| 摘要 |
A first electrode structure row formed on a piezoelectric substrate, and including N1 pairs of an input/output IDT, N2 pairs of a connection IDT, and reflectors is cascade-connected to a second electrode structure row formed on the piezoelectric substrate, and including N1 pairs of an input/output IDT, N2 pairs of a connection IDT, and reflectors, the connection IDT of the first electrode structure row, and the connection IDT of the second electrode structure row being arranged to be electrically symmetric with respect to the cascade-connected plane. The pair number N1 of the input/output IDT is different from the pair number N2 of the connection IDT. When a normalized electrode film thickness of the input/output IDT and the connection IDT is represented by h/L, the pair number N1 of the input/output IDT satisfies the following formula <MATH> The surface acoustic wave device can realize good filter characteristics of low insertion losses, small amplitude ripples and group delay time ripples, relatively large specific bandwidths, good shape factors, large attenuation, and is useful as filters for use in mobile communications, etc., especially as intermediate frequency filters for use in digital communications. <IMAGE>
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