A Fully Integrated Synchronous Piezoelectric-Electromagnetic Hybrid Energy Harvesting Platform with Coil-Sharing Scheme

Abstract

Piezoelectric (PE) and electromagnetic (EM) methods are two popular techniques for harvesting kinetic vibration energy. When combined, these methods can power self-sustaining wireless sensors that require higher power consumption. However, existing hybrid energy systems necessitate at least one large off-chip inductor for either bias-flip or DC-DC conversion. This large inductor significantly increases the system's volume, leading to integration issues in space-constrained Internet-of-Things (IoT) applications.
This thesis proposes a fully integrated PE-EM hybrid energy harvesting platform to address this issue. By properly arranging synchronous PE and EM phases, the new active-to-passive coil-sharing technique eliminates the need for an additional energy reservoir for bias-flip and DC-DC. The IC prototype, fabricated using the 0.18um BCD CMOS process, has been experimentally tested. Results show a flipping efficiency of up to 70%. Additionally, the proposed single-stage system structure allows the output to be parallel with the battery stage, achieving high end-to-end (E2E) efficiency.