In this paper, a DC-DC buck converter using a multi-bit (two-bits) delta-sigma modulator to control segmented output switches of the converter is proposed to enhance its efficiency and improve its output ripple. This converter operates in continuous condition mode (CCM). Here, the two output bits of the modulator control the switching of the main and the supplementary switches. The circuit is simulated in 180 nm CMOS technology and the simulation results show a peak efficiency of 92% for the converter. The output current can reach up to 1.2A and the input voltage range is from 3.6 V to 1.8 V. The output ripple is 19 mV, 23 mV and 27 mV for 1.5 V, 1.8 V and 2 V output voltages, respectively.