Murata Manufacturing Co., Ltd.

Norihiko Nakahashi

Teruhisa Shibahara

Masaru Yata

Yuichi Takamine

Hajime Kando

Masakazu Mimura

Yasuhisa Fujii

Yasumasa Taniguchi

Minefumi Ouchi

Koji Miyamoto

Hiroki Watanabe

Norihiko Takada

Junji Osada

A multiplexer includes a first filter connected between a common terminal and an input/output terminal and having a pass band including a first frequency band, a second filter connected between the common terminal and an input/output terminal and having a pass band including a second frequency band higher than the first frequency band, and an additional circuit connected in parallel to a path connecting the common terminal and the input/output terminal. The additional circuit includes a longitudinally coupled resonator including IDT electrodes. If a peak frequency in an IDT response occurring in a bandpass characteristic of the additional circuit is f1, and if a frequency corresponding to a lowest impedance among frequencies higher than the second frequency band in an impedance characteristic viewing the multiplexer from the common terminal is f2, f2×(1−0.0012)≤f1≤f2×(1+0.0012) is satisfied.

Multiplexer

An extractor includes an external connection terminal, a common terminal, input-output terminals, a band elimination filter that is connected to the common terminal and the first input-output terminal input-output terminal and that uses a first frequency band as a stop band, a band pass filter connected to the common terminal and the second input-output terminal and that uses a second frequency band overlapped with at least a portion of the first frequency band as a pass band, and an inductor connected on a path connecting the common terminal to the external connection terminal. The band elimination filter includes series arm resonators located on a series arm connecting the common terminal to the input-output terminal and an inductor that is located on the series arm between the series arm resonator and the first input-output terminal. The inductor is inductively coupled to the inductor.

Extractor

A filter device includes a common connection terminal, a first bandpass filter connected to the common connection terminal and including an inductor, and a second bandpass filter connected to the common connection terminal and having a pass band lower in frequency than a pass band of the first bandpass filter. The filter device uses SH waves. The first bandpass filter is a ladder filter. Each of series arm resonators and parallel arm resonators includes an interdigital transducer electrode. Of the parallel arm resonators of the first bandpass filter, the inductor is connected in series to the parallel arm resonator with a shortest electrode finger pitch of the interdigital transducer electrode.

Filter device

An extractor includes a band elimination filter that is connected between a common terminal and a first input-output terminal and that has a stop band equal or substantially equal to a first frequency band, and a band pass filter that is connected between the common terminal and a second input-output terminal and that has a pass band equal or substantially equal to a second frequency band that overlaps the first frequency band. The band pass filter includes, series arm resonators, three or more parallel arm resonators, and three or more inductors that are connected between the ground and the parallel arm resonators. The L value of a first inductor that is connected and nearest to the common terminal is smaller than the L value of a third inductor, and the L value of a second inductor that is connected and second-nearest to the common terminal is smaller than the L value of the third inductor.

An extractor includes a band pass filter and a band elimination filter. In the band pass filter, an IDT electrode in at least one of a first series arm resonator and a first parallel arm resonator that are arranged at a series arm and a parallel arm, respectively, closest to a common terminal is a first IDT electrode in which neither a plurality of first electrode fingers nor a plurality of second electrode fingers is partially missing, and an IDT electrode in at least one of the first series arm resonator or the first parallel arm resonator that does not include the first IDT electrode, second series arm resonators, and second parallel arm resonators is a second IDT electrode in which at least one of a plurality of electrode fingers and a plurality of second electrode fingers is partially missing.

A ladder filter includes serial arm resonators disposed along a serial arm and parallel arm resonators disposed along corresponding parallel arms. Ladder circuit units are disposed along a path from an input terminal, which is a first end, to an output terminal, which is a second end. Each of the ladder circuit units includes a single serial arm resonator and a single parallel arm resonator. The ladder circuit units are mirror-connected to one another. The impedance at the first end is different from the impedance at the second end.

Ladder filter

A ladder-type surface acoustic wave filter includes interdigital transducer electrodes disposed on a LiTaOpiezoelectric substrate, and series resonators and parallel resonators defined by the interdigital transducer electrodes, and utilizes a leaky wave that propagates on the LiTaOpiezoelectric substrate. A bandwidth ratio indicating a bandwidth of a passband of the ladder-type surface acoustic wave filter is about 2.5% or greater, and a cutoff frequency due to bulk wave radiation of one of the parallel resonators, is in a frequency range higher than the passband.

Surface acoustic wave filter

A filter apparatus includes a plurality of stages of ladder circuits connected between an input terminal and an output terminal, and a band width ratio is about 4.3 % or higher. The ladder circuits of respective stages include series arm resonators, parallel arm resonators, first inductors respectively connected between a ground potential and first end portions, and second inductors respectively connected between the ground potential and second end portions.

