Abstract: A method and system for tuning a bulk acoustic wave device at wafer level by reducing the thickness non-uniformity of the topmost surface of the device using a chemical vapor deposition process. A light beam is used to enhance the deposition of material on the topmost surface at one local location at a time. Alternatively, an electrode is used to produce plasma for locally enhancing the vapor deposition process. A moving mechanism is used to move the light beam or the electrode to different locations for reducing the thickness non-uniformity until the resonance frequency of the device falls within specification.

Abstract: A method and system for tuning a bulk acoustic wave device at wafer level by reducing the thickness non-uniformity of the topmost surface of the device using a chemical vapor deposition process. A light beam is used to enhance the deposition of material on the topmost surface at one local location at a time. Alternatively, an electrode is used to produce plasma for locally enhancing the vapor deposition process. A moving mechanism is used to move the light beam or the electrode to different locations for reducing the thickness non-uniformity until the resonance frequency of the device falls within specification.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. An FBAR is fabricated on a substrate by introducing a mass loading electrode to a bottom electrode layer. For a substrate having multiple resonators, mass loading bottom electrode is introduced for only selected resonator to provide resonators having different resonance frequencies on the same substrate.

Abstract: The invention describes a filter arrangement as well as an electronic component, each with a bulk acoustic wave resonator unit which is present on a carrier substrate (1). A reflection element (2) is provided between the carrier substrate (1) and the bulk acoustic wave resonator unit for the purpose of acoustic insulation of the generated oscillations. This reflection element (2) may consist either of several layers of alternately high and low impedance or, if the acoustically reflecting substance has a sufficiently low impedance, of a single layer. In addition, a mobile telephone device, a transmitter, a receiver, and a wireless data transmission system as well as a method of manufacturing an electronic component are described.

Abstract: A method and system for tuning a bulk acoustic wave device at the wafer level by adjusting the device thickness. In particular, the device thickness has a non-uniformity profile across the device surface. A mask with an aperture is placed over the device surface and a particle beam is applied over the mask to allow part of the particle beam to make contact with the device surface at a localized area beneath the aperture. The particles that pass through the aperture are deposited on the device surface to add material on the device surface, thereby increasing the surface thickness to correct for thickness non-uniformity. Alternatively, the particles that pass through the aperture remove part of the device surface in an etching process, thereby reducing the surface thickness. Prior to thickness adjustment, a frequency measurement device or thickness measurement device is used to map the device surface for obtaining the non-uniformity profile.

Abstract: A bulk acoustic wave device has a number of resonator elements (14) which are laterally spaced such that a signal (26) applied between to one resonator element (141) at a resonant frequency of the device is coupled to the other resonator elements (142, 143, 144) by acoustic coupling between piezoelectric layers of the resonator elements (14). There are two outer resonator elements (141, 145) and at least one inner resonator element (142, 143, 144). The terminals of the inner resonator elements are electrically connected together. This connection provides an AC short which eliminates the effect of the parasitic capacitances of the inner resonator elements, and provides electromagnetic shielding between the input and output of the device, by reducing the parasitic capacitance between the input and output upper electrodes.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. A resonator is fabricated on a substrate, and its top electrode 56 is oxidized to form a oxide layer 58. For a substrate having multiple resonators, the top electrode 56 of only selected resonator is oxidized to provide resonators having different resonance frequencies on the same substrate.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. An FBAR is fabricating on a substrate by introducing a mass loading electrode to a bottom electrode layer. For a substrate having multiple resonators, mass loading bottom electrode is introduced for only selected resonator to provide resonators having different resonance frequencies on the same substrate.

Abstract: An electric filter comprises a plurality of thin film bulk acoustic resonators (10, 11) arranged in series and in parallel which have different thicknesses (T) of one or more non-piezoelectric layers for example top electrode (24).

Abstract: An electric filter comprises a plurality of thin film bulk acoustic resonants (10, 11) arranged in series and in parallel which have electrodes (24, 25) of different working area (L) and optionally a piezoelectric layer (23) of different thickness (T).

