In an array of single crystal acoustic resonators, the effective coupling coefficient of first and second strained single crystal filters are individually tailored in order to achieve desired frequency responses. In a duplexer embodiment, the effective coupling coefficient of a transmit band-pass filter is lower than the effective coupling coefficient of a receive band-pass filter of the same duplexer. The coefficients can be tailored by varying the ratio of the thickness of a piezoelectric layer to the total thickness of electrode layers or by forming a capacitor in parallel with an acoustic resonator within the filter for which the effective coupling coefficient is to be degraded. Further, a strained piezoelectric layer can be formed overlying a nucleation layer characterized by nucleation growth parameters, which can be configured to modulate a strain condition in the strained piezoelectric layer to adjust piezoelectric properties for improved performance in specific applications.

A BAW device includes a substrate, a first reflector, and at least two BAW transducers. The first reflector resides over the substrate and has a plurality of reflector layers. A first BAW transducer resides over a first section of the first reflector, has a first series resonance frequency, and has a first piezoelectric layer of a first thickness between a first top electrode and a first bottom electrode. The second BAW transducer resides over a second section of the first reflector, has a second series resonance frequency that is different than the first series resonance frequency, and has a second piezoelectric layer of a second thickness, which is different than the first thickness, between a second top electrode and a second bottom electrode.

A method for making a bandpass filter including a first and second bulk acoustic wave resonators, the resonant frequency of the second resonator being offset from that of the first resonator by a predetermined offset, the method including providing a piezoelectric on insulator substrate, forming a lower electrode of the first resonator and a lower electrode of the second resonator, assembling by bonding the donor substrate to a receiver substrate, removing the donor substrate with a barrier on the piezoelectric layer, forming an upper electrode of the first resonator and an upper electrode, forming the lower electrodes being preceded by forming a mass overload pattern at the second zone, and/or forming the upper electrodes being preceded by forming a mass overload pattern at the second zone, the total thickness of the mass overload pattern or patterns being chosen to offset the resonant frequency of the second resonator by the offset.

The present invention relates to a filter circuit (100) comprising a first and a second bulk acoustic wave resonator (2, 3), the first resonator (2) having a first piezoelectric layer (4) structured such that the first resonator (2) has a lower resonant frequency than the second resonator (3), wherein the first piezoelectric layer (4) is structured by recesses (14) passing through the first piezoelectric layer (4), the first resonator (2) and the second resonator (3) as series resonators (102, 105) connected in series with a signal path of the filter circuit (100) or wherein the first resonator (2) and the second resonator (3) as parallel resonators (103, 106) are connected to the signal path of the filter circuit (100) in such a way that in each case one electrode of the resonators is connected to the signal path.

A method for fabricating a film bulk acoustic resonator (FBAR) filter device is provided. The method includes: forming a first electrode of each one of a first resonator and a second resonator on a first surface of a piezoelectric layer, forming a first passivation layer of each one of the first resonator and the second resonator on a corresponding one of the first electrodes, forming a second electrode of each one of the first resonator and the second resonator on a second surface of the piezoelectric layer, conducting a radio frequency (RF) performance test on the FBAR filter device, adjusting a thickness of the second electrode of the first resonator based on a result of the RF performance test, and forming a second passivation layer of each one of the first resonator and the second resonator on a corresponding one of the second electrodes.

A MEMS component includes a lower electrode. The MEMS component also includes an upper electrode. The upper electrode overlies the lower electrode. The MEMS component also includes a first piezoelectric layer between the lower electrode and the upper electrode. The first piezoelectric layer has a first piezoelectric material comprising AlN and Sc.

A single-die multi-FBAR (film bulk acoustic resonator) device includes multiple FBARs having different resonant frequencies formed over a single substrate. The FBARs include piezoelectric layers having different thicknesses but with upper electrodes formed at a same height over the substrate, lower electrodes at different heights over the substrate, and different sized air gaps separating the lower electrodes from the substrate.

A single-die multi-FBAR (film bulk acoustic resonator) device includes multiple FBARs having different resonant frequencies formed over a single substrate. The FBARs include piezoelectric layers having different thicknesses but with upper electrodes formed at a same height over the substrate, lower electrodes at different heights over the substrate, and different sized air gaps separating the lower electrodes from the substrate.

A method for the batch production of acoustic wave filters comprises: synthesizing N theoretical filters, each filter defined by a set of j theoretical resonator(s) having a triplet C.sub.0ij,eq, .sub.rij,eq and .sub.aij,eq, these parameters grouped into subsets; determining a reference resonator structure for each subset, naturally having a resonant frequency .sub.r,ref, where .sub.aij,eq<.sub.r,ref<.sub.rij,eq; determining, for each theoretical resonator, an elementary building block comprising an intermediate resonator R.sub.ij, a parallel reactance Xp.sub.ij and/or a series reactance Xs.sub.ij, the intermediate resonator R.sub.ij having a triplet C.sub.0ij, .sub.r,ref and .sub.a,ref, the parameters C.sub.0ij, Xpij and/or Xs.sub.ij defined so the elementary building block has a triplet: C.sub.0ij,eq, .sub.rij,eq and .sub.aij,eq; determining the geometrical dimensions of the actual resonators R.sub.ij of the filters so they have a capacitance C.sub.0ij; producing each actual resonator; associating series and/or parallel reactances with actual resonators in order to form the elementary building blocks.

A resonant circuit comprises an input terminal and an output terminal and at least: a group of N resonators, where N1, the resonators having the same resonance frequency and the same antiresonance frequency; a first and a second impedance matching element having a non-zero reactance, the first element being in series with the group of resonators, and the second element being in parallel with the group of resonators, the resonant circuit comprising: first means for controlling the group of resonators, enabling the static capacitance of the group to be fixed at a first value; second control means, enabling the impedance of the first impedance matching element and that of the second element to be fixed at second values; the first and second values being such that the triplet of values composed of the static capacitance of the group, the impedance of the first element, and the impedance of the second element can be used to determine the following triplet of parameters: the characteristic impedance Z.sub.c of the assembly formed by the group, the first impedance matching element and the second matching element; the resonance frequency .sub.r of the assembly; the antiresonance frequency .sub.a of the assembly, in order to stabilize the impedance of the circuit at a chosen characteristic impedance.