Abstract: A small-sized surface acoustic wave filter device having favorable filter characteristics includes a transmission-side surface acoustic wave filter chip including a ladder surface acoustic wave filter unit located on a piezoelectric substrate. The ladder surface acoustic wave filter unit includes a series arm connected between an input pad and an output pad and a plurality of resonators and including at least one first resonator connected to the input pad or the output pad. A die-attach surface is provided with an inductor connected to the first resonator. The inductor is arranged such that at least a portion thereof faces the first resonator and does not face any of the plurality of resonators and other than the first resonator.

Abstract: A 5-IDT longitudinally coupled resonator type elastic wave filter device includes a narrow-pitch electrode finger portion arranged to increase the steepness of the filter characteristic includes first to fifth IDTs. When the total number of electrode fingers in a first area and a fourth area is Nx and the total number of electrode fingers in a second area and a third area is Ny, an average period of electrode fingers in one of the areas including larger total numbers of the electrode fingers Nx and Ny is greater than that in the area including smaller total numbers of the electrode fingers Nx and Ny.

Abstract: An elastic wave apparatus includes a balanced-unbalanced transforming function, and an elastic wave filter and a multilayer wiring board on which the elastic wave filter is mounted. The elastic wave filter includes an unbalanced terminal and first and second balanced terminals. External electrodes used are provided on the multilayer wiring board. A first internal line connects the first balanced terminal and the external electrode. A second internal line connects the second balanced terminal and the external electrode. The lengths or shapes of the first internal line and the second internal line are set so that a capacitance used for the improvement of a balance is generated in an adjacent area A where the first internal line and the second internal line are adjacent to each other. In the adjacent area A, the directions of currents passing through the first internal line and the second internal line are the same.

Abstract: A small-sized surface acoustic wave filter device having favorable filter characteristics includes a transmission-side surface acoustic wave filter chip including a ladder surface acoustic wave filter unit located on a piezoelectric substrate. The ladder surface acoustic wave filter unit includes a series arm connected between an input pad and an output pad and a plurality of resonators and including at least one first resonator connected to the input pad or the output pad. A die-attach surface is provided with an inductor connected to the first resonator. The inductor is arranged such that at least a portion thereof faces the first resonator and does not face any of the plurality of resonators and other than the first resonator.

Abstract: An elastic wave device includes an unbalanced terminal and first and second balanced terminals. A longitudinally-coupled-resonator-type first elastic wave filter is provided between the unbalanced terminal and the first balanced terminal. An elastic wave filter, which is connected in parallel with the first elastic wave filter, is connected between the unbalanced terminal and the second balanced terminal. The current paths through which IDT electrodes of the elastic wave filters of the elastic wave device are connected to ground terminals, are not symmetrical.

Abstract: A surface acoustic wave device in which miniaturization and a flat design implemented, is resistant to a deformation responsive to a pressure of a molten resin in the formation of a mold resin layer, and is less susceptible to a characteristic degradation. In the surface acoustic wave device, an IDT electrode is located on a piezoelectric substrate, and an insulator member is arranged such that a space B surrounding the IDT electrode is provided. For the purpose of reducing the area of the space B, reflectors having weighted portions are arranged on both sides of the IDT electrode. The weighted portions include electrode fingers of the reflectors that become shorter in length as they extend farther away from the IDT electrode. The shape of the space B is reduced accordingly.

Abstract: An elastic wave device includes an unbalanced terminal and first and second balanced terminals. A longitudinally-coupled-resonator-type first elastic wave filter is provided between the unbalanced terminal and the first balanced terminal. An elastic wave filter, which is connected in parallel with the first elastic wave filter, is connected between the unbalanced terminal and the second balanced terminal. The current paths through which IDT electrodes of the elastic wave filter and the elastic wave filter are connected to ground terminals, are not symmetrical.

