Abstract: A variable frequency filter includes a series arm resonant circuit and first and second parallel arm resonant circuits. The series arm resonant circuit is connected between a first connection terminal and a second connection terminal. The first parallel arm resonant circuit is connected to the first connection terminal side of the series arm resonant circuit. In the first parallel arm resonant circuit, a first piezoelectric resonator and a variable capacitor are connected in series to each other. The second parallel arm resonant circuit is connected to the second connection terminal side of the series arm resonant circuit. In the second parallel arm resonant circuit, a second piezoelectric resonator and a variable capacitor are connected in series to each other. The impedance of the first piezoelectric resonator is lower than the impedance of the second piezoelectric resonator. The series arm resonant circuit includes a characteristic adjusting capacitor at the first connection terminal side.

Abstract: A filter comprises a series unit, and a shunt unit disposed between the series unit and a ground. The shunt unit includes resonators that are selectively operated, and each of the shunt resonators includes a film bulk acoustic resonator.

Abstract: A filter using bulk acoustic wave resonators (BAWRs) is provided including BAWRs connected in series or in parallel to each other. A BAWR set is configured by connecting an inductance and capacitance (L/C) element to each BAWR in series or in parallel.

Abstract: A band-pass filter is provided that is configured to output a signal with a frequency within a desired frequency range and to attenuate signals with frequencies outside the desired frequency range. The band-pass filter comprises a CMOS resonator that comprises a resonator cavity and a reflector. The band-pass filter also comprises an impedance convertor that is configured to inhibit at least some insertion losses on the band-pass filter. The band-pass filter also comprises a variable capacitor that is connected between the CMOS resonator and the impedance convertor. The desired frequency range of the band-pass filter can be tuned by adjusting the capacitance of the variable capacitor.

Abstract: Embodiments for adaptively performing clutter filtering upon in an ultrasound system are disclosed. In one embodiment, the ultrasound system includes: an ultrasound data acquisition unit configured to transmit ultrasound signals to a target object and receive ultrasound echoes reflected from the target object to thereby acquire ultrasound data; and a processing unit configured to form a Doppler signal corresponding to each of a plurality of pixels constructing a Doppler mode image based on the ultrasound data, as well as to adjust coefficients of a clutter filter based on characteristics of the Doppler signal for each of the pixels for performing clutter filtering upon the Doppler signal.

Abstract: A Dual Input, Dual Output filtering apparatus using a Bulk Acoustic Wave Resonators (BAWR), and a resonator used as the BAWR may be provided. A Dual Input, Dual Output filtering apparatus may include a plurality of BAWRs connected in series and parallel.

Abstract: A filter device including an input electronic circuit having an input load admittance Yin, an output electronic circuit having an output load admittance Yout, a lattice filter with two types of two piezoelectric resonators having a characteristic impedance Zc; those of the first type have a resonant frequency Fr1 and an antiresonant frequency Fa1; those of the second type have a resonant frequency Fr2 different from Fr1 and an antiresonant frequency Fa2 different from Fa1. The input and output impedances are matched to the reciprocal of the real part Re{Yin} of the admittance Yin and the reciprocal of the real part Re{Yout} of the admittance Yout, which are at least two to five times greater than the characteristic impedance Zc of the resonators. The frequency differences Fa1?Fr1 and Fa2?Fr2 are at least two to three times greater than the absolute value of the difference Fr1?Fr2.

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: 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: A microelectromechanical (MEM) filter is disclosed which has a plurality of lattice networks formed on a substrate and electrically connected together in parallel. Each lattice network has a series resonant frequency and a shunt resonant frequency provided by one or more contour-mode resonators in the lattice network. Different types of contour-mode resonators including single input, single output resonators, differential resonators, balun resonators, and ring resonators can be used in MEM filter. The MEM filter can have a center frequency in the range of 10 MHz-10 GHz, with a filter bandwidth of up to about 1% when all of the lattice networks have the same series resonant frequency and the same shunt resonant frequency. The filter bandwidth can be increased up to about 5% by using unique series and shunt resonant frequencies for the lattice networks.

