Abstract: A boundary acoustic wave filter device includes an electrode structure provided at a boundary between a piezoelectric body and a dielectric body laminated on the piezoelectric body and utilizes an SH-type boundary acoustic wave that propagates along the boundary. In the boundary acoustic wave filter device, the electrode structure includes a longitudinally coupled resonator boundary acoustic wave filter portion that has a first IDT and second and third IDTs arranged respectively on both sides of the IDT in a direction in which the boundary acoustic wave propagates. At portions at which two IDTs are located adjacent to each other in the direction in which the boundary acoustic wave propagates, narrow pitch electrode finger portions are provided in the IDTs, and the pitch of the electrode fingers of the narrow pitch electrode finger portion is different from the pitch of the electrode fingers of each of the narrow pitch electrode finger portions.

Abstract: A longitudinally-coupled resonator-type acoustic wave device includes first to third IDT electrodes disposed on a piezoelectric material and first and second reflectors disposed in acoustic wave propagation directions. Each of any two IDT electrodes adjacent to each other in the acoustic wave propagation directions, of the first to third IDT electrodes, has a narrower-pitch electrode finger portion at an edge thereof adjacent to the other IDT electrode. Most portions of the first to third IDT electrodes are apodized, and the narrower-pitch electrode finger portions and the electrode finger portions adjacent thereto are normally shaped.

Abstract: An acoustic wave filter device is capable of increasing the steepness of a filter characteristic at a boundary between a passband and an attenuation band and achieving a low loss in the passband. The acoustic wave filter device has a ladder circuit configuration including a plurality of series arm resonators and at least one parallel arm resonator. The anti-resonant frequency of the series arm resonator is different from that of the series arm resonator. The series arm resonator having the lowest anti-resonant frequency has a resonant frequency located in the passband and an electromechanical coupling coefficient less than an average of electromechanical coupling coefficients of the series arm resonators.

Abstract: In an elastic wave apparatus, a first dielectric layer is laminated on a piezoelectric substrate. An electrode structure is provided at an interface between the first dielectric layer and the piezoelectric substrate. The electrode structure includes a first electrode structure of an elastic wave filter and a second electrode structure of elastic wave resonators. The elastic wave resonators are electrically connected to the elastic wave filter. An anti-resonant frequency at which the extreme impedance values of the elastic wave resonators are obtained is in a frequency band in which the higher-order mode spurious response of the elastic wave filter appears.

Abstract: A boundary acoustic wave device includes a piezoelectric substance made of LiNbO3 having a surface obtained by rotating a Y axis by about 15°±10° as a primary surface, a dielectric substance which is made of a silicon oxide and which is laminated to the piezoelectric substance, and an electrode structure disposed at a boundary between the piezoelectric substance and the dielectric substance and which includes an IDT arranged to utilize a boundary acoustic wave propagating along the boundary. When the density of the IDT, the thickness thereof, the wavelength deter-mined by the period of electrode fingers of the IDT, and the duty ratio thereof are represented by ? (kg/m3), H (?m), ? (?m), and x, respectively, x and the product of H/? and ? are set in a range that satisfies the following formula (1): (H/?)×?>70.7924(x+0.055)(?2.884)+797.09??Formula (1).

Abstract: A longitudinally-coupled resonator-type acoustic wave device includes first to third IDT electrodes disposed on a piezoelectric material and first and second reflectors disposed in acoustic wave propagation directions. Each of any two IDT electrodes adjacent to each other in the acoustic wave propagation directions, of the first to third IDT electrodes, has a narrower-pitch electrode finger portion at an edge thereof adjacent to the other IDT electrode. Most portions of the first to third IDT electrodes are apodized, and the narrower-pitch electrode finger portions and the electrode finger portions adjacent thereto are normally shaped.

Abstract: A longitudinally coupled resonator boundary acoustic wave filter device includes a piezoelectric substrate made of LiNbO3 having a principal plane obtained by rotating the Y-axis through about 15 degrees +?10 degrees, a dielectric substrate made of silicon oxide and laminated on the piezoelectric substrate, and an electrode structure arranged at a boundary between the piezoelectric substrate and the dielectric substrate. The electrode structure includes a plurality of IDTs arranged in a direction in which a boundary acoustic wave propagates, and reflectors, wherein where in each of the plurality of IDTs, the overlap width of electrode fingers is W and the interval of electrode fingers is P, W/P is in a range of about 20 to about 45.

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: An acoustic wave filter device is capable of increasing the steepness of a filter characteristic at a boundary between a passband and an attenuation band and achieving a low loss in the passband. The acoustic wave filter device has a ladder circuit configuration including a plurality of series arm resonators and at least one parallel arm resonator. The anti-resonant frequency of the series arm resonator is different from that of the series arm resonator. The series arm resonator having the lowest anti-resonant frequency has a resonant frequency located in the passband and an electromechanical coupling coefficient less than an average of electromechanical coupling coefficients of the series arm resonators.

Abstract: A longitudinally coupled resonator acoustic wave filter device that utilizes an inter-IDT resonance mode with a reduced insertion loss has a structure in which apodization weights are assigned in first to third IDTs having narrow pitch electrode finger portions in portions other than the narrow pitch electrode finger portions, such that the electrode finger overlap width sequentially varies in an acoustic wave propagating direction in which an acoustic wave propagates, and portions of the IDTs located at ends adjacent to the narrow pitch electrode finger portions have a maximum electrode finger overlap width.