Abstract: An elastic wave apparatus includes a balanced-unbalanced transforming function, and an elastic wave filter and a multilayer wiring board on which the elastic wave filter is mounted. The elastic wave filter includes an unbalanced terminal and first and second balanced terminals. External electrodes used are provided on the multilayer wiring board. A first internal line connects the first balanced terminal and the external electrode. A second internal line connects the second balanced terminal and the external electrode. The lengths or shapes of the first internal line and the second internal line are set so that a capacitance used for the improvement of a balance is generated in an adjacent area A where the first internal line and the second internal line are adjacent to each other. In the adjacent area A, the directions of currents passing through the first internal line and the second internal line are the same.

Abstract: An acoustic wave filter device includes longitudinally coupled resonator-acoustic wave filters having a balanced-unbalanced conversion function, and increases the amount of attenuation in an attenuation band and improves the isolation characteristics when the acoustic wave filter device is used as a reception filter of a duplexer. The acoustic wave filter device includes an unbalanced terminal, first and second balanced terminals, first and second longitudinally coupled resonator-acoustic wave filters that are connected between the unbalanced terminal and the first balanced terminal and between the unbalanced terminal and the second balanced terminal, respectively, a first parallel resonator connected between the first balanced terminal and a ground potential, and a second parallel resonator connected between the second balanced terminal and the ground potential. The electrostatic capacitance of the first parallel resonator is different from the electrostatic capacitance of the second parallel resonator.

Abstract: A piezoelectric device includes a piezoelectric substrate, a conductive pattern which is provided on one main surface of the piezoelectric substrate and which includes an IDT electrode, a supporting layer which is arranged on the one main surface of the piezoelectric substrate so as to surround the periphery of an IDT-forming region in which the IDT electrode is provided and which has a thickness greater than that of the IDT electrode, and a cover layer which is arranged on the supporting layer and which covers the IDT-forming region. The supporting layer includes removed sections provided at a plurality of positions at least in a region close to the IDT-forming region, the removed sections being obtained by partially removing a portion of the supporting layer to be bonded to the one main surface of the piezoelectric substrate.

Abstract: An acoustic wave filter device includes longitudinally coupled resonator-acoustic wave filters having a balanced-unbalanced conversion function, and increases the amount of attenuation in an attenuation band and improves the isolation characteristics when the acoustic wave filter device is used as a reception filter of a duplexer. The acoustic wave filter device includes an unbalanced terminal, first and second balanced terminals, first and second longitudinally coupled resonator-acoustic wave filters that are connected between the unbalanced terminal and the first balanced terminal and between the unbalanced terminal and the second balanced terminal, respectively, a first parallel resonator connected between the first balanced terminal and a ground potential, and a second parallel resonator connected between the second balanced terminal and the ground potential. The electrostatic capacitance of the first parallel resonator is different from the electrostatic capacitance of the second parallel resonator.

Abstract: A 5-IDT longitudinally coupled resonator type elastic wave filter device includes a narrow-pitch electrode finger portion arranged to increase the steepness of the filter characteristic includes first to fifth IDTs. When the total number of electrode fingers in a first area and a fourth area is Nx and the total number of electrode fingers in a second area and a third area is Ny, an average period of electrode fingers in one of the areas including larger total numbers of the electrode fingers Nx and Ny is greater than that in the area including smaller total numbers of the electrode fingers Nx and Ny.

Abstract: An elastic wave filter device having improved sharpness of filter characteristics includes a longitudinally-coupled resonator-type elastic wave filter section including first to third IDT electrodes each including a plurality of electrode fingers, and first and second reflectors. The first to third IDT electrodes include narrower-pitch portions provided in end portions thereof, which are each adjacent to another IDT electrode in a direction of propagation of elastic waves, each of the narrower-pitch portions having a smaller period of electrode fingers than a period of electrode fingers in the remaining portion of the relevant IDT electrode. The number of electrode fingers in the narrower-pitch portion of the second IDT electrode, which is disposed on the side closer to the first IDT electrode, and the number of electrode fingers in the narrower-pitch portion of the second IDT electrode, which is disposed on the side closer to the third IDT electrode, differ from each other.

