摘要:
A surface acoustic wave device includes a Y-cut, X-propagation LiTaO3 substrate, at least one interdigital transducer provided on the LiTaO3 substrate and made of Al or a metal containing Al as a major component, and an SiO2 film provided on the surface of the LiTaO3 substrate so as to cover the interdigital transducer, wherein the thickness Hs of the SiO2 film normalized by the wavelength λ of a surface acoustic wave and the cut angle θ of the LiTaO3 substrate are set to be in any one of the ranges represented by formulae (1) to (8): in the case of 0.00
摘要:
An end-surface reflection type surface acoustic wave filter is capable of increasing an attenuation amount outside a pass band while insertion loss characteristics are not seriously deteriorated. The filter is a longitudinally coupled resonator type surface acoustic wave filter using an SH type surface acoustic wave, which has first and second grooves formed in a piezoelectric substrate at the top surface thereof so as to be substantially parallel to each other and spaced from each other by a predetermined distance. In addition, IDTs which are provided between the grooves for defining the longitudinally coupled resonator type surface acoustic wave filter, reflection end-surfaces disposed on side surfaces of the first and the second grooves at the IDT sides, and one of a resin-coating layer and a protective layer made of SiO2, are provided on the top surface of the piezoelectric substrate. The resin-coating layer is arranged to cover at least a region at which the IDTs are located and at least one of the first and the second grooves so as to intrude into one of them, and the protective layer is arranged so as to cover the IDTs.
摘要:
An end-surface reflection type surface acoustic wave filter is capable of increasing an attenuation amount outside a pass band while insertion loss characteristics are not seriously deteriorated. The filter is a longitudinally coupled resonator type surface acoustic wave filter using an SH type surface acoustic wave, which has first and second grooves formed in a piezoelectric substrate at the top surface thereof so as to be substantially parallel to each other and spaced from each other by a predetermined distance. In addition, IDTs which are provided between the grooves for defining the longitudinally coupled resonator type surface acoustic wave filter, reflection end-surfaces disposed on side surfaces of the first and the second grooves at the IDT sides, and one of a resin-coating layer and a protective layer made of SiO2, are provided on the top surface of the piezoelectric substrate. The resin-coating layer is arranged to cover at least a region at which the IDTs are located and at least one of the first and the second grooves so as to intrude into one of them, and the protective layer is arranged so as to cover the IDTs.
摘要:
A method for adjusting a frequency characteristic of an edge reflection type surface acoustic wave device includes the step of obtaining a frequency characteristic of an edge reflection type surface acoustic wave device having a piezoelectric substrate. The edge reflection type surface acoustic wave device has a pair of edges of the piezoelectric substrate which define a predetermined distance therebetween. The piezoelectric substrate is cut at a position which defines a distance that is shorter than the predetermined distance when a final frequency characteristic of the edge reflection type surface acoustic wave device is to be higher than the obtained frequency characteristic. The piezoelectric substrate is cut at a position which defines a distance that is longer than the predetermined distance when a final frequency characteristic of the edge reflection type surface acoustic wave device is to be lower than the obtained frequency characteristic.
摘要:
An edge reflection type surface acoustic wave device utilizes a Shear Horizontal type surface acoustic wave and includes a surface acoustic wave substrate, and at least two interdigital transducers provided on one main surface of the surface acoustic wave substrate. First and second grooves are formed on the opposite ends in the surface acoustic wave propagation direction of the area where the interdigital transducer is provided. The first and second grooves extend from the one main surface of the surface acoustic wave substrate toward the other main surface thereof without reaching the other main surface. The grooves extend substantially perpendicularly to the surface acoustic wave propagation direction so as to define first and second edges for reflecting the surface acoustic wave. The first and second edges are defined by the inner sideively. walls of the first and second grooves, respectively.
摘要:
A surface acoustic wave filter apparatus includes a plurality of stages of multi-mode filters defined by edge-reflection type surface acoustic wave devices and electrically connected in series with each other. The plurality of stages of multi-mode filters are provided on a common piezoelectric substrate and arranged in a direction which is substantially perpendicular to the propagation direction of surface acoustic waves. Ground electrodes are located between the stages of the plurality of stages of multi-mode filters.
摘要:
A free edge reflective-type surface wave resonator for reflecting SH-type surface waves between two confronting free edges of a piezoelectric substrate includes a piezoelectric substrate having two confronting free edges and an interdigital transducer having a plurality of electrode fingers which are weighted by a cross width weighting method or an electrode thinning method. The weighting of the electrode fingers is performed so that an attenuation pole of a main lobe of the weighted IDT is located outside of a frequency of an attenuation pole of a normal non-weighted IDT which has the same number of electrode finger pairs as the weighted IDT. The weighting of the electrodes is such that the main lobe of the weighted IDT and a plurality of resonance characteristics determined by the attenuation poles of the normal unweighted IDT are obtained.
摘要:
A longitudinally coupled resonator-type surface acoustic wave device includes interdigital transducers including a plurality of electrode fingers disposed along the propagation direction of a surface acoustic wave on a surface acoustic wave device. An electrically discontinuous portion is provided in a central portion, in the finger overlap direction, in adjacent electrode fingers in adjacent interdigital transducers, and at least one floating electrode is disposed in the finger overlap direction in the electrically discontinuous portion.
摘要:
A method of manufacturing an edge reflection type surface acoustic wave device includes the step of preparing a surface acoustic wave mother substrate having a plurality of interdigital transducers formed on one main surface thereof. A cut groove is formed in the substrate by cutting the surface acoustic wave mother substrate beginning from the one main surface side thereof. This step of forming a cut groove is repeated so as to produce a plurality of cut grooves so that the first reflection edge of the respective surface acoustic wave devices are sequentially formed. Next, similarly, cut grooves are sequentially formed on the surface acoustic wave mother substrate from the one main-face side thereof so as not to reach the other main surface thereof, whereby the second reflection edges of the respective surface acoustic wave devices are sequentially formed.
摘要:
An edge reflection type surface acoustic wave filter includes a piezoelectric substrate having two opposing edges and at least one interdigital transducer. The interdigital transducer includes split electrodes of paired electrode fingers arranged on the piezoelectric substrate such that a shear horizontal (SH-type) surface acoustic wave is excited on the piezoelectric substrate and is reflected between the two opposing edges. Each of the edges is preferably located at a distance of at least about &lgr;/2−5&lgr;/128 from a center of the paired equipotential electrode fingers, located at the respective outermost portions, in the surface acoustic wave propagation direction, of the interdigital transducer and less than about &lgr;/2 from the center of the paired equipotential electrode fingers, where &lgr; is a wavelength of the SH-type surface acoustic wave excited on the piezoelectric substrate.