Abstract: A surface acoustic wave device, comprising a lithium-tantalate substrate and an IDT electrode that excites a pseudo-longitudinal wave type leaky surface acoustic wave in the surface of the lithium-tantalate substrate, wherein a normalized substrate thickness t/?, which is a thickness t of the lithium-tantalate substrate normalized by an IDT wavelength ?, is in a range of 1?t/??22.

Abstract: A new surface acoustic wave device in which higher frequency can be achieved and that shows enhanced temperature characteristics, is provided in a surface acoustic wave device utilizing an SH type high speed surface wave, when an IDT electrode is formed on a quartz substrate whose Euler angle is represented as (0°, ? [? is from 125 to 142]°, 90°), temperature coefficient of frequency of the quartz substrate at given temperature is made be minus by controlling the film thickness of the IDT electrode, and thereafter the IDT electrode is covered by a thin film having temperature coefficient of frequency that is plus at the given temperature. According to this, since the temperature coefficient of frequency TCF of the whole device becomes zero and second order temperature coefficient ? is enhanced, a surface acoustic wave device in which higher frequency is easily achieved and that has enhanced temperature characteristics can be provided.

Abstract: It is aimed to provide a resonator type SAW filter having a relatively wide fractional bandwidth by canceling and decreasing reflection coefficients of electrode fingers each other with a ¼ wavelength electrode in a multi-longitudinal-mode-coupled resonator type SAW filter. The resonator type SAW filter includes, on a piezoelectric substrate, an input interdigital transducer that excites a surface acoustic wave, an output interdigital transducer that receives the surface acoustic wave excited by the input interdigital transducer, a control interdigital transducer interposed between the input interdigital transducer and the output interdigital transducer that controls a state of the surface acoustic wave, and a pair of reflectors arranged on outer sides of both the input interdigital transducer and the output interdigital transducer. And, the input interdigital transducer, the output interdigital transducer, and the control interdigital transducer alternatively arrange two different zones C and E.

Abstract: A method for adjusting frequency of a surface acoustic wave device includes performing a frequency adjustment. The surface acoustic wave device includes a substrate including at least one of a lithium tantalate substrate, a lithium niobate substrate, and a lithium tetraborate substrate. The surface acoustic wave device further includes an IDT electrode formed on the substrate that excites a pseudo-longitudinal leaky surface acoustic wave. The performing includes frequency adjustment by adjusting a thickness of the substrate at a side opposite in a thickness direction to a side on which the IDT electrode is formed.

Abstract: A surface acoustic wave device, comprising a lithium-tantalate substrate and an IDT electrode that excites a pseudo-longitudinal wave type leaky surface acoustic wave in the surface of the lithium-tantalate substrate, wherein a normalized substrate thickness t/?, which is a thickness t of the lithium-tantalate substrate normalized by an IDT wavelength ?, is in a range of 1?t/??22.

Abstract: A method for adjusting frequency of a surface acoustic wave device includes performing a frequency adjustment. The surface acoustic wave device includes a substrate including at least one of a lithium tantalate substrate, a lithium niobate substrate, and a lithium tetraborate substrate. The surface acoustic wave device further includes an IDT electrode formed on the substrate that excites a pseudo-longitudinal leaky surface acoustic wave. The performing includes frequency adjustment by adjusting a thickness of the substrate at a side opposite in a thickness direction to a side on which the IDT electrode is formed.

Abstract: The invention provides a surface acoustic wave device capable of precisely controlling a frequency, of reducing changes in the center frequency with the lapse of time after controlling the frequency, and of performing a stable operation for a long time. The thickness of an IDT electrode formed on a quartz substrate is set to be slightly larger than the desired thickness so that the center frequency is slightly lower than the desired frequency. Next, a voltage is applied to the IDT electrode and the center frequency is measured. At this time, the measured center frequency is slightly lower than the desired frequency. The rear surface of the quartz substrate is etched while checking the measured center frequency. As a result, the measured center frequency gradually increases and approaches the desired frequency by etching the rear surface of the quartz substrate. Further, the rear surface of the quartz substrate is continuously etched until the center frequency is the desired frequency.

