P1-36 端面反射型共振子の高周波化と温度特性改善(ポスター発表)

概要

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Most of Surface Acoustic Wave (SAW) RF filters and duplexers are composed of Al electrodes/36-48°YX-LiTaO_3 substrate, which has optimum coupling factor and optimum reflection coefficient but doesn't have a good temperature coefficient of frequency (TCP). The TCP can be improved by depositing SiO_2 film on a transversal SAW filter consisting of this substrate. However, because (a) a SiO_2/thin Al electrodes/LiTaO_3 structure with small bump on the SiO_2 surface and (b) a flattened SiO_2/thick Al electrodes/LiTaO_3 without bump have small reflection coefficient and (c) a SiO_2/thick Al electrodes/LiTaO_3 with large bump has small coupling factor, resonator type SAW devices using these structures don't show a good frequency characteristics. It is considered that an edge reflection of (a) and (b) structures has large reflection coefficient It has been difficult to obtain a high frequency edge reflection resonator because it requires very fine substrate edge. However, a high frequency edge reflection resonator with a good TCP and a frequency characteristic has been realized using the method to obtain fine edge developed by the authors.
超音波エレクトロニクスの基礎と応用に関するシンポジウム運営委員会の論文
2006-11-15