Abstract: A contour mode micromechanical piezoelectric resonator. The resonator has a bottom electrode; a top electrode; and a piezoelectric layer disposed between the bottom electrode and the top electrode. The piezoelectric resonator has a planar surface with a cantilevered periphery, dimensioned to undergo in-plane lateral displacement at the periphery. The resonator also includes means for applying an alternating electric field across the thickness of the piezoelectric resonator. The electric field is configured to cause the resonator to have a contour mode in-plane lateral displacement that is substantially in the plane of the planar surface of the resonator, wherein the fundamental frequency for the displacement of the piezoelectric resonator is set in part lithographically by the planar dimension of the bottom electrode, the top electrode or the piezoelectric layer.

Abstract: A filter device including an input electronic circuit having an input load admittance Yin, an output electronic circuit having an output load admittance Yout, a lattice filter with two types of two piezoelectric resonators having a characteristic impedance Zc; those of the first type have a resonant frequency Fri and an antiresonant frequency Fa1; those of the second type have a resonant frequency Fr2 different from Fr1 and an antiresonant frequency Fa2 different from Fa1. The input and output impedances are matched to the reciprocal of the real part Re{Yin} of the admittance Yin and the reciprocal of the real part Re{Yout} of the admittance Yout, which are at least two to five times greater than the characteristic impedance Zc of the resonators. The frequency differences Fa1?Fr1 and Fa2?Fr2 are at least two to three times greater than the absolute value of the difference Fr1?Fr2.

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: A Radio Frequency (RF) duplexer including Bulk Acoustic Wave Resonators (BAWRs) and an RF filter including BAWRs are provided. The RF duplexer may convert the received signal into a balance signal and output the balance signal via a dual-output port. The RF duplexer may also include a BAWR receiving filter unit including an input end to receive the balance signal from the dual-output port, and an output end used for dual output. The RF duplexer may also include a BAWR transmitting filter unit to transmit a transmitted signal to the antenna via a single-output port.

Abstract: A band-pass filter device includes: a plurality of band-pass filter elements on a principal plane of a substrate; wherein the band-pass filter elements correspond to a plurality of respective channels divided by frequency regions, and each have a plurality of piezoelectric resonators. Each of the piezoelectric resonators includes a piezoelectric film whose periphery is supported by the substrate, a first electrode formed on a lower surface of the piezoelectric film, a second electrode formed on an upper surface of the piezoelectric film and formed in a state of overlapping at least a part of the first electrode with the piezoelectric film interposed between the second electrode and the first electrode, a lower space formed between the substrate and the piezoelectric film, and an upper space formed over the piezoelectric film.

Abstract: The invention relates to a filter operating with bulk acoustic waves, comprising at least one first resonator and at least one second resonator. In the at least one first and second resonator, a longitudinal acoustic mode is capable of propagation, for which normal dispersion is adjusted in the first resonator and abnormal dispersion in the second resonator by selection of the material and the relative layer thicknesses. In particular, the power compatibility of the filter at the higher frequency edge of its passband can be improved.

Abstract: A lattice tunable filtering circuit includes a first input and a second input, and a first output and a second output. The circuit includes two series branches and two parallel branches. The first and second series branches include a Tunable Resonator Component (TRC) which presents a first series resonance frequency whereas the third and fourth parallel branches present a second series resonance frequency which has a value being lower than that of the first series resonance frequency. The first and second series resonance frequencies are tunable by one analog control quantity. The filtering circuit further includes a feedback control loop for the control of the analog quantity, which feedback is based on a criterion of equality between the modulus of impedances Zs and Zp.

Abstract: A Dual Input, Dual Output filtering apparatus using a Bulk Acoustic Wave Resonators (BAWR), and a resonator used as the BAWR may be provided. A Dual Input, Dual Output filtering apparatus may include a plurality of BAWRs connected in series and parallel.

Abstract: A lattice-type filter circuit includes first and second balanced signal terminals; first and second balanced signal terminals; a first resonator connected to a series arm between the first balanced signal terminal on the input side and the first balanced signal terminal on the output side; a second resonator connected to a series arm between the second balanced signal terminal on the input side and the second balanced signal terminal on the output side; a first resonant circuit including impedance elements, being connected to a lattice arm between the first balanced signal terminal on the output side and the second balanced signal terminal on the input side; and a second resonant circuit including impedance elements, being connected to a lattice arm between the second balanced signal terminal on the output side and the first balanced signal terminal on the input side.