Abstract: A duplexer includes a transmission filter having a ladder circuit configuration and a reception filter. The reception filter includes an input terminal connected to an antenna terminal, a first reception output terminal, and a second reception output terminal. A first filter element and a second filter element, each of which is a longitudinally coupled resonator filter element including a plurality of IDTs, are connected in parallel to the input terminal so that IDTs are connected to the input terminal. The first filter element the second filter element are connected to the first reception output terminal and the second reception output terminal, respectively.

Abstract: A surface acoustic wave (SAW) filter device includes first and second longitudinally coupled SAW filter units. The first and second filter units are cascade-connected to each other. A phase of a signal flowing through a first signal line electrically connecting second IDTs of the first and second SAW filter units is different by about 180° from a phase of a signal flowing through a signal line electrically connecting third IDTs of the first and second SAW filter units. A SAW resonator is connected between the first and second signal lines. A resonance point of the SAW resonator is set in an attenuation region in the vicinity of the edge of a low frequency side of a filter passband or an anti-resonance point of the SAW resonator is set in an attenuation region in the vicinity of the edge of a high frequency side of the filter passband.

Abstract: An acoustic wave filter device includes first to fourth longitudinally coupled resonator type surface acoustic wave filters that are configured such that the first and second filters are connected to a first balanced signal terminal, the third and fourth filters are connected to a second balanced signal terminal, and a transmission phase of a signal output from the first balanced signal terminal relative to an input signal differs by about 180 degrees with respect to a transmission phase of a signal output from the second balanced signal terminal relative to an input signal. In addition, the number of pairs of electrode fingers of at least one of IDTs of at least one of the first to fourth longitudinally coupled resonator type surface acoustic wave filters is different from the number of pairs of electrode fingers of corresponding IDTs of the remaining first to fourth filters.

Abstract: A piezoelectric device includes a piezoelectric substrate, a conductive pattern which is provided on one main surface of the piezoelectric substrate and which includes an IDT electrode, a supporting layer which is arranged on the one main surface of the piezoelectric substrate so as to surround the periphery of an IDT-forming region in which the IDT electrode is provided and which has a thickness greater than that of the IDT electrode, and a cover layer which is arranged on the supporting layer and which covers the IDT-forming region. The supporting layer includes removed sections provided at a plurality of positions at least in a region close to the IDT-forming region, the removed sections being obtained by partially removing a portion of the supporting layer to be bonded to the one main surface of the piezoelectric substrate.

Abstract: A surface acoustic wave device in which miniaturization and a flat design implemented, is resistant to a deformation responsive to a pressure of a molten resin in the formation of a mold resin layer, and is less susceptible to a characteristic degradation. In the surface acoustic wave device, an IDT electrode is located on a piezoelectric substrate, and an insulator member is arranged such that a space B surrounding the IDT electrode is provided. For the purpose of reducing the area of the space B, reflectors having weighted portions are arranged on both sides of the IDT electrode. The weighted portions include electrode fingers of the reflectors that become shorter in length as they extend farther away from the IDT electrode. The shape of the space B is reduced accordingly.

Abstract: An elastic wave filter device includes first and second elastic wave filter units connected to an unbalanced terminal. The first and second elastic wave filter units include first to third IDTs and fourth to sixth IDTs, respectively. One end of the first IDT, one end of the second IDT, one end of the fourth IDT, and one end of the sixth IDT are commonly connected together and are connected to the unbalanced terminal. The second IDT and the fifth IDT are each divided into first to third sub-IDT portions in the elastic wave propagation direction, respectively. The second sub-IDT portions of the second and fifth IDTs are connected to first and second balanced terminals, respectively.

Abstract: A duplexer includes a transmission filter having a ladder circuit configuration and a reception filter. The reception filter includes an input terminal connected to an antenna terminal, a first reception output terminal, and a second reception output terminal. A first filter element and a second filter element, each of which is a longitudinally coupled resonator filter element including a plurality of IDTs, are connected in parallel to the input terminal so that IDTs are connected to the input terminal. The first filter element the second filter element are connected to the first reception output terminal and the second reception output terminal, respectively.