In modern portable devices, except during short periods of busy time, application processors work at low-power state most of the time to prolong battery life. Thus, high efficiency and low consumption are essential for their power management under light-load conditions. This study presents a dual-phase DC-DC buck converter with light-load performance enhancement for power supply. As load decreases, the converter could transfer the adaptive-on-time-based control strategy from pulse-width modulation to pulse-frequency modulation to enhance efficiency. An extra power-save mode is introduced into design to minimise the power consumption at extremely light load. Besides, a novel current-balance circuit with additional offset elimination block is implemented, which results in equal distribution of load current between phases over wide load range. Moreover, instead of a conventional high precision and fast response comparator, a simple comparator with self-calibration is used in zero-current switching circuit to reduce design complexity, as well as to improve light-load efficiency. The converter is fabricated in 0.18-μm Globalfoundry CMOS process. Experimental results show that91% peak efficiency and 6 µA standby quiescent current is achieved. With the aid of mode switching, current-balance and zero-current switching, the light-load performance enhancement is verified by measurements.