Abstract: A piezoelectric thin-film filter includes a first electrode pair having two or more first electrode fingers disposed on one main surface of a piezoelectric thin film and second electrode fingers disposed on the other main surface of the piezoelectric thin film so as to face the first electrode fingers. A second electrode pair includes two or more third electrode fingers disposed on the main surface such that the third electrode fingers and the first electrode fingers are disposed alternately with gaps therebetween and fourth electrode fingers disposed on the other main surface so as to face the third electrode fingers with the piezoelectric thin film therebetween. Insulating films are provided between the first and third electrode fingers. Each of the center-to-center distances Wa+Wm and Wf+Wm between the first and third electrode fingers that are disposed alternately is larger than a value twice the thickness T of the piezoelectric thin film.

Abstract: A tunable filter circuit having inputs IN1-IN2 and outputs OUT1-OUT2, comprising at least a primary four-pole circuit including in cascade: a first varactor having a first electrode connected to IN1 and a second electrode; a first inductive resistor connected between the second electrode of the varactor and input IN2, a secondary four-pole circuit comprising four BAW resonators. First and second of these resonators have a first electrode connected to a first input of the secondary four-pole circuit and a second electrode connected to first and second outputs of the secondary four-pole circuit, respectively. Similarly, third and fourth of these resonators have a first electrode connected to a second input of the secondary four-pole circuit and a second electrode connected to the second and first outputs of the secondary four-pole circuit, respectively.

Abstract: An electromagnetic composite metamaterial including an electromagnetic medium and a plurality of spaced electromechanical resonators disposed in or on the electromagnetic medium configured to control electromagnetic wave propagation properties in the electromagnetic composite metamaterial.

Abstract: A filtering circuit based on a lattice structure comprising a first and a second input and a first and second output. The circuit further comprises two series impedance and two parallel impedance which each comprises an acoustic resonator associated with two inductive and capacitive components which can be adjusted by a first control value. The second and fourth impedance comprise each an acoustic resonator associated to two inductive and capacitive components which are adjustable by means of a second control value. A control circuit generates the two control values which simultaneously comprise a common mode potential and a differential mode potential which allows the emergence of first and second pass bands which are usable for realizing two different bandpass filters.

Abstract: RF telemetry for an active medical device such as active implant or programmer for such implant. The device includes at least one RF antenna (14), and at least one RF telemetry transmitter/receiver (44) with, for coupling to the antenna, an associated band rejection filter (54). The band rejection filter (54) comprises at least one volume acoustic wave BAW resonator (40) of the SMR type with insulation by Bragg acoustic reflector (42). The device can be a multi-band device comprising a plurality of RF transmitters/receivers (12, 44) operating in respective distinct bands of frequencies such as the 402˜405-MHz, 863˜870-MHz, 902˜928-MHz and 2.4-GHz bands or by UWB transmission.

Abstract: The invention relates to a resonator operating with bulk acoustic waves (BAW resonator, BAW=Bulk Acoustic Wave) and band-pass filters constructed of such resonators. To increase the edge steepness of the transmission band of a BAW band-pass filter, the invention proposes reducing the effective coupling of a BAW resonator by using the connection in parallel of a BAW resonator and a capacitor instead of only one resonator. In addition, to increase the edge steepness of the transmission band, the use of a connection of coupled BAW resonators in the serial branch of a filter circuit with another resonator or resonator stack in the parallel branch of the filter circuit is proposed, the additional resonator or resonator stack being connected to the center electrode of the resonator stack specified initially.

Abstract: A lattice tunable filtering circuit includes a first input and a second input, and a first output and a second output. The circuit includes two series branches and two parallel branches. The first and second series branches include a Tunable Resonator Component (TRC) which presents a first series resonance frequency whereas the third and fourth parallel branches present a second series resonance frequency which has a value being lower than that of the first series resonance frequency. The first and second series resonance frequencies are tunable by one analog control quantity. The filtering circuit further includes a feedback control loop for the control of the analog quantity, which feedback is based on a criterion of equality between the modulus of impedances Zs and Zp.

