Abstract: Acoustic resonators and filter devices. An acoustic resonator includes a piezoelectric plate having front and back surfaces, a portion of the piezoelectric plate forming a diaphragm, and a conductor pattern on the front surface, the conductor pattern including a multi-mark interdigital transducer (IDT), fingers of the IDT on the diaphragm. A thickness between the front and back surfaces is greater than or equal to 200 nm and less than or equal to 1000 nm.

Abstract: An acoustic resonator is provided that includes a piezoelectric layer having at least a portion attached to a substrate either directly or via one or more intermediate layers; and a conductor pattern on the piezoelectric layer. The conductor pattern includes a multi-mark interdigital transducer having a plurality of interleaved fingers extending from opposing busbars, and a length between outermost fingers of the interleaved fingers. The IDT is divided along the length into at least three sections. A change in the mark between the at least three sections has a smaller effect on a resonance frequency of a primary shear acoustic mode of all of the at least three sections of the acoustic resonator in comparison to an effect that the change in the mark has on a spurious acoustic mode other than the primary shear acoustic mode of all of the at least three sections.

Abstract: An acoustic resonator is provided that includes a piezoelectric layer; an interdigital transducer on the piezoelectric layer and that includes a plurality of interleaved fingers; a lid disposed above the piezoelectric layer and defining a first cavity between the lid and the piezoelectric layer; a substrate disposed below the piezoelectric layer opposite the lid; and a second cavity between at least a portion of the piezoelectric layer and at least a portion of the substrate. Moreover, a height of the first cavity is greater than a pitch of at least two interleaved fingers of the plurality of interleaved fingers and at most four times greater than a height of the second cavity.

Abstract: An acoustic resonator is provided that includes a piezoelectric layer, an interdigital transducer (IDT) including a plurality of interleaved fingers on the piezoelectric layer, a substrate, and an acoustic reflector between the piezoelectric layer and the substrate. The acoustic reflector that is on the piezoelectric layer includes alternating first layers of first materials and second layers of second materials. A first acoustic impedance of the first materials is different from a second acoustic impedance of the second materials. A ratio of a pitch of the IDT over a thickness of the piezoelectric layer is less than 10. A first thickness of at least one of the first layers is larger than a quarter of a first wavelength ?1. ?1 is an acoustic wavelength of a shear bulk wave in the at least one of the first layers at a resonance frequency of the transversely-excited bulk acoustic resonator.

Abstract: An acoustic resonator is provided that includes a substrate; an intermediate layer on the substrate; a piezoelectric layer on the intermediate layer; an interdigital transducer (IDT) on a surface of the piezoelectric layer, the IDT including opposing busbars that have interleaved fingers extending therefrom. Moreover, an inner surface of at least one busbar of the opposing busbars of the IDT has a curved shape.

Abstract: Acoustic resonator devices and acoustic filter devices. An acoustic resonator includes a piezoelectric plate having front and back surfaces. The back surface is attached to a surface of a substrate. The piezoelectric plate comprises a diaphragm spanning a cavity. A conductor pattern is formed on the front surface. The conductor pattern includes a multi-mark multi-pitch interdigital transducer (IDT), wherein fingers of the IDT are on the diaphragm.

Abstract: An apparatus for filtering radio frequency signals is provided. The apparatus includes a substrate and a membrane coupled to the substrate that includes piezoelectric material. The apparatus also includes an interdigital transducer (IDT) coupled to the membrane and includes a plurality of interleaved fingers. The apparatus also includes a lid, in which the membrane is arranged between the substrate and the lid with a first cavity having a first height between the lid and a first main surface of the membrane and a second cavity having a second height between the substrate and a second main surface of the membrane that opposes the first main surface. Moreover, the first height between the lid and the first main surface of the membrane is greater than a pitch of at least one pair of interleaved fingers of the plurality of interleaved fingers and at most four times greater than the second height.

