发明授权
US5874869A Surface acoustic wave filter device on 40.degree. to 42.degree. rotated
Y-X LITAO.sub.3
失效
表面声波滤波器装置在40°〜42°旋转Y-X LITAO3
- 专利标题: Surface acoustic wave filter device on 40.degree. to 42.degree. rotated Y-X LITAO.sub.3
- 专利标题(中): 表面声波滤波器装置在40°〜42°旋转Y-X LITAO3
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申请号: US925732申请日: 1997-09-09
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公开(公告)号: US5874869A公开(公告)日: 1999-02-23
- 发明人: Masanori Ueda , Osamu Kawachi , Gou Endoh , Yoshiro Fujiwara
- 申请人: Masanori Ueda , Osamu Kawachi , Gou Endoh , Yoshiro Fujiwara
- 申请人地址: JPX Kanagawa
- 专利权人: Fujitsu Limited
- 当前专利权人: Fujitsu Limited
- 当前专利权人地址: JPX Kanagawa
- 优先权: JPX8-318270 19961128
- 主分类号: H01L41/09
- IPC分类号: H01L41/09 ; H03H9/00 ; H03H9/02 ; H03H9/145 ; H03H9/25 ; H03H9/64
摘要:
A surface acoustic wave device includes a piezoelectric substrate of a LiTaO.sub.3 single crystal, the crystal having X, Y and Z axes and a cut plane. The X axis of the crystal is oriented in a direction of propagation of surface acoustic waves. The cut plane of the crystal is rotated around the X axis at a rotated angle from the Y axis to the Z axis, the rotated angle being in a range between 40.degree. and 42.degree.. A pair of reflectors are formed on the substrate and aligned in a row in the direction of propagation. Interdigital transducers are formed on the substrate and aligned in the row in the direction of propagation, the interdigital transducers interposed between the reflectors, each interdigital transducer having pairs of mutually opposed primary electrode fingers and secondary electrode fingers, the interdigital transducers including at least a front transducer, a middle transducer and a rear transducer aligned in the row in the direction of propagation. In the device, a ratio of the number of pairs of the electrode fingers in one of the front transducer and the rear transducer to the number of pairs of the electrode fingers in the middle transducer is in a range between 55% and 80%.