This article presents the implementation of a three-stage Doherty power amplifier to enhance the efficiency at power back-off. In this, a three-stage power amplifier with the final stage as a Doherty amplifier optimized for efficiency peaks at 3 and 6 dB back-off. The amplifier is realized on the WIN Semiconductors 150nm Gallium Arsenide (GaAs) p-HEMT process for 5G application operating at 24.25-27.5GHz. The design achieves an output power of more than 3 watts (34.8 dBm) and power-added efficiency of 37.5 and 34.8% at 3dB and 6dB back-off respectively. With this design, a gain of 24.8dB is obtained when operating at 24.25-27.5GHz.