Abstract: A radio frequency filter system includes a first acoustic resonator (54, 56) for a first frequency and a second acoustic resonator (54, 56) for a second frequency. An acoustic reflector array (102, 152, 202) is coupled to an electrode of the first acoustic resonator (54, 56) and to an electrode of the second acoustic resonator (54, 56). The acoustic reflector array (102, 152, 202) includes a plurality of reflector layers (112, 152, 210). A first reflector layer (112, 152, 210) is operable to reflect a signal at substantially the first frequency. A second reflector layer (112, 152, 210) is operable to reflect a signal at substantially the second frequency.

Abstract: A method and system for tuning a bulk acoustic wave device at the wafer level by adjusting the thickness of the device. In particular, the thickness of the device has a non-uniformity profile across the device surface. A mask having a thickness non-uniformity profile based partly on the thickness non-uniformity profile of the device surface is provided on the device surface for etching. A dry etching method is used to remove part of the mask to expose the underlying device surface and further removed the exposed device surface until the thickness non-uniformity of the device surface falls within tolerance of the device.

Abstract: The present invention provides a method for tuning a thin film resonator (TFR) filter comprising a plurality of TFR components formed on a substrate. Each of the TFR components has a set of resonant frequencies that depend on material parameters and construction. TFR bandpass filter response for example can be produced by shifting the set of resonant frequencies in at least one of the series branch TFR components so as to establish the desired shape of the bandpass response and the desired performance of the filter. The shifting may be advantageously performed by removing piezoelectric material from the series branch TFR component, providing a TFR filter with bandwidth and attenuation advantages over that conventionally achieved by down-shifting resonant frequency sets of the shunt TFR components by adding metal material.

Abstract: A method and system for tuning a bulk acoustic wave device at the wafer level by adjusting the thickness of the device. In particular, the thickness of the device has a non-uniformity profile across the device surface. A mask with an aperture is placed over the device surface and a particle beam is applied over the mask so as to allow part of the particle beam to make contact with the device surface at a localized area beneath the aperture. The particles that pass through the aperture are deposited on the device surface to add material on the device surface, thereby increasing the surface thickness to correct for the thickness non-uniformity. Alternatively, the particles that pass through the aperture remove part of the device surface in an etching process, thereby reducing the surface thickness. Prior to thickness adjustment, a frequency measurement device or thickness measurement device is used to map the device surface for obtaining the non-uniformity profile.

Abstract: A bulk acoustic resonator having a high quality factor is formed on a substrate having a depression formed in a top surface of the substrate. The resonator includes a first electrode, a piezoelectric material and a second electrode. The first electrode is disposed on the top surface of the substrate and extends beyond the edges of the depression by a first distance to define a first region therebetween. The piezoelectric material is disposed on the top surface of the substrate and over the first electrode, and the second electrode is disposed on the piezoelectric material. The second electrode includes a portion that is located above the depression. The portion of the second electrode that is located over the depression has at least one edge that is offset from a corresponding edge of the depression by a second distance to define a second region therebetween. The first and second regions have different impedances, as a result of the different materials located in the two regions.

Abstract: A method of fabricating a bulk acoustic wave (BAW) resonator and a BAW resonator so fabricated, the method including the steps of: providing a substrate; providing a first isolation structure; and providing a resonator section including a piezolayer; wherein the first isolation structure includes an acoustic mirror made from only electrically conductive layers of alternating high and low acoustic impedance. In some applications, the first isolation structure is situated between the resonator section and the substrate, while in other applications, the first isolation structure is situated above the resonator section (on the side of the resonator section facing away from the substrate), so that the resonator section lies between the first isolation structure and the substrate, and the resonator then further comprises a second isolation structure situated between the resonator section and the substrate.

