An Efficient On-chip Switched-Capacitor DC-DC Converted for Ultra - Low Power Applications

Abstract

Advancements in CMOS technology has enabled the evolution of the internet of things that are based on ultra-low power devices and circuits in many applications such as WSNs, implantable and wearable electronics. However, battery life time has become critical in ultra-low power devices in term of power management and delivery. Therefore, reducing the power consumption of the integrated circuits will certainly extend the battery lifetime. Dynamic voltage scaling is a key requirement for the SoC to support optimum operating point of both energy and performance. Dynamic voltage scaling can be achieved by DC-DC converter which is commonly used in today's SoCs. This thesis introduces an efficient on-chip reconfigurable multiple gain switched-capacitor DC-DC buck converter. The proposed switched-capacitor converter takes an input of 1.2V and provides various voltage levels, namely 1V, 0.8V and 0.6V based on two reconfigurable bits. The proposed switched-capacitor converter is capable of driving a wide range of load currents from 10 A to 800 A as set by the operating frequency and switch modulation to regulate the output voltage. The switched-capacitor converter is designed and fabricated in 65nm low power CMOS technology and occupies an area of 0.43mm2. The design utilizes both MIM and MOS capacitances stacked above each other in order to achieve high area and power efficiency. The measured maximum power efficiency from silicon is 83% for a load current of 400 A at 0.8V. In addition, a closed loop switched-capacitor converter including the frequency modulation controller is designed in 65nm CMOS and a spice simulation shows a maximum power efficiency of 83% comparing it with the open loop switched-capacitor converter where the maximum power reaches 85%.

Date of Award	2015
Original language	American English