Abstract: A bulk acoustic wave (BAW) device comprises a piezoelectric layer disposed between a first electrode layer and a sandwich electrode. The sandwich electrode includes a first layer of a first material having a first acoustic impedance and a second layer of a second material having a second acoustic impedance that is less than the first acoustic impedance of the first layer. The second layer of the sandwich electrode having the lower acoustic impedance is disposed between the first layer and the piezoelectric layer. The sandwich electrode combined with the piezoelectric layer and first electrode can cause the BAW device to resonate at a frequency whose wavelength corresponds to an acoustic cavity length of the BAW device, depending on an acoustic mirror included on one side of the BAW device. In one example, the acoustic cavity length is about 1.5 times of the resonant frequency wavelength.

Abstract: An apparatus is disclosed for bridge filters. In example aspects, the apparatus includes a filter circuit with a current balun and a filter core. The current balun includes a first terminal coupled to a first port of the filter circuit, a second terminal, a third terminal, and a fourth terminal. The current balun also includes a first inductor galvanically coupled between the first terminal and the second terminal. The current balun further includes a second inductor galvanically coupled between the third terminal and the fourth terminal. The filter core is coupled between the current balun and a second port of the filter circuit. The filter core is galvanically coupled to the second terminal of the current balun and to the fourth terminal of the current balun.

Abstract: An apparatus is disclosed for a bridge-type filter. In example aspects, the apparatus includes a filter circuit having a first port, a second port, and a filter core. The filter core is coupled between the first port and the second port. The filter core includes at least one transformer, a first resonator arrangement, and a second resonator arrangement. The first resonator arrangement is coupled to the at least one transformer and includes multiple acoustic resonators. The second resonator arrangement is coupled to the at least one transformer and includes multiple acoustic resonators.

Abstract: An apparatus is disclosed for a lattice-type filter. In example aspects, the apparatus includes a filter circuit having a first port that is single-ended and a second port that is single-ended. The filter circuit also includes a transformer, a first resonator, a second resonator, a third resonator, and a fourth resonator. The transformer includes a first terminal, a second terminal, and a third terminal, with the third terminal coupled to the second port. The first resonator is coupled between the first port and the first terminal of the transformer. The second resonator is coupled between the first port and the second terminal of the transformer. The third resonator is coupled between the first terminal of the transformer and a ground. The fourth resonator is coupled between the second terminal of the transformer and the ground.

Abstract: A BAW resonator (BAWR) with improved power durability and improved heat resistance is provided. The resonator comprises a layer stack with a piezoelectric material (PM) between a bottom electrode (ELI) and a top electrode (EL2) and a shunt path parallel (PCPP) to the layer stack provided to enable an RF signal to bypass the layer stack, e.g. to ground (GND). The shunt path (PCPP) has a temperature dependent conductance with a negative temperature coefficient, NTC, of resistance. When the temperature of the device rises due to high power operation, currents that would otherwise permanently damage the device are shunted to ground or another dedicated terminal by the temperature dependent shunt path. Upon cooling down normal operation is resumed.

Abstract: An apparatus is disclosed for harmonic reduction with filtering. In example aspects, the apparatus includes a filter circuit with first and second filter ports, first and second lattice filters, and first and second signal manipulator circuits. The first signal manipulator circuit includes a first port, a second port, and a third port coupled to the first filter port. The first signal manipulator circuit splits an input signal into multiple split signals, shifts a phase thereof to produce at least one phase-shifted split signal, and provides the phase-shifted split signal to the first and second ports. The first lattice filter is coupled to the first port, and the second lattice filter is coupled to the second port. The second signal manipulator circuit includes a first port coupled to the first lattice filter, a second port coupled to the second lattice filter, and a third port coupled to the second filter port.

Abstract: A micro-acoustic bandstop filter comprises a serial inductor (130) coupled between first and second ports (110, 120). A circuit block (140) coupled between the first and second port comprises at least one serial capacitance (141) and at least one shunt capacitance (142), wherein the serial and/or the shunt capacitance is realized by a micro-acoustic resonator (141). A shunt inductor (150) is coupled between the circuit block (140) and a terminal for a reference potential (160).

Abstract: A reconfigurable microacoustic filter is specified which comprises a ladder-type-like filter topology and a suitably placed adjustable capacitive element.

