Adaptive voltage positioning (AVP) technique has been widely used in voltage regulator (VR) applications. In this paper, a digitally controlled buck converter with the proposed current sensor-less AVP technique is presented. Without the need for sensing or sampling the loading condition, the proposed control architecture utilizes the error signal of the digitalized controller to obtain the current information. The elimination of a current analog-to-digital converter (ADC) or any current sensing circuits significantly reduced the size and cost of the digital controller. A 781.25-kHz, single-phase synchronous buck converter which the input voltage is ranging from 2.7 to 4.2 V and an optional output between 0.9 to 1.2 V was implemented using the field-programmable gate array (FPGA). Experimental results show that an optimal AVP function was achieved in transient response to a 200-650 mA step load change within 30 μs.