Abstract: A radio frequency (RF) filtering circuit. The RF circuit includes a first acoustic resonator disposed over a substrate; a second acoustic resonator disposed over the first acoustic resonator; and a via structure disposed between the first acoustic resonator and the second acoustic resonator, in contact with the first acoustic resonator and the second acoustic resonator. The first acoustic resonator and the second acoustic resonator are conductively connected to each other through the via structure.

Abstract: A filter circuit includes a first inductor circuit connected in series with a second inductor circuit, and a first capacitor circuit connected in series with a second capacitor circuit. The first inductor circuit and the second inductor circuit are connected between a first input/output port and a second input/output port of the filter circuit. A third inductor circuit is connected between a reference node and a first node that is between the first inductor circuit and the second inductor circuit. A resonator circuit is connected to a second node between the first capacitor circuit and the second capacitor circuit. A fourth inductor circuit is connected between the resonator circuit and the reference node. In some embodiments, another resonator circuit is connected between the input port and the output port of the filter circuit.

Abstract: Disclosed is a Bulk Acoustic Wave (BAW) filter structure with a conductive bridge forming an electrical loop with an electrode for reduced electrical losses. In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes, a piezoelectric layer between the electrodes, and at least one conductive bridge offset from at least a portion of one of the electrodes by an insulating volume. The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses for improved electrical loss of the BAW filter structure.

Abstract: Disclosed is a Bulk Acoustic Wave (BAW) filter structure with a conductive bridge forming an electrical loop with an electrode for reduced electrical losses. In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes, a piezoelectric layer between the electrodes, and at least one conductive bridge offset from at least a portion of one of the electrodes by an insulating volume. The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses for improved electrical loss of the BAW filter structure.

Abstract: Reversed semilattice filters with improved common mode rejection characteristics are disclosed. In one aspect, a filter may include two interior nodes coupled with an impedance that treats unwanted signals as common mode signals and provides rejection for common mode signals while passing differential signals of interest. The impedance is modified to have a resonant circuit that improves signal rejection in the stop band by lowering the effective impedance at those frequencies while leaving the pass band unaffected.

Abstract: A bulk acoustic wave (BAW) is provided. The BAW structure includes a transducer that includes a first electrode, a second electrode, a piezoelectric layer between the first electrode and the second electrode, and a conductive bridge structure extending in a lateral direction and in contact with the first electrode at a central stripe area of the first electrode.

Abstract: A duplexer system includes a first signal path from a transmit port to a receive port and a second signal path from the transmit port to the receive port. The first signal path includes a first transmit filter, an antenna, and a first receive filter. The second signal path includes a second receive filter, a load, and a second transmit filter. The first signal path and the second signal path are configured such that a first signal received at the receive port from the first signal path is inverted relative to a second signal received at the receive port from the second signal path and the first signal and the second signal destructively interfere at the receive port.

Abstract: An acoustic resonator includes a first piezoelectric layer, a second piezoelectric layer, and a coupler layer between the first piezoelectric layer and the second piezoelectric layer. The first piezoelectric layer and the second piezoelectric layer have a same polarity. The coupler layer includes a first metal layer, a second metal layer, a dielectric layer between the first metal layer and the second metal layer, and conductive vias through the dielectric layer and electrically connecting the first metal layer and the second metal layer. A first electrode is positioned on the first piezoelectric layer opposite the coupler layer. A second electrode is positioned on the second piezoelectric layer opposite the coupler layer.

Abstract: A bridge-T filter is disclosed. In one aspect, the bridge-T filter may include one or more inductors associated with acoustic resonators to assist in providing out-of-band rejection while improving fractional bandwidth of the filter. In specific aspects, the additional inductors may be placed in series or parallel to the acoustic resonators. The improved fractional bandwidth and better out-of-band rejection reduces unwanted signals and improves the user experience.

Abstract: A transformer balun for high rejection unbalanced lattice filters includes two symmetrical coils separated by a shielding element. In a further exemplary aspect, the transformer may include a conductor, which may be a third coil that operates with a capacitor to form a resonant circuit that enhances mutual coupling. Using either of the exemplary transformers provides improved performance in the passband while concurrently providing out-of-band rejection at levels exceeding seventy decibels (70 dB).

Abstract: Reversed semilattice filters with improved common mode rejection characteristics are disclosed. In one aspect, a filter may include two interior nodes coupled with an impedance that treats unwanted signals as common mode signals and provides rejection for common mode signals while passing differential signals of interest. The impedance is modified to have a resonant circuit that improves signal rejection in the stop band by lowering the effective impedance at those frequencies while leaving the pass band unaffected.