Abstract: A filter device is provided that includes a substrate having a surface and a piezoelectric plate supported by the substrate. A plurality of interdigital transducers (IDTs) for multiple resonators are provided that each have interleaved fingers at respective diaphragms of the piezoelectric plate disposed over one or more cavities. Moreover, a first resonator includes a first plurality of interleaved fingers having a first pitch and a second resonator includes a second plurality of interleaved fingers having a second pitch that is different than the first pitch. This configuration adjusts the resonance frequencies of each resonator. Moreover, a dielectric layer may be uniformly disposed over at least one surface of the respective diaphragms of the piezoelectric plate.

Abstract: Filter devices are disclosed. A filter device includes a piezoelectric plate comprising a supported portion, a first diaphragm, and a second diaphragm. The supported portion is attached to a substrate and the first and second diaphragms spans respective cavities in the substrate. A first interdigital transducer (IDT) has interleaved fingers on the first diaphragm. A second interdigital transducer (IDT) has interleaved fingers on the second diaphragm. A first dielectric layer is between the interleaved fingers of the first IDT, and a second dielectric layer is between the interleaved fingers of the second IDT. A thickness of the first dielectric layer is greater than a thickness of the second dielectric layer. The piezoelectric plate and the first and second IDTs are configured such that radio frequency signals applied to first and second IDTs excite primary shear acoustic modes in the respective diaphragms.

Abstract: An acoustic resonator has a substrate having a surface and a single-crystal piezoelectric plate, with a portion of the piezoelectric plate forming a diaphragm that spans a cavity in the substrate. An interdigital transducer (IDT) is formed on a surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT are disposed on the diaphragm. The ends of IDT interleaved fingers or inner surfaces of the opposing busbars have a curved shape. In some cases, gaps between ends of the interleaved fingers and opposing busbars have one of circular gap shapes or parabolic gap shapes. The cavity may be formed in an intermediate layer of the substrate.

Abstract: A bulk acoustic resonator is provided that includes a piezoelectric layer; first and second busbars on a surface of the piezoelectric layer and that extend along a first direction; and units of fingers that are adjacent to each other. Each of the units of fingers includes a first finger that extends from the first busbar and a second finger that extends from the second busbar. Moreover, a first pitch of each unit of fingers indicates a distance along the first direction between the first finger and the second finger in the respective unit, with the first pitch varying along a second direction that is orthogonal to the first direction. A unit pitch indicates a center-to-center distance along the first direction between respective first fingers of adjacent units that extend from the first busbar, with the unit pitch being substantially constant across the plurality of units of fingers.

Abstract: An acoustic resonator device is provided that includes a piezoelectric layer; and a conductor pattern on a surface of the piezoelectric layer. The conductor pattern includes an interdigital transducer that includes a first busbar, a second busbar, and interleaved fingers that each extend from one of the first and second busbars. The interleaved fingers includes a first finger and a last finger at opposing ends of the IDT. The conductor pattern includes a first reflector element proximate to the first finger; and a second reflector element proximate to the last finger. A distance between the first reflector element and the first finger is greater than a pitch p of the IDT, the pitch p being a center-to-center spacing between adjacent interleaved fingers. Moreover, a distance between the second reflector element and the last finger is greater than the pitch p of the IDT.

Abstract: A filter device is provided that includes a substrate comprising a base and an intermediate layer; a piezoelectric layer coupled to the substrate; a first interdigital transducer (IDT) of a first bulk acoustic resonator device on the piezoelectric layer and having interleaved fingers over a first cavity the first bulk acoustic resonator device; a second IDT of a second bulk acoustic resonator device on the piezoelectric layer and having interleaved fingers over a second cavity of the second bulk acoustic resonator device; a first dielectric layer having a first thickness disposed on the piezoelectric layer and between the interleaved fingers of the first IDT; and a second dielectric layer having a second thickness disposed on the piezoelectric layer and between the interleaved fingers of the second IDT. Moreover, the first thickness is greater than the second thickness.

