Abstract: The invention relates to a laterally coupled bulk acoustic wave (LBAW) filter comprising a vibration layer for carrying bulk acoustic waves, electrode means comprising a first electrode coupled to the vibration layer for exciting to the vibration layer at least one longitudinal wave mode having a first frequency band and one shear wave mode having a second frequency band, and a second electrode coupled to the vibration layer for sensing the filter pass signal, the first and second electrodes being laterally arranged with respect to each other, and an acoustic reflector structure in acoustic connection with the vibration layer. According to the invention, the reflector structure is adapted to acoustically isolate the vibration layer from its surroundings at the first frequency band more efficiently than at the second frequency band for suppressing the effect of the shear wave mode at the second frequency band from the filter pass signal. The invention helps to improve the quality of LBAW filter passbands.

Abstract: A quartz crystal unit has a quartz crystal tuning fork resonator having a thickness within a range of 0.05 mm to 0.18 mm, and at least one groove formed in at least one of opposite main surfaces of each of first and second tuning fork tines so that a length of the at least one groove is within a range of 20% to 78% of an overall length of the resonator and less than 1.29 mm. An electrode is disposed on at least one of a base portion and a surface of the at least one groove so that the electrode of the first tuning fork tine has an electrical polarity opposite to an electrical polarity of the electrode of the second tuning fork tine. The capacitance ratio r2 of a second overtone mode of vibration of the quartz crystal tuning fork resonator is greater than 1500. The quartz crystal tuning fork resonator is housed in a case having an open end, and a lid is connected to the case.

Abstract: A method of manufacturing an elastic wave device is provided with a lamination step of forming, on a substrate (1), a plurality of elastic wave devices, each of which includes a lower electrode (2), a piezoelectric film (3), and an upper electrode (4); a measuring step for measuring the operation frequency distribution of the elastic wave devices on the substrate (1); and an adjusting step for forming an adjusting region, in which the thickness of the elastic wave device is different from the thicknesses of other portions in a resonance portion of each elastic wave device, corresponding with the distribution of the operation frequencies. The adjusting region is formed so that the size of the area of the adjusting region of the resonator portion of each elastic wave device is different in accordance with the operation frequency distribution that is measured. Thus, the frequency characteristics of the elastic wave devices are easily adjusted by a small number of steps.

Abstract: A thin-film piezoelectric resonator including a substrate (6); a piezoelectric layer (2), a piezoelectric resonator stack (12) with a top electrode (10) and bottom electrode (8), and a cavity (4). The piezoelectric resonator stack (12) has a vibration region (40) where the top electrode and bottom electrode overlap in the thickness direction, and the vibration region comprises a first vibration region, second vibration region, and third vibration region. When seen from the thickness direction, the first vibration region is present at the outermost side, the third vibration region is present at the innermost side and does not contact the first vibration region, and the second vibration region is interposed between the first vibration region and third vibration region.

Abstract: An acoustic wave device includes: a first piezoelectric thin film resonator including a first lower electrode, a first upper electrode and a first piezoelectric film sandwiched between the first lower and upper electrodes; a decoupler film provided on the first upper electrode; and a second piezoelectric thin film resonator provided on the decoupler film and including a second lower electrode, a second upper electrode and a second piezoelectric film sandwiched between the second lower and upper electrodes, wherein the first piezoelectric film and the second piezoelectric film comprise aluminum nitride and include an element increasing a piezoelectric constant of the aluminum nitride.

Abstract: Embodiments provide a solidly-mounted bulk acoustic wave (BAW) resonator and method of making same. In embodiments, the BAW resonator may include one or more extensions that are acoustical similar to active region components of the BAW resonator. Other embodiments may be described and claimed.

Abstract: An acoustic microwave filter comprises an input and an output, and a plurality of acoustic resonators coupled between the input and the output. The difference between the lowest resonant frequency and the highest resonant frequency of a plurality of resonators in the filter is at least 1.25 times the frequency separation of the resonator with the highest resonant frequency in the plurality of resonators. Another acoustic microwave filter comprises an input and an output, and a plurality of acoustic resonators coupled between the input and the output to form a passband. The frequency difference between a local minimum or a local maximum of a return loss magnitude of the acoustic microwave filter and the edge of the passband is at least once the frequency separation of the resonator with the highest resonant frequency.