Abstract: A monolithic bulk acoustic wave (BAW) duplexer, and a method for fabricating same, the duplexer having a transmitter section as a first component filter and a receiver section as a second component filter, both component filters fabricated on a single substrate and both including at least one shunt BAW resonator and one series BAW resonator, each BAW resonator including a resonator section atop an isolation structure provided so as to separate the resonator section from the substrate, including: a patterned bottom electrode material for use as the bottom electrode of each of the resonators of the duplexer; a patterned piezoelectric material for use as the piezolayer of each of the resonators of the duplexer; a patterned top electrode material for use as the top electrode of each of the resonators of the duplexer; a tuning layer for the shunt resonator of each of the two component duplexer filters; and a tuning layer for both the series and shunt resonators of one of the two component duplexer filters.

Abstract: A method of fabricating a plurality of bulk acoustic wave (BAW) resonators on a single substrate, and the corresponding product, the BAW resonators having substantially different resonant frequencies, the method including the steps of: providing a substrate having an upper facing surface; depositing an isolation structure on the upper facing surface of the substrate; depositing a first metallic layer on the isolation structure, the first metallic layer serving as a bottom electrode; and depositing piezolayer material on the bottom electrode so as to have thicknesses corresponding to each of the different resonant frequencies, each different thickness located in a location where a resonator having a resonant frequency corresponding to the thickness is to be located.

Abstract: A method of fabricating a multi-resonator bulk acoustic wave (BAW) filter and a filter provided by such a method, the filter having a plurality of layers of materials serving as an acoustic mirror for a plurality of resonator sections, each resonator section including at least a top electrode and a bottom electrode sandwiching a piezolayer, the method including the steps of: choosing dielectric materials for some of the layers of materials serving as the acoustic mirror and metallic materials for the others of the layers; and providing at least one of the metallic layers via a fabrication procedure in which the metallic layer is patterned into distinct portions by an etching process that removes enough of the metallic layer between where different resonator sections are to be placed as to provide electrical isolation between the portions of the layer beneath the different resonator sections; thereby providing a multi-resonator BAW filter with reduced capacitive coupling between resonators, compared to the cap

Abstract: A bulk acoustic resonator having a high quality factor is formed on a substrate having a depression formed in a top surface of the substrate. The resonator includes a first electrode, a piezoelectric material and a second electrode. The first electrode is disposed on the top surface of the substrate and extends beyond the edges of the depression by a first distance to define a first region therebetween. The piezoelectric material is disposed on the top surface of the substrate and over the first electrode, and the second electrode is disposed on the piezoelectric material. The second electrode includes a portion that is located above the depression. The portion of the second electrode that is located over the depression has at least one edge that is offset from a corresponding edge of the depression by a second distance to define a second region therebetween. The first and second regions have different impedances, as a result of the different materials located in the two regions.

Abstract: A surface mount type four-pole monolithic filter having two monolithic filter elements formed on a single rectangular crystal blank and connected in cascade, and being suppressed in its frequency change against the temperature change. The filter includes first and second connecting electrodes respectively formed at corners located at opposite ends of one diagonal line of the blank, and third and fourth connecting electrodes respectively formed in central portions of both long sides of the blank. The two filter elements are connected between the first and second connecting electrodes. The cascade connection point and the ground electrodes of the filter elements are led out to the third and fourth electrode, respectively. The first to fourth connecting electrodes are bonded, by means of conductive adhesive, to first to fourth holding electrodes formed in the container for surface mount for a mechanical holding as well as an electric conduction.

Abstract: A monolithic bulk acoustic wave (BAW) duplexer, and a method for fabricating same, the duplexer having a, transmitter section as a first component filter and a receiver section as a second component filter, both component filters fabricated on a single substrate and both including at least one shunt BAW resonator and one series BAW resonator, each BAW resonator including a resonator section atop an isolation structure provided so as to separate the resonator section from the substrate, including: a patterned bottom electrode material for use as the bottom electrode of each of the resonators of the duplexer; a patterned piezoelectric material for use as the piezolayer of each of the resonators of the duplexer; a patterned top electrode material for use as the top electrode of each of the resonators of the duplexer; a tuning layer for the shunt resonator of each of the two component duplexer filters; and a tuning layer for both the series and shunt resonators of one of the two component duplexer filters.

