Surface acoustic wave device and communications apparatus using the same
AssigneeSeiko Epson Corporation
InventorsTakashi Yamazaki, Keigo Iizawa, Shigeo Kanna
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Abstract
The invention provides an in-plane rotational ST-cut SAW resonator that is formed of an in-plane rotational ST-cut crystal plate having Eulerian angles of (0°, 113° to 135°, and ±(40° to 49°)). The in-plane rotational ST-cut SAW resonator can include an interdigital transducer (IDT) electrode for exciting a Rayleigh wave on the main surface. The ratio Lt/Pt of the electrode width Lt and the interelectrode pitch Pt of the IDT electrode is 0.5 or more and 0.65 or less. Accordingly, a reduction in the fluctuation in resonance frequency relative to the variations in an IDT electrode of a surface acoustic wave device by using the in-plane rotated ST-cut crystal plate around the Z′-axis can be achieved.
Claims2
A surface acoustic wave device having an interdigital transducer electrode that excites a Rayleigh wave on a main surface of an in-plane rotational ST-cut crystal plate having Eulerian angles of (0°, 113° to 135°, and ±(40° to 49°)), a ratio of an electrode width (Lt) and an interelectrode pitch (Pt) of said interdigital transducer electrode being 0.5 or more and 0.65 or less,
- when said Eulerian angles are expressed by (φ, θ, and ±ψ), that a lower limit of ψ is within the range of |ψ|=|−0.317θ+81.82°|, and an upper limit of ψ is within the range of |ψ|=|0.160θ+27.78°|.
Dependencies are inferred from the claim text.