Abstract: In one aspect of the present invention, an integrated wafer level package includes a first wafer and a second wafer spaced apart to define a first gap therebetween, a first bulk acoustic wave (BAW) filter disposed on the first wafer and a second BAW filter disposed on the second wafer, where the second BAW filter faces directly the first BAW filter to define a second gap therebetween, a seal ring disposed between the first wafer and the second wafer in the first gap such that a seal is formed surrounding the first BAW filter and the second BAW filter and defining a cavity between the seal ring and the first BAW filter and the second BAW filter, and at least one external contact accessible externally to the wafer level package and electrically coupled to at least one of the first BAW filter and the second BAW filter.

Abstract: In one aspect of the invention, the acoustic wave resonator includes a resonator structure having a first electrode, a piezoelectric layer formed on the first electrode, and a second electrode formed on the piezoelectric layer, and a composite layered structure associated with the resonator structure such that the immunity of the acoustic wave resonator to environmental change and aging effects is improved, the trimming sensitivity is substantially minimized, and/or dispersion characteristics of the acoustic wave resonator is optimized.

Abstract: A solidly mounted resonator (SMR) device includes an acoustic reflector having stacked acoustic reflector layer pairs, each of which includes a low acoustic impedance layer formed of low acoustic impedance material stacked on a high acoustic impedance layer formed of high acoustic impedance material. The SMR device further includes a bottom electrode disposed on the acoustic reflector, a piezoelectric layer disposed on the bottom electrode, and a top electrode disposed on the piezoelectric layer. A collar is formed outside a main active region defined by an overlap between the top electrode, the piezoelectric layer and the bottom electrode, and at least one frame is disposed within the main active region. The collar has an inner edge substantially aligned with a boundary of or overlapping the main active region, and the at least one frame has an outer edge substantially aligned with the boundary of the main active region.

Abstract: An acoustic resonator structure comprises a substrate having an air cavity, an acoustic stack disposed over the substrate and comprising a piezoelectric material disposed between a first electrode and a second electrode, and an acoustic reflector disposed over the substrate and comprising a single pair of acoustic impedance layers configured to reflect acoustic waves produced by vibration of the acoustic stack, wherein at least one of the acoustic impedance layers comprises a temperature compensating material.

Abstract: An acoustic resonator structure comprises a first electrode disposed on a substrate, a piezoelectric layer disposed on the first electrode, a second electrode disposed on the piezoelectric layer, and an air cavity disposed in the substrate below at least a portion of a main membrane region defined by an overlap between the first electrode. The acoustic resonator structure may further comprise various integrated structures at or around the main membrane region to improve its electrical performance.

Abstract: An acoustic resonator comprises a substrate having a trench with lateral boundaries, a first electrode formed on the substrate over the trench and having lateral edges that are laterally offset from the lateral boundaries of the trench by a first distance, a first piezoelectric layer formed on the first electrode, a second electrode formed on the first piezoelectric layer and having edges that are laterally aligned inside the lateral boundaries of the trench, a second piezoelectric layer located on the second electrode, and a third electrode located on the second piezoelectric layer and having edges that are laterally offset from the edges of the second electrode.

Abstract: A piezoelectric thin film resonator includes: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode facing each other across at least a part of the piezoelectric film; and an insertion film that is inserted into the piezoelectric film, is located in at least a part of an outer periphery region in a resonance region in which the lower electrode and the upper electrode face each other across the piezoelectric film, and is not located in a center region of the resonance region.

Abstract: In one aspect of the invention, an acoustic wave device includes a substrate, an acoustic isolator formed in or on the substrate, a bottom electrode formed on the acoustic isolator, a piezoelectric layer formed on the bottom electrode, a top electrode formed on the piezoelectric layer, and boundary means such as a gasket surrounding one of the first and second electrodes whose perimeter is aligned inside the perimeter of the acoustic isolator. The gasket has a lateral side having a wall profile, a curve profile, a multi-step profile, a gradually variable profile, or a combination of them.

Abstract: An elastic wave device includes a medium layer, a piezoelectric body, and an IDT electrode that are disposed on a supporting substrate. The medium layer is made of a medium containing a low-velocity medium in which a propagation velocity of a same bulk wave as that which is a main vibration component of an elastic wave propagating in the piezoelectric body and being used is lower than a propagation velocity of the elastic wave, and a high-velocity medium in which the propagation velocity of the same bulk wave as that which is a main vibration component of the elastic wave is higher than the propagation velocity of the elastic wave.

Abstract: A radio frequency filter and a manufacturing method thereof are provided. A radio frequency filter includes bulk acoustic wave resonators (BAWRs), the BAWRs including first BAWRs connected in series, second BAWRs connected in parallel, or a combination thereof.