Abstract: Method (800) for adjusting the center frequency of a balanced filter comprising at least four resonators, comprises the following steps: specifying (801) a nominal center frequency for the balanced filter when connected to a circuitry having a certain nominal impedance; determining (802) the actual center frequency of the balanced filter when connected to a circuitry having a certain actual impedance, comparing (803, 804) the actual center frequency of the filter to the nominal one, and adjusting (805, 806) the impedance ratio between the circuitry and the balanced filter within certain limits based on the comparison. A plurality of balanced filters (1610, 1620, 1630) on a substrate (1600) is characterized in that the total area of bulk acoustic wave resonators in the balanced resonators depends on the position of the balanced filter on the substrate. Further, the balanced filters have substantially the same actual center frequency.

Abstract: A multilayer type piezoelectric filter is provided which includes at least two chambers for receiving therewithin resonators, respectively. The chambers are partly defined by a top printed circuit board and an intermediate printed circuit board. The top printed circuit board and the intermediate printed circuit board are formed with communication holes for communicating the chambers with the outside.

Abstract: A piezoelectric resonator using an nth-order mode of a thickness longitudinal vibration or a thickness-shear vibration includes a vibrating section having a piezoelectric layer, a pair of electrodes and a support member for holding the vibrating section. The pair of electrodes are provided on opposite sides of the piezoelectric layer, respectively, and the pair of electrodes partially overlap with each other via the piezoelectric layer to define an opposite electrode portion. The support member holds the vibrating section such that the vibrating section vibrates under an nth-order mode of a thickness longitudinal vibration or a thickness-shear vibration. The opposite electrode portion preferably has a substantially circular shape having a radius r or is a polygonal shape circumscribing the substantially circular shape. The radius r satisfies the inequality 20t/n≦r, where t is a thickness of the vibrating section.

Abstract: A ladder filter comprises series and shunt resonators (2,4). The or each shunt resonator (4) has a static capacitance which is more than four times the static capacitance of the input or output series resonators (2i,2o). This provides increased shunt resonator capacitance which reduces the effective coupling across the a series-shunt section, thereby enabling a smaller number of series-shunt filter sections to used to achieve good stop-band rejection, while still providing good performance in the pass-band. The invention is based on the recognition that filter bandwidth can be traded for improved out-of-band rejection.

Abstract: The invention describes a tunable filter arrangement with at least two resonators which are coupled to one another and of which at least one is connected to a capacitor with tunable capacitance. The electrical properties of the resonator, and thus the overall filter characteristic, can be changed through a change in the capacitance of the capacitor.

Abstract: A TFR ladder filter which may yield less degradation in the stopband near the passband edges than conventionally grounded TFR ladder filters. Each of the plurality of shunt-coupled TFR elements of the ladder filter has its own dedicated ground path which is to connected to a final ground external from the ladder filter, so that each shunt-coupled TFR element is individually isolated from one another. Particularly, each shunt-coupled TFR element has a corresponding wirebond to individually connect its top metal ground electrode to a final external ground of a carrier or package on which the die encompassing the TFR ladder filter rests.

Abstract: The present invention is a method for adjusting different resonant frequencies of a plurality of mechanical resonators formed on a common substrate, in a case where the resonant frequencies of the resonators are a function of each resonator thickness. According to this method the resonators are each formed with an etchable top electrode layer which includes a material having different etching properties as a topmost layer for each of the resonators having different resonant frequencies. By selectively etching these etchable layers one at a time in the presence of the others, one may adjust the resonant frequencies of each of the resonators without need to mask the resonators during the etching process. Associated with this method there is a resonator structure having a top electrode structure having a topmost layer having different etching characteristics for different resonators.

Abstract: The invention describes a tunable filter arrangement with a plurality of resonators which are coupled to one another and of which there is at least one which comprises a piezoelectric component made of a ferroelectric material and to which a DC voltage source is connected. The application of a DC voltage to the resonator renders it possible to change its electrical properties and thus the overall filter characteristic.

