A Synchronous Piezoelectric–Electromagnetic Hybrid Energy Harvesting Platform With Coil-Sharing Scheme Yuchen Wei

Abstract

Vibration energy harvesting is a promising power solution for autonomous wireless sensor nodes, particularly in volume-constrained Internet-of-Things (IoT) applications. Piezo- electric (PE) and electromagnetic (EM) transducers are widely used to convert vibration energy into electrical power. While hybrid PE–EM harvesters can deliver higher output power to support self-sustained systems, existing implementations invari- ably rely on at least one o ff-chip inductor for either PE bias-flip or dc–dc conversion, substantially increasing system volume. This article presents an inductor-less, capacitor-less PE–EM hybrid energy harvesting platform that eliminates this limitation. By leveraging the inherent phase synchronization between PE and EM sources, the proposed coil-sharing technique enables both bias-flip and dc–dc conversion without additional passive components, enabling the first fully integrated hybrid energy harvesting system. Fabricated in 0.18- µm CMOS technology, the prototype delivers dual-regulated outputs at 1.8 and 5 V for multi-domain sensor nodes, achieving a maximum output power of 2.72 mW and a peak end-to-end (E2E) e fficiency of 90%. These results highlight the platform’s potential for ultra- compact, high-performance energy harvesting in next-generation IoT applications.