Abstract: A tunable filter circuit having inputs IN1-IN2 and outputs OUT1-OUT2, comprising at least a primary four-pole circuit including in cascade: a first varactor having a first electrode connected to IN1 and a second electrode; a first inductive resistor connected between the second electrode of the varactor and input IN2, a secondary four-pole circuit comprising four BAW resonators. First and second of these resonators have a first electrode connected to a first input of the secondary four-pole circuit and a second electrode connected to first and second outputs of the secondary four-pole circuit, respectively. Similarly, third and fourth of these resonators have a first electrode connected to a second input of the secondary four-pole circuit and a second electrode connected to the second and first outputs of the secondary four-pole circuit, respectively.

Abstract: A miniaturised half-wave balun comprises a single-ended I/O port comprising a first signal carrying terminal for connection to a source impedance and a differential I/O port comprising second and third signal carrying terminals for connection to a load impedance. First and second transmission line sections of equal length and characteristic impedance are connected together at a common end and at opposite ends to the second and third terminals. The first signal carrying terminal is coupled to the first transmission line section. The combined length of the first and second transmission line sections is substantially less than one half of the wavelength of an RF signal at the operating frequency. First and second loading shunt capacitors are connected to respective first and second transmission line sections. A shunt capacitive element is connected at the common end of the transmission line sections.

Abstract: An acoustic wave sensor assembly includes piezoelectric material, a first acoustic wave resonator element structure mounted on the piezoelectric material for interacting with an electrical signal, the acoustic wave resonator element structure being operable to interact with an acoustic wave propagating within the piezoelectric material to produce a first frequency response. Further acoustic wave resonator element structures are mounted on the piezoelectric material for interacting with electrical signals, the further acoustic wave resonator element structures being operable to interact with further acoustic waves propagating within the piezoelectric material to produce subsequent frequency responses. The first acoustic wave resonator element structure and further acoustic wave resonator element structures are combined to form a ladder or lattice filter network to produce an overall frequency response.

Abstract: A pizoelectric filter capable of improving the shielding property and increasing the heat releasing property is provided. The piezoelectric device includes a cover and piezoelectric device chips which are stacked and sealed together. The piezoelectric device also includes first external electrodes exposed at an upper surface of the cover and a grounded second external electrode exposed at the upper surface and a side surface of the cover. Electroconductive bonding materials are disposed between the cover and the piezoelectric device chips and all around an outer edge which connects the cover to the piezoelectric device chips so as to form a seal. The electroconductive bonding materials are also connected to the grounded second external electrode.

Abstract: Providing is a piezoelectric thin-film filter including resonators connected in a lattice pattern, which can achieve large attenuation at frequencies away from a passband and improve steepness near two ends of the passband without involving an additional special step. Second resonators C—2 or first and third resonators C—1 and Cx—1 connected in parallel form series-arm resonators or parallel-arm resonators C—1 connected in a lattice pattern. The capacitance of each second resonator C—2 is larger than the capacitance of each first resonator C—1. The capacitance of each third resonator Cx—1 is substantially equal to the difference between the capacitance of the second resonator C—2 and the capacitance of the first resonator C—1. The resonant frequency of the first resonator C—1 higher than the resonant frequency of the second resonator C—2.

Abstract: A lattice-type filter circuit includes first and second balanced signal terminals; first and second balanced signal terminals; a first resonator connected to a series arm between the first balanced signal terminal on the input side and the first balanced signal terminal on the output side; a second resonator connected to a series arm between the second balanced signal terminal on the input side and the second balanced signal terminal on the output side; a first resonant circuit including impedance elements, being connected to a lattice arm between the first balanced signal terminal on the output side and the second balanced signal terminal on the input side; and a second resonant circuit including impedance elements, being connected to a lattice arm between the second balanced signal terminal on the output side and the first balanced signal terminal on the input side.

Abstract: The invention relates to a resonator filter structure (10) for radio frequency (RF) filters, especially a bulk acoustic wave (BAW) filter structure. According to the invention, a resonator filter structure (10) is constructed with a BAW lattice filter section (20), in which all of the BAW resonator elements (20-1, 20-2, 20-3, 20-4) within the BAW lattice filter section (20) have substantially equal resonance frequencies. According to the invention, there are parallel capacitances (30-1, 30-2) connected in parallel to the BAW resonators (20-2, 20-3) of one branch type of the BAW lattice filter section (20). Thus, anti-resonance frequency of the respective BAW resonator (20-2, 20-3) is tuned. That results in a very narrow passband which corresponds approximately to the difference in anti-resonance frequencies between diagonal and horizontal branches of the lattice filter section (20). The parallel capacitances (30-1, 30-2) are used to tune the bandwidth: the smaller the capacitance, the smaller the bandwidth.