Abstract: The present invention relates to a BAW filter operating with bulk acoustic waves, which has a multilayer construction, wherein functional layers of a BAW resonator operating with bulk acoustic waves are realized by the multilayer construction, and wherein an interconnection of passive components is furthermore formed by the multilayer construction, said interconnection forming a balun, wherein the balun has at least one inductance (L1, L2, L3) and at least one capacitance (C1, C2) which are formed from structured functional layers of the BAW resonator. Furthermore, the invention relates to a method for producing the BAW filter.

Abstract: An acoustic resonator device includes a bottom electrode disposed on a substrate over an air cavity, a piezoelectric layer disposed on the bottom electrode, and a top electrode disposed on the piezoelectric layer, where an overlap between the top electrode, the piezoelectric layer and the bottom electrode over the air cavity defines a main membrane region. The acoustic resonator device further includes at least one air-ring defining a boundary of the main membrane region, and at least one first frame formed between the bottom electrode and the piezoelectric layer or formed between the substrate and the bottom electrode, and a second frame formed between the piezoelectric layer and the top electrode.

Abstract: A method of manufacturing a ladder filter including first and second resonators includes: forming a piezoelectric film on an entire surface of a substrate that has respective lower electrodes of the first and second resonator formed thereon, an conductive film on the piezoelectric film, and a second film on the conductive film; forming a pattern of the second film in a prescribed region in the second area; forming a first film on an entire surface of the substrate; etching the first film, forming a pattern of the first film, the second film and the conductive film in the second area, and forming a pattern of the first film and the conductive film in the first area, to form respective upper electrodes from the conductor film; and thereafter, etching the piezoelectric film to form respective patterns of the piezoelectric film in the first and second areas, respectively.

Abstract: An acoustic wave device includes piezoelectric thin-film resonators, each of which includes: a substrate; a piezoelectric thin-film on the substrate; an lower electrode provided on a first surface of the piezoelectric film; an upper electrode provided on a second surface of the piezoelectric film opposite to the first surface; and a first addition film that is provided in a resonance portion in which the lower electrode and the upper electrode face each other through the piezoelectric film and is located between the piezoelectric thin-film and the upper electrode, the first addition film having a shape different from that of the resonance portion.

Abstract: An improved method of packaging a sensor is provided. The method includes the step of affixing a tuning fork to a platform. The tuning fork includes tines comprising one or more surfaces, with each tine further comprising an electrode and a piezoelectric material. An application specific integrated circuit (ASIC) is affixed to the platform. Electrical communication between the ASIC and the electrode of each tine is established for providing stimulus to the tuning fork and for receiving a response signal from the tuning fork. A protective layer is applied to cover the platform and a portion of the tuning fork while maintaining a portion of a surface of each tine free from the protective layer such that the surface can displace the fluid in contact therewith.

Abstract: The elementary filter of the HBAR type includes two resonators (20, 22) of the HBAR type which are each formed by a transducer (8) and a substrate (12) which are coupled in a suitable manner by electroacoustic waves. The first resonator (20), the second resonator (22) and the coupling element (28) by way of evanescent waves include the same monobloc acoustic substrate (12) which is arranged facing and coupled to the piezoelectric transducer (8) by waves having the same longitudinal or transverse vibration mode through the same reference electrode (10).

Abstract: A MEMS device includes a substrate, one or more anchors formed on a first surface of the substrate, and a piezoelectric layer suspended over the first surface of the substrate by the one or more anchors. Notably, the piezoelectric layer is a bimorph including a first bimorph layer and a second bimorph layer. A first electrode may be provided on a first surface of the piezoelectric layer facing the first surface of the substrate, such that the first electrode is in contact with the first bimorph layer of the piezoelectric layer. A second electrode may be provided on a second surface of the piezoelectric layer opposite the substrate, such that the second electrode is in contact with the second bimorph layer of the piezoelectric layer. The second electrode may include a first conducting section and a second conducting section, which are inter-digitally dispersed on the second surface.

Abstract: A bulk acoustic wave resonator includes a substrate, a resonator section in which a piezoelectric film is sandwiched between a pair of electrodes, and a vibration region where the electrodes overlap when viewed in a film thickness direction is defined, an elastically deformable support section that connects the substrate and the resonator section, a membrane arranged between the resonator section and the substrate to face the vibration region of the resonator section and be fixed on the substrate with a space in between, and driver sections that are defined in the resonator section and the substrate adjacent to the vibration region and the membrane, and that move the resonator section toward and away from the substrate. The vibration region of the resonator section contacts the membrane when the driver sections move the resonator section close to the substrate.

