A 10 nW–1 $\upmu {\rm{W}}$ Power Management IC With Integrated Battery Management and Self-Startup for Energy Harvesting Applications

This paper presents a 10 nW–1 $\upmu{\rm{W}}$ 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 $\upmu{\rm{W}}$ with input voltage of 3 V and output voltage of 1 V.