Transversely-excited film bulk acoustic resonator with spiral interdigitated transducer fingers
AssigneeMurata Manufacturing Co., Ltd.
InventorsSean McHugh, Neal Fenzi
Life of this patent
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Abstract
Acoustic resonator devices, filers, and methods. An acoustic resonator includes a substrate and a piezoelectric plate, a portion of the piezoelectric plate being a diaphragm spanning a cavity in the substrate. A conductor pattern on a front surface of the piezoelectric plate includes interleaved interdigital transducer (IDT) fingers connected alternately to first and second busbars. The interleaved IDT fingers are on the diaphragm, and the interleaved IDT fingers include at least a first pair of interleaved spiral IDT fingers.
Claims17
An acoustic resonator, comprising:
- a substrate;
- a piezoelectric plate include a portion that forms a diaphragm that is over a cavity in the substrate;
- and
- a conductor pattern on a front surface of the piezoelectric plate, the conductor pattern comprising interleaved interdigital transducer (IDT) fingers connected alternately to first and second busbars,
- wherein the interleaved IDT fingers are on the diaphragm and comprise at least a first pair of interleaved spiral IDT fingers that each comprise one or more semicircular curved portions, and
- wherein each of the first and second busbars includes recesses such that gaps between each of the first and second busbars and the one or more semicircular curved portions of the first pair of interleaved spiral IDT fingers are effectively equal to a gap between adjacent interleaved fingers of the first pair of interleaved spiral IDT fingers.
A filter device, comprising:
- a piezoelectric plate including portions that form diaphragms that are over respective cavities in a substrate;
- and
- a conductor pattern on a front surface of the piezoelectric plate, the conductor pattern comprising a plurality of interdigital transducers (IDTs), each IDT comprising interleaved IDT fingers connected alternately to first and second busbars,
- wherein the interleaved IDT fingers of each IDT are on a respective diaphragm, and the interleaved IDT fingers of a least one IDT comprise a pair of interleaved spiral IDT fingers,
- wherein the pair of interleaved spiral IDT fingers that each comprise one or more semicircular curved portions, and
- wherein each of the first and second busbars includes recesses such that gaps between each of the first and second busbars and the one or more semicircular curved portions of the pair of interleaved spiral IDT fingers are effectively equal to a gap between adjacent interleaved fingers of the pair of interleaved spiral IDT fingers.
A method of fabricating an acoustic resonator, comprising:
- attaching a back surface of a piezoelectric plate to a substrate;
- forming a conductor pattern on a front surface of the piezoelectric plate, the conductor pattern comprising interleaved interdigital transducer (IDT) fingers connected alternately to first and second busbars;
- and
- forming a cavity in the substrate such that the interleaved IDT fingers are on a portion of the piezoelectric plate spanning the cavity,
- wherein the interleaved IDT fingers include at least a first pair of interleaved spiral IDT fingers that each comprise one or more semicircular curved portions, and
- wherein each of the first and second busbars includes recesses such that gaps between each of the first and second busbars and the one or more semicircular curved portions of the first pair of interleaved spiral IDT fingers are effectively equal to a gap between adjacent interleaved fingers of the first pair of interleaved spiral IDT fingers.
Dependencies are inferred from the claim text.