Abstract: A bulk acoustic wave (BAW) resonator structure includes a first electrode disposed over a substrate, a piezoelectric layer disposed over the first electrode and a second electrode disposed over the first piezoelectric layer. The piezoelectric layer is formed of a piezoelectric material doped with multiple rare earth elements for improving piezoelectric properties of the piezoelectric layer.

Abstract: A bulk acoustic wave (BAW) resonator structure includes a first electrode disposed over a substrate, a piezoelectric layer disposed over the first electrode and a second electrode disposed over the first piezoelectric layer. The piezoelectric layer is formed of a piezoelectric material doped with one of erbium or yittrium at an atomic percentage of greater than three for improving piezoelectric properties of the piezoelectric layer.

Abstract: A bulk acoustic wave (BAW) resonator structure comprises a first electrode disposed over a substrate, a first piezoelectric layer disposed over the first electrode, a second electrode disposed over the first piezoelectric layer, and a collar structure disposed around a perimeter of an active region defined by an overlap between the first electrode, the second electrode, and the piezoelectric layer.

Abstract: A bulk acoustic wave (BAW) resonator device includes a bottom electrode on a substrate over one of a cavity and an acoustic reflector, a piezoelectric layer on the bottom electrode, and a top electrode on the piezoelectric layer. At one of the bottom electrode and the top electrode is a composite electrode having an integrated lateral feature, arranged between planar top and bottom surfaces of the composite electrode and configured to create a cut-off frequency mismatch.

Abstract: A bulk acoustic wave (BAW) resonator device includes a bottom electrode on a substrate over one of a cavity and an acoustic mirror, a piezoelectric layer on the bottom electrode, a top electrode on the piezoelectric layer, and a temperature compensation feature having positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer. At least one of the bottom electrode and the top electrode includes an integrated lateral feature configured to create at least one of a cut-off frequency mismatch and an acoustic impedance mismatch.

Abstract: An electronic component module includes: a multi-layered wiring board formed by stacking insulating layers, an inner wiring layer formed between the insulating layers, and a surface wiring layer formed on an outermost insulating layer of the insulating layers; and an acoustic wave device located inside the multi-layered wiring board, wherein the acoustic wave device includes a functional element and a sealing portion, the functional element being located on a substrate and exciting an acoustic wave, and the sealing portion sealing the functional element so as to form an air-space above the functional element, and a terminal portion of the surface wiring layer does not overlap the air-space of the acoustic wave device as viewed from a stacking direction of the multi-layered wiring board, the terminal portion being a region to which a terminal of an electronic component is fixed in the surface wiring layer.

Abstract: A bulk acoustic wave (BAW) resonator structure comprises a first electrode disposed over a substrate, a piezoelectric layer disposed over the first electrode, a second electrode disposed over the first piezoelectric layer, and a guard ring structure formed around a perimeter of an active region corresponding to an overlap of the first electrode, the first piezoelectric layer, and the second electrode.

Abstract: A bulk acoustic wave resonator comprising a substrate, a Bragg reflector, a top and a bottom electrode and a piezoelectric layer with means for suppression of the pass-band ripples in a bulk acoustic wave filter. The means for absorbing or scattering the spurious modes are a roughened rear side of the substrate, an absorbing layer disposed on the rear side of the substrate and/or an absorbing layer disposed on the front side of the substrate.

Abstract: An acoustic resonator with improved quality factor and electro-mechanical coupling is disclosed. In one embodiment, the acoustic resonator includes an acoustic mirror formed on the top surface of a substrate or in the substrate, a first electrode having a end portion, formed on the acoustic mirror, a piezoelectric layer formed on the first electrode; and a second electrode formed on the piezoelectric layer, where at least one of the first electrode and the second electrode and the piezoelectric layer define a gap in a region that overlaps the end portion of the first electrode. In one embodiment, a dielectric film is deposited on the surface of the end portion of the first electrode to form completely planarized surface before the piezoelectric layer deposition. In another embodiment, a gap between the second electrode and the piezoelectric layer, so that the piezoelectric coupling in the end portion area of the first electrode is minimally contributed into the whole resonator.

Abstract: Aspects of the subject disclosure include, for example, obtaining a mechanical resonating structure comprising a compensating structure, where the compensating structure comprises one or more materials having an adaptive stiffness that reduces a variance in a resonating frequency of the mechanical resonating structure (f0), and adjusting at least one of a value of f0 of the obtained mechanical resonating structure or a value of a temperature for which temperature coefficient of frequency of the obtained mechanical resonating structure is approximately zero (T0) by altering a thickness of at least one targetable material of the mechanical resonating structure. Other embodiments are disclosed.

