Wave transmission lines and networks – Coupling networks – Electromechanical filter
Reexamination Certificate
2005-07-01
2009-08-25
Summons, Barbara (Department: 2817)
Wave transmission lines and networks
Coupling networks
Electromechanical filter
C310S31300R, C310S31300R, C333S193000
Reexamination Certificate
active
07579932
ABSTRACT:
A longitudinally coupled multi-mode SAW resonator filter includes input and output interdigital transducers (IDTs) with a control IDT therebetween to control a state of the surface acoustic wave. The input, output, and control IDTs alternatively arrange two different zones C and E having respective electrode period lengths PC and PE, being equal to a sum of the electrode finger width L and spacing S between electrode fingers, and a number of respective pairs MC and ME of electrode fingers is set to 1 in both zones C and E. Electrode fingers in zones C and E are all connected to a feeder conductor. Hence, a filter having small insertion loss, and a wide fractional bandwidth of 2000-4000 ppm is achieved by canceling and decreasing sums of reflected waves from the electrode fingers in zones C and E, and decreasing the effective reflection coefficient per the electrode finger.
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Machine translation of JP 8-298432 published Nov. 12, 1996.
T. Nishikawa et al., “SH-Type Surface Acoustic Waves on Rotated Y-Cut Quartz”, Proc. 34thAnn. Freq. Control Symposium, (May 1980) pp. 286-291.
H. Yatsuda, “SAW Device Assembly Technology”, International Symposium on Acoustic Wave Device for Future Mobile Communication System, Chiba University, (Mar. 5, 2001) pp. 189-194.
Oshio Masahiro
Takagi Michiaki
Yoneya Katsuro
Oliff & Berridg,e PLC
Seiko Epson Corporation
Summons Barbara
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