Abstract: The invention relates to resonator structures of radio communication apparatus, especially bulk acoustic wave filter structures. According to the invention, a bulk acoustic filter structure is constructed with a lattice configuration, in which two of the filters have a different area than other two for creating very steep passband edges in the frequency response of the filter. Preferably, the filter structure further comprises a second lattice structure for increasing the stopband rejection ratio of the filter structure, and for allowing the use of a simple mechanical structure. The cascaded configuration allows the construction of the filter structure in such a way, that the electrodes of the input and output port are at the same layer, thereby removing the need to make vias in the piezoelectric layer, which results in considerable simplification of the manufacturing process.

Abstract: A very small size ladder filter has various numbers defining different stages. The ladder filter includes units each defined by stacking a top surface surface-electrode of a bending resonator defining a serial resonator and the bottom surface surface-electrode of a bending resonator defining a parallel resonator with a metallic terminal plate sandwiched therebetween. Two of these units are two-dimensionally arranged on a substrate, and a metallic lid is put on the substrate so as to cover the units. The bottom surface surface-electrode of the serial resonator in a first-stage unit is connected to an input terminal, then the metallic terminal plate in the first stage unit is connected to the bottom surface surface-electrode of the serial resonator in the next-stage unit, and the metallic terminal plate in the next-stage unit is connected to an output terminal. The top-surface surface electrodes of the parallel resonators of all of the units are made conductive to one another by the lid.

Abstract: An FBAR-based duplexer that comprises a first port, a second port, a third port, a first band-pass filter connected between the first port and the third port and a series circuit connected between the second port and the third port. The first band-pass filter includes a first ladder circuit having shunt and series elements. Each of the elements of the first ladder circuit comprises a film bulk acoustic resonator (FBAR). The series circuit includes a 90° phase shifter in series with a second band-pass filter. The second band-pass filter includes a second ladder circuit having shunt and series elements. Each of the elements of the second ladder circuit comprises a film bulk acoustic resonator. A band-pass filter comprising shunt elements and series elements in which the series elements and the shunt elements are connected to form a ladder circuit, and each of the elements includes a film bulk acoustic resonator (FBAR).

Abstract: A semiconductor bulk acoustic resonator (SBAR) with improved passband insertion loss and phase performance characteristics is suitable for use in a wide variety of narrowband filtering applications. The SBAR is configured to suppress lateral propagating acoustical wave modes. The lateral acoustical wave modes are controlled by varying the lateral dimension of the resonator electrodes and or utilizing a viscous acoustic damping material, such as a viscoelastic material, such as polyimide, applied along at least a portion of the perimeter of the electrodes to attenuate reflections of the lateral acoustic modes at the electrode edges back into the electrode region.

Abstract: There is provided a Multi-pole Bulk Acoustic Wave Resonator-Stacked Crystal Filter (Multi-pole BAWR-SCF) filtering circuit or device. In one embodiment the Multi-pole BAWR-SCF circuit comprises a first pair of ports, a second pair of ports, a first lead that is coupled between a first and a second one of the first pair of ports, and a second lead that is coupled between a first and a second one of the second pair of ports. The Multi-pole BAWR-SCF circuit also comprises at least one BAW resonator that is coupled in series in the first lead, and at least one Stacked Crystal Filter (SCF). The SCF has first and second terminals that are coupled in the first lead, and a third terminal that is coupled in the second lead. The Multi-pole BAWR-SCF circuit further comprises a plurality of impedance inverting elements and at least one inductive element.

Abstract: A piezoelectric filter has a significantly reduced size and a sufficient coupling capacitance while avoiding an uneven outer configuration of an overall shape of the filter. The piezoelectric filter includes a first resonating unit and a second resonating unit and a coupling capacitance unit disposed in a piezoelectric substrate. The coupling capacitance unit is provided with a first coupling capacitance electrode located on an upper surface of the piezoelectric substrate and a second coupling capacitance electrode located on a lower surface thereof and the first and second coupling capacitance electrodes are arranged to extend to side edge surfaces of the piezoelectric substrate.