Abstract: A method of manufacturing a boundary acoustic wave device includes the steps of forming an electrode on a first medium layer, forming a second medium layer so as to cover the electrode on the first medium layer, and forming a sound absorbing layer on an external surface of the second medium layer. The sound absorbing layer has an acoustic velocity of transverse waves that is lower than an acoustic velocity of transverse waves of the second medium layer.

Abstract: A single-chip duplexer, interfacing a receiver and a transmitter with a common antenna, includes transmit and receive filters, an annular sealing ring and a conductive stripe. The transmit filter is connected between the antenna and the transmitter, and has a transmit passband. The receive filter is connected between the antenna and the receiver, and has a receive passband different from the transmit passband. The annular sealing ring is connected between a surface of the chip and a surface of a cap to form a sealed cavity between the chip and the cap. The conductive stripe extends across at least a portion of the surface of the chip between the transmit filter and the receive filter, the conductive stripe being directly connected to the sealing ring and electrically connected to ground. The conductive stripe provides at least one of magnetic shielding and capacitive shielding between the transmit filter and the receive filter.

Abstract: A periodic signal generator is configured to generate high frequency signals characterized by relatively low temperature coefficients of frequency (TCF). This generator may include an oscillator containing a pair of equivalent MEMs resonators therein, which are configured to support bulk acoustic wave and surface wave modes of operation at different resonance frequencies. Each resonator includes a stack of layers including a semiconductor resonator body (e.g., Si-body), a piezoelectric layer (e.g., AIN layer) on the resonator body and interdigitated drive and sense electrodes on the piezoelectric layer. The oscillator is configured to support the generation of first and second periodic signals having unequal first and second frequencies (f1, f2) from first and second resonators within the pair. These first and second periodic signals are characterized by respective first and second temperature coefficients of frequency (TCf1, TCf2), which may differ by at least about 10 ppm/° C.

Abstract: The invention concerns a micromechanical device and method of manufacturing thereof. The device comprises an oscillating or deflecting element made of semiconductor material comprising n-type doping agent and excitation or sensing means functionally connected to said oscillating or deflecting element. According to the invention, the oscillating or deflecting element is essentially homogeneously doped with said n-type doping agent. The invention allows for designing a variety of practical resonators having a low temperature drift.

Abstract: One embodiment of the present inventions sets forth a method for decreasing a temperature coefficient of frequency (TCF) of a MEMS resonator. The method comprises lithographically defining slots in the MEMS resonator beams and filling the slots with a compensating material (for example, an oxide) wherein the temperature coefficient of Young's Modulus (TCE) of the compensating material has a sign opposite to a TCE of the material of the resonating element.

Abstract: A method of making a handheld, electromechanical device useful in mammalian body-care includes the steps of: a) forming a one-piece housing having a single opening defined by a rim; b) assembling a unitary insert; c) inserting the unitary insert through the single opening of the housing; d) removably applying a cover having an exterior surface to close the opening of the one-piece housing; and e) attaching the unitary insert to at least one of the one-piece housing and the removable cover. The rim of the one-piece housing circumscribes a rim area, and the one-piece housing has a projected area that is substantially larger than the rim area. The unitary insert is dimensioned to be insertable through the opening defined by the rim, and it has a frame having disposed thereon electromechanical elements interconnected in an electrical circuit. The cover closes off the opening of the one-piece housing.

Abstract: A multimode elastic wave device includes a pair of reflectors, and a first interdigital transducer (IDT) electrode through a fifth IDT electrode arranged between the pair of reflectors. In this configuration, each of the average of electrode-finger pitches in the first IDT electrode and the average of electrode-finger pitches in the fifth IDT electrode is smaller than both of the average of electrode-finger pitches in the second IDT electrode and the average of electrode-finger pitches in the fourth IDT electrode.

Abstract: A piezoelectric thin film resonator of the present has a substrate 1, an intermediate layer 7 disposed on the substrate 1 and is formed of an insulator, a lower electrode 3 disposed on the intermediate layer 7, a piezoelectric film 4 disposed on the lower electrode 3, and an upper electrode 5 disposed on a position facing the lower electrode 3 with the piezoelectric film 4 interposed therebetween, in which, in a resonant region 8 where the lower electrode 3 and the upper electrode 5 face each other, a space 6 is formed in the substrate 1 and the intermediate layer 7 or between the lower electrode 3 and the intermediate layer 7 and the region of the space 6 is included in the resonant region 8. With the structure, the dissipation of the vibrational energy to the substrate from the resonance portion can be suppressed, thereby improving the quality factor.

