Abstract: The filter includes a series arm piezoelectric thin film resonator placed in the series arm and a parallel arm piezoelectric thin film resonator placed in the parallel arm. Each of the series arm piezoelectric thin film resonator and the parallel arm piezoelectric thin film resonator includes a substrate (21), a lower electrode (22) placed on the substrate (21), a piezoelectric film (23) placed on the lower electrode (22) and a upper electrode (24) placed on the piezoelectric film (23). The ratio of the major axis length A to the minor axis length B of the resonant portion (29) in the series arm piezoelectric thin film resonator is larger than that in the parallel arm piezoelectric thin film resonator.

Abstract: A piezoelectric thin film resonant element includes a resonant portion having a laminate structure made up of a lower electrode, an upper electrode and a piezoelectric film arranged between these two electrodes. The lower electrode has an ellipsoidal plan-view shape and an outer circumference formed with an inclined portion inclined at an angle (about 30° for example) lying within a range of 25° through 55°. The upper electrode has an ellipsoidal plan-view shape. An additional film is provided on the upper electrode at a portion corresponding to the inclined portion of the lower electrode.

Abstract: A piezoelectric thin-film resonator includes: a lower electrode that is formed on a substrate; a piezoelectric film that is formed on the substrate and the lower electrode; an upper electrode that is formed on the piezoelectric film, with a portion of the piezoelectric film being interposed between the lower electrode and the upper electrode facing each other; and an additional film that is formed on the substrate on at least a part of the outer periphery of the lower electrode at the portion at which the lower electrode and the upper electrode face each other, with the additional film being laid along the lower electrode.

Abstract: There is provided a piezoelectric thin film resonator that decreases only transverse mode waves selectively while maintaining resonance characteristics due to original thickness longitudinal vibration. The piezoelectric thin film resonator includes: a piezoelectric film (14); a first electrode (15a) formed on a first principal surface of the piezoelectric film (14); and a second electrode (13) formed on a second principal surface of the piezoelectric film (14) opposite to the first principal surface. The resonator has a resonance region (20) where the first electrode (15a) and the second electrode (13) are opposed to each other. An electrically discontinuous portion (18a) that is insulated from the first electrode (15a) is provided on the first principal surface of the piezoelectric film (14) in the resonance region (20), and the electrically discontinuous portion (18a) is surrounded by the first electrode (15a) on the first principal surface.

Abstract: There is provided a filter including a first resonator, a second resonator in which an excitation efficiency is reduced more than the first resonator, and an inductor connected in parallel with the second resonator.

Abstract: A resonator includes a substrate, a lower electrode, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film. The lower electrode includes a first film provided on the substrate, and a second film that is provided on the first film and has a specific gravity greater than that of the first film. The piezoelectric film is provided on the second film. The upper electrode includes a third film provided on the piezoelectric film, and a fourth film provided on the third film, the third film having a specific gravity greater than that of the fourth film. The third film is thicker than the second film.

Abstract: A duplexer of the present invention includes a reception filter (3) for passing signals in a predetermined frequency band and attenuates signals in the other frequency bands among reception signals input to an antenna port, and a transmission filter (4) for passing signals in a predetermined frequency band and attenuates signals in the other frequency bands among transmission signals input from the outside and outputting them to the antenna port. The duplexer further includes a conversion circuit (22) provided with a single-ended input terminal connected to the antenna port and balanced output terminals. The reception filter (3) is provided with a balanced input terminal connected to the output terminal of the conversion circuit (22) and a balanced output terminal for outputting the filtered reception signal.

Abstract: An acoustic wave filter having excellent steepness is provided without adding any exterior components or any new manufacturing steps. A plurality of filters (10-1) each having a first resonator (2a-1) placed in a serial arm and having a resonance frequency frs and an anti-resonance frequency fas, and a second resonator (4a-1) placed in a parallel arm and having a resonator frp and an anti-resonance frequency fap are provided on a same substrate, where the resonance frequency frs of the first resonator is higher than the resonance frequency frp of the second resonator; the anti-resonance frequency fas of the first resonator is higher than the anti-resonance frequency fap of the second resonator; and the filters (10-1) are connected in multiple stages. At least one of the filters (10-1) connected in multiple stages has a third resonator (6-1) having a resonance frequency frp and an anti-resonance frequency fap.

Abstract: A ladder filter includes a series resonator having a first film laminate in which an upper electrode and a lower electrode face each other across a piezoelectric film, and a first film provided on the first film laminate, and a parallel resonator having a second film laminate having a structure similar to that of the first film laminate, a second film provided on the second film laminate, and another first film identical to the first film.

Abstract: An acoustic wave device includes a piezoelectric substrate, a resonator having comb electrodes that are provided above the piezoelectric substrate and excite an acoustic wave, and a capacitor that is provided above the piezoelectric substrate and is connected in series or parallel with the resonator, the capacitor including electrodes that horizontally face each other above the piezoelectric substrate. The electrodes of the capacitor are further from the piezoelectric substrate than the comb electrodes of the resonator.