Abstract: A filter circuit includes a first inductor circuit connected in series with a second inductor circuit, and a first capacitor circuit connected in series with a second capacitor circuit. The first inductor circuit and the second inductor circuit are connected between a first input/output port and a second input/output port of the filter circuit. A third inductor circuit is connected between a reference node and a first node that is between the first inductor circuit and the second inductor circuit. A resonator circuit is connected to a second node between the first capacitor circuit and the second capacitor circuit. A fourth inductor circuit is connected between the resonator circuit and the reference node. In some embodiments, another resonator circuit is connected between the input port and the output port of the filter circuit.

Abstract: A transformer balun for high rejection unbalanced lattice filters includes two symmetrical coils separated by a shielding element. In a further exemplary aspect, the transformer may include a conductor, which may be a third coil that operates with a capacitor to form a resonant circuit that enhances mutual coupling. Using either of the exemplary transformers provides improved performance in the passband while concurrently providing out-of-band rejection at levels exceeding seventy decibels (70 dB).

Abstract: Disclosed is a Bulk Acoustic Wave (BAW) filter structure with a conductive bridge forming an electrical loop with an electrode for reduced electrical losses. In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes, a piezoelectric layer between the electrodes, and at least one conductive bridge offset from at least a portion of one of the electrodes by an insulating volume. The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses for improved electrical loss of the BAW filter structure.

Abstract: Disclosed is a Bulk Acoustic Wave (BAW) filter structure with a conductive bridge forming an electrical loop with an electrode for reduced electrical losses. In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes, a piezoelectric layer between the electrodes, and at least one conductive bridge offset from at least a portion of one of the electrodes by an insulating volume. The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses for improved electrical loss of the BAW filter structure.

Abstract: Disclosed is a Bulk Acoustic Wave (BAW) filter structure with a conductive bridge forming an electrical loop with an electrode for reduced electrical losses. In exemplary aspects disclosed herein, the BAW filter structure includes a transducer with electrodes, a piezoelectric layer between the electrodes, and at least one conductive bridge offset from at least a portion of one of the electrodes by an insulating volume. The conductive bridge forms a first electrical loop between a medial end and a distal end of the electrode. Such a configuration reduces electrical resistance, heat resistance, and/or ohmic losses for improved electrical loss of the BAW filter structure.

Abstract: Acoustic resonators, such as bulk acoustic wave (BAW) resonators and, in particular, acoustic resonators including stacked crystal filters (SCFs) are disclosed. SCF structures are disclosed with increased spurious free ranges by providing various arrangements of acoustically soft materials in one or more locations that correspond with high stress regions of one or more modes. For SCFs operating in first order modes, relative amounts of acoustically soft materials within shared electrodes may be increased. One or more additional layers of acoustically soft materials may also be added to SCF structures near shared electrodes. Accordingly, SCFs may be provided with increased frequency spreads between first order modes and second order modes.

Abstract: Acoustic resonators, such as bulk acoustic wave (BAW) resonators, are disclosed that include phase shift structures. Acoustic resonators, including stacked crystal filters (SCFs) and coupled resonator filters (CRFs), may include inverted piezoelectric layers that are configured to provide built-in phase shift capabilities. Circuit topologies that include such SCFs may be provided with simplified structures and reduced loss. Circuit topologies with such CRFs may be provided with more symmetrical electrical connections and improved phase balance over operating frequencies. SCFs with phase shift structures may additionally include spurious mode suppression by modifying piezoelectric coupling profiles within one or more layers. Mode suppression configurations may include structures with one or more inverted polarity piezoelectric layers, one or more non-piezoelectric layers, one or more thicker electrodes of the SCF, and combinations thereof.

Abstract: Acoustic resonators, such as bulk acoustic wave (BAW) resonators, are disclosed that include mode suppression structures. Acoustic resonators, including stacked crystal filters (SCFs), are disclosed that include spurious mode suppression by modifying a piezoelectric coupling profile within one or more layers of an SCF. Mode suppression configurations may include structures with one or more inverted polarity piezoelectric layers, one or more non-piezoelectric layers, one or more thicker electrodes of the SCF, and combinations thereof. Symmetric input and output electrical response for SCFs with mode suppression configurations may be exhibited by including piezoelectric materials with different electromechanical coupling values and/or by dividing stress profiles differently by configuring different thicknesses for input and output sides of SCFs.

Abstract: Acoustic resonators, such as bulk acoustic wave (BAW) resonators, are disclosed that include mode suppression structures. Acoustic resonators, including stacked crystal filters (SCFs), are disclosed that include spurious mode suppression by modifying a piezoelectric coupling profile within one or more layers of an SCF. Mode suppression configurations may include structures with one or more inverted polarity piezoelectric layers, one or more non-piezoelectric layers, one or more thicker electrodes of the SCF, and combinations thereof. Symmetric input and output electrical response for SCFs with mode suppression configurations may be exhibited by including piezoelectric materials with different electromechanical coupling values and/or by dividing stress profiles differently by configuring different thicknesses for input and output sides of SCFs.