Surface acoustic wave apparatus and communications unit
First Claim
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1. A surface acoustic wave apparatus comprising:
- a piezoelectric substrate;
a first surface acoustic wave filter device including a plurality of interdigital electrodes provided on the piezoelectric substrate along a direction in which a surface acoustic wave propagates; and
a second surface acoustic wave filter device including a plurality of interdigital electrodes provided on the piezoelectric substrate along a direction in which a surface acoustic wave propagates, a propagation path of said first surface acoustic wave filter device being partially overlapped with a propagation path of said second surface acoustic wave filter device, wherein when the center-to-center distance between said first surface acoustic wave filter device and said second surface acoustic wave filter device is indicated by d1, and when the thickness of said piezoelectric substrate indicated by t, said first surface acoustic wave filter device, said second surface acoustic wave filter device, and said piezoelectric substrate are arranged to satisfy a condition d1≦
2.3×
t or d1≧
2.8×
t.
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Abstract
In a surface acoustic wave (SAW) apparatus, a first SAW filter device and a second SAW filter device are disposed on a piezoelectric substrate such that their respective propagation paths overlap. When the center-to-center distance between the first and second SAW filter devices are indicated by d1, and when the thickness of the piezoelectric substrate is indicated by t, the first and second SAW filter devices and the piezoelectric substrate are arranged so as to satisfy the condition d1≦2.3×t or d1≧2.8×t.
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Citations
20 Claims
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1. A surface acoustic wave apparatus comprising:
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a piezoelectric substrate;
a first surface acoustic wave filter device including a plurality of interdigital electrodes provided on the piezoelectric substrate along a direction in which a surface acoustic wave propagates; and
a second surface acoustic wave filter device including a plurality of interdigital electrodes provided on the piezoelectric substrate along a direction in which a surface acoustic wave propagates, a propagation path of said first surface acoustic wave filter device being partially overlapped with a propagation path of said second surface acoustic wave filter device, wherein when the center-to-center distance between said first surface acoustic wave filter device and said second surface acoustic wave filter device is indicated by d1, and when the thickness of said piezoelectric substrate indicated by t, said first surface acoustic wave filter device, said second surface acoustic wave filter device, and said piezoelectric substrate are arranged to satisfy a condition d1≦
2.3×
t or d1≧
2.8×
t. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A surface acoustic wave apparatus comprising:
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a piezoelectric substrate;
a first surface acoustic wave filter device including a plurality of interdigital electrodes provided on said piezoelectric substrate along a direction in which a surface acoustic wave propagates;
a second surface acoustic wave filter device including a plurality of interdigital electrodes provided on said piezoelectric substrate along a direction in which a surface acoustic wave propagates;
a third surface acoustic wave filter device including a plurality of interdigital electrodes provided on said piezoelectric substrate along a direction in which a surface acoustic wave propagates; and
a fourth surface acoustic wave filter device including a plurality of interdigital electrodes provided on said piezoelectric substrate along a direction in which a surface acoustic wave propagates, said first surface acoustic wave filter device and said third surface acoustic wave filter device being cascade-connected, said second surface acoustic wave filter device and said fourth surface acoustic wave filter device being cascade-connected, a propagation path of said first surface acoustic wave filter device being partially overlapped with a propagation path of said second surface acoustic wave filter device, and a propagation path of said third surface acoustic wave filter device being partially overlapped with a propagation path of said fourth surface acoustic wave filter device;
whereinwhen the center-to-center distance between said first surface acoustic wave filter device and said second surface acoustic wave filter device is indicated by d1, when the center-to-center distance between said third surface acoustic wave filter device and said fourth surface acoustic wave filter device is indicated by d2, and when a wavelength of a surface acoustic wave to be excited is indicated by λ
, said first through fourth surface acoustic wave filter devices are arranged such that the center-to-center distance d1 is differentiated from the center-to-center distance d2 by an amount approximately equal to (2n+1)×
0.5λ
(n=0, 1, 2, 3, and so on). - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification