High frequency resonators with excellent temperature characteristic using edge reflection

Michio Kadota, Tetsuya Kimura, Daisuke Tamasaki

研究成果: Conference contribution

8 被引用数 (Scopus)

抄録

Most surface acoustic wave (SAW) radio frequency (RF) filters and duplexers have the Al-electrodes/36-48°YX-LiTaO3 substrate structure, which has an optimum coupling factor and an optimum reflection coefficient but does not have a good temperature coefficient of frequency (TCF). The TCF can be improved by depositing SiO2 film with positive TCF on a transversal SAW filter consisting of a substrate with negative TCF such as LiTaO3 and LiNbO3. However, resonator-type SAW devices combining SiO 2 film, Al electrodes, and LiTaO3 substrate do not show a good frequency characteristics regardless of Al thickness. Because both (a) a SiO2/thin Al-electrodes/LiTaO3 structure with small convex portions on the SiO2 surface and (b) a flattened SiO 2/Al-electrodes/LiTaO3 structure have a small reflection coefficient, and (c) a SiO2/thick Al-electrodes/LiTaO3 structure with large convex portions has a small coupling factor. It is considered as a counter-measure that a resonator using the reflection of a shear horizontal (SH) wave at substrate edges of their structures shows a good frequency characteristic because its reflection coefficient is very large regardless of Al thickness. It has been difficult to obtain a high-frequency edge reflection resonator because it requires too fine substrate edges for ordinary machining techniques. However, a high-frequency edge reflection resonator with a good TCF and an excellent frequency characteristic has been realized using our newly developed method of obtaining fine edges.

本文言語English
ホスト出版物のタイトル2006 IEEE International Ultrasonics Symposium, IUS
ページ1878-1882
ページ数5
DOI
出版ステータスPublished - 2006 12月 1

出版物シリーズ

名前Proceedings - IEEE Ultrasonics Symposium
1
ISSN(印刷版)1051-0117

ASJC Scopus subject areas

  • 音響学および超音波学

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