Properties of Pseudo-mode Surface Acoustic Waves and Analysis of Layered SAW devices
Date Issued
2007
Date
2007
Author(s)
Huang, Chih-Yung
DOI
en-US
Abstract
As the development of communication equipments, the demand of faster information transferring is increasing. SAW devices are usually used in the mobile phones, radio system and global positioning systems (GPS). Increasing the frequency and decreasing the insertion loss of SAW become more and more important. SAW devices are usually consist of piezoelectric substrate with interdigital electrodes. The aim of this study is to investigate the propagation characteristics of SAW on substrate and simulate the frequency response of SAW to improve the design of SAW.
In the analysis of substrate, the matrix method was used to solve the propagation characterstics of semi-infinite piezoelectric medium. By utilizing the corrected wave number, the pseudo-modes SAW (PSAW) and the high velocity pseudo-modes SAW (HVPSAW) with higher phase velocity can be found and the propagation direction with lower propagation loss in the piezoelectric medium can also be calculated. On the other hand, the surface impedance tensor and the reflection tensor are introduced into the matrix to evaluate the propagation characteristics and dispersion effect of layered piezoelectric substrate. The effect of the thickness of metallic electrode and metallic film on the piezoelectric substrate was investigated, and the relation of dispersion effect in ZnO/Diamond/Si layered substrate was also calculated.
For simulation of SAW devices, the delta function model is applied to the preliminary analysis. The COM model that Abbott proposed is then used to simulate frequency responses of SAW filters and resonators, and investigate the effect of the number of IDT pairs and grating, overlap length and delay distance etc.. Finally, based on the ZnO/Diamond/Si substrate, the effect of the thickness of ZnO film and dispersion effect on COM parameters are evaluated. By using parameters of COM model, the SAW device with 1.5GHz center frequency can be designed.
In conclusion, the present study established a complete SAW device analysis theory and provided efficient analysis in the design and production of high frequency SAW devices.
Subjects
表面聲波
虛擬表面聲波
表面聲波元件
saw
psaw
hvpsaw
saw device
Type
thesis
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