Abstract: A filter structure, comprising a first signal line, a second signal line, a third signal line and a fourth signal line, said first and third signal lines defining an input port and said second and fourth signal lines defining an output port of a section of said filter structure, said section being defined by a first bulk acoustic wave resonator (A) which is connected between said first signal line and said second signal line, a second bulk acoustic wave resonator (G) which is connected between said third signal line and said fourth signal line, a third bulk acoustic wave resonator (C) which is connected between said first signal line and said fourth signal line, and a fourth bulk acoustic wave resonator (E) which is connected between said second signal line and said third signal line; is characterized in that a frequency pulling factor defined d of at least one of said acoustic wave resonators is non-zero, said frequency pulling factor d being defined by for first and second bulk acoustic wave resonators havi

Abstract: An FBAR filter includes a wafer, a filter circuit unit and a balun circuit unit. The filter circuit unit includes a plurality of FBAR resonators formed on a predetermined region on a top of the wafer. The balun circuit unit includes a plurality of metal layers electrically connected to each other to implement a balun circuit and a plurality of dielectric layers each placed between the plurality of metal layers. The balun circuit unit is electrically connected to the filter circuit unit on a predetermined region of the wafer.

Abstract: A dual-channel passband filtering system having a first, second and third balanced ports for connecting, respectively, to a first transceiver, an antenna and a second transceiver. A first lattice-type passband filter is connected between the first and the second port, and a second lattice-type passband filter is connected between the second and the third port. A phase shifter is used to match the first and second transceiver and the second port. A balun can be used for each port to convert the balanced port to a single-ended port. In each passband filter, two series resonators are use to provide two balanced ends, and two shunt resonators are connected to the series resonators in a crisscross fashion to form a differential or balanced topology. The first and second passband filters have different frequencies.

Abstract: A filter and method of manufacturing a filter having a lattice arrangement that efficiently utilizes substrate space. An embodiment of the invention is directed to a filter having a plurality of resonators disposed on a substrate, each resonator comprising a first electrode and a second electrode disposed vertically adjacent such that an acoustic cavity of a piezoelectric material is formed between each first electrode and each second electrode of each resonator, the first and second electrodes of each resonator electrically isolated from each other via the piezoelectric material. In this manner, the filter is realized without having to use any vias. Additionally, the resonators may be of a shape that allows each to be disposed close together such that some sides of each of the resonators are parallel to each other. Thus, substrate space can be preserved even further.

Abstract: A component that functions with bulk acoustic waves, particularly a bandpass filter, has an increased number of degrees of design freedom in order to improve the transmission characteristics of the component. The component has BAW resonators coupled acoustically in the vertical and/or lateral direction through common electrodes, coupling layer systems and through the excitation of lateral acoustic modes. Through the acoustic coupling of the resonators, it is possible to create additional pole points in the transfer function so that in this manner, the rejection band characteristics of a bandpass filter can be improved. Through acoustic paths which are added in addition to the electrical connection, the insertion loss can be reduced. Through an acoustic coupling instead of an electrical connection, decoupling between input and output loops of a circuit can be achieved.

Abstract: A piezoelectric element contains a piezoelectric ceramic body having a layered perovskite structure, and has the C axis selected and oriented in the thickness direction. In the piezoelectric ceramic body, line shaped electrodes are formed perpendicular to the C axis selected and oriented. The electrodes exposed at both of the end faces of the piezoelectric ceramic body are covered with conductive materials and insulation materials. The piezoelectric ceramic body is polarized in the opposite directions on both of the sides of electrodes arranged in the width direction. Moreover, external electrodes are formed on the faces where the conductive materials and the insulation materials are formed, whereby two groups of the electrodes are arranged in an interdigital electrode form.

Abstract: An SAW element 11 comprises a first wiring section 20 formed between an input terminal 18 and an output terminal 19, a plurality of first SAW resonators 15 which are located in serial to the first wiring section 20, a plurality of second SAW resonators 16 which are located in serial to the first wiring section 20 at the side of the input terminal 18 or at the side of the output terminal 19 with respect to the first SAW resonators 15, a plurality of second wiring section 22 which are formed between an intermediate point of the second SAW resonators 16 each other in the first wiring section 20 and a reference voltage electrode 21, and a plurality of third SAW resonators 17 which are located in the second wiring section 22, respectively, and which have anti-resonant frequencies corresponding with resonant frequencies of the second SAW resonators 16.

