A method of constructing an RF filter comprises designing an RF filter that includes a plurality of resonant elements disposed, a plurality of non-resonant elements coupling the resonant elements together to form a stop band having a plurality of transmission zeroes corresponding to respective frequencies of the resonant elements, and a sub-band between the transmission zeroes. The non-resonant elements comprise a variable non-resonant element for selectively introducing a reflection zero within the stop band to create a pass band in the sub-band. The method further comprises changing the order in which the resonant elements are disposed along the signal transmission path to create a plurality of filter solutions, computing a performance parameter for each of the filter solutions, comparing the performance parameters to each other, selecting one of the filter solutions based on the comparison of the computed performance parameters, and constructing the RF filter using the selected filter solution.

A frequency equalizer is provided. The frequency equalizer includes a coupler including a main segment extending between a first port and a second port and a coupled segment disposed in a coupling relationship with the main segment and extending between a third port and a fourth port. The frequency equalizer further includes a first thermistor electrically coupled in series between the first port and an input line, a second thermistor electrically coupled in series between the second port and an output line, and a first shunt resistor coupled across the third port. The frequency equalizer simultaneously provides frequency equalization and temperature compensation for signals transmitted through the frequency equalizer.

A frequency equalizer is provided. The frequency equalizer includes a coupler including a main segment extending between a first port and a second port and a coupled segment disposed in a coupling relationship with the main segment and extending between a third port and a fourth port. The frequency equalizer further includes a first thermistor electrically coupled in series between the first port and an input line, a second thermistor electrically coupled in series between the second port and an output line, and a first shunt resistor coupled across the third port. The frequency equalizer simultaneously provides frequency equalization and temperature compensation for signals transmitted through the frequency equalizer.

Methods and apparatuses for signal attenuation is described. In an example, an attenuator can be configured to perform attenuation of signals for an integrated circuit. The attenuator can vary the attenuation with an ambient temperature. The attenuator can further adjust the attenuation based on a control signal applied to the attenuator. The control signal can be based on one or more of a temperature profile of the attenuator and a target gain variation of the integrated circuit.

A filter with three phases comprising for each phase an input terminal, an output terminal and a capacitor, wherein for each of the three phases the input terminal is electrically connected via a connection point to the output terminal, wherein the connection points of the three phases are electrically connected via the three capacitors in star and/or delta form, wherein the filter comprises a housing containing two coil blocks, wherein the housing comprises a first side and a second side opposite the first side, wherein the two coil blocks are arranged along a line between the first side and the second side, wherein a fan for cooling the two coil blocks is arranged on the first side of the housing, wherein the larger of the two coil blocks is arranged between the fan and the smaller of the two coil blocks.

A filter with three phases comprising for each phase an input terminal, an output terminal and a capacitor, wherein for each of the three phases the input terminal is electrically connected via a connection point to the output terminal, wherein the connection points of the three phases are electrically connected via the three capacitors in star and/or delta form, wherein the filter comprises a housing containing two coil blocks, wherein the housing comprises a first side and a second side opposite the first side, wherein the two coil blocks are arranged along a line between the first side and the second side, wherein a fan for cooling the two coil blocks is arranged on the first side of the housing, wherein the larger of the two coil blocks is arranged between the fan and the smaller of the two coil blocks.

A matching circuit includes an input terminal, an output terminal, a first impedance component, a first set of switching devices, a second impedance component, a second set of switching devices and a controller. The first impedance component includes a first terminal coupled between the input terminal and the output terminal, and a second terminal. The first set of switching devices is coupled to the second terminal of the first impedance component, the controller and a reference terminal. The second impedance component includes a first terminal coupled between the second terminal of the first impedance component and the first set of switching devices, and a second terminal. The second set of switching devices is coupled to the second terminal of the second impedance component, the controller and the reference terminal. The controller controls the first set of switch devices and the second set of switch devices according to a detection signal.

A filter assembly is disclosed that includes a monolithic filter having a surface and a heat sink coupled to the surface of the monolithic filter. The heat sink includes a layer of thermally conductive material that can have a thickness greater than about 0.02 mm. The heat sink may provide electrical shielding for the monolithic filter. In some embodiments, the filter assembly may include an organic dielectric material, such as liquid crystalline polymer or polyphenyl ether. In some embodiments, the filter assembly may include an additional monolithic filter.

A matching circuit includes an input terminal, an output terminal, a first impedance component, a first set of switching devices, a second impedance component, a second set of switching devices and a controller. The first impedance component includes a first terminal coupled between the input terminal and the output terminal, and a second terminal. The first set of switching devices is coupled to the second terminal of the first impedance component, the controller and a reference terminal. The second impedance component includes a first terminal coupled between the second terminal of the first impedance component and the first set of switching devices, and a second terminal. The second set of switching devices is coupled to the second terminal of the second impedance component, the controller and the reference terminal. The controller controls the first set of switch devices and the second set of switch devices according to a detection signal.

Aspects of this disclosure relate to a surface acoustic wave resonator having a multi-layer substrate with heat dissipation. The multi-layer substrate includes a support substrate, a piezoelectric layer, and a thermally conductive layer configured to dissipate heat associated with the surface acoustic wave resonator. The thermally conductive layer is disposed between the support substrate and the piezoelectric layer. Related surface acoustic wave filters, radio frequency modules, and wireless communication devices are also disclosed.