An Integrated Piezoelectric Energy Harvesting Interface Circuit with Adaptive S3BF Control

Abstract

To increase the energy extraction capability and thus improve the power efficiency, it is critical to reduce the energy loss of interface circuit in the energy harvesting (EH) system. The synchronized multiple bias-flip (SMBF) control has been proposed and proved to be highly effective to increase the output power in piezoelectric EH systems. However, many existing designs based on bias-flip suffer from the limitations in real application as the external control or supply are required. Moreover, the control algorithm is often only suitable for a designated transducer and inductor. In this paper, an integrated piezoelectric EH interface circuit with synchronized triple bias-flip (S3BF) has been proposed to flip the voltage across the parasitic capacitor of piezoelectric transducer during the zero-crossing. Meanwhile, the adaptive control of the flipping signal has also been adopted to meet the requirement of different configurations of transducers and inductors. The proposed interface circuit has been designed in 0.18-μm CMOS technology. Without any external control circuit or power supply, it can achieve cold start-up when the external inductances vary from 33 μH to 500 μH. When the external inductance is 50 μH, the simulated flip efficiency is 87.2 %, and the maximum output power is 17.4 μW, which is 3.4 times of the full-bridge rectifier.