Radio-frequency splitter circuits, devices and methods. In some embodiments, a power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.

A multilayer substrate includes a dielectric substrate, a pair of capacitor electrodes, and an input/output electrode that is an electrode for input, an electrode for output, or an electrode for input and output. The dielectric substrate has a first main surface and a second main surface that are opposite to each other in a thickness direction of the dielectric substrate. The pair of capacitor electrodes is disposed in the dielectric substrate. Electrodes of the pair of capacitor electrodes face each other in the thickness direction. The input/output electrode is disposed on the second main surface of the dielectric substrate. A capacitor that includes the pair of capacitor electrodes and a portion being part of the dielectric substrate and located between the electrodes of the pair of capacitor electrodes at least partially overlaps the input/output electrode electrically connected to the capacitor.

A frontend module includes a first filter having a passband of a first frequency band, a second filter having a passband of a second frequency band, the second frequency band being higher than the first frequency band, a third filter having a passband of a third frequency band, the third frequency band being higher than the second frequency band, and a sub-filter, connected to the second filter, configured to provide attenuation characteristics for the first frequency band, wherein the second filter comprises a plurality of parallel LC resonance circuits arranged between a ground and different nodes, from among a plurality of nodes between a first terminal and a second terminal, wherein an inductor is connected to a portion of the plurality of parallel LC resonance circuits.

A multiplexer includes a first acoustic wave filter, a second acoustic wave filter, and an inductor-capacitor (LC) filter each connected to a common terminal. A passband of the second acoustic wave filter is between a passband of the first acoustic wave filter and a passband of the LC filter, a frequency gap between the passband of the second acoustic wave filter and the passband of the LC filter is greater than a frequency gap between the passband of the first acoustic wave filter and the passband of the second acoustic wave filter, the passband of the first acoustic wave filter includes a transmission band of the first communication band, the passband of the LC filter includes a reception band of the first communication band, and the passband of the second acoustic wave filter includes a reception band of a second communication band.

A radio frequency circuit includes a filter of a Band A, a filter of a Band B, a filter of a Band C, a low pass filter that is connected between a common terminal and a first terminal, a high pass filter that is connected between the common terminal and a second terminal, and an impedance variable circuit. The frequency interval between the Band A and the Band B is smaller than the frequency interval between the Band A and the Band C. In CA of the Band A and the Band B, the filter is connected to the first terminal, the filter is connected to the second terminal, and an impedance of the low pass filter when viewed from the first terminal and an impedance of the high pass filter when viewed from the second terminal have a complex conjugate relationship.

A frontend module includes a first filter having a passband of a first frequency band, a second filter having a passband of a second frequency band, the second frequency band being higher than the first frequency band, a third filter having a passband of a third frequency band, the third frequency band being higher than the second frequency band, and a sub-filter, connected to the second filter, configured to provide attenuation characteristics for the first frequency band, wherein the second filter comprises a plurality of parallel LC resonance circuits arranged between a ground and different nodes, from among a plurality of nodes between a first terminal and a second terminal, wherein an inductor is connected to a portion of the plurality of parallel LC resonance circuits.

A method for reducing a quantity of cable runs to antennas can include the step of providing a circuit of reactive elements coupled between an input terminal and at least two output terminals. The circuit can be used to separate a broadband signal into two or more disjoint expected frequency ranges. The circuit can match the impedance at the at least two output terminals to the impedance expected by the antennas. The elements of the circuit can have reactances and arrangement so that when a broadband RF signal is applied at the input terminal, two or more disjoint expected frequencies can be applied to the respective output terminals. The power at each output terminal can sufficiently match the antennas' expected power, and insertion losses can be minimized.

An input/output apparatus of a multiplexer is provided, including: a main tap and at least two branch taps of the main tap, where each of the at least two branch taps is configured to couple to a different resonant cavity in the multiplexer, and the at least two branch taps include a first branch tap and a second branch tap; a coupling polarity of the first branch tap is opposite to that of the second branch tap; and a coupling calculation frequency of the second branch tap is closest to a coupling calculation frequency of the first branch tap. The input/output apparatus of the multiplexer enables two channels with closest frequencies to use different coupling polarities. Because the coupling polarities are different, signals naturally do not interfere with each other, and signal interference between channels is eliminated in principle. The embodiments of the present disclosure further provide a corresponding multiplexer.

Broadband power splitter. In some embodiments, a power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.

A method for reducing a quantity of cable runs to antennas can include the step of providing a circuit of reactive elements coupled between an input terminal and at least two output terminals. The circuit can be used to separate a broadband signal into two or more disjoint expected frequency ranges. The circuit can match the impedance at the at least two output terminals to the impedance expected by the antennas. The elements of the circuit can have reactances and arrangement so that when a broadband RF signal is applied at the input terminal, two or more disjoint expected frequencies can be applied to the respective output terminals. The power at each output terminal can sufficiently match the antennas' expected power, and insertion losses can be minimized.