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US 6,583,691 B2Granted
Longitudinally coupled resonator type surface acoustic wave filter with an IDT having a narrow pitch portion
AssigneeMurata Manufacturing Co., Ltd.
InventorYuichi Takamine
Life of this patent
Estimating the term…
Abstract
In a longitudinally coupled resonator type surface acoustic wave filter including narrow pitch electrode finger portions provided in the end portions of the neighboring IDT's, respectively each which contains a portion of the electrode fingers of the IDT having a narrower pitch than the remaining portions of the electrode fingers of the IDT, the inter-center distance between the centers of at least one pair of adjacent electrode fingers is deviated from 0.25λA+0.25λB, in which λA represents the wavelength determined by the pitch of one of the electrode fingers, and λB represents the wavelength determined by the pitch of the other electrode.
Claims32
A longitudinally coupled resonator type surface acoustic wave filter comprising:
- a piezoelectric substrate;
- and
- first, second, and third IDT's provided on the piezoelectric substrate to extend along the surface acoustic wave propagation direction and having plural electrode fingers, respectively;
- at least one of the first, second, and third IDT's including at least one narrow pitch electrode finger portion in which the pitches of a portion of the electrode fingers arranged from the end of the IDT on the neighboring IDT side are less than the remaining portions of the electrode fingers in the IDT;
- the distance between the centers of at least one pair of adjacent electrode fingers being deviated from 0.25 λA+0.25 λB in which λA represents the wavelength determined by the pitch of one electrode finger of the at least one pair of adjacent electrode fingers, and λB represents the wavelength determined by the pitch of the other electrode finger of the at least one pair of adjacent electrode fingers.
2 more elements
A longitudinally coupled resonator type surface acoustic wave filter comprising:
- a piezoelectric substrate;
- and
- first, second, and third IDT's provided on the piezoelectric substrate to extend along the surface acoustic wave propagation direction and having plural electrode fingers, respectively;
- at least one of the first, second, and third IDT's including at least one narrow pitch electrode finger portion in which the pitches of a portion of the electrode fingers arranged from the end of the IDT on the neighboring IDT side are less than the remaining portions of the electrode fingers in the IDT;
- wherein
- λI2 represents the wavelength determined by the electrode finger pitch in the narrow pitch electrode finger portion, and λI1 represents the pitch in the electrode finger portion provided in the IDT containing the narrow pitch electrode finger portion and being other than the narrow pitch electrode finger portion;
- the distance between the centers of the adjacent electrode fingers of the neighboring IDT's being deviated from 0.5 λI2, when the narrow pitch electrode finger portions are arranged on both of the neighboring sides of the IDT's, respectively, and set to be different from 0.25 λI1+0.25 λI2, when the narrow pitch electrode finger portion is provided in only one of the IDT's.
4 more elements
A longitudinally coupled resonator type surface acoustic wave filter comprising:
- a piezoelectric substrate;
- and
- first, second, and third IDT's provided on the piezoelectric substrate to extend along the surface acoustic wave propagation direction and having plural electrode fingers, respectively;
- at least one of the first, second, and third IDT's including at least one narrow pitch electrode finger portion in which the pitches of a portion of the electrode fingers arranged from the end of the IDT on the neighboring IDT side are less than the remaining portion of the electrode fingers in the IDT;
- wherein
- λI2 represents the wavelength determined by the electrode finger pitch of the narrow pitch electrode finger portion, and λI1 represents the pitch of the electrode finger portion provided in the IDT containing the narrow pitch electrode finger portion and being other than the narrow pitch electrode finger portion;
- the distance between the centers of the adjacent electrode fingers provided in the narrow pitch electrode finger portion and the electrode finger portion other than the narrow pitch electrode finger portion being deviated from 0.25 λI1+0.25 λI2.
4 more elements
A longitudinally coupled resonator type surface acoustic wave filter comprising:
- a piezoelectric substrate;
- and
- first, second, and third IDT's provided on the piezoelectric substrate so as to extend along the surface acoustic wave propagation direction and having plural electrode fingers, respectively;
- at least one of the first, second, and third IDT's including at least one narrow pitch electrode finger portion in which the pitches of a portion of the electrode fingers arranged from the end of the IDT on the neighboring IDT side are shorter than the remaining portions of the electrode fingers, and an electrode finger portion succeeding the narrow pitch electrode finger portion has a relatively wide electrode finger pitch;
- an electrode finger portion having a different electrode finger pitch being provided in the narrow pitch electrode finger portion.
2 more elements
A longitudinally coupled resonator type surface acoustic wave filter comprising:
- a piezoelectric substrate;
- and
- first, second, and third IDT's provided on the piezoelectric substrate to extend along the surface acoustic wave propagation direction and having plural electrode fingers, respectively;
- at least one of the first, second, and third IDT's including at least one narrow pitch electrode finger portion in which the pitch of a portion of the electrode fingers arranged from the end of the IDT on the neighboring IDT side is shorter than that of the remaining portions of the electrode fingers in the IDT;
- wherein
- λI2 represents the wavelength determined by the electrode finger pitch in the narrow pitch electrode finger portion, and λI1 represents the pitch in the electrode finger portion provided in the IDT containing the narrow pitch electrode finger portion and being other than the narrow pitch electrode finger portion;
- the distance between the centers of the adjacent electrode fingers provided in the neighboring IDT's, respectively, being set to be different from 0.5 λI2, when the narrow pitch electrode finger portions are provided adjacently to each other in both of the neighboring IDT's, and moreover, being deviated from 0.25 λI1+0.25 λI2, when the narrow pitch electrode finger portion is provided in only one of the IDT's;
- the distance between the centers of the adjacent electrode fingers provided in the narrow pitch electrode finger portion and the electrode finger portion other than the narrow pitch electrode finger portion being deviated from 0.25 λI1+0.25 λI2.
5 more elements
Dependencies are inferred from the claim text.