Acoustic wave device, high frequency front end circuit, and communication apparatus
AssigneeMurata Manufacturing Co., Ltd.
InventorMasakazu Mimura
Life of this patent
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Abstract
An acoustic wave device includes a piezoelectric substrate made of LiNbO3, and a dielectric film provided on the piezoelectric substrate to cover first and second IDT electrodes on the piezoelectric substrate. The first and second IDT electrodes include main electrode layers. When wave lengths determined by electrode finger pitches of the first and second IDT electrodes are λ1 and λ2, respectively, the average value thereof is λ0, λ1/λ0=1+X, and λ2/λ0=1−X, a relationship of 0.05≤X≤0.65 is satisfied. The wavelength λ1 is the longest, and the wavelength λ2 is the shortest. In Euler angles (φ, θ, ψ) of the piezoelectric substrate, φ is 0°±5°, ψ is 0°±10°, and θ satisfies Expression 1, wherein a relationship of B1<T×r≤0.10λ0 and B2<T×r≤0.10λ0 are satisfied.
Claims3
A high frequency front end circuit comprising:
- a power amplifier;
- and
- an acoustic wave device including:
- a piezoelectric substrate made of LiNbO3 (lithium niobate);
- a plurality of interdigital transducer (IDT) electrodes provided on the piezoelectric substrate and including a first IDT electrode and a second IDT electrode;
- and
- a dielectric film provided on the piezoelectric substrate to cover the plurality of IDT electrodes;
- wherein
- the dielectric film includes silicon oxide as a main ingredient;
- the first IDT electrode and the second IDT electrode include main electrode layers;
- a film thickness and a material of the main electrode layer of the first IDT electrode are the same or substantially the same as a film thickness and a material of the main electrode layer of the second IDT electrode;
- a film thickness of a portion of the dielectric layer provided on the first IDT electrode is equal or substantially equal to a film thickness of a portion of the dielectric film provided on the second IDT electrode;
- a plurality of band pass filters belonging to communication bands of different pass bands are provided on the piezoelectric substrate;
- an antenna terminal to be connected to an antenna is provided on the piezoelectric substrate;
- the plurality of band pass filters are commonly connected to the antenna terminal to define a composite filter;
- and
- among the plurality of IDT electrodes, a wave length λ1 determined by an electrode finger pitch of the first IDT electrode is the longest, and a wave length λ2 determined by an electrode finger pitch of the second IDT electrode is the shortest.
Dependencies are inferred from the claim text.