This paper presents a sensor-less approach to achieve current balance and thermal balance in a digital voltage mode controlled four-phase buck converter. Rather than utilize current and temperature sensors to gather the current and thermal information as most of previous researches, the sensor-less equivalent resistance (R eq ) ratio estimation is used in this work to obtain the current and thermal information implicitly. Based on the estimative results, the duty offset is further calculated and compensated for each phase to carry out either equal current sharing or uniform thermal distribution. The digital controller was manufactured by TSMC 0.18-μm 1P6M standard CMOS process. The experimental results are proved the practicability of the proposed balancing mechanism. The current balance scheme improves the current sharing error from 35% to 6.3%, while the thermal balance technique narrows down the peak temperature difference from 6.6°C to 1.8°C.