Interdigital capacitors and acoustic wave devices

Abstract

The present invention provides an interdigital capacitor that suppresses the excitation of elastic waves, and an elastic wave device comprising the interdigital capacitor and a resonator. [Solution] The device comprises a piezoelectric substrate 40, a resonator 10 formed on the piezoelectric substrate for exciting the main mode wave, and an interdigital capacitor 20 formed on the piezoelectric substrate, consisting of a pair of comb-shaped electrodes 21 and 22 with electrode fingers spaced apart from each other, wherein the interdigital capacitor constitutes an elastic wave device in which the pitch of the electrode fingers is unevenly arranged so as not to excite waves of modes other than the main mode and the main mode wave.

Claims

1. Piezoelectric substrate and A resonator formed on the piezoelectric substrate for exciting the main mode wave, An interdigital capacitor consisting of a pair of comb-shaped electrodes formed on the piezoelectric substrate, with electrode fingers interlocked with each other, Equipped with, The interdigital capacitor has an unevenly spaced electrode ring pitch so as not to excite waves of modes other than the dominant mode and waves of the dominant mode. Elastic wave device.

2. In the interdigital capacitor, in a direction perpendicular to the extension direction of the electrode fingers, the pitch of the electrode fingers from one end to the other of the interdigital capacitor gradually increases in the direction of the electrode fingers. The elastic wave device according to claim 1.

3. The interdigital capacitor is formed in a direction perpendicular to the extension direction of the electrode fingers, with multiple sections having different pitches for the electrode fingers from one end to the other, from the first section to the nth section, where n is a natural number of 3 or more. Within each of the aforementioned multiple sections, the pitch of the electrode fingers is the same, with multiple electrode fingers arranged at the same pitch. From the first section to the n section, the pitch of the electrode fingers gradually increases. The elastic wave device according to claim 1.

4. From the first section to the n section, the pitch of the electrode fingers increases by 10% or more. The elastic wave device according to claim 3.

5. The resonator formed on the piezoelectric substrate and which excites the main mode wave has IDT electrode fingers, and the extension direction of the IDT electrode fingers and the extension direction of the electrode fingers of the interdigital capacitor are not orthogonal. The elastic wave device according to claim 1.

6. Piezoelectric substrate and An interdigital capacitor comprising a pair of comb-shaped electrodes formed on the piezoelectric substrate, with electrode fingers interlocked with each other, The interdigital capacitor has an unevenly spaced electrode ring pitch so as not to excite waves of modes other than the dominant mode and waves of the dominant mode. Interdigital capacitor.

7. In the interdigital capacitor, in a direction perpendicular to the extension direction of the electrode fingers, the pitch of the electrode fingers from one end to the other of the interdigital capacitor gradually increases in the direction of the electrode fingers. The interdigital capacitor according to claim 6.

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