A ladder-type filter includes: one or more series resonators connected in series between an input terminal and an output terminal; two or more parallel resonators connected in parallel between the input terminal and the output terminal; a first inductor connected in series between at least two nodes, each of the at least two nodes being located between a corresponding parallel resonator of at least two parallel resonators of the two or more parallel resonators and ground; and a first capacitor connected in series with the first inductor between the at least two nodes.

Disclosed examples include digital isolator modules, isolation circuitry and low-loss multi-order bandpass filter circuits, including a capacitive coupled galvanic isolation circuit with first and second coupling capacitors individually including a first plate and a second plate, and a bond wire connecting the first plates of the coupling capacitors, a first circuit with a first inductor coupled to form a first resonant tank circuit with a first parasitic capacitor associated with the second plate of the first coupling capacitor, and a second circuit with a second inductor coupled to form a second resonant tank circuit with a second parasitic capacitor associated with the second plate of the second coupling capacitor.

A noise elimination circuit includes a coupling line and a resonance unit, and is connected between a first transmission line and a second transmission line to eliminate noise between the first and second transmission lines. The coupling line is connected to the first and second transmission lines. The resonance unit includes a plurality of resonance circuits connected in parallel to the coupling line. A band pass filter includes the coupling line and the resonance unit. A real part and an imaginary part of an admittance between the transmission lines are canceled out by the noise elimination circuit.

A multilayer circuit board with an LC resonant circuit that has an electronic component package including the multilayer circuit board with the LC resonant circuit are provided. The multilayer circuit board with the LC resonant circuit configured by alternately laminating conductive layers and insulating resin layers on both sides of a core substrate includes a first set of wiring lines, a set of vias, and a second set of wiring lines. The first set of wiring lines configures both ends of the LC resonant circuit and is formed in a first one of the conductive layers. The set of vias extends through the insulating resin layers. The second set of wiring lines is connected to an input/output terminal of the LC resonant circuit and is formed in a second one of the conductive layers. The first set of wiring lines is connected to the second set of wiring lines.

A circuit device includes a substrate and a coil component including a first coil and a second coil that are magnetically coupled to each other. A wiring pattern includes a first wiring line, a second wiring line, a third wiring line on which capacitors are mounted in series, and a fourth wiring line that electrically connects the first wiring line or the second wiring line to a ground electrode. A distance between a first current path on which a current flows from the coil component to a ground electrode via the third wiring line and a second current path on which a current flows from the first wiring line or the second wiring line to the ground electrode via the fourth wiring line on which capacitors are mounted at an electrode is not constant.

A diplexer includes a multilayer substrate, first, second, and third terminals, and a ground terminal provided on the multilayer substrate. The first filter is between the first terminal and the second terminal, the second filter is between the first terminal and the third terminal. An interlayer spacing of the multilayer substrate includes a first filter ground electrode, a second filter ground electrode, and a shield ground electrode shielding between the first filter and the second filter. The ground terminal includes a first filter ground terminal connected to the first filter ground electrode, a second filter ground terminal connected to the second filter ground electrode, and a shield ground terminal connected to the shield ground electrode.

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.

An analog time delay filter circuit including a first delay circuit block arranged in a modular layout, having a first time delay filter, a first input, a first output, and first and second pass-throughs; and a second delay circuit block arranged in the same modular layout, having a second time delay filter, a second input, a second output, and third and fourth pass-throughs.

Radio frequency (RF) filters configured to filter undesired signal components (e.g., noise and harmonics) from RF signals are disclosed. In one embodiment, an RF filter includes a first inductor coil having a first winding and a second inductor coil having a second winding and a third winding. The second winding of the second inductor coil is configured to have a first mutual magnetic coupling with the first winding, while the third winding of the second inductor coil is configured to have a second mutual magnetic coupling with the first winding. The second winding is connected to the third winding such that the first mutual magnetic coupling and the second mutual magnetic coupling are in opposition. In this manner, the first inductor coil and the second inductor coil may be provided in a compact arrangement while providing weak mutual magnetic coupling between the first inductor coil and the second inductor coil.

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.