An electromagnetic wave shielding filter is configured in a magnetic field transmission scheme, not in a low pass filter or band pass filter scheme, and thus allows a desired signal to pass, while maintaining unintended electromagnetic waves shielded.

The present embodiment relates to an electromagnetic wave shielding filter for high-frequency communication, having a structure in which an elliptical ferrite magnetic core is formed inside the filter, a primary coil and a secondary coil are installed at both ends of the magnetic core, and then a shielding and penetration unit is formed of a shielding material on the elliptical magnetic field core, so that a signal from the primary coil is transmitted in the form of a magnetic field to the secondary coil, and the other unintended common-mode components are eliminated.

A transformer device includes a first and a second trace, a first and a second connection member, and a first input/output member. A second sub-trace of the first trace is coupled to a first sub-trace of the first trace at a first and a second area. The first connection member is coupled to the first and the second sub-trace. The first and a third sub-trace of the second trace are disposed in turn. A fourth sub-trace of the second trace is coupled to the third sub-trace at the first and the second area. The second and the fourth sub-trace are disposed in turn. The second connection member is coupled to the third and the fourth sub-trace. The first sub-trace includes first wires, and the first input/output member is coupled to the first wire which is located at an inner side among the first wires.

A matching circuit includes first and second input/output ports; first, second, and third coils; and a capacitor. The first coil is connected in series between the first and second input/output ports, and the second coil is connected in shunt between a ground and an input/output line between the first and second input/output ports. The first and second coils are magnetically coupled to each other, the third coil is magnetically coupled to at least one of the first and second coils, the capacitor is directly or indirectly connected to the third coil, and a closed circuit including the capacitor and the third coil is provided.

A digital isolator can include: a first die having one of an encoding circuit and a decoding circuit; a second die having one of the encoding circuit and the decoding circuit that is not in the first die, where the first die and the second die are separated from each other; and an isolated transmission structure configured to transmit an encoded signal generated by the encoding circuit to the decoding circuit.

A transformer has a first inductor that includes a first port. The transformer also has a second inductor magnetically coupled to the first inductor. The second inductor includes a second port. The second inductor includes a first portion configured to permit current flow in a clockwise direction and a second portion configured to permit current flow in a counter-clockwise direction. The transformer also has a third inductor magnetically coupled to the first inductor. The third inductor includes a third port. The counter-clockwise direction is opposite the clockwise direction to reduce magnetic coupling between the second inductor and the third inductor based on magnetic coupling cancellation.

A transformer has a first inductor that includes a first port. The transformer also has a second inductor magnetically coupled to the first inductor. The second inductor includes a second port. The second inductor includes a first portion configured to permit current flow in a clockwise direction and a second portion configured to permit current flow in a counter-clockwise direction. The transformer also has a third inductor magnetically coupled to the first inductor. The third inductor includes a third port. The counter-clockwise direction is opposite the clockwise direction to reduce magnetic coupling between the second inductor and the third inductor based on magnetic coupling cancellation.

In a coil device, a first coil includes a common terminal side first coil conductor connected to a ground terminal, an intermediate first coil conductor, and an input/output terminal side first coil conductor connected to a first input/output terminal, and a second coil includes a common terminal side second coil conductor connected to the ground terminal, an intermediate second coil conductor, and an input/output terminal side second coil conductor connected to a second input/output terminal. The input/output terminal side first coil conductor is located between the intermediate second coil conductor and the input/output terminal side second coil conductor, and the input/output terminal side second coil conductor is located between the intermediate first coil conductor and the input/output terminal side first coil conductor.

A matching circuit includes first and second input/output ports; first, second, and third coils; and a capacitor. The first coil is connected in series between the first and second input/output ports, and the second coil is connected in shunt between a ground and an input/output line between the first and second input/output ports. The first and second coils are magnetically coupled to each other, the third coil is magnetically coupled to at least one of the first and second coils, the capacitor is directly or indirectly connected to the third coil, and a closed circuit including the capacitor and the third coil is provided.

An isolation transformer includes a transformer core. First and second through-bores extend through the transformer core from a first surface to a second surface. Each through-bore has an elongated profile with at least a portion of the elongated profile providing a respective flat winding surface. The flat winding surfaces are spaced apart by a central portion of the transformer core. The transformer is wound with a six-wire cable having a central non-conductive core. First, second, third, fourth, fifth and sixth conductive wires are positioned around and adjacent to the central non-conductive core in a substantially equally spaced angular relationship. The second conductive wire is positioned between the first conductive wire and the third conductive wire; and the fifth conductive wire is positioned between the fourth conductive wire and the sixth conductive wire. The conductive wires are twisted about the central non-conductive core at a selected twist density.

An isolation transformer includes a transformer core. First and second through-bores extend through the transformer core from a first surface to a second surface. Each through-bore has an elongated profile with at least a portion of the elongated profile providing a respective flat winding surface. The flat winding surfaces are spaced apart by a central portion of the transformer core. The transformer is wound with a six-wire cable having a central non-conductive core. First, second, third, fourth, fifth and sixth conductive wires are positioned around and adjacent to the central non-conductive core in a substantially equally spaced angular relationship. The second conductive wire is positioned between the first conductive wire and the third conductive wire; and the fifth conductive wire is positioned between the fourth conductive wire and the sixth conductive wire. The conductive wires are twisted about the central non-conductive core at a selected twist density.