Research Of Bulk Acoustic Wave Resonator Based On Lamb Wave

With the application of 5G communication which puts forward higher performance requirements for traditional acoustic filter technology.As the design unit of the filter,the traditional acoustic resonator technology also faces new challenges.The increase of new communication bands means acoustic resonators need to be designed in higher frequency,and the larger bandwidth also means that the acoustic resonators should have higher electromechanical coupling coefficients.But traditional bulk acoustic wave resonators also have their own limitations,which leading to both of the above requirements cannot be met at the same time.At present,the industry has not found a perfect technology that can replace acoustic devices.Therefore,designing higher-performance acoustic resonators has become a common goal of the industry and academia.The Lamb wave resonator with high frequency and large coupling coefficient has become a research hotspot as soon as it is proposed.This thesis takes the lamb wave resonator with high frequency and large coupling coefficient as the research goal,and the research topic is how to take the principle and design of this kind of device.This research focuses on the internal mechanism,design method,manufacturing and application of the device,and on the basis of the design of the basic structure,the design method and principle of its performance improvement are explored,and the comparative study is carried out.The main research content is divided into four parts.Firstly,the characteristics of basic Lamb waves,different types of Lamb wave mode characteristics and excitation methods are explored,and the characteristics of Lamb waves in piezoelectric materials are analyzed to carry out theoretical research on Lamb wave resonators,and the equivalent model method of MBVD circuit is given.Secondly,based on the theoretical research,the basic structure design and mechanism analysis of the A₁ mode Lamb wave resonator with high frequency and high coupling coefficient is carried out,and the parameters of the A₁ mode Lamb wave resonator are designed in combination with theory and finite element simulation software.Exploring the influence and mechanism of the solidly mounted resonator(SMR)type substrate on the electromechanical coupling coefficient of the A₁ mode resonator,and the SMR type A₁mode resonator have been fabricated and tested.In the third part,the transverse mode in the resonator and its suppression are analyzed.Comparing and analyzing two kinds of improved structures in transverse mode suppression by calculation.The fourth part applies the hierarchical cascading technology(HCT)and the traveling wave excitation source(TWES)technique to analyze the improved structures.Using these two techniques,the reflection coefficient of the improved structure is calculated,and the improved structures are further analyzed,the method of exploring the internal mechanism of the transverse mode suppression structure that cannot be realized by traditional finite element simulation is shown by calculating the reflection coefficient,which is a good method to keep research of A₁ mode Lamb wave resonator with high frequency and high coupling coefficient.