Abstract: A multi-pole monolithic crystal filter with at least three acoustically coupled resonators (50,52,54) on a piezoelectric blank (56). Each resonator (50,52,54) has associated top and bottom electrodes (70,72,74,76,78,80). An input connection (62) is coupled to the top electrode (70) of a first resonator (50) and a ground connection (64) is coupled to the bottom electrode (72) of the first resonator (50). An output connection (68) is coupled to the bottom electrode (80) of a last resonator (54) and a ground connection (66) is coupled to the top electrode (78) of the last resonator (54). The top and bottom electrodes (74,76) of each of the remaining resonators (52) are coupled to each other.

Abstract: A microwave filter made of piezoelectric resonators fabricated in a monolithic device. Combinations of resonators connected in series and and parallel to each other are laid out in a symmetrical compact arrangement providing symmetrical and similar paths connecting the resonators together and to the ground. The symmetrical layout thus avoids differences in the connector inductances that otherwise would degrade filter performance.

Abstract: There is provided a Bulk Acoustic Wave Resonator-Stacked Crystal Filter (BAWR-SCF) filtering circuit or device. The BAWR-SCF circuit comprises a first pair of ports, a second pair of ports, a first lead that is connected between a first and a second one of the first pair of ports, and a second lead that is connected between a first and a second one of the second pair of ports. The BAWR-SCF circuit also comprises a first BAW resonator connected in series in the first lead, and a second BAW resonator connected between the first and second leads. The BAWR-SCF further comprises a Stacked Crystal Filter (SCF) having first and second terminals connected in the first lead between the first BAW resonator and the second one of the first pair of ports. The SCF also has a third terminal that is connected to a node of the second lead.

Abstract: A piezoelectric resonator having excellent filter characteristics and effectively suppressing unnecessary ripples and/or spurious components includes first and second excitation electrodes disposed on a first major surface of a piezoelectric substrate, a first common electrode on a second major surface so as to oppose the first and second excitation electrodes with the substrate being located therebetween, and two lead lines extending along portions of longitudinal edges of the piezoelectric substrate. An excitation-lead line is connected to the first and second excitation electrodes which partly overlap a ground-terminal electrode provided on the lower surface with the piezoelectric substrate located therebetween.

Abstract: A Bulk Acoustic Wave (BAW) filter, comprising at least one resonator structure that is disposed over a substrate, and an acoustic mirror that is disposed over the resonator structure. The acoustic mirror includes a plurality of layers. The acoustic mirror substantially isolates acoustic vibrations produced by the resonator from reaching beyond an upper surface of the acoustic mirror. The acoustic mirror also prevents environmental contaminants from coming into contact with the resonator. Also disclosed are surface-mountable BAW components.

Abstract: Multiple piezoelectric ceramic filter elements have different center frequencies from each other and are cascade connected together. The piezoelectric ceramic filter elements satisfy the condition 0<.vertline.dF.sub.0 .vertline./BW.sub.3 <0.8; where .vertline.dF.sub.0 .vertline. is the absolute value of the frequency difference dF.sub.0 between the center frequencies, and BW.sub.3 is the band width of each piezoelectric ceramic filter element in which the amplitude loss is 3 dB or less. A low insertion loss and an improvement in the group delay characteristics are compatible at the same time.

Abstract: A high frequency acoustic wave piezoelectric device (10) having parallel etched channels cut into a surface of a piezoelectric substrate so as to form micromachined ridges (20). Top electrodes (30) are located on tops (26) of the ridges (20) and bottom electrodes (32) are located on bottoms of the channels in spacings (22) between ridges (20). The top and bottom electrodes (30, 32) are offset from each other and substantially non-opposing. The electrodes (30, 32) generate a sufficient vertical electrical field (38) when driven to cause the ridges (20) to resonate. A height (28) of the ridges (20) define the operating frequency. The ridges (20) can be made small enough to produce frequencies well over 100 MHz in a fundamental bulk acoustic wave mode.

