Matching Network Design for Ultrasonic Guided Wave Interdigital Transducers

Abstract

Highlights: This is a study of the analysis and design rules of a resonant matching network for ultrasonic guided wave interdigital transducers involving integrated implementation with a piezopolymer interdigital transducer and validation with low-voltage-power-supply-driving electronics. What are the main findings? A passive component matching network for interdigital guided wave transducers; Transfer function analysis and design rules/methods. What are the implications of the main findings? Easier integration of interdigital transducers into structural health monitoring systems; Driving electronic circuit with low power supply voltage. Ultrasonic guided wave interdigital transducers realized with piezoelectric materials are of interest for structural health monitoring systems because of their capability of performing Lamb wave mode selection with respect to single-element transducers. Besides this advantage, the coverage of large areas with a minimum number of elements is an important challenge and the problem of efficient excitation with integrated electronics must be solved. This work proposes an electrical matching network topology made of L and C passive components that can be designed for the trade-off between electrical to mechanical conversion efficiency and bandwidth. The network circuit is analyzed considering the equivalent transducer impedance and the output impedance of the driving electronics. The design rules derived by the transfer function analysis are described and a case study for a piezopolymer IDT is presented. Finally, with the implementation of the integrated matching network with the connector of the IDT, the effect of cable capacitance is minimized. In conclusion this article is a contribution to the study of using IDT efficiently and in a versatile mode for different electronic front-ends that usually operate at low power supply voltage.