Surface Acoustic Wave Devices and Filters

Abstract

Surface acoustic wave devices and filters. A surface acoustic wave device includes: a pair of comb electrodes formed on a piezoelectric substrate, each of the pair of comb electrodes includes a plurality of electrode fingers, a plurality of dummy electrode fingers, and a combination of the electrode fingers and the dummy electrodes. Refers to the bus bar connected, the electrode finger and the dummy electrode finger of one of the pair of comb-shaped electrodes face the dummy electrode finger and the electrode finger of the other comb-shaped electrode respectively; and in the first direction in which the electrode fingers are arranged side by side a plurality of additional films extending strip-like, each of the additional films covering an end defined by an electrode finger end of one of the pair of comb electrodes and a dummy electrode finger end of the other comb electrode at least part of the gap.

Description

technical field [0001] Certain aspects of the invention relate to a surface acoustic wave device and filter. Background technique [0002] As an acoustic wave device utilizing acoustic waves, there is known a surface acoustic wave (SAW) device comprising: an interdigital transducer (IDT) including a pair of comb-shaped electrodes on a piezoelectric substrate; and a For reflectors, the IDT is located on the piezoelectric substrate between the pair of reflectors. SAW devices are used in bandpass filters in various circuits that process wireless signals in the frequency range from 45 MHz to 2 GHz (commonly used in cellular phones). In recent years, with the improvement in performance (for example, multi-band or multi-mode performance) of wireless communication devices, usually cellular phones, for the purpose of improving receiver sensitivity and reducing power consumption of these wireless communication devices, reductions have been required. The insertion loss of the filter...

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Problems solved by technology

However, this method results in a frequency shift and is difficult to manufacture

In addition, a structure in which a metal film or the like is added to the end of the electrode fingers (for example, see Japanese Patent Application Laid-Open No. 2012-186808) may adversely affect a certain characteristic such as a decrease in electromechanical coupling coefficient

There is difficulty in manufacturing an acoustic wave device using such a method described in Japanese Patent Application Laid-Open No. 2009-278429 which discloses a structure in which an insulator is buried between an electrode finger and a bus bar or between an electrode finger and a dummy electrode

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