Abstract: In an energy trapping type ceramic filter vibrating in the thickness shear-slide mode, vibrating electrodes are formed on opposite sides of a piezoelectric ceramic substrate, while an input terminal electrode and an output terminal electrode are provided on both end portions of the substrate so that lead terminals are soldered to the terminal electrodes. A distance l.sub.5 between the input terminal electrode and the adjacent vibrating electrode and a distance l.sub.6 between the output terminal electrode and the adjacent vibrating electrode are set within a range of one to three times the thickness of the substrate. Thus, it is possible to suppress undesired vibration other than principal vibration, thereby improving filter characteristics.

Abstract: In a piezoelectric filter, two vibrating element parts are arranged on longitudinal side portions of a rectangular flat plate shaped piezoelectric substrate, and a capacitor is arranged therebetween. Each of the vibrating element parts comprises a pair of vibrating electrodes which are arranged on an upper surface of the piezoelectric substrate at a distance, and an opposite electrode which is arranged on a back surface of the piezoelectric substrate to be opposed to the vibrating electrodes. The pair of vibrating electrodes of each Vibrating element part is arranged along an electrode arrangement direction which is inclined with respect to side surfaces of the rectangular piezoelectric substrate. The electrode arrangement direction for the vibrating electrodes is inclined with respect to the side surfaces of the piezoelectric substrate at an angle .theta. of inclination which is preferably in excess of 0.degree. and not more than 45.degree..

Abstract: A multi-pole monolithic crystal filter (100) having at least three asymmetrically acoustically coupled resonators (104) on a piezoelectric blank (102) to provide an improved phase response (302). The resonators (104) are positioned substantially in inverse proportion to predetermined ladder network coupling coefficients to achieve an improved phase response filter. The ladder network coupling coefficients are selected from designs including Bessel, Gaussian, linear phase and equiripple models. In this way, a predetermined improved phase response (302) is obtained monolithically without discrete interstage tuning components.

Abstract: A tunable electromicromechanical resonator structure incorporates an electrostatic actuator which permits reduction or enhancement of the resonant frequency of the structure. The actuator consists of two sets of opposed electrode fingers, each set having a multiplicity of spaced, parallel fingers. One set is mounted on a movable portion of the resonator structure and one set is mounted on an adjacent fixed base on substrate, with the fingers in opposed relationship and their adjacent ends spaced apart by a gap. An adjustable bias voltage across the sets of electrodes adjusts the resonant frequency of the movable structure.

Abstract: A multi-mode piezoelectric filter includes a piezoelectric substrate made of a LiTaO.sub.3 single crystal, a plurality of spaced electrodes which are formed adjacently on a front major surface of the substrate, and a counter electrode which is formed on a rear major surface of the substrate in opposition to the spaced electrodes. The spaced electrodes and the counter electrode coact with the intervening portion of the substrate to form two or more energy trapped type multi-mode filter elements vibrating in the thickness shear mode such that the filter elements are coupled to form a cascade connection. Damping material such as silicone gel is applied at least on the filter elements.

Abstract: A ladder type piezoelectric filter of the present invention is made usable in high frequency ranges by employing a piezoelectric resonator having the second harmonic wave mode SM. A series resonator and a parallel resonator of the ladder type piezoelectric filter of the present invention are so arranged that center electrode regions and outer electrode regions are mutually polarized along opposite directions, and the center electrode regions are connected to the outer electrode regions, respectively.

Abstract: A piezoelectric component includes an input terminal plate, a series ceramic resonator, an output terminal plate, a parallel ceramic resonator and a ground terminal plate stacked between a first case and a second case. Lead portions of the input terminal plate, the output terminal plate and the ground terminal plate are outwardly projected from the cases. These terminal plates and the ceramic resonators are in pressure contact with each other to attain electrical conduction therebetween and thus, form a single-section ladder type filter.