The Characteristics of SAW Devices with IIDT Structure

• Main Authors: Jiann-Chuan Jong, 鐘建川
• Other Authors: Long Wu
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/82931592158249618018

碩士 === 國立成功大學 === 電機工程學系碩博士班 === 91 === In this thesis, the principles and the character of the Surface Acoustic Wave (SAW) devices are introduced first. Then six different IDT types and one normal IDT type are based on IIDT structure. By way of simulation and experiment results realized on 64o YX-LiNbO3 substrates are pressented. Each of IIDT SAW devices has the three different input and output pairs (3:2,4:3,5:4), so there are totally twenty one experiment results. The experiment results are when normal IDT’s input and output pairs rate is 3:2, and its insertion loss is —8.02dB, when the rate is 4:3, its insertion loss is —7.17dB, and when the rate is created to 5:4, its insertion loss is —5.82dB. In the thesis, we can creat the input and output rate unlimited, then the insertion loss will be closed to the ideal value zero, but it will also increase the devices size. Acording to the results, when we use 4 Fingers as IDT structure, it’s the best insertion loss is —10.1dB, and 3 Fingers insertion loss is —10.75dB, and 2 Fingers insertion loss is —12.75dB. Therefore, using the 4 Fingers IDT structure its insertion loss character will better than 3 Fingers and 2 Fingers. Compare the normal and different IDT structure, the former has better insertion loss and bassband ripple, and the latter has more than 5 dB sidelobe rejection.