This paper presents a Doherty power amplifier with an enhanced power back-off efficiency and a high linearity using an adaptive bias circuit. The silicon area reduction is achieved with an active balun driver topology. The operating frequency range is 1.49GHz to 2.17GHz for NB-IoT applications. The post layout simulations (PLS) show a maximum output power of 31.6dBm with a peak PAE of 35.3% at 1.85GHz. The efficiency drops to 28% at 6dB back-off. The robustness to the 2:1 SWR achieves a variation in Gain and Psat of 3dB and 0.8dB, respectively.