Acoustic wave device
AssigneeMurata Manufacturing Co., Ltd.
InventorsTetsuya Kimura, Yutaka Kishimoto, Takeshi Nakao
Life of this patent
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Abstract
An acoustic wave device includes a piezoelectric board including a piezoelectric layer with a first principal surface and a second principal surface opposed to each other, an intermediate layer on the first principal surface or the second principal surface of the piezoelectric layer, and a functional electrode on the intermediate layer. A material of the intermediate layer is a same type as a material of the piezoelectric layer, and an electromechanical coupling coefficient of the intermediate layer is smaller than an electromechanical coupling coefficient of the piezoelectric layer.
Claims25
An acoustic wave device comprising:
- a piezoelectric board including a piezoelectric layer with a first principal surface and a second principal surface opposed to each other;
- an intermediate layer on the first principal surface or the second principal surface of the piezoelectric layer;
- and
- a functional electrode on the intermediate layer;
- wherein
- a material of the intermediate layer is a same type as a material of the piezoelectric layer, and an electromechanical coupling coefficient of the intermediate layer is smaller than an electromechanical coupling coefficient of the piezoelectric layer;
- and
- where a dielectric constant of the piezoelectric layer is εa and a dielectric constant of the intermediate layer is εb, about 0.9εa≤εb≤about 1.1εa.
An acoustic wave device comprising:
- a piezoelectric board including a piezoelectric layer with a first principal surface and a second principal surface opposed to each other;
- an intermediate layer on the first principal surface or the second principal surface of the piezoelectric layer;
- and
- a functional electrode on the intermediate layer;
- wherein
- a material of the intermediate layer is a same type as a material of the piezoelectric layer, and an electromechanical coupling coefficient of the intermediate layer is smaller than an electromechanical coupling coefficient of the piezoelectric layer;
- and
- the functional electrode is an interdigital transducer electrode including a plurality of electrode fingers.
An acoustic wave device comprising:
- a piezoelectric board including a piezoelectric layer with a first principal surface and a second principal surface opposed to each other;
- an intermediate layer on the first principal surface or the second principal surface of the piezoelectric layer;
- and
- a functional electrode on the intermediate layer;
- wherein
- a material of the intermediate layer is a same type as a material of the piezoelectric layer, and an electromechanical coupling coefficient of the intermediate layer is smaller than an electromechanical coupling coefficient of the piezoelectric layer;
- the piezoelectric board includes a high acoustic velocity material layer, and the piezoelectric layer is provided on the high acoustic velocity material layer;
- and
- an acoustic velocity of bulk waves to propagate in the high acoustic velocity material layer is higher than an acoustic velocity of acoustic waves to propagate in the piezoelectric layer.
Dependencies are inferred from the claim text.