Reflection inversion surface acoustic wave transducer and filter
AssigneeToyo Communication Equipment Co., Ltd.
InventorKazuhiro Hirota
Life of this patent
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Abstract
A surface acoustic wave transducer is provided having three electrode fingers disposed as one reference segment (λ) on a piezoelectric substrate, each segment including an electrode finger 1 having a width W1, an electrode finger 2 having a width W2 with a gap of g1, and an electrode 3 having a width 3 with a gap g2. The electrode fingers 1 and 3 are set in-phase, and the electrode finger 2 is set in an opposite phase for driving. Further, W1 is set equal to W3, and g1 is set equal to g2. Thus, it is possible to provide a SAW transducer that has improved a shape factor at a high-pass side near a pass band of a primary-third order longitudinally coupled double mode SAW filter.
Claims4
A reflection reversed type surface acoustic wave transducer, wherein a surface acoustic wave transducer is structured by a repetition of a plurality of unit segments formed on a piezoelectric substrate, each segment comprising:
- a first electrode finger having a width W1;
- a second electrode finger having a width W2 disposed adjacent to the first electrode finger with a gap g1;
- a third electrode finger having a width W3 disposed adjacent to the second electrode finger with a gap g2;
- and
- a space of (g3)/2 disposed adjacent said first electrode finger and opposite side of said gap g1;
- a space of (g3)/2 disposed adjacent said third electrode finger and opposite side of said gap g2;
- wherein
- said first and third electrode fingers are driven by AC signal in-phase respectively, and said second electrode finger is driven by AC signal which is an opposite phase with said AC signal applied to said first and third electrode fingers, the width W1 of the first electrode finger and the width W3 of the third electrode finger are set equal to each other, the gap g1 and the gap g2 are set equal to each other, and except the condition that W1=W2 and g1=g3.
Dependencies are inferred from the claim text.