A Gain-Controlled, Low-Leakage Dickson Charge Pump for Energy-Harvesting Applications

Abstract

This paper presents a single-stage power management unit to boost and regulate a low supply voltage for CMOS system-on-chip (SoC) applications. It consists of low-leakage, enhanced Dickson charge pump (DCP) that utilizes both stage and frequency modulation (FM) techniques to achieve high efficiency and lower area. In addition, the proposed design uses an enhanced stage-switch structure for the charge pump, which significantly reduces the cross-stage leakage. A stage number controller is used to control the gain of the charge pump by changing the number of stages based on the desired output voltage. FM is utilized to further fine-tune the output voltage through a closed-loop control based on a predetermined reference voltage. Silicon measurement results for the four-stage charge pump in 65-nm CMOS technology show a maximum end-to-end efficiency of 66% at an input voltage of 0.7 V and an output power of $27~\mu \text{W}$ . The proposed design achieved more than a $100\times $ reduction in leakage compared to traditional DCP. The system supports a range of load currents between 0.1 and $34~\mu \text{A}$ with a maximum operating frequency of 1.8 MHz. The proposed system supports an input voltage range of 0.55–0.7 V which makes it an excellent candidate for solar and thermal energy-harvesting applications targeting low-power internet-of-things SOC.