基于小波的叉指换能器（IDT）结构算法研究

发布时间：2018-04-10 14:07

本文选题：声表面波 + 叉指换能器　；参考：《贵州大学》2015年硕士论文

【摘要】：随着声表面波(Surface Acoustic Wave,SAW)技术的快速发展,SAW器件在电子信息等领域得到了越来越广泛的应用,与此同时,对SAW器件的要求越来越高:更高的响应频率、更宽的带宽、更低的插入损耗以及更小的尺寸等。由于叉指换能器(Inter Digital Transducer,IDT)是SAW器件的一个重要组成部分,要满足上述一系列要求,改进IDT的结构,优化其描述算法显得尤为重要,为了改善SAW器件的特性,提高其性能,就必须从IDT的描述模型着手,首先建立数学模型,再进行模拟仿真,对比传统模型的仿真结果,改进模型参数达到优化IDT建模分析算法,满足IDT结构优化为目的。改进IDT的结构,不仅可以获得较好的旁瓣抑制和较高的频率响应,还可以获得较低的插入损耗。因此,对IDT结构的改进研究是提高SAW器件性能的关键之一。IDT的结构变了,用于描述IDT的传统数学方法就失去了意义,这就需要找到一种适应于新结构的描述方法。本文是在贵州省自然科学基金项目:“声表面波(SAW)滤波器插入损耗的补偿方法研究”的基础上进行的拓展研究,主要研究SAW器件的IDT的建模方法。本文首先介绍了IDT的工作原理和压电效应以及原有的几种算法模型,然后阐述选择小波函数去描述IDT结构的依据,最后在改进型?函数模型以及脉冲响应模型的基础上选择Morlet小波函数对IDT进行数学建模,将IDT结构参数(如指条宽度a、指间间距b、耦合长度w等)引入新建数学模型(简称为IDT的Morlet小波函数模型),并进行仿真验证。对于IDT结构,再利用传统的数学模型进行仿真对比,结果表明,IDT的Morlet小波函数模型比传统的?函数模型更精确。本文的创新之处是用Morlet小波函数对IDT进行数学建模,由于Morlet小波函数是可变换的,这样就可得出多种描述IDT结构的Morlet小波函数模型,使得描述IDT结构的数学模型具有灵活的可变性,分别有Morlet母小波函数模型以及进行伸缩变换后的Morlet小波函数模型,而且可以通过对IDT的Morlet小波函数模型的频率响应进行校正得到更精确的结构模型,解决了原先基本?函数模型只适合规则型IDT结构的限制。同时,分别针对IDT的结构参数对其插入损耗以及频率响应影响进行仿真分析。结果表明:IDT的Morlet母小波函数模型相对于规则的IDT结构,旁瓣电平得到了很好的抑制,插入损耗较小。
[Abstract]:With the rapid development of surface acoustic wave surface Acoustic wave (saw) technology, saw devices have been more and more widely used in the field of electronic information and other fields. At the same time, the requirements for SAW devices are becoming higher and higher: higher response frequency, wider bandwidth, and so on.Lower insertion loss and smaller dimensions, etc.Because InterDigital Digital Transducer (IDT) is an important part of SAW device, it is very important to improve the structure of IDT and optimize its description algorithm in order to meet the above requirements. In order to improve the characteristics and performance of SAW device, it is very important to improve the structure of IDT.It is necessary to start with the description model of IDT, first establish the mathematical model, then carry on the simulation, compare the simulation results of the traditional model, improve the model parameters to optimize the IDT modeling analysis algorithm, meet the purpose of IDT structure optimization.The improved structure of IDT can not only obtain better sidelobe suppression and higher frequency response, but also obtain lower insertion loss.Therefore, the research on the improvement of IDT structure is one of the key factors to improve the performance of SAW devices. The structure of SAW device has changed, and the traditional mathematical method used to describe IDT has lost its significance. Therefore, it is necessary to find a description method suitable for the new structure.This paper is based on the project of Guizhou Provincial Natural Science Foundation, "study on the compensation method of saw filter insertion loss", mainly on the IDT modeling method of SAW device.This paper first introduces the working principle of IDT, the piezoelectric effect and several original algorithm models, then expounds the basis of choosing wavelet function to describe the structure of IDT, and finally improves the structure of IDT.On the basis of function model and impulse response model, Morlet wavelet function is selected to model IDT.The structural parameters of IDT (such as the width of the strip a, the distance between fingers b, the coupling length w etc.) are introduced into the new mathematical model (Morlet wavelet function model called IDT for short) and verified by simulation.For the IDT structure, the traditional mathematical model is used to carry out the simulation. The results show that the Morlet wavelet function model is better than the traditional Morlet wavelet function model.The function model is more accurate.The innovation of this paper is the mathematical modeling of IDT with Morlet wavelet function. Because the Morlet wavelet function is transformable, various Morlet wavelet function models describing IDT structure can be obtained.The mathematical model of describing IDT structure has flexible variability, which includes Morlet mother wavelet function model and Morlet wavelet function model after extensional transformation, respectively.And by correcting the frequency response of IDT's Morlet wavelet function model, we can get a more accurate structural model, and solve the original basic?The function model is only suitable for the restriction of regular IDT structure.At the same time, the influence of structure parameters on insertion loss and frequency response of IDT are simulated.The results show that compared with the regular IDT structure, the sidelobe level of the Morlet mother wavelet function model of WIDT is well suppressed and the insertion loss is relatively small.
【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN65

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