Filter apparatus

An inexpensive compact band rejection filter realizes a high sharpness of a filter characteristic at ends of passbands and has a large attenuation. In the band rejection filter, at least one of a plurality of elastic wave resonators, which contributes to formation of a transition band, has a propagation angle larger than those of the other elastic wave resonators. Accordingly, the at least one of the plurality of elastic wave resonators which contributes to the formation of the transition band has an electromechanical coupling coefficient that is smaller than electromechanical coupling coefficients of the other elastic wave resonators.

Band rejection filter

A surface acoustic wave device includes an electrode and a dielectric layer laminated on a piezoelectric substrate, in which the electrode includes a first electrode film containing Pt, Au, Ag, or Cu and a second electrode film containing Al, the normalized film thickness h/&#x3bb; of the first electrode film is about 0.005 or more and at most about 0.015 in the case of Pt, the normalized film thickness h/&#x3bb; of the Al film is about 0.06 or more and at most about 0.185, and the normalized film thickness h/&#x3bb; of the dielectric layer is about 0.2 or less.

Surface acoustic wave device

An elastic wave device that achieves an improved frequency-temperature characteristic and a sufficiently reduced spurious component includes a piezoelectric body including a LiNbOsubstrate, a first dielectric layer including a SiOlayer, a second dielectric layer, and IDT electrodes disposed at an interface between the piezoelectric body and the first dielectric layer. Each of the IDT electrodes includes a multilayer structure in which a first electrode film including at least one layer including Pt or a Pt-based alloy and a second electrode film including Al or an Al-based alloy are provided. &#x3c6; and &#x3b8; of Euler angles (&#x3c6;, &#x3b8;, &#x3c8;) of the LiNbOsubstrate are in the range of &#x3c6;=0&#xb1;about 2&#xb0; and the range of about 80&#xb0;&#x2266;&#x3b8;&#x2266;about 130&#xb0;, respectively. &#x3c8; is in the range of about 5&#xb0;&#x2266;&#x3c8;&#x2266;about 30&#xb0;. The normalized thickness h/&#x3bb; and &#x3c8; satisfy the following expression: h/&#x3bb;&#xd7;100&#x2266;about 0.0019&#xd7;&#x3c8;2+about 0.0115&#xd7;&#x3c8;+3.0.

Elastic wave device using SH waves as the principal component

A boundary acoustic wave device includes a piezoelectric substance made of LiNbOhaving a surface obtained by rotating a Y axis by about 15&#xb0;&#xb1;10&#xb0; 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 &#x3c1; (kg/m), H (&#x3bc;m), &#x3bb; (&#x3bc;m), and x, respectively, x and the product of H/&#x3bb; and &#x3c1; are set in a range that satisfies the following formula (1):(/&#x3bb;)&#xd7;&#x3c1;&#x3e;70.7924(+0.055)+797.09&#x2003;&#x2003;Formula (1).

Boundary acoustic wave device

A boundary acoustic wave filter device capable of increasing an out-of-band attenuation includes a dielectric film formed on a piezoelectric substrate, at least one longitudinally coupled resonator boundary acoustic wave filter having a plurality of IDTs disposed along a boundary between the piezoelectric substrate and the dielectric film, and at least two one-terminal-pair boundary acoustic wave resonators. At least one boundary acoustic wave resonator is connected in series to the longitudinally coupled resonator boundary acoustic wave filter, and at least remaining one boundary acoustic wave resonator is connected in parallel to the longitudinally coupled resonator boundary acoustic wave filter. An anti-resonant frequency of the serially connected boundary acoustic wave resonator is located in a higher frequency range than a passband of the boundary acoustic wave filter device, and a resonant frequency of the parallel-connected boundary acoustic wave resonator is equal to or higher than the anti-resonant frequency of the serially connected boundary acoustic wave resonator.

Boundary acoustic wave filter device

A surface acoustic wave (SAW) filter includes a piezoelectric substrate. A resin pattern having a permittivity less than that of the piezoelectric substrate and first and second conductor patterns are disposed on the piezoelectric substrate. The first conductor pattern defines two one-terminal-pair SAW resonators and two longitudinally coupled resonator SAW filters. A portion of the second conductor pattern defines wiring traces having different potentials. Portions of the wiring traces facing each other in a plan view are disposed on the resin pattern.

Surface acoustic wave filter and communication apparatus

A surface acoustic wave device includes first stage longitudinally coupled resonator type surface acoustic wave elements and second stage longitudinally coupled resonator type surface acoustic wave elements that are cascaded to each other and are arranged on a piezoelectric substrate. Each of the first and second stage longitudinally coupled resonator type surface acoustic wave elements is provided with at least three IDTs arranged along the direction of transmission of a surface acoustic wave. The central IDT of each of the longitudinally coupled resonator type surface acoustic wave elements includes narrow pitch electrode finger portions. At least one of the number and the pitch of the electrode fingers of the narrow pitch electrode finger portions of the first stage longitudinally coupled resonator type surface acoustic wave elements is set to be different from that of the second stage longitudinally coupled resonator type surface acoustic wave elements.

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Nagaokakyo, Japan

Norihiko Nakahashi