Hybrid Dickson Switched-Capacitor Converter With Wide Conversion Ratio in 65-nm CMOS

Abstract

Hybrid switched-capacitor (SC) converters have shown great promise in achieving high efficiency and power density for dc-dc conversion. By combining an SC stage with an inductor filter stage, benefits from both approaches can be realized. In this work, a hybrid Dickson SC converter with a 4:1 native conversion ratio and regulated output voltage range of 0.3-0.9 V from a 3.4 to 4.2-V lithium-ion battery and the effective switching frequency of 1 MHz was implemented in 65-nm bulk CMOS process. The converter achieves maximum output current of 1.5 A, the power density of 330 mW/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and a peak efficiency of 92.6%. The converter is packaged using flip-chip technology with passive devices co-packaged through a high-density interposer to minimize the packaging parasitics and volume. A segmented gate driver is used to enhance the converter efficiency and reliability by maintaining low-voltage ringing across the power switches. The converter is integrated with closed-loop output voltage regulation, dead-time control, and active capacitor-voltage balancing to maximize the active and passive device utilizations.