摘要:
An acoustic wave element includes: a piezoelectric substrate; an IDT (Interdigital Transducer) formed on the piezoelectric substrate; and an end face of the piezoelectric substrate that is formed on at least one end of the IDT in a propagation direction of an acoustic wave; wherein when a wavelength of the acoustic wave which the IDT excites is expressed by “λ” and a metallization ratio of the IDT is expressed by “D”, a distance between an inner end of an electrode finger of the IDT nearest to the end face and the end face is equal to or more than 7λ/16+D×λ/4 and equal to or less than 3λ/4+D×λ/4.
摘要:
A duplexer includes a reception filter that is connected between a reception terminal and an antenna terminal and includes one or a plurality of series resonators that are acoustic wave resonators, and a transmission filter that is connected between a transmission terminal and the antenna terminal and includes one or a plurality of acoustic wave resonators, a resonance frequency of a first series resonator that is one of the one or the plurality of series resonators and is closest to the antenna terminal in the reception filter being higher than an upper limit frequency of a reception band of the reception filter.
摘要:
An electromechanical device having a resonator using acoustic waves propagating laterally within a piezoelectric plane resonant structure and electrodes on a face of said structure. The resonant structure comprises: a transduction region having a transduction length and generating acoustic waves; a free propagation region for the acoustic waves, adjacent to the transduction region and defined the plane of the transduction region; the resonant structure length being equal to an integer number of half-wavelengths, the resonance frequency of said resonator equaling the average propagation velocity of the wave within the structure divided by said wavelength, to adjust the quality factor of the resonator fixed by the length of the resonant structure and the coupling coefficient fixed by the ratio of the transduction length over the length of the resonant structure; the resonant structure defined by the assembly of the transduction region and the propagation region being laterally bounded by reflection regions.
摘要:
A transversal filter operates using surface acoustic waves and has a piezoelectric substrate and an acoustic track that is arranged on the substrate and in which a first transducer and a second transducer are arranged. Each transducer has electrode fingers. A function, which characterizes the weighting of the overlap length of electrode fingers of different polarity in the second transducer, has a half main lobe and at least one side lobe. The amplitude of the lobes decreases monotonally in a direction that points to the first transducer.
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:
The invention provides a piezoelectric substrate in the form of a rectangular plate in which a Rayleigh wave is propagated, and an IDT and a reflector are provided by forming interdigital electrodes on the piezoelectric substrate. At least an end face on a shorter side of the piezoelectric substrate on a top side thereof is formed as a vertical smooth surface that is substantially in parallel with a conductor strip at an end of the reflector in the position of an imaginary node of a stress wave exiting the conductor strip, thereby providing a reflecting end face to reflect the stress wave.
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-face reflecting-type surface wave resonator using the SH-type surface wave achieves two types of resonance characteristics by use of only a single device. An interdigital transducer having a pair of comb-like electrodes are formed on a piezoelectric substrate having two oppositely-facing end faces. The interdigital transducer has two peaks of main lobes and are assigned with weights so that the two peaks of main lobes substantially coincide with frequency positions of attenuation poles disposed across a main lobe of a virtual normal-type interdigital transducer having the same number of pairs of electrodes as the weighted interdigital transducer. Thus, two types of resonance characteristics can be obtained.
摘要:
A coupled cavity filter structure that uses a surface acoustic wave, in particular, a guided surface acoustic wave, comprises an acoustic wave propagating substrate, at least one input transducer structure and one output transducer structure, provided over the substrate, each comprising inter-digitated comb electrodes, at least one reflecting structure comprising at least one or more metallic strips positioned at a distance and in between the input and output transducer structures, in the direction of propagation of an acoustic wave. The acoustic wave propagating substrate is a composite substrate comprising a base substrate and a piezoelectric layer. In additional embodiments, a coupled cavity filter structure comprises a groove. In additional embodiments, a SAW ladder filter device comprises at least two coupled cavity filter structures as described herein, wherein the at least two coupled cavity filter structures are positioned on a single line.
摘要:
A surface acoustic wave (SAW) resonator and a SAW oscillator and an electronic apparatus including the resonator are to be provided. A SAW resonator includes: an IDT exciting a SAW using a quartz crystal substrate of Euler angles (−1.5°≦φ≦1.5°, 117°≦θ≦142°, 42.79°≦|ψ|≦49.57°); one pair of reflection units arranged so as allow the IDT to be disposed therebetween; and grooves acquired by depressing the quartz crystal substrate located between electrode fingers. When a wavelength of the SAW is λ, and a depth of the grooves is G, “0.01λ≦G” is satisfied.