声表面波器件可变结构叉指换能器的数学建模与损耗补偿的关键技术研究

Interdigital transducer ( IDT) is a key component of SAW (Surface Acoustic Wave) devices,Its role is to be sound - electrical, electro - acoustic conversionIDT structure directly related to the output response of the SAW device (including a wave shape and phase) consisting of IDT, To accurately analyze and design IDT structure, we need to consider the overall structural parameters, Including interdigitated electrode width, fork fingers spacing and coupling length. Now, IDT design algorithms not fully consider these parameters, This method is not suitable for the analysis and design of variable structure IDT.Therefore, The first main contents of the study project is to construct a mathematical model of IDT design. And Insertion loss is main technical indicators of evaluation performance of SAW . The key technology of developed SAW devices is how to reduce insertion loss、to reduce size and to Increase the carrying capacity of the power power. Traditional SAW device is passive, Its performance is subject to the performance of piezoelectric material、Interdigitated structure and preparation process. Another main study content is active compensation method of the insertion loss of the SAW device.

叉指换能器（Interdigital transducer,IDT）是声表面波（Surface Acoustic Wave,SAW）器件的关键组成部分，其作用是进行声-电，电-声转换。IDT的结构直接关系到其构成的SAW器件的输出响应（包括波形形状及相位），要准确分析和设计IDT结构，就需要整体考虑其结构参数，包括叉指电极宽度、指间间距及耦合长度。目前的IDT设计算法没有完全考虑这些参数，不利于可变结构IDT的分析与设计，因此，本项目研究的主要内容之一就是构建IDT设计的数学描述模型。而插入损耗又是评价SAW器性能的一个主要技术指标，研制SAW器件的关键技术是如何降低其插入损耗，减小体积，提高功耗承载能力。传统的SAW器件都是无源的，其性能指标受制于压电材料性能、叉指结构及制备工艺。本课题研究的另一个主要内容就是SAW器件插入损耗的有源补偿方法，在器件内部对前端的损耗进行能量的有源补偿。

本项目的研究从声表面波器件叉指换能器（IDT）的结构建模出发，在分析（IDT）传统数学模型基础上，构建了叠加式δ函数模型、积分式δ函数模型及Morlet小波函数模型等三种IDT建模模型。设计出7种不同结构的IDT，利用SI基AlN薄膜作为压电材料进行流片加工，封装测试，取得了较为满意的结果，为声表面波器件叉指换能器（IDT）的结构建模及损耗补偿提供了一种新的手段。