic range for systems accommodating high peak-to-average power ratio (PAPR) signals. By eliminating the impedance transformation network (ITN) and lowering the impedance transformation ratio (ITR) of the output combiner, the bandwidth and efficiency of the ADPA can be simultaneously improved, especially the peak efficiency at back-off (BO). The evenly-driven ADPA has been implemented using 6 W and 10 W GaN-HEMTs as carrier and peaking devices, respectively. The measured peak drain (η) and power-added (PAE) efficiencies are 75.7 % and 64.3 %, respectively at 1 dB compression point output power of 40.6 dBm. The corresponding η and PAE at 10 dB OBO are measured to be 66.7 % and 53.7 %, respectively. To the best of our knowledge, this is the highest efficiency of a wideband (250 MHz) ADPA ever reported at this frequency.