A 10 nW–1 µW Power Management IC With Integrated Battery Management and Self-Startup for Energy Harvesting Applications

This paper presents a 10 nW-1 μW power management IC with 3.2 nW quiescent power consumption for solar energy harvesting applications. The chip integrates a switch matrix that can be configured as a buck or a boost dc-dc converter using a single inductor as well as output voltage regulation logic, battery management block, and self-startup. The control circuit of the converter is designed in an asynchronous fashion that scales the effective switching frequency of the converter with the level of power transferred. The on-time of the converter switches adapts dynamically to the input and output voltages for peak-current control and zero-current switching. For input power of 500 nW, the proposed chip achieves an efficiency of 82%, including the control circuit overhead, while charging the energy storage device at 3 V from 0.5 V input. In buck mode, it achieves a peak efficiency of 87% and maintains efficiency greater than 80% for output power of 50 nW-1 μW with input voltage of 3 V and output voltage of 1 V.

I. Introduction

The advances in sensor technologies, embedded processing, and wireless connectivity have fueled the emergence of myriad of wearable and implantable devices. Rather than being carried in a pocket or a bag, these devices actually live on and in us and unobtrusively become part of our daily life. Since the users are always looking for seamless operation of this class of devices, which does not require their intervention to change or charge the battery, energy harvesting has emerged as a key solution for such systems [1]–[5].