Piezoelectric thin-film filter

A piezoelectric thin-film filter comprising:

• a substrate;
• a piezoelectric thin film supported by the substrate and including a portion that is acoustically separated from the substrate;
• at least two first electrode fingers disposed on one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and at least two third electrode fingers disposed on the one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate such that the first electrode fingers and the third electrode fingers are disposed alternately with gaps therebetween;
• and
• a common electrode disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and including portions facing the first electrode fingers and the third electrode fingers with the piezoelectric thin film therebetween;
• wherein
• a first electrode pair is defined by the first electrode fingers and the common electrode;
• a second electrode pair is defined by the third electrode fingers and the common electrode;
• a filter element defined by the first electrode pair and the second electrode pair is provided between a set including a first terminal connected to each of the first electrode fingers and a second terminal connected to the common electrode and a set including a third terminal connected to each of the third electrode fingers and a fourth terminal connected to the common electrode;
• insulating films provided between the first electrode fingers and the third electrode fingers are disposed alternately with the gaps therebetween on the one main surface of the piezoelectric thin film;
• each of the center-to-center distances between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween is larger than a value twice the thickness of the piezoelectric thin film;
• the filter element is a unit;
• at least two units connected in series to one of input terminals and output terminals are provided;
• and
• at least two of the at least two units are connected in parallel to the other one of the output terminals and the input terminals.

A piezoelectric thin-film filter comprising:

• at least two filter elements;
• each of the at least two filter elements comprises:
• a substrate;
• a piezoelectric thin film supported by the substrate and including a portion that is acoustically separated from the substrate;
• a first electrode pair including at least two first electrode fingers disposed on one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and at least two second electrode fingers disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate so as to face the first electrode fingers with the piezoelectric thin film therebetween;
• and
• a second electrode pair including at least two third electrode fingers disposed on the one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate such that the first electrode fingers and the third electrode fingers are disposed alternately with gaps therebetween and fourth electrode fingers disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate so as to face the third electrode fingers with the piezoelectric thin film therebetween;
• wherein
• the first electrode pair and the second electrode pair is provided between a set including a first terminal connected to each of the first electrode fingers and a second terminal connected to each of the second electrode fingers and a set including a third terminal connected to each of the third electrode fingers and a fourth terminal connected to each of the fourth electrode fingers;
• the piezoelectric thin-film filter includes insulating films provided between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween on the one main surface of the piezoelectric thin film;
• and
• each of center-to-center distances between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween is larger than a value twice the thickness of the portion of the piezoelectric thin film that is acoustically separated from the substrate;
• the first terminal and the second terminal of each of the filter elements are connected in parallel to one of input terminals and output terminals, and the third terminal and the fourth terminal of each of the filter elements are connected in series between the other one of the input terminals and the output terminals.

A piezoelectric thin-film filter comprising:

• a substrate;
• a piezoelectric thin film supported by the substrate and including a portion that is acoustically separated from the substrate;
• a first electrode pair including at least two first electrode fingers disposed on one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and at least two second electrode fingers disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate so as to face the first electrode fingers with the piezoelectric thin film therebetween;
• and
• a second electrode pair including at least two third electrode fingers disposed on the one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate such that the first electrode fingers and the third electrode fingers are disposed alternately with gaps therebetween and fourth electrode fingers disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate so as to face the third electrode fingers with the piezoelectric thin film therebetween;
• wherein
• a filter element defined by the first electrode pair and the second electrode pair is provided between a set including a first terminal connected to each of the first electrode fingers and a second terminal connected to each of the second electrode fingers and a set including a third terminal connected to each of the third electrode fingers and a fourth terminal connected to each of the fourth electrode fingers;
• the piezoelectric thin-film filter include insulating films provided between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween on the one main surface of the piezoelectric thin film;
• each of center-to-center distances between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween is larger than a value twice the thickness of the portion of the piezoelectric thin film that is acoustically separated from the substrate;
• and
• the number of pairs of first electrode fingers and second electrode fingers included in the first electrode pair is different from the number of pairs of third electrode fingers and fourth electrode fingers included in the second electrode pair.

A piezoelectric thin-film filter comprising:

• a substrate;
• a piezoelectric thin film supported by the substrate and including a portion that is acoustically separated from the substrate;
• at least two first electrode fingers disposed on one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and at least two third electrode fingers disposed on the one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate such that the first electrode fingers and the third electrode fingers are disposed alternately with gaps therebetween;
• and
• a common electrode disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and including portions facing the first electrode fingers and the third electrode fingers with the piezoelectric thin film therebetween;
• wherein
• a first electrode pair is defined by the first electrode fingers and the common electrode;
• a second electrode pair is defined by the third electrode fingers and the common electrode;
• a filter element defined by the first electrode pair and the second electrode pair is provided between a set including a first terminal connected to each of the first electrode fingers and a second terminal connected to the common electrode and a set including a third terminal connected to each of the third electrode fingers and a fourth terminal connected to the common electrode;
• insulating films provided between the first electrode fingers and the third electrode fingers are disposed alternately with the gaps therebetween on the one main surface of the piezoelectric thin film;
• each of the center-to-center distances between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween is larger than a value twice the thickness of the piezoelectric thin film;
• and
• the number of pairs of first electrode fingers and the common electrode included in the first electrode pair is different from the number of pairs of third electrode fingers and the common electrode included in the second electrode pair.