Abstract: A boundary acoustic wave device includes a piezoelectric substance made of LiNbO3 having a surface obtained by rotating a Y axis by about 15°±10° as a primary surface, a dielectric substance which is made of a silicon oxide and which is laminated to the piezoelectric substance, and an electrode structure which is disposed at a boundary between the piezoelectric substance and the dielectric substance and which includes an IDT arranged to utilize a boundary acoustic wave propagating along the boundary. When the density of the IDT, the thickness thereof, the wavelength determined by the period of electrode fingers of the IDT, and the duty ratio thereof are represented by ? (kg/m3), H (?m), ?(?m), and x, respectively, x and the product of H/? and ? are set in a range that satisfies the following formula (1): (H/?)×?>70.7924(x+0.055)(?2.0884)+797.09??Formula (1).

Abstract: A boundary acoustic wave filter device includes an electrode structure provided at a boundary between a piezoelectric body and a dielectric body laminated on the piezoelectric body and utilizes an SH-type boundary acoustic wave that propagates along the boundary. In the boundary acoustic wave filter device, the electrode structure includes a longitudinally coupled resonator boundary acoustic wave filter portion that has a first IDT and second and third IDTs arranged respectively on both sides of the IDT in a direction in which the boundary acoustic wave propagates. At portions at which two IDTs are located adjacent to each other in the direction in which the boundary acoustic wave propagates, narrow pitch electrode finger portions are provided in the IDTs, and the pitch of the electrode fingers of the narrow pitch electrode finger portion is different from the pitch of the electrode fingers of each of the narrow pitch electrode finger portions.

Abstract: A longitudinally coupled resonator acoustic wave filter device that utilizes an inter-IDT resonance mode with a reduced insertion loss has a structure in which apodization weights are assigned in first to third IDTs having narrow pitch electrode finger portions in portions other than the narrow pitch electrode finger portions, such that the electrode finger overlap width sequentially varies in an acoustic wave propagating direction in which an acoustic wave propagates, and portions of the IDTs located at ends adjacent to the narrow pitch electrode finger portions have a maximum electrode finger overlap width.

Abstract: A longitudinally coupled resonator boundary acoustic wave filter device includes a piezoelectric substrate made of LiNbO3 having a principal plane obtained by rotating the Y-axis through about 15 degrees +?10 degrees, a dielectric substrate made of silicon oxide and laminated on the piezoelectric substrate, and an electrode structure arranged at a boundary between the piezoelectric substrate and the dielectric substrate. The electrode structure includes a plurality of IDTs arranged in a direction in which a boundary acoustic wave propagates, and reflectors, wherein where in each of the plurality of IDTs, the overlap width of electrode fingers is W and the interval of electrode fingers is P, W/P is in a range of about 20 to about 45.

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: In a longitudinally-coupled-resonator-type elastic wave filter device, at least one of two IDTs which are adjacent to each other is provided with a dummy electrode for series weighting in a portion in which the IDTs are adjacent to each other, and at least one of series-weighted portions includes at least one of metallization ratio reducing portion in a first acoustic track and metallization ratio increasing portion in a second acoustic track so as to reduce the difference between the metallization ratio of the first acoustic track passing through a connecting portion of the dummy electrode and the metallization ratio of each of second and third acoustic tracks each placed on either side of the first acoustic track in the direction of propagation of an elastic wave.

Abstract: In a longitudinally-coupled-resonator-type elastic wave filter device, at least one of two IDTs which are adjacent to each other is provided with a dummy electrode for series weighting in a portion in which the IDTs are adjacent to each other, and at least one of series-weighted portions includes at least one of metallization ratio reducing portion in a first acoustic track and metallization ratio increasing portion in a second acoustic track so as to reduce the difference between the metallization ratio of the first acoustic track passing through a connecting portion of the dummy electrode and the metallization ratio of each of second and third acoustic tracks each placed on either side of the first acoustic track in the direction of propagation of an elastic wave.

Abstract: In a balanced acoustic wave filter device, first and second acoustic wave filter sections that are connected in parallel to an unbalanced terminal are connected to first and second balanced terminals, respectively. The first and second surface acoustic wave filter sections are configured such that the phases of the first and second balanced terminals differ by 180 degrees. The first and second acoustic wave filter sections are longitudinally coupled resonator-type acoustic wave filter sections each including a plurality of IDTs disposed in a direction in which acoustic waves propagate.

Abstract: In a balanced acoustic wave filter device, first and second acoustic wave filter sections that are connected in parallel to an unbalanced terminal are connected to first and second balanced terminals, respectively. The first and second surface acoustic wave filter sections are configured such that the phases of the first and second balanced terminals differ by 180 degrees. The first and second acoustic wave filter sections are longitudinally coupled resonator-type acoustic wave filter sections each including a plurality of IDTs disposed in a direction in which acoustic waves propagate.

Abstract: A surface acoustic wave apparatus includes a piezoelectric substrate mounting a surface acoustic wave filter having a plurality of comb-like electrode sections, and another surface acoustic wave filter also having a plurality of comb-like electrode sections, in a manner such that a balun function is obtained. Further, a wiring pattern is provided on the piezoelectric substrate for a connecting reference terminal side electrode of a comb-like electrode section with a reference terminal side electrode of another comb-like electrode section. Moreover, another wiring pattern is provided on the piezoelectric substrate for connecting a reference terminal side electrode of a further comb-like electrode section with a reference terminal side electrode of a still further comb-like electrode section.