Power consumption is the primary concern in battery-operated portable applications. Buck converters have gained popularity in powering portable devices due to their compact size, good current delivery capability and high efficiency. However, portable devices are operating under light load condition for the most of the time. Conventional buck converters suffer from low light-load efficiency which severely limits battery lifetime. In this project, a novel technique for buck converter is proposed to reduce the switching loss by reducing the effective input supply voltage at light load. This is achieved by switching between two different input voltages (3.3V and 1.65V) depending on the output current value. Experimental results show that this technique improves the efficiency at light loads by 18.07%. The buck voltage possesses an output voltage of 0.9V and provides a maximum output current of 400mA. The buck converter operates at a switching frequency of 1MHz. The prototype was fabricated using 0.18µm CMOS technology, and occupies a total active area of 0.6039mm^2.