A notch filter includes an inductor coupled between an input node and an output node, and a dual-resonator structure coupled between the input node, the output node, and ground.

A bandpass filter includes a capacitor coupled between an input node and an output node, and a dual-resonator structure coupled between the input node, the output node, and ground.

In accordance with an embodiment, a method of operating an RF system includes generating a first RF signal having a first frequency; filtering the generated first RF signal to form a first filtered transmitted signal; producing a first coupled signal and a first transmitted signal from the first filtered transmitted signal; transmitting the first transmitted signal; transmitting a second RF signal having a second frequency; bandpass filtering the first coupled signal to form a first tunable bandpass filtered signal; and measuring a parameter of the first tunable bandpass filtered signal.

According to some embodiments, an on-chip diplexer circuit is disclosed. The on-chip diplexer circuit includes a LC resonator module, the LC resonator module further comprises a first port, a first LC resonator unit and a second LC resonator unit; a first filter unit, the first filter unit is electrically connected to the first LC resonator unit in the LC resonator module, and the first filter unit is electrically connected to a second port; and a second filter unit, the second filter unit is electrically connected to the second LC resonator unit in the LC resonator module, and the second filter unit is electrically connected to a third port. According to some embodiments, the first LC resonator unit serves as an impedance matching circuit for a first signal having a first resonant frequency and serves as an open circuit for a second signal having a second resonant frequency that is different from the first resonant frequency; the second LC resonator unit serves as an impedance matching circuit for the second signal having the second resonant frequency and serves as an open circuit for the first signal having the first resonant frequency. The first filter unit passes signals with the first resonant frequency; and the second filter unit passes signals with the second resonant frequency.

Disclosed are devices and methods for fabricating devices. A device can include a passive portion having at least one metal insulator metal (MIM) capacitor and at least one 2-dimensional (2D) inductor. The device further includes a substrate and the passive portion is formed on the substrate. A magnetic core is embedded in the substrate. A 3-dimensional (3D) inductor is also included having windings formed at least in part in the substrate and at least a portion of the windings being formed around the magnetic core.

A multiplexer includes a first filter circuit including a pass band that is a first frequency band, a second filter circuit including a pass band that is a second frequency band, and an additional circuit. The first filter circuit includes a first terminal connected to a common terminal and a second terminal connected to a first input/output terminal. The second filter circuit includes a third terminal connected to the common terminal and a fourth terminal connected to a second input/output terminal. The additional circuit is connected to the fourth terminal and one of the first and second terminals and includes a series-arm circuit on a series-arm path connecting the fourth terminal to the one of the terminals and a parallel-arm circuit on a parallel-arm path connecting the series-arm path to the ground. The parallel-arm circuit includes only an inductor, a capacitor, or an LC parallel-arm resonant circuit in series with the parallel-arm path.

A resonator element for use in a filter is provided. The resonator element includes a first resonator acoustically coupled to a second or third resonator or both. The first resonator has terminals for incorporation in a filter structure. A tuning circuit is coupled to the second or third resonator or both to enable tuning of the resonator element. The tuning circuit includes a variable capacitor and an inductor.

In accordance with an embodiment, a method of operating an RF system includes filtering a first wideband RF signal using a wideband filter bank. Filtering the first RF signal includes separating the first wideband RF signal into frequency cluster signals, where each frequency cluster signal of the frequency cluster signals includes different frequency ranges, the first wideband RF signal includes multiple RF bands, and each of the different frequency ranges comprises a plurality of RF bands of the multiple RF bands. The method further includes band stop filtering at least one of the frequency cluster signals to produce a band stopped frequency cluster signal.

A notch filter includes a first inductor coupled between an input node and an output node, a dual-resonator structure coupled between the input node and the output node, and a second inductor coupled between the dual-resonator structure and ground, and a bandpass filter includes a capacitor coupled between an input node and an output node, and a dual-resonator structure coupled between the input node, the output node, and ground.

The present disclosure provides an inductive element capable of lowering a Q-value. An inductive element includes a first cover and a second cover covering an annular core, and a first winding and a second winding wound around a region of the core, the first cover and the second cover. The first cover covers a part of an inner circumferential surface of the core, a part of an outer circumferential surface and an end surface on one end side in an axial direction. The second cover covers a part of the inner circumferential surface of the core, a part of the outer circumferential surface an end surface on the other end side in the axial direction.