Abstract: Radio frequency filters are disclosed. A bandpass filter is discloses that includes one first bulk acoustic resonator on a first chip including a first piezoelectric layer having an LN-equivalent thickness less than or equal to 535 nm; a second bulk acoustic resonator on a second chip including a second piezoelectric layer having a thickness greater than the LN-equivalent thickness of the piezoelectric layer on the first chip; and a circuit card coupled to the first chip and the second chip and that electrically connects the first chip to the second chip.

Abstract: A filter device is provided that includes at least two resonators connected in parallel that each include a substrate, a piezoelectric layer attached either directly or via one or more intermediate layers to the substrate, and an interdigital transducer (IDT) at the piezoelectric layer, the IDT including a plurality of interleaved fingers The resonators include a physical layout such that lengths of the resonators extend in a first direction that is substantially orthogonal to a second direction of the interleaved fingers, a position of a first resonator is offset in the second direction from a position of a second resonator, such that the respective lengths of the resonators are not aligned in a same axis in the first direction, and the length of the first resonator is offset in the first direction from the length of the second resonator.

Abstract: An acoustic resonator is provided that a substrate; a piezoelectric layer, a Bragg reflector layer disposed between the substrate and the piezoelectric layer, and an IDT at a surface of the piezoelectric layer that faces the Bragg reflector layer. The IDT includes a plurality of interleaved fingers extending from first and second busbars. Moreover, an etched region extends into at least a portion of the piezoelectric layer, the etched region including an area between the first busbar and a tip of at least one finger of the plurality of interleaved fingers extending from the second busbar in a first direction substantially parallel to a direction in which the interleaved fingers extend.

Abstract: An acoustic resonator device includes a portion of a piezoelectric plate is a diaphragm spanning a cavity in a substrate. A conductor pattern on a surface of the piezoelectric plate includes an interdigital transducer (IDT) with a first busbar, a second busbar, and a plurality of interleaved fingers extending alternately from the first and second busbars, first and second reflector elements proximate and parallel to a first finger of the interleaved fingers, and third and fourth reflector element proximate and parallel to a last finger of the interleaved fingers. Overlapping portions of the interleaved fingers and the first to fourth reflector elements are on the diaphragm. pr1 is a center-to-center distance of the first and second reflector elements and a center-to-center distance of the third and fourth reflector elements, p is a pitch of the interleaved fingers, and 1.1p?pr1?1.5p.

Abstract: An acoustic resonator device includes a diaphragm including a portion of the piezoelectric plate spanning a cavity in a substrate. A conductor pattern on a surface of the piezoelectric plate includes an interdigital transducer (IDT) with a first busbar, a second busbar, and a plurality of interleaved fingers, wherein the plurality of interleaved fingers extend alternately from the first and second busbars, overlapping portions of the plurality of interleaved fingers on the diaphragm. The conductor pattern also includes first and second reflector elements on the diaphragm proximate and parallel to a first finger of the plurality of interleaved fingers, and third and fourth reflector element on the diaphragm proximate and parallel to a last finger of the plurality of interleaved fingers.

Abstract: Acoustic resonators and filters are disclosed. An acoustic resonator includes a substrate, a piezoelectric plate and an acoustic Bragg reflector between a surface of the substrate and a back surface of the piezoelectric plate. A conductor pattern on a front surface of the piezoelectric plate includes an interdigital transducer (IDT). The IDT includes a first busbar, a second busbar, and interleaved parallel fingers extending alternately from the first and second busbars. The fingers include a first finger and a last finger at opposing ends of the IDT. A first reflector element is proximate and parallel to the first finger and a second reflector element is proximate and parallel to the last finger. A distance pr between the first reflector element and the first finger and between the second reflector element and the last finger is greater than a pitch p of the IDT.

Abstract: Acoustic resonators, filters and methods of making resonators are disclosed. An acoustic resonator includes a substrate, a piezoelectric plate, and an acoustic Bragg reflector between a surface of the substrate and a back surface of the piezoelectric plate. An interdigital transducer (IDT) on a front surface of the piezoelectric plate includes first and second busbars and a plurality of interleaved fingers extending alternately from the first and second busbars. At least a portion of the first busbar contacts the substrate through an opening in the piezoelectric plate and acoustic Bragg reflector.