发明名称 |
Surface acoustic wave filter |
摘要 |
A surface acoustic wave filter has a plurality of interdigital transducers arranged in a ladder circuit structure. Each of the interdigital transducers (1) has a first comb-shaped electrode (10) and a second comb-shaped electrode (11), each of which has a plurality of electrode fingers (6; 7) and a bus bar (4; 5) connected to first ends of the plurality of electrode fingers (6; 7). The first and second comb-shaped electrodes (10, 11) interdigitate with each other so that second ends of the plurality of electrode fingers (6) of the first comb-shaped electrode (10) extend toward the bus bar (5) of the second comb-shaped electrode (11). A gap (W2) is created in at least one of the interdigital transducers (1) to cause a ripple in the pass band of the surface acoustic wave filter such that the ripple increases the steepness of the filter characteristics at the high frequency shoulder of the pass band. The gap (W2) is defined between the bus bar (4) of the first comb-shaped electrode (10) and the second ends of the plurality of electrode fingers (7) of the second comb-shaped electrode (11). The gap width should be in the range of about 0.50 lambda to about 4 lambda , wherein lambda is a wavelength of a surface acoustic wave to be excited on the piezoelectric substrate. <IMAGE> |
申请公布号 |
EP1005153(A3) |
申请公布日期 |
2001.01.17 |
申请号 |
EP19990402919 |
申请日期 |
1999.11.24 |
申请人 |
MURATA MANUFACTURING CO., LTD. |
发明人 |
TANIGUCHI, NORIO |
分类号 |
H03H9/145;H03H9/25;H03H9/64;(IPC1-7):H03H9/64 |
主分类号 |
H03H9/145 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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