Abstract: A microwave filter made of acoustically coupled, bulk wave acoustic resonators. The resonators utilize piezoelectric materials sandwiched between conducting electrodes. Layers of material that intervene between the resonators control the amount of acoustic coupling between the resonators and the amount of coupling is selected to obtain desired filter characteristics. The resonators and the intervening layers may be supported upon a substrate by means of a series of layers of material that function as an acoustic mirror or reflector.

Abstract: A method for fabricating patterned layers of a desired material in a desired, design pattern upon a substrate, which method may be used in circumstances where the removal of photo-resist material may not be used to lift-off undesired portions of the material from the substrate. The method uses copper or some other conducting material instead of the photo-resist material, Which copper or other conducting material may be removed by chemical processes to lift-off the undesired portions of material deposited upon the conducting material and substrate. The copper or other conducting material is fabricated upon the substrate so as to have a lip that overhangs and shadows the boundary of photo-resist material previously fabricated upon the substrate in the desired pattern.

Abstract: An improved piezoelectric resonator having multiple layers of material within each electrode of the resonator. One layer of material within each electrode is selected and used to increase the effective coupling coefficient between the piezoelectric layer of material in the resonator and the electric fields resulting from the voltages applied to the electrodes. The second layer of material within each electrode is selected and used to decrease the electrical losses within the electrodes.

Abstract: A interdigital, slow-wave coplanar transmission line resonator utilizing a coupler. Sections of interdigital, slow-wave coplanar transmission lines having lengths of an integral number of quarter waves act as resonators. In one embodiment shorted transmission lines proximately located to the resonators electromagnetically coupled to the resonators to provide input and output ports to the resonators. In another embodiment, transmission lines are connected by taps to the resonators to provide input and output ports.

Abstract: A thin-film piezoelectric resonator and method of fabrication that includes a barrier layer of material between the underlying electrode and a layer of piezoelectric material. For example, in a resonator that uses zinc oxide for the layer of piezoelectric material, a barrier layer of aluminum nitride is deposited upon an underlying aluminum electrode to protect the aluminum electrode from oxidation or structural deformation during the subsequent deposition of the piezoelectric layer of zinc oxide. The barrier layer of aluminum nitride is deposited in a manner so as to provide a substrate having a substantial degree of uniformity of crystal orientation upon which the layer of piezoelectric material may then be deposited in a manner such that the piezoelectric layer will, itself, also have a substantial degree of uniformity in the orientations of its crystals.

Abstract: A chip-scale sized package for acoustic wave devices, acoustic resonators and similar acoustic devices located upon, or fabricated upon, or as part of, a die. The package includes a lid that is bonded to the die by a strip of solder or other bonding material so as to leave a space between the lid and that portion of the die that acoustically deforms or vibrates. The upper surface of the lid includes electrical connectors that are electrically connected via plated through holes or other means to electrical connectors, or pads on the lower surface of the lid, which pads, in turn, are electrically connected by solder or other electrically conducting material to electrical connectors to the device that are located upon the surface of the die.

Abstract: Piezoelectric resonators utilizing a differentially offset reflector. One or more piezoelectric resonators are supported upon a substrate by one or more intervening layers of material, which intervening layers of material act as a reflector. The reflector isolates the resonators from the substrate. A portion of one or more of the intervening layers of material includes a differential layer of material, which differential layer shifts the resonant frequencies of the resonators that overlie the differential layer as compared with the resonant frequencies of those resonators that do not overlie the differential layer of material.

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: A method for fabricating piezoelectric resonators on a substrate such that the resonant frequency of one resonator is shifted by a small amount from another of the resonators. By means of differential fabrication of the electrodes, the thickness of the metal in an electrode for one resonator is increased relative to that of another resonator to obtain the shift in resonant frequency. The frequency of a single resonator also may be adjusted to a specific frequency by the addition of a differential layer of metal to one of the electrodes comprising the resonator. Mask alignment errors in the differential fabrication process cause non-uniformities in the thickness of the metal in the electrode which non-uniformities significantly degrade the performance of the resonator. The areas of non-uniform thickness of electrode that degrade the performance are removed in this process.

Abstract: A piezoelectric device includes a stacked crystal filter, a supporting substrate and an acoustic reflector between the filter and substrate for suppressing undesired resonant frequencies. The acoustic reflector includes a set of quarter wavelength layers of alternating higher and lower impedances. The reflector provides a large reflection coefficient for a bandwidth that encompasses only desired frequencies generated by the stacked crystal filter. By changing the nature of the material and the number of layers, the bandwidth and center frequency of the acoustic reflector may be varied to encompass a desired range of frequencies. To reduce the magnitude of side lobes at undesired frequencies, the impedance differences between layers of the reflector are reduced with depth into the reflector. The side lobes may also be reduced by serially connecting two stacked crystal filters having acoustic reflectors of the same material but with a different number of quarter wavelength layers.

Abstract: A coplanar microwave transmission line on a substrate utilizes the interdigital capacitance between overlapped conducting fingers that extend from the conductors of the transmission line to reduce substantially the velocity of electromagnetic waves propagating on the transmission line without introducing prohibitive losses. The arrays of fingers extending from the conductors of the transmission line substantially overlap each other and are relatively densely packed. Layered substrates may be used to provide lower loss and a substantial reduction in velocity, which layered substrates may include layers of dielectric material located both above and below the conductors of the transmission line.

Abstract: Resonator fabricating method and apparatus employ the resonance conditions of the piezoelectric resonator itself to control an RF-powered plasma etching or deposition process. In its basic implementation, the apparatus does not require monitoring of the resonant frequency of the resonator as it is being trimmed. Rather, the resonator provides an impedance which changes as the plasma action changes the thickness of the resonator and thereby changes the resonant frequency of the piezoelectric resonator. The changing impedance in turn changes the rate of plasma action until the action substantially stops with the resonant frequency of the resonator substantially equal to the frequency of the RF source.

Abstract: The method comprises decomposing an original resonator within a network into a pair of series connected resonators to add an additional connecting electrode to the network. The pair of resonators are series connected by a shared electrode. To preserve the original electrical characteristics of the network, the composite characteristics of the series connected resonators are chosen to match those of the original resonator. With this method, the additional electrode is placed on a surface of the piezoelectric material opposing the surface to which the shared electrode is mounted. The method allows for the addition of an electrode to a piezoelectric resonator-based network so that the electrodes which connect the network to other circuitry may be placed where desired. This may be on the upper surface of the piezoelectric material for connection to discrete components or on the lower, buried surface for connection to buried layers of an adjacent integrated circuit.

Abstract: The method comprises decomposing an original resonator within a network into a pair of series connected resonators to add an additional connecting electrode to the network. The pair of resonators are series connected by a shared electrode. To preserve the original electrical characteristics of the network, the composite characteristics of the series connected resonators are chosen to match those of the original resonator. With this method, the additional electrode is placed on a surface of the piezoelectric material opposing the surface to which the shared electrode is mounted. The method allows for the addition of an electrode to a piezoelectric resonator-based network so that the electrodes which connect the network to other circuitry may be placed where desired. This may be on the upper surface of the piezoelectric material for connection to discrete components or on the lower, buried surface for connection to buried layers of an adjacent integrated circuit.