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.