Abstract: A configurable micro-acoustic RF filter comprises first and second filter subsections (140, 150) and at least one switch (160) to selectively bypass or activate the second filter subsection (150). The filter sections include at least one serially connected and at least one shunt connected micro-acoustic resonator.

Abstract: A micro-acoustic RF filter comprises first and second ports (101, 102). First and a second signal paths (120, 110) are coupled between the first and second ports and include a corresponding resonator (111, 121). The resonator of at least one of the signal paths is a micro-acoustic resonator. One of the signal paths includes also a phase shifter (232) serially connected with the resonator (111). The micro-acoustic RF filter achieves a broad passband determined by the resonance frequencies of the micro-acoustic resonators. The filter allows flexible adaption of the passband and stopband performance.

Abstract: A micro-acoustic device comprises a confinement structure (CS) adapted to block propagation of acoustic waves of an acoustic wave resonator (TEL, PL, BEL; ES) at an operation frequency of the device to confine the acoustic waves to the acoustic path or the acoustic volume. It is proposed to use a phononic crystal material for producing the confinement structure.

Abstract: An RF filter is disclosed. In an embodiment, the RF filter includes series-interconnected basic elements, each basic element having an electroacoustic resonator and impedance converters interconnected in series between the basic elements, wherein the impedance converters are impedance inverters and/or admittance inverters, and wherein the resonators of the basic elements are either only series resonators or only parallel resonators.

Abstract: A BAW resonator (BAWR) with improved power durability and improved heat resistance is provided. The resonator comprises a layer stack with a piezoelectric material (PM) between a bottom electrode (ELI) and a top electrode (EL2) and a shunt path parallel (PCPP) to the layer stack provided to enable an RF signal to bypass the layer stack, e.g. to ground (GND). The shunt path (PCPP) has a temperature dependent conductance with a negative temperature coefficient, NTC, of resistance. When the temperature of the device rises due to high power operation, currents that would otherwise permanently damage the device are shunted to ground or another dedicated terminal by the temperature dependent shunt path. Upon cooling down normal operation is resumed.

Abstract: A reconfigurable multiplexer including a plurality of filter and/or duplexers, each respectively associated with a frequency band and can be connected to an antenna connector via a band switch individually or several at the same time. One or more phase shifters capable of adjusting a phasing of a filter or duplexer during a multiplex mode so as to improve the interband insulation in a given multiplex mode. A variable notch can be connected to one of the filters or partial filters of a duplexer.

Abstract: A duplexer is disclosed. In an embodiment, the duplexer includes a Tx filter and an Rx filter, wherein the Tx filter includes first series-interconnected basic elements, each first basic element having a first electroacoustic resonator and first impedance converters interconnected in series between the first basic elements, wherein the Rx filter comprises second series-interconnected basic elements, each second basic element having a second electroacoustic resonator and second impedance converters interconnected in series between the second basic elements, wherein the first impedance converters in the Tx filter are impedance inverters, wherein the first resonators of the first basic elements in the Tx filter are only series resonators, wherein the second impedance converters in the Rx filter are admittance inverters, and wherein the second resonators of the second basic elements in the Rx filter are only parallel resonators.

Abstract: A passive on glass (POG) on filter capping apparatus may include an acoustic filter die. The apparatus may further include a capping die electrically coupled to the acoustic filter die. The capping die may include a 3D inductor.

Abstract: The invention relates to an HF circuit, for example for use in front-end circuits, having improved signal quality in carrier aggregation. According to the invention, a signal path between a duplexer and a diplexer comprises a phase shifter.

Abstract: The specification relates to an RF filter in which characteristic filter variables have a decreased dependency on tuning. A filter in this case comprises series-interconnected basic elements that each have an electroacoustic resonator and impedance converters interconnected in series between the basic elements.

Abstract: A reconfigurable microacoustic filter is specified which comprises a ladder-type-like filter topology and a suitably placed adjustable capacitive element.

Abstract: The invention specifies a tunable RF filter which may operate using electroacoustic components and provides good electrical properties despite having a wide tuning range. For this purpose, the RF filter comprises a tunable filter core (AFK) having electroacoustic (EAK) and detunable (AKE) filter elements, and impedance restoration circuits (IWS1, IWS2) for compensating for an impedance change by tuning the filter core.