A high‐efficiency, S‐band Doherty power amplifier (DPA) with wide output power back‐off (OPBO) range is presented. A novel parasitic capacitance compensation approach is applied at the output of Cree's GaN high‐electron‐mobility transistor to achieve high saturation efficiency in a wide OPBO range. Specifically, a parallel shorting microstrip line between the transistor output and its match network is adopted to realise parasitic capacitance compensation. The measurement results indicate good Doherty behaviour with 10 dB back‐off efficiency of 40.6–44.2% and saturation efficiency of 70.2–73.3% over 2.9–3.3 GHz. When stimulated by a 20‐MHz LTE signal with 7.5 dB PAPR, the proposed Doherty amplifier power, combined with digital pre‐distortion, achieved adjacent channel leakage ratios below −47.2 dBc. The DPA demonstrate superior performance in OPBO range and efficiency, which makes it an ideal component for base station communication systems.

A kind of broadband power amplifier for wide-band coverage of the next-generation base station communications systems is obtained through using GaN HEMT transistor CGH40010 supplied by CREE as carrier or peak power amplifiers, and a novel load modulation network (LMN) is presented in this paper. With continuous wave (CW) measurements, the results for the obtained Doherty power amplifier (DPA) show that the saturation drain efficiency is between 61% and 71%, the 6 dB back off efficiency is greater than 35%, and the maximum efficiency is 52% in the 2.8-4.0 GHz frequency range. The performance of this improved DPA is more excellent than that of the unimproved one. Furthermore, 20 MHz long term evolution (LTE) modulated signals are applied for and digital predistortion (DPD) to evaluate its linearization performance. And lower than −46 dBc adjacent leak power ratio (ACLR) can be achieved at 3.5 GHz.