A flat cable high-frequency filter includes a dielectric substrate extending in a transmission direction of a high-frequency signal. The dielectric substrate includes dielectric layers stacked on each other. Elongated conductor patterns are provided on a flat surface of one dielectric layer which faces another dielectric layer. The conductor patterns are as wide as possible in the dielectric substrate in accordance with a desired inductance. A capacitive coupling conductor pattern opposes one conductor pattern by a predetermined area with a dielectric layer therebetween. By using a connecting conductor, the capacitive coupling conductor pattern is connected to the conductor pattern which does not oppose the capacitive coupling conductor pattern.

An EMC filtering device comprises a printed circuit comprising at least two parallel layers of a high-permittivity material, which are positioned between two layers of an insulating material that are parallel to one another and to the high-permittivity material layers. A core made of a magnetic material comprises three cylindrical arms passing perpendicularly through the high-permittivity and insulating material layers. At least two windings winding around the first arm of the magnetic material core, the windings and the first arm forming a first coil. At least two windings winding around the second arm of the magnetic material core, the windings and the second arm forming a second coil. The two coils being coupled coils.

A resonance device and a filter including the same are provided. The resonance device includes a case having a first ground surface and a second ground surface which are facing each other, and a first conductive layer located in the case, and the first conductive layer includes a main part grounded via the first ground surface, and a protruding part which has a width different from that of the main part and is located to be spaced apart from the second ground surface.

A radio frequency filters and methods for implementing the filters in multilayer metallic-dielectric structures, such as printed circuit boards (PCB), low temperature co-fired ceramic (LTCC) components and integrated circuits (IC). The methods and filters utilize vertical stacking of transmission lines and related frequency-selective structures to obtain compact implementation of filters of high order. The methods and filters are applicable to a variety of filter types and related structures such as multiplexers.

A filter of the present invention comprises a multilayer substrate, two terminals, a ground conductor and a hybrid resonator. The multilayer substrate includes a plurality of conductor layers and a dielectric configured to isolate said plurality of conductor layers from each other. The hybrid resonator is disposed in the multilayer substrate and comprises a first and a second resonant elements and a coupling strip connecting the first and said second resonant elements. Each resonant element comprises a signal via, a group of ground vias and an artificial dielectric. Each signal via is disposed through the multilayer substrate. Each group of ground vias is disposed through the multilayer substrate and configured to surround the signal via. Each artificial dielectric is disposed in the multilayer substrate and between the signal via and the group of ground vias. The artificial dielectric comprises a conductive plate connected to the first signal via and an isolating slit isolating the first conductive plate from the group of ground vias.

A flat cable high-frequency filter includes a dielectric substrate extending in a transmission direction of a high-frequency signal. The dielectric substrate includes dielectric layers stacked on each other. Elongated conductor patterns are provided on a flat surface of one dielectric layer which faces another dielectric layer. The conductor patterns are as wide as possible in the dielectric substrate in accordance with a desired inductance. A capacitive coupling conductor pattern opposes one conductor pattern by a predetermined area with a dielectric layer therebetween. By using a connecting conductor, the capacitive coupling conductor pattern is connected to the conductor pattern which does not oppose the capacitive coupling conductor pattern.

A microstrip filter is provided in the present disclosure. The microstrip filter includes a substrate having a first surface and a second surface opposite to each other, a first spiral metal line formed on the first surface of the substrate, and a second spiral metal line formed on the second surface of the substrate. At least part of the first spiral metal line overlaps and is coupled to the second spiral metal line for forming a filter capacitor. The present disclosure also provides a microphone device using the microstrip filter.

A filter device includes a body, a ground terminal, and resonators in the body and coupled to each other by electromagnetic field coupling. The resonators include a first resonator coupled to an input terminal, a second resonator coupled to an output terminal, and third and fourth resonators. The second resonator is adjacent to the first resonator in a first direction. The third resonator is adjacent to the first resonator in a second direction perpendicular to the first direction. The fourth resonator is adjacent to the third resonator in the first direction. The third and fourth resonators partially share a path to the ground terminal.

Multi-pair differential lines printed circuit board common mode filters are generally described. In one embodiment, the apparatus includes a multi-layer printed circuit board, a first signal line and a second signal line forming a first differential pair on a first layer of the printed circuit board, a second differential pair on the first layer of the printed circuit board, and a common mode filter on a second layer of the printed circuit board, the common mode filter comprising an absence of a predominantly occurring dielectric material of the printed circuit board, the common mode filter spanning an area directly below at least a portion of both the first and the second differential pairs. Other embodiments are also described and claimed.

Embodiments of a low-complexity and potentially physically small wideband impedance transformer that can be used in a combining network of a wideband Doherty amplifier are disclosed. In one embodiment, a wideband Doherty amplifier includes Doherty amplifier circuitry and a wideband combining network. The wideband combining network includes a wideband quarter-wave impedance transformer that includes a quarter-wave impedance transformer and compensation circuitry connected in parallel with the quarter-wave impedance transformer at a low-impedance end of the quarter-wave impedance transformer. The compensation circuitry is configured to reduce a total quality factor of the wideband quarter-wave impedance transformer as compared to a quality factor of the quarter-wave impedance transformer, which in turn increases a bandwidth of the wideband quarter-wave impedance transformer, and thus a bandwidth of the wideband Doherty amplifier.