A tunable inductor circuit includes a first common transmission line having one end connected to a first terminal; a first uncommon transmission line having one end connected to another end of the first common transmission line; a first switch circuit configured to selectively connect one of the other end of the first common transmission line and another end of the first uncommon transmission line to a first common node; a second common transmission line having one end connected to the first common node; a second uncommon transmission line having one end connected to another end of the second common transmission line; and a second switch circuit configured to selectively connect one of the other end of the second common transmission line and another end of the second uncommon transmission line to a second terminal.

An adjustable inductor including a toroidal core defining a plurality of gaps, a compressible gap material positioned in the gaps, at least one winding wound on the core, a force-applying structure, and a film substantially covering the adjustable inductor. The force-applying structure is operable to apply a force to the core to adjust the gaps and thereby an inductance of the adjustable inductor. The film is configured to prevent movement of force-applying structure when above a predetermined temperature threshold, and allow movement of the force-applying structure when below the predetermined threshold.

A package for a tunable filter is disclosed. In an embodiment, the tunable filter includes a substrate having a first interconnection plane and a semiconductor device assembled on the substrate in a first component plane, the semiconductor device electrically connected to the first interconnection plane and containing tunable passive components. The filter further includes a control unit arranged in the first component plane, a dielectric layer arranged above the first component plane, a second component plane arranged on the dielectric layer and discrete passive devices arranged in the second component plane and interconnected with the semiconductor device, wherein the tunable passive components are tunable by the control unit.

A frequency tunable filter and an associated apparatus are provided, where the frequency tunable filter may include a plurality of ports including an input port and an output port, and may further include an inductor-capacitor (LC) resonator, a switching unit that is coupled between the LC resonator and a ground terminal of the frequency tunable filter, and a resonance adjustment unit that is coupled between the LC resonator and the ground terminal. For example, the LC resonator may include a first terminal coupled to each of the input port and the output port, and may further include a second terminal, the switching unit may selectively provide a conduction path between the second terminal of the LC resonator and the ground terminal, and the resonance adjustment unit may selectively change a resonance characteristic of the LC resonator.

Disclosed are a power matching method and apparatus for wireless charging, and a wireless charging apparatus. The method includes receiving first sensing information sensed from a transmitting coil of the wireless transmitter, wherein the transmitting coil includes at least one of a capacitor assembly with adjustable capacitance and an inductor assembly with adjustable inductance; detecting whether resonant frequency has changed according to the first sensing information; and adjusting at least one of capacitance of the capacitor assembly in the transmitting coil of the wireless transmitter and inductance of the inductor assembly in the transmitting coil in response to the resonant frequency changing to make transmitting power of the wireless transmitter be matched with receiving power of a wireless receiver in the wireless charging system, wherein the first sensing information comprises at least one of a first sensing voltage value and a first sensing current value.

A variable frequency filter includes a series arm resonant circuit and first and second parallel arm resonant circuits. The series arm resonant circuit is connected between a first connection terminal and a second connection terminal. The first parallel arm resonant circuit is connected to the first connection terminal side of the series arm resonant circuit. In the first parallel arm resonant circuit, a piezoelectric resonator and a variable capacitor are connected in series to each other. The second parallel arm resonant circuit is connected to the second connection terminal side of the series arm resonant circuit. In the second parallel arm resonant circuit, a piezoelectric resonator and a variable capacitor are connected in series to each other. The impedance of the piezoelectric resonator is lower than the impedance of the piezoelectric resonator. The series arm resonant circuit includes a characteristic adjusting capacitor at the first connection terminal side.

A technique relates to a lossless microwave switch discussed herein. Multiple ports are included in the lossless microwave switch. Tunable filters are included in the lossless microwave switch. Each of the ports is operatively coupled a corresponding one of the tunable filters.

A technique relates to a lossless microwave switch discussed herein. Multiple ports are included in the lossless microwave switch. Tunable filters are included in the lossless microwave switch. Each of the ports is operatively coupled a corresponding one of the tunable filters.

A tunable multi-path filter, a method for filtering a radio frequency signal with the tunable multi-path filter, and a communication device including the tunable multi-path filter. In one embodiment, the tunable multi-path filter includes a voltage controlled current source, an oscillator source, and at least two filter paths. The voltage controlled current source for receiving a radio frequency (RF) signal and generating a current signal. The oscillator source for generating a tunable clock signal. Each of the at least two filter paths are coupled to the voltage controlled current source and the oscillator source, and are configured to generate an output voltage signal based at least in part on the current signal and the tunable clock signal. In some embodiments, the tunable multi-path filter further includes a carrier signal rejection component that is configured to reduce the carrier feedthrough in the output voltage signals.

A frequency tunable filter and an associated apparatus are provided, where the frequency tunable filter may include a plurality of ports including an input port and an output port, and may further include an inductor-capacitor (LC) resonator, a switching unit that is coupled between the LC resonator and a ground terminal of the frequency tunable filter, and a resonance adjustment unit that is coupled between the LC resonator and the ground terminal. For example, the LC resonator may include a first terminal coupled to each of the input port and the output port, and may further include a second terminal, the switching unit may selectively provide a conduction path between the second terminal of the LC resonator and the ground terminal, and the resonance adjustment unit may selectively change a resonance characteristic of the LC resonator.