A tunable filter includes at least two tunable resonators, a resonator comprising at least one inductance or transmission line, the inductance or transmission line having a first end connected to the ground M and a second end coupled to another resonator via a coupling impedance, and several switched capacitors, wherein the inductance or transmission line comprises several access points or connection points distributed along the inductance allowing for the connection or non-connection of a switched capacitor whose value is defined as a function of its position on the inductance, the capacitors of low weights are situated close to the end of the inductance linked to the ground M. A use of the filter in radio transceivers is also provided.

A tunable notch filter comprising a transmission line, a tunable bandstop filter and a tunable bandpass filter. The transmission line has an input port, an output port and a length electrically connecting the input port to the output port and receiving an RF signal at the input port. The tunable bandstop filter comprises a first direct current voltage source, a first coupling line and a first tunable capacitor. The first direct current voltage source provides a first adjustable voltage to the first tunable capacitor. The first tunable capacitor adjusts its capacitance based on the first adjustable voltage. The tunable bandpass filter comprises a second direct current voltage source, a second coupling line and a second tunable capacitor. The second direct current voltage source provides a second adjustable voltage to second tunable capacitor. The second tunable capacitor adjusts its capacitance based on the second adjustable voltage.

Front-end systems with an adjustable filter architecture are provided. In certain embodiments, a front-end system includes a first bandpass filter with a first passband, a second bandpass filter with a second passband, a stopband filter with a stopband, and switches for controlling connectivity of the filters along transmit and receive paths. The first passband and the second passband include a frequency overlap region, which the stopband at least partially overlaps. The re-configurability of the switches allows for the overall filtering characteristic of the adjustable filter to adjust the duplex gap between transmit and receive passband edges, as well as the passband edges themselves.

Systems, devices, and methods for tunable filters that are configured to support multiple frequency bands, such as within the field of cellular radio communication, can include a first resonator and a second resonator configured to block signals within one or more frequency ranges, and one or more coupling element connected to both the first resonator and the second resonator. The one or more coupling element can be configured to provide low insertion loss within a pass band.

A high-frequency front end circuit includes a fixed frequency filter and an interference-wave suppression variable filter. The fixed frequency filter attenuates a high-frequency signal outside a specific frequency band. The interference-wave suppression variable filter attenuates a high-frequency signal in at least one used communication channel, among used communication channels that are used by a system and that causes an interference wave occurring in a neighbor frequency domain including a wireless communication channel.

A tunable passband filter including a signal input port for receiving an input radio frequency (RF) signal, a signal output port for transmitting a filtered output RF signal, a first high-pass section having a first tunable microelectromechanical system (MEMS) switch array to receive the input RF signal from the signal input port, a second high-pass section having a second tunable MEMS switch array to transmit the output RF signal to the signal output port, and a low pass section operatively coupled between the first high-pass section and the second high-pass section, and having each of a first tunable MEMS bridge array, a second tunable MEMS bridge array, and a high impedance line. The tunable passband filter is configured to filter the input RF signal to yield the filtered output RF signal.

Embodiments of an apparatus that includes a substrate and an inductor residing in the substrate are disclosed. In one embodiment, the inductor is formed as a conductive path that extends from a first terminal to a second terminal. The conductive path has a shape corresponding to a two-dimensional (2D) lobe laid over a three-dimensional (3D) volume. Since the shape of the conductive path corresponds to the 2D lobe laid over a 3D volume, the magnetic field generated by the inductor has magnetic field lines that are predominately destructive outside the inductor and magnetic field lines that are predominately constructive inside the inductor. In this manner, the inductor can maintain a high quality (Q) factor while being placed close to other components.

A tunable notch filter comprising a transmission line, a tunable bandstop filter and a tunable bandpass filter. The transmission line has an input port, an output port and a length electrically connecting the input port to the output port and receiving an RF signal at the input port. The tunable bandstop filter comprises a first direct current voltage source, a first coupling line and a first tunable capacitor. The first direct current voltage source provides a first adjustable voltage to the first tunable capacitor. The first tunable capacitor adjusts its capacitance based on the first adjustable voltage. The tunable bandpass filter comprises a second direct current voltage source, a second coupling line and a second tunable capacitor. The second direct current voltage source provides a second adjustable voltage to second tunable capacitor. The second tunable capacitor adjusts its capacitance based on the second adjustable voltage.

A multiband radio frequency transmitter of a transceiver in which a receiving band is varied, includes a transmitting circuit, a receiving band-rejection filter, a power amplifying circuit, and an impedance compensating circuit. The transmitting circuit is configured to generate a transmission signal. The receiving band-rejection filter is configured to vary a rejection band in response to a variation of the receiving band, and reject the receiving band from the transmission signal provided from the transmitting circuit. The power amplifying circuit is configured to amplify the transmission signal that passes through the receiving band-rejection filter. The impedance compensating circuit is configured to compensate for impedance mismatch due to the variation of the rejection band of the receiving band-rejection filter.

A resonator element for use in a filter is provided. The resonator element includes a first resonator acoustically coupled to a second resonator. The first resonator has terminals for incorporation in a filter structure. A tuning circuit is coupled to the second resonator to enable tuning of the resonator element.