Abstract: A high frequency filter comprises thin film piezoelectric resonators connected in series between the input/output nodes, thin film piezoelectric resonators connected in parallel between the input/output nodes and a variable voltage circuit adapted to change the voltage applied to at least either the thin film piezoelectric resonators connected in series or the thin film piezoelectric resonators connected in parallel. The resonance characteristic of at least either the thin film piezoelectric resonators connected in series or the thin film piezoelectric resonator connected in parallel is shifted by changing the voltage applied by the variable voltage circuit to change the pass characteristic of the filter.

Abstract: A piezoelectric resonator comprising a piezoelectric substrate having a tapered portion as viewed from the side thereof, and drive electrodes provided on both opposing tapered surfaces of said tapered portion. The piezoelectric resonator corrects the dispersion in the thickness of the piezoelectric substrate relying upon the positions where the drive electrodes are formed, and makes it easy to finely adjust he frequency for compensating the dispersion in the thickness.

Abstract: A piezoelectric thin film resonator which comprises a first electrode, a second electrode, and a piezoelectric film which is interposed between the first electrode and the second electrode, and formed of an epitaxial ferroelectric thin film containing barium titanate, a spontaneous polarization of the epitaxial ferroelectric thin film being uniaxially orientated in a direction normal to a film surface.

Abstract: A filter structure (1090, 1100, 1200) comprises a first piezoelectric resonator (1021a), whose resonance frequency is a first resonance frequency and which is connected to an input conductor (1030a, 1030b). In order to increase the power handling capacity of the filter structure, it comprises other piezoelectric resonators connected in series with the first piezoelectric resonator. In this plurality (1020, 1110, 1220) of piezoelectric resonators, each resonator has a resonance frequency substantially equal to the first resonance frequency. The plurality (1020, 1110, 1220) of piezoelectric resonators is connected to the rest of the filter structure only through the first piezoelectric resonator (1021a) at one end of said plurality and through a second piezoelectric resonator (1021b), which is at the other end said plurality. The impedance of said plurality is arranged to match the impedance level of the filter structure.

Abstract: A filter structure (900, 1300, 1400, 1610) comprises a filter section (900) having at least two branches (901, 902) connected in parallel. A first branch (901) of said at least two branches comprises a first plurality (921, 701) of piezoelectric resonators connected in series, and a second branch (902) of said at least two branches comprises a second plurality (922, 702) of piezoelectric resonators and phase shifting means (910) connected in series. The phase shifting means are arranged to provide a phase shift of substantially 180 degrees.

Abstract: A bulk acoustic wave device having two resonators in a stacked-up configuration separated by a dielectric layer. The device can be coupled to a lattice filter or a ladder filter to form a passband filter with an unbalanced input port and two balanced output ports. One or more such passband filters can be used, together with another lattice or ladder filter, to form a duplexer having an unbalanced antenna port, two balanced ports for one transceiver part and two balanced ports for another transceiver part.

Abstract: The present invention provides a filter device constructed of a combined ladder and lattice filter topology. The filter device synergistically combines the good features of both types of filters. Using the filter device, an integrated unbalanced-to-balanced filter device can be realized. Accordingly, a substantial decrease in the number of components can be achieved. Furthermore, the filter device can be integrated with further components, preferably active RF-components, on a single chip.

Abstract: Even when a difference between the series resonance frequency and the parallel resonance frequency of each resonator cannot be made large, the passing band will be rendered capable of being widened without causing any ripple in the passing band.

Abstract: A differential filter includes a first input, a second input, a first output, a second output, and a plurality of acoustic resonator elements. The plurality of acoustic resonator elements is connected to the first input, the second input, the first output and the second output. The acoustic resonator elements are arranged to form at least two of a lattice structure, a full ladder structure and a paired half ladder structure.

Abstract: A differential filter includes a first input, a second input, a first output, a second output, and a plurality of acoustic resonator elements. The plurality of acoustic resonator elements is connected to the first input, the second input, the first output and the second output. The acoustic resonator elements are arranged to form at least two of a lattice structure, a full ladder structure and a paired half ladder structure.