High-Efficiency and High-Current GaN-Based Microwave Rectifier for Wireless Strain Sensing and Monitoring

Abstract

In this article, a gallium nitride (GaN) Schottky barrier diode (SBD)-based microwave rectifier with high efficiency, current, and power bandwidth is proposed for wireless strain sensing and monitoring. Solutions including semiconductor devices, rectification circuits, and sensing mechanisms are discussed. A microwave rectifier working at 928 MHz is designed for wireless rectification strain sensing, with a measured power efficiency over 85% and a load resistance lower to 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> based on a customized quasi-vertical GaN SBD. The finger layout and TiN anode make the SBD series resistance reduced to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.81~\Omega $ </tex-math></inline-formula> , but saturation current enhanced to 11.8 nA, which significantly reduces rectification loss when the load resistance is small. Finally, a rectification strain sensor (RSS) is proposed by dielectric coupling the rectifier and a piezo-permittivity liquid metal elastomer foam (LMEF), with a measured relative output power variation and wireless working distance over 437%/mm and 3 m, respectively.