US 2003/0164657 A1 · Surface acoustic wave device and piezoelectric substrate used therefor

Abstract

A compact and wide band surface acoustic wave device for intermediate-frequency is disclosed. A piezoelectric substrate for use in a surface acoustic wave device having high electromechanical coupling factor and low SAW velocity is also disclosed. The surface acoustic wave device is constituted of a piezoelectric substrate 1 and inter-digital electrodes 2, 2 formed on the piezoelectric substrate 1. The piezoelectric substrate 1 has a crystal structure of Ca3Ga2Ge4O14 and is represented by the chemical formula, Ca3TaGa3Si2O14. A cut angle of the piezoelectric substrate 1 cut out of the single crystal and a direction of propagation of surface acoustic waves on the piezoelectric substrate represented in terms of Euler's angles (φ, θ, ψ) are found in an area represented by −2.5°≦φ≦2.5°, 30°≦θ≦90°, and −65°≦ψ≦65°.

Claims59

Dependent claims

A surface acoustic wave device comprising a piezoelectric substrate and inter-digital electrodes formed on the piezoelectric substrate, wherein:

the piezoelectric substrate has a crystal structure of the Ca3Ga2Ge4O14 type and is represented by the chemical formula, Ca3TaGa3Si2O14;
and
a cut angle of the piezoelectric substrate cut out of the single crystal and a direction of propagation of surface acoustic waves on the piezoelectric substrate represented in terms of Euler's angles (φ, θ, ψ) are found in an area represented by −2.5°≦φ≦2.5°, 30°≦θ≦90°, and −65°≦ψ≦65°.

A piezoelectric substrate for use in a surface acoustic wave device, characterized in that the piezoelectric substrate has a crystal structure of Ca3Ga2Ge4O14 type and is represented by the chemical formula, Ca3TaGa3Si2O14;

and a cut angle of the piezoelectric substrate cut out of the single crystal and a direction of propagation of surface acoustic waves on the piezoelectric substrate represented in terms of Euler's angles (φ, θ, ψ) are found in one of a first area represented by −2.5°≦φ≦2.5°, 30°≦θ≦90°, and −65°≦ψ≦65°, a second area represented by −2.5°≦φ≦2.5°, 120°≦θ≦155°, and 65°≦ψ≦85°, a third area represented by −2.5°≦φ2.5°, 120°≦θ≦155°, and −85°≦ψ≦−65°, a fourth area represented by 2.5°≦φ≦7.5°, 30°≦θ≦90°, and −75°≦ψ≦60°, a fifth area represented by 2.5°≦φ≦7.5°, 120°≦θ≦150°, and 75°≦ψ≦85°, a sixth area represented by 2.5°≦φ≦7.5°, 120°≦θ≦155°, and −85°≦ψ≦−60°, a seventh area represented by 7.5°≦φ≦12.5°, 30°≦θ≦100°, and −80°≦ψ≦55°, an eighth area represented by 7.5°≦φ≦12.5°, 120°≦θ≦150°, and 75°≦ψ85°, a ninth area represented by 7.5°≦φ≦12.5°, 110°≦θ≦155°, and −85°≦ψ≦55°, a tenth area represented by 12.5°≦φ≦17.5°, 20°≦θ≦105°, and −85°≦ψ≦−50°, an eleventh area represented by 12.5°≦φ≦17.5°, 125°≦θ≦140°, and 80°≦ψ≦85°, a twelfth area represented by 12.5°≦φ≦17.5°, 115°≦θ≦155°, and −85°≦ψ≦−50°, a thirteenth area represented by 17.5°≦φ≦22.5°, 25°≦θ≦70°, and −80°≦ψ≦−20°, a fourteenth area represented by 17.5°≦φ≦22.5°, 25°≦θ≦110°, and −20°≦ψ≦40°, a fifteenth area represented by 17.5°≦φ≦22.5°, 115°≦θ≦155°, and −80°≦ψ≦−45°, a sixteenth area represented by 22.5°≦φ≦27.5°, 25°≦θ≦70°, and −85°≦ψ≦−20°, a seventeenth area represented by 22.5°≦φ≦27.5°, 25°≦θ≦145°, and −20°≦ψ≦−40°, an eighteenth area represented by 22.5°≦φ≦27.5°, 110°≦θ≦155°, and −80°≦ψ≦−40°, a nineteenth area represented by 27.5°≦φ≦32.5°, 25°≦θ≦70°, and −85°≦ψ≦−30°, a twentieth area represented by 27.5°≦φ≦32.5°, 30°≦θ≦150°, and −30°≦ψ≦40°, and a twenty-first area represented by 27.5°≦φ≦32.5°, 110°≦θ≦155°, and −85°≦ψ≦−30°.

Dependencies are inferred from the claim text.

Surface acoustic wave device and piezoelectric substrate used therefor

Life of this patent

Surface acoustic wave device and piezoelectric substrate used therefor

Life of this patent

Abstract

Claims59