| The demand for high-performance surface acoustic wave filters is escalating due to the swift advancement of mobile communication technology.As the number of frequency bands for mobile communications continues to increase to meet the huge demand for high-speed mobile communications data,many SAW filters and diplexers are used in each mobile terminal to support more frequency bands,and there is an urgent need to reduce the size of small surface wave devices.As a solution to achieve miniaturization,this thesis studies the acoustic velocity control technology of the surface acoustic wave resonator with low cut angle lithium niobate as piezoelectric material.While reducing the acoustic velocity,other important properties are maintained,so as to achieve high performance design of low acoustic velocity surface acoustic wave resonator.The design and research of low acoustic velocity horizontal shear surface wave resonator are carried out,including the design of metal electrode configuration,the influence of material characteristics of heavy metal electrode on acoustic velocity and electromechanical coupling coefficient.The double electrode structure of heavy metal and high conductivity metal layer is used to improve the overall conductivity and reduce the ohmic loss.The design of double-layer electrode structure,the selection of electrode material and the influence of electrode material properties on the device performance are studied.The design rules of single-layer electrode and double-layer electrode were obtained.In addition,the spurious suppression effect of lithium niobate cut angle and the optimal design of lithium niobate cut angle were studied,and the Rayleigh mode suppression was realized by adjusting the cut angle of lithium niobate.The optimal cut angle change under different electrode thickness and the effect of using the optimal cut angle on the electromechanical coupling coefficient were studied to complete the design of the optimal cutting Angle of lithium niobate.The double-layer electrode structure is applied to the I.H.P.SAW structure to further improve the performance of the resonator.The design of multilayer structure parameters of I.H.P.SAW structure is studied,and the design law of piezoelectric layer LN layer and Si O2 layer thickness is obtained.The temperature compensation design of the resonator is completed by optimizing the thickness of LN layer and Si O2 layer.The periodic three-dimensional model’s lateral design is completed by utilizing the optimized structural parameters,thereby attaining transverse mode suppression. |
