A balun includes an unbalanced terminal; balanced terminals; first and second main lines; and first and second sub-lines. The first main line has an end connected to the unbalanced terminal. The second main line has an end connected to the first main line and an end that is open. Each of the first and the second sub-lines is connected between the balanced terminal and a reference potential, respectively. The second sub-line includes a first partial line connected to the balanced terminal, and a second partial line connected between the first partial line and the reference potential. The second main line includes a third partial line connected to the first main line, and a fourth partial line connected to the third partial line. The distance between the first partial line and the third partial line is shorter than the distance between the second partial line and the fourth partial line.

An LC filter includes a multilayer body including dielectric layers layered therein, plate electrodes, capacitor electrodes, inductor vias, and ground vias. The plate electrodes are provided on different layers of the multilayer body. The capacitor electrodes each define a capacitor between itself and the electrode. The inductor via is connected with the electrode and the capacitor electrode, while the inductor via is connected with the electrode and the capacitor electrode. The ground vias connect the plate electrodes to each other. The inductor via and the capacitor electrode define a resonance circuit that receives a signal from an input terminal. The inductor via and the capacitor electrode define a resonance circuit that transfers a signal to the output terminal.

An LC filter includes a multilayer body, plate electrodes, capacitor electrodes, and inductor vias. The capacitor electrodes each define a capacitor between the plate electrode and a corresponding one of the capacitor electrodes. A first inductor via is connected between a first capacitor electrode and a first plate electrode. A second inductor via is connected between a second capacitor electrode and the first plate electrode. A third inductor via is connected between a third capacitor electrode and the first plate electrode. A fourth capacitor electrode faces the first and second capacitor electrodes. A fifth capacitor electrode faces the second and third capacitor electrodes. A sixth capacitor electrode faces the first and third capacitor electrodes.

Radio frequency filtering circuitry blocks certain frequencies in an outgoing signal so that the signal may be transmitted over a desired frequency. The radio frequency filtering circuitry includes a first inductor having a first coil and a second inductor coupled to and disposed within the first coil. The second inductor has a second coil and a third coil symmetrical to the second coil. When current is applied to the radio frequency filtering circuitry, the current in the second coil causes a first induced current in the first coil and the current in the third coil causes a second induced current in the first coil, wherein the second induced current is approximately equal in magnitude and opposite in direction to the first induced current. As such, the second induced current may compensate for the first induced current.

An integrated transformer and an electronic device are disclosed. The integrated transformer includes at least one first base plate and at least one second base plate. Each of the first and second base plate defines multiple annular accommodating grooves. The annular accommodating grooves divide each of the first and second base plate into multiple central parts and a peripheral part Each central part defines multiple inner via holes there through. The peripheral part defines multiple outer via holes there through. The integrated transformer further includes multiple magnetic cores disposed in the respective annular accommodating groove and transmission wires disposed on both sides of the first and second base plates. Transformers and the filters are arranged on two base plates respectively, and the thickness of the transmission wire layers of the filters is less than that of the transformers. Thus, the structure of the electromagnetic device may be more compact.

An integrated passive die includes a substrate, an input node, an output node, and RF filtering circuitry. The RF filtering circuitry includes a number of LC tank circuits coupled between the input node and the output node. Each one of the LC tank circuits include an inductor and a capacitor. The inductor is formed by a metal trace over the substrate. The capacitor is coupled in parallel with the inductor over the substrate. The inductor and the capacitor are provided such that a resonance frequency of the combination of the inductor and the capacitor is less than a self-resonance frequency of the inductor.

A circuit board having excellent reliability of connection between layers while being capable of achieving a compact and low-profile electronic device. In the circuit board has an LC circuit built therein with the use of a glass core having a through hole, a conductor layer formed in the through hole is connected to a wiring pattern formed on one surface of the glass core, and connected to a wiring pattern formed on the other surface of the glass core, with the conduction layer projected from the surface of the glass core. Thus, the area of contact between the conduction layer and the through hole is increased, thus making it possible to prevent the reliability of connection between layers in the through hole from being decreased, even when the glass core is reduced in thickness for achieving a low-profile device.

A filter device includes an unbalanced terminal, balanced terminals, and first and second resonant circuits. The first resonant circuit is connected to the unbalanced terminal. The second resonant circuit is connected to the balanced terminals and electromagnetically coupled with the first resonant circuit. The first resonant circuit includes a resonator in which an inductor and a capacitor are connected in parallel between the unbalanced terminal and a reference potential. The second resonant circuit includes a resonator including an inductor connected between the balanced terminals and capacitors connected in series between the balanced terminals.

An electronic component includes a stack and an inductor wound about an axis orthogonal to a stacking direction. The inductor includes a first conductor layer portion and two through hole columns. The first conductor layer portion includes two conductor layers disposed at positions different from each other in the stacking direction and connected in parallel to each other. Area of a first conductor layer is larger than area of a second conductor layer.

An electronic component includes a stack and first to third inductors. Area of a region obtained by perpendicularly projecting a first space including a first axis and surrounded by the first inductor onto an XZ plane is larger than area of a region obtained by perpendicularly projecting a second space including a second axis and surrounded by the second inductor onto a YZ plane. The third inductor is disposed such that a third axis does not intersect the first space but intersects the second space.