Abstract: The invention provides a longitudinal double-mode SAW filter that has a large reflection coefficient by the electrode conductors and having flat pass band characteristics. In the longitudinal double-mode SAW filter, nearly all of higher-order natural mode oscillation displacements A0, S1 and A1 are made present in the first and second interdigital transducer regions. An electrode finger phase weighting is formed to correspond to a BPSK sign where a phase sign changes into 0 or ? at a polarity-changing point on an electrode charge distribution function Q(x) that generates on the electrode due to natural modes of oscillation. A single pair of natural modes, which exist stationary in the direction X of propagation of the surface acoustic waves that are utilized, is selected. A symmetrical mode charge distribution (Q(x), ?Q(x)) and an obliquely symmetrical mode charge distribution (Q(x), Q(x)) are generated in order to correspond to the regions of IDT1 and IDT2.

Abstract: A surface acoustic wave element is provided including, as a substrate, a quartz-rotator Y plate whose Euler angle is expressed as (0, ?, ?), and an IDT and reflectors provided on this substrate. The IDT is formed of Al as its main ingredient, and arranged so that an angle ?, which the propagation direction of a surface acoustic wave and the X-axis of the quartz-rotator Y plate make, is 90±10°, and a normalized film-thickness H/? of the IDT, and the cut angle ? satisfy the following Relation A: ? min???? max (where, ?=129 through 144°); ? min=857.06(H/?)2+23.656(H/?)+123.68; and ? max=2502.4(H/?)2+73.1(H/?)+121.7.

Abstract: A new surface acoustic wave device in which higher frequency can be achieved and that shows enhanced temperature characteristics, is provided in a surface acoustic wave device utilizing an SH type high speed surface wave, when an IDT electrode is formed on a quartz substrate whose Euler angle is represented as (0°, ? [? is from 125 to 142]°, 90°), temperature coefficient of frequency of the quartz substrate at given temperature is made be minus by controlling the film thickness of the IDT electrode, and thereafter the IDT electrode is covered by a thin film having temperature coefficient of frequency that is plus at the given temperature. According to this, since the temperature coefficient of frequency TCF of the whole device becomes zero and second order temperature coefficient ? is enhanced, a surface acoustic wave device in which higher frequency is easily achieved and that has enhanced temperature characteristics can be provided.

Abstract: The invention provides a longitudinal double-mode SAW filter that has a large reflection coefficient by the electrode conductors and having flat pass band characteristics. In the longitudinal double-mode SAW filter, nearly all of higher-order natural mode oscillation displacements A0, S1 and A1 are made present in the first and second interdigital transducer regions. An electrode finger phase weighting is formed to correspond to a BPSK sign where a phase sign changes into 0 or &pgr; at a polarity-changing point on an electrode charge distribution function Q(x) that generates on the electrode due to natural modes of oscillation. A single pair of natural modes, which exist stationary in the direction X of propagation of the surface acoustic waves that are utilized, is selected. A symmetrical mode charge distribution (Q(x), −Q(x)) and an obliquely symmetrical mode charge distribution (Q(x), Q(x)) are generated in order to correspond to the regions of IDT1 and IDT2.

Abstract: The present invention provides a surface acoustic wave device using a quasi-longitudinal leaky surface acoustic wave, which is capable of effectively suppressing spurious response and improving a Q value and a CI value. In particular, the present invention relates to a surface acoustic wave device including at least a quartz substrate and IDT electrodes arranged on the quartz substrate and exciting a quasi-longitudinal leaky surface acoustic wave, wherein a standardized electrode thickness t/&lgr;, which standardizes a thickness t of the quartz substrate to an IDT wavelength &lgr;, is set to be 1<t/&lgr;<35, and the quartz substrate is cut out in the Euler angle range (0°, 100 to 150°, 0°).

Abstract: The invention provides a surface acoustic wave device capable of precisely controlling a frequency, of reducing changes in the center frequency with the lapse of time after controlling the frequency, and of performing a stable operation for a long time. The thickness of an IDT electrode formed on a quartz substrate is set to be slightly larger than the desired thickness so that the center frequency is slightly lower than the desired frequency. Next, a voltage is applied to the IDT electrode and the center frequency is measured. At this time, the measured center frequency is slightly lower than the desired frequency. The rear surface of the quartz substrate is etched while checking the measured center frequency. As a result, the measured center frequency gradually increases and approaches the desired frequency by etching the rear surface of the quartz substrate. Further, the rear surface of the quartz substrate is continuously etched until the center frequency is the desired frequency.