Low-Power ASIC for Microwatt Electrostatic Energy Harvesters

This paper presents a technique for enhancing the power output from vibration-based charge-constrained electrostatic energy harvesters (EEHs). Starting from a diode-based charge pump and a buck converter stage with an inductive energy flyback scheme, a novel controller integrated circuit is proposed to monitor and control the charging/discharging events of the electrostatic converter. The fundamental challenges of designing self-powered event-synchronization circuits for charge-constrained EEHs are addressed. Synchronous energy conversion is accomplished with minimal power dissipation without the complexity of precise timing circuitry. Experimental results are presented for the design, implemented in AMI 0.7-μm high-voltage CMOS process, using a macroscale electrostatic converter prototype. The energy-harvesting circuit produces a measured 1.688 μW of power for a power investment of 417 nW. The measured power consumption associated with the on-chip controller unit is 24nW, approximately 1.42% of the total power harvested.