Abstract: A filter has a plurality of piezoelectric thin film resonators formed by sandwiching a piezoelectric film with a lower electrode disposed on a substrate and an upper electrode. Each of the piezoelectric thin film resonators has an electrode region formed with the upper electrode and the lower electrode overlapping each other, whose outline includes a curve. Among the plural piezoelectric thin film resonators, the piezoelectric thin film resonators in the opposing electrode regions of the adjacent piezoelectric thin film resonators are shaped to have outlines complementary to each other. With the filter, influences caused by transverse mode undesired wave of the piezoelectric thin film resonators can be suppressed. Therefore, miniaturization can be achieved without sacrificing the mechanical strength of electrodes having hollow structures.

Abstract: A piezoelectric thin film resonator includes a substrate, a lower electrode formed on the substrate, a piezoelectric film formed on the substrate and the lower electrode, and an upper electrode formed on the piezoelectric film and opposing the lower electrode, an upper electrode formed on the piezoelectric film. The upper electrode has a main portion and an extended portion connected to the main portion, the main portion opposing the lower electrode and an opening disposed between the substrate and the lower electrode, the extended portion having a portion which opposes the opening and the substrate.

Abstract: A piezoelectric thin film resonator includes a substrate, a lower electrode formed on the substrate, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film, the lower electrode and the upper electrode opposing each other through the piezoelectric film to form an opposing region, the opposing region including a space at a boundary of the opposing region. The space extends from an innerside to an outer side of the opposing region and is formed in or on the piezoelectric film.

Abstract: An acoustic wave device includes a piezoelectric substrate, a first dielectric film formed on the piezoelectric substrate, and electrodes that are provided on the first dielectric film and excite an acoustic wave, the electrodes including electrode fingers. At least a part of the first dielectric film is cut out between adjacent electrode fingers among the electrode fingers.

Abstract: A filter includes: a converter circuit, provided with a single-type common terminal and two balanced terminals, for performing conversion between a balanced line and an unbalanced line; two filter units coupled to each of the balanced terminals of the converter circuit and allowing passage of a signal in a pass band; and a bridging capacitor arranged to extend across the converter circuit and one of the filter units in a bridging manner, wherein the inductance of an opposite-side line of one of the filter units relative to the converter circuit is electromagnetically coupled to the inductance of a line coupling the other filter unit and the converter circuit.

Abstract: A filter includes: a first filter unit includes: a series resonators connected in series to each other between a first input terminal and a first output terminal; a parallel resonators each having one end connected to one terminal of each of the series resonators; and a common inductance having one end connected to the other ends of the parallel resonators and the other end connected to a ground terminal, and a second filter unit includes: a series resonators connected in series to each other between a second input terminal and a second output terminal; a parallel resonators each having one end connected to one terminal of each of the series resonators; and a common inductance having one end connected to the other ends of the parallel resonators and the other end connected to the ground terminal.

Abstract: There is provided a film bulk acoustic resonator which has a substrate, a lower electrode formed on the substrate, a piezoelectric membrane formed on the lower electrode, an upper electrode formed on the piezoelectric membrane, and an insulating film disposed adjacent to the piezoelectric membrane between the upper electrode and the substrate and at a position at which the upper electrode and the substrate are opposed each other. The substrate is preferably formed so as to form a void at a portion facing to the lower electrode. The lower electrode has preferably a tapered end and a part of the boundary between the piezoelectric membrane and the insulating film is disposed on an inside from the upper end of the tapered end.

Abstract: An acoustic wave device includes a substrate and a plurality of piezoelectric thin film resonators formed over the substrate. Each of the plurality of the piezoelectric thin film resonators includes lower electrode provided on the substrate, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film and opposed to the lower electrode through the piezoelectric film. Each of the piezoelectric thin film resonators is partly supported by the substrate and extends above the substrate to form a cavity between the substrate and each lower electrodes. The cavity continuously extending under the plurality of the piezoelectric thin film resonators.

Abstract: A light non-transmitive layer and resist are coated on a surface of a mask. By carrying out exposing, developing, and etching, a positive/negative reversed pattern is formed on the surface of the mask. A light non-transmitive layer and a resist are coated on a portion of the workpiece where the pattern is to be formed. Exposure is carried out by using the mask that can be changed by a connector. The pattern of the mask is transferred to the resist, and the resist is developed. After the resist is developed, a mask pattern is formed on a surface of the workpiece by etching.

Abstract: A duplexer includes: a first filter that is connected to a common terminal and a first terminal, and includes a first series-arm resonator; a second filter that is connected to the common terminal and a second terminal; a first inductor that is connected in parallel to the first series-arm resonator; a mounting unit that has the first filter and the second filter mounted thereon; a first inductor line that is provided on the mounting unit, and connects the first inductor and the first series-arm resonator; and a first terminal line that is provided on the mounting unit, and connects the first filter and the first terminal. In this duplexer, the directions of currents flowing through the first inductor line and the first terminal line cross each other.