94.6% peak efficiency DCM buck converter with fast adaptive dead-time control

Abstract

This paper presents a dynamic logic based adaptive dead-time control circuit (DADTC) for fast and adaptive control to minimize body diode conduction losses and dead-time of the buck regulator operating in discontinuous conduction mode (DCM). Dead-time is an important metric for improving efficiency of low voltage converters. DADTC provides instant sensing and feedback based on the load to minimize dead-time significantly compared to prior art and enables higher overall power efficiency of the converter. Further, the presented buck converter has inherent pulse skipping mode to lower the switching frequency at light loads further enhancing light load efficiency. The buck regulator was fabricated in 0.35 μm CMOS process with an input voltage range of 1.8V-3V and load current range of 1mA-200mA. Measurement results show that the proposed design achieves peak power efficiency of 94.6% and a high overall power efficiency ( > ~89%) for load currents greater than 5mA with a sensing delay of only ~5ns for VIN = 1.8V.