Abstract: This disclosure provides implementations of filters and filter topologies, circuits, structures, devices, apparatus, systems, and related processes. In one aspect, a device includes one or more LC resonant circuit stages. In some implementations, each LC stage includes an inductor and a capacitor. Each LC stage also has a corresponding resonant frequency. The one or more LC stages are arranged to produce an unmodified passband over a range of frequencies having a corresponding bandwidth. One or more microelectromechanical systems (MEMS) resonators are arranged with the one or more LC stages. The one or more MEMS resonators are arranged with the one or more LC stages so as to modify characteristics of the unmodified passband such that the hybrid filter produces a modified passband having a modified bandwidth and one or more other modified band characteristics.

Abstract: An apparatus for providing impedance matching between a single-ended circuit and a differential circuit includes first and second capacitors and first and second inductors. The first capacitor is connected between an input/output of the single-ended circuit and a first differential input/output of the differential circuit. The first inductor is connected between the input/output of the single-ended circuit and a second differential input/output of the differential circuit. The second capacitor is connected between the second differential input/output of the differential circuit and ground. The second inductor is connected between the first differential input/output of the differential circuit and the second differential input/output of the differential circuit.

Abstract: The IDT electrode has the first bus bar and second bus bar; the plurality of first electrode fingers and the plurality of second electrode fingers mutually intersect; the plurality of first dummy electrodes and the plurality of second dummy electrodes which extend have front ends facing front ends of the plurality of first electrode fingers and the plurality of second electrode fingers with the gap s1; the plurality of first auxiliary electrodes which protrude laterally from the front end side portions of the pluralities of first dummy electrodes; and the plurality of second auxiliary electrodes which protrude laterally from the front end side portions of the plurality of second dummy electrodes. The plurality of first auxiliary electrodes have edge portions located a side of the second bus bar. The edge portions are located a side of the second bus bar the more to a side of the front end.

Abstract: According to an exemplary embodiment, a bulk acoustic wave structure includes a lower electrode situated over a substrate. The bulk acoustic wave structure further includes a piezoelectric layer situated over the lower electrode, where the piezoelectric layer comprises aluminum copper nitride. The bulk acoustic wave structure further includes an upper electrode situated over the lower electrode. The bulk acoustic wave structure can further include a bond pad connected to the upper electrode, where the bond pad comprises aluminum copper. The lower electrode can include a high density metal situated adjacent to the piezoelectric layer and a high conductivity metal layer underlying the high density metal layer.

Abstract: A bulk acoustic wave (BAW) resonator is constructed to reduce phase and amplitude ripples in a frequency response. The BAW resonator is fabricated on a substrate 400 ?m thick or less, preferably approximately 325 ?m, having a first side and a polished second side with a peak-to-peak roughness of approximately 1000 A. A Bragg mirror having alternate layers of a high acoustic impedance material, such as tungsten, and a low acoustic impedance material is fabricated on the first side of the substrate. A BAW resonator is fabricated on the Bragg mirror. A lossy material, such as epoxy, coats the second side of the substrate opposite the first side. The lossy material has an acoustic impedance in the range of 0.01× to 1.0× the acoustic impedance of the layers of high acoustic impedance material.

Abstract: A piezoelectric thin-film filter reduces insertion loss and deterioration of steepness of a shoulder characteristic and reduces the ripple in the passband. In a first vibration portion, a piezoelectric thin film is disposed between a pair of electrodes along one main surface of a substrate. In a second vibration portion, the piezoelectric thin film is disposed between a pair of electrodes along the one main surface of the substrate. The vibration portions are both acoustically isolated from the substrate. In the first resonator, an additional film is disposed outside the electrode constituting half or more the overall length of the perimeter of the first vibration portion that is in contact with the electrode when seen from a thickness direction. In the second resonator, the external shape of the vibration portion when seen from a thickness direction is a polygon, and each side of the polygon is not parallel with any of the other sides thereof.

Abstract: An apparatus, comprises a piezoelectric layer, a first acoustic resonator comprising first and second electrodes formed on opposite sides of the piezoelectric layer, and a second acoustic resonator comprising first and second electrodes formed on opposite sides of the piezoelectric layer and acoustically coupled to the first acoustic resonator.