A piezoelectric thin-film filter comprising:

• a substrate;
• a piezoelectric thin film supported by the substrate and including a portion that is acoustically separated from the substrate;
• a first electrode pair including at least two first electrode fingers disposed on one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and at least two second electrode fingers disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate so as to face the first electrode fingers with the piezoelectric thin film therebetween;
• and
• a second electrode pair including at least two third electrode fingers disposed on the one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate such that the first electrode fingers and the third electrode fingers are disposed alternately with gaps therebetween and fourth electrode fingers disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate so as to face the third electrode fingers with the piezoelectric thin film therebetween;
• wherein
• a filter element defined by the first electrode pair and the second electrode pair is provided between a set including a first terminal connected to each of the first electrode fingers and a second terminal connected to each of the second electrode fingers and a set including a third terminal connected to each of the third electrode fingers and a fourth terminal connected to each of the fourth electrode fingers;
• the piezoelectric thin-film filter include insulating films provided between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween on the one main surface of the piezoelectric thin film;
• each of center-to-center distances between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween is larger than a value twice the thickness of the portion of the piezoelectric thin film that is acoustically separated from the substrate;
• the filter element is a unit;
• at least two units connected in series to one of input terminals and output terminals are provided;
• and
• at least two of the at least two units are connected in parallel to the other one of the output terminals and the input terminals.

A piezoelectric thin-film filter comprising:

• at least two filter elements;
• each of the at least two filter elements comprises:
• a substrate;
• a piezoelectric thin film supported by the substrate and including a portion that is acoustically separated from the substrate;
• at least two first electrode fingers disposed on one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and at least two third electrode fingers disposed on the one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate such that the first electrode fingers and the third electrode fingers are disposed alternately with gaps therebetween;
• and
• a common electrode disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and including portions facing the first electrode fingers and the third electrode fingers with the piezoelectric thin film therebetween;
• wherein
• a first electrode pair is defined by the first electrode fingers and the common electrode;
• a second electrode pair is defined by the third electrode fingers and the common electrode;
• the first electrode pair and the second electrode pair is provided between a set including a first terminal connected to each of the first electrode fingers and a second terminal connected to the common electrode and a set including a third terminal connected to each of the third electrode fingers and a fourth terminal connected to the common electrode;
• insulating films provided between the first electrode fingers and the third electrode fingers are disposed alternately with the gaps therebetween on the one main surface of the piezoelectric thin film;
• and
• each of the center-to-center distances between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween is larger than a value twice the thickness of the piezoelectric thin film;
• the first terminal and the second terminal of each of the filter elements are connected in parallel to one of input terminals and output terminals, and the third terminal and the fourth terminal of each of the filter elements are connected in series between the other one of the input terminals and the output terminals.

A piezoelectric thin-film filter comprising:

• a substrate;
• a piezoelectric thin film supported by the substrate and including a portion that is acoustically separated from the substrate;
• at least two first electrode fingers disposed on one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and at least two third electrode fingers disposed on the one main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate such that the first electrode fingers and the third electrode fingers are disposed alternately with gaps therebetween;
• and
• a common electrode disposed on the other main surface of the portion of the piezoelectric thin film that is acoustically separated from the substrate and including portions facing the first electrode fingers and the third electrode fingers with the piezoelectric thin film therebetween;
• wherein
• a first electrode pair is defined by the first electrode fingers and the common electrode;
• a second electrode pair is defined by the third electrode fingers and the common electrode;
• a filter element defined by the first electrode pair and the second electrode pair is provided between a set including a first terminal connected to each of the first electrode fingers and a second terminal connected to the common electrode and a set including a third terminal connected to each of the third electrode fingers and a fourth terminal connected to the common electrode;
• insulating films provided between the first electrode fingers and the third electrode fingers are disposed alternately with the gaps therebetween on the one main surface of the piezoelectric thin film;
• each of the center-to-center distances between the first electrode fingers and the third electrode fingers that are disposed alternately with the gaps therebetween is larger than a value twice the thickness of the piezoelectric thin film;
• and
• further comprising a second insulating film provided in at least one of a first area covering the first electrode fingers, the third electrode fingers, and the insulating films, and a second area covering the common electrode.