Nihon Dempa Kogyo Co., Ltd.

Nrs Technologies, Inc.

Tadaaki Tsuda

Yasushi Yamamoto

Yoshihiro Takahashi

Hiroshi Kawahara

Minoru Sakai

Takashi Ohtani

There is provided a tapered elastic wave filter higher in impedance than a conventional filter where one input-side IDT electrode and one output-side IDT electrode are disposed. Filter parts which are the same in the structure of an input-side IDT electrode and in the structure of an output-side IDT electrode are disposed, and when the first filter part is disposed on a lower side and the second filter part is disposed on an upper side of the first filter part so that the input-side IDT electrodes are connected and the output-side IDT electrodes are connected, in cascade (in series) between a signal port and a ground port, an upper busbar in each of the IDT electrodes of the first filter part and a lower busbar in each of the IDT electrodes of the second filter part are electrically connected to each other.

Elastic wave filter

Disclosed is a pass band type acoustic wave filter capable of obtaining an excellent attenuation characteristic in attenuation bands, in which an IDT electrode having a meander structure is used as at least one of the input-side electrode and the output-side electrode, and the attenuation band is provided over/under the pass band. An electrode having a meander structure in which a plurality of IDT blocks are connected to each other in series between the input port or the output port and the ground port is arranged as the input-side IDT electrode and the output-side IDT electrode, and the electrode finger between the neighboring IDT blocks is removed, so as to suppress excitation of an undesired acoustic wave.

Acoustic wave filter

An elastic wave filter includes electrode fingers, a first busbar and a second busbar, and inclined electrode portions each having a narrower distance between the electrode fingers from the first busbar toward the second busbar. The elastic wave filter includes a dummy electrode disposed in at least one of the input-side IDT electrode portion and the output-side IDT electrode portion to suppress reflection of a diffracted elastic wave by the busbar and to suppress spurious response at an end portion in a frequency pass-band. The dummy electrode has a width dimension and a pitch that are determined such that none of a period shorter than a shortest period of the electrode fingers and a period longer than a longest period of the electrode fingers is satisfied.

To provide an elastic wave filter capable of obtaining steep attenuation at a high band side or a low band side in a pass band and having high selectivity. An elastic wave filter is configured in a manner that when seen in a propagation direction of an elastic wave, as for respective electrode fingers composing each group of electrode fingers in an input side tapered IDT electrode and an output side tapered IDT electrode, width dimensions thereof are the same one another, and a distance dimension between the adjacent electrode fingers is formed to be the same as the width dimension of the electrode finger, when seen in the propagation direction of an elastic wave, as for a group of electrode fingers in a grating reflector, width dimensions of respective electrode fingers composing the group of the electrode fingers are the same, and a distance dimension between the adjacent electrode fingers is formed to be the same as the width dimension, and the width dimension of the electrode finger and the distance dimension between the electrode fingers are set to be equal to or less than a minimum value or equal to or more than a maximum value of the width dimension of the electrode finger and the distance dimension between the electrode fingers in the input side tapered IDT electrode and the output side tapered IDT electrode.

Elastic wave filter including a grating reflector between tapered input and output IDT electrodes

To provide a transversal type filter having weighted finger electrodes of at least either of an input IDT and an output IDT provided on a piezoelectric substrate, in which a diffraction of elastic wave output from an end face of the weighted IDT electrode is suppressed, a band width is wide, and a high flatness and a high selectivity are realized. In at least either of an input IDT and an output IDT, an apodized region in which a weighting is performed by using an apodizing method with which an aperture of finger electrodes is continuously changed is formed on a center portion of the electrode with respect to a propagation direction of an elastic wave, and dog-leg regions in which a weighting is performed by using a dog-leg method with which the aperture is made into 1/n by floating electrodes to form n tracks are formed on both sides of the apodized region. Subsequently, finger electrodes in each track of the dog-leg region are further weighted by using the apodizing method.

Transversal type filter

In an elastic wave filter in which an IDT is configured in a tapered shape, an object of the present invention is to provide a technology capable of suppressing deterioration of attenuation characteristics due to refraction and the like of the elastic wave and also suppressing loss. Then, an input side area adjacent to an input side tapered IDT electrode of this short grating electrode and an output side area close to an output side tapered IDT electrode are made patterns continuous (as if extended) from the input side tapered IDT electrode and the output side tapered IDT electrode respectively. The areas between the input side tapered IDT electrode, the output side tapered IDT electrode and the short grating electrode are set in a manner that the cycle unit &#x3bb; which is a repeating unit of the electrode fingers is continued without breaking.

Elastic wave filter with tapered IDT electrodes

In the surface acoustic wave device including a lead frame made of metal in which a plurality of inner leadsare formed, wherein a chipcomprising at least one piezoelectric substrate is mounted on a resin baseinto which a lead frame is molded integrally, are provided a wire lead section metal surfacethat is formed by exposing a wire lead section, which is electrically connected with an electrode of the chip through a bonding wire, out of inner leads that are arranged on both sides of the chip, from the resin base, and a chip lead section metal surfacethat is formed by exposing a chip lead section, which is partially covered with the chip, from the resin base.

Surface acoustic wave device

The present invention relates to a surface acoustic wave filter in which a plurality of pairs of comb electrode patterns are formed on an upper surface of a chip substrate made of a piezoelectric material. The surface acoustic wave filter includes a high-resistance pattern formed to surround a peripheral portion of the chip substrate on an upper surface side thereof, and a plurality of patterns formed to connect the high-resistance pattern to the respective comb electrode patterns.

Growing community of inventors

Sayama, Japan

Tadaaki Tsuda