A Current-Mode DC-DC Buck Converter with Efficiency-Optimized Frequency Control and Reconfigurable Compensation

Large input voltage range and wide output current range are usually needed for dc-dc converters. For these input and output conditions, the converter's efficiency can bemaximized by a proposed method, efficiency-optimized switching-frequency (EOF) control. The optimal switching frequency for maximizing the efficiency is generated by the low-complexity and low-power EOF generator. A reconfigurable compensator is developed for improving the load regulation and the transient response. A piecewise-linear current sensor (PLCS) is employed to reduce controller power loss without sacrificing the sensing accuracy. With the aforementioned three proposed methods, a monolithic current-mode dc-dc buck converter is implemented in a 0.35-mu m 3.3-V CMOS process. The measured power-loss reductions and efficiency improvements achieve 16 and 15mW, and 16% and 1%, both in light and heavy loads, respectively. The load regulation and the transient recovery time are improved by 40 mV and 12 mu s, respectively, while the PLCS can reduce 3mW of power loss. Compared with other published converters in 0.35-mu m CMOS process, the implemented converter achieves a higher efficiency of 96.3% and smaller chip area of 0.97mm(2).