A multilayer board includes a laminated insulating body, signal conductors inside the laminated insulating body and extending in a transmission direction, and ground conductors sandwiching each of the signal conductors in a lamination direction via the insulating base material layers. The multilayer board includes a parallel extending portion in which the signal conductors extend parallel and that includes signal conductors arranged separately from each other in a direction orthogonal to the transmission direction in a planar view in the lamination direction, and a signal conductor overlapping with the signal conductor in a planar view in the lamination direction and arranged separately from the signal conductor in the lamination direction. The parallel extending portion includes first and second regions arranged separately in a direction orthogonal to the transmission direction in a planar view in the lamination direction.

A circuit board includes a first section on a left side of a third section in a signal-conductor-layer left-right direction and extending in parallel or substantially in parallel with the third section in a signal-conductor-layer front-back direction when viewed in a stacking direction. The first section includes first thin line portions and first thick line portions, each of the first thick line portions has a line width greater than a line width of each of the first thin line portions. The first thin line portions and the first thick line portions are alternately arranged in the signal-conductor-layer front-back direction. In the signal-conductor-layer left-right direction, center lines of the first thin line portions are positioned leftward relative to center lines of the first thick line portions.

Disclosed herein are dual-spiral common-mode filters, printed circuit boards (PCBs) comprising such dual-spiral common-mode filters, and devices comprising such dual-spiral common-mode filters and PCBs. A dual-spiral common-mode filter is patterned into the reference plane of a PCB. The dual-spiral common-mode filter comprises a first spiral portion connected to a second spiral portion. The spiral portions may be substantially identical, or mirror images of each other, or different from each other. One or more signal traces in a signal trace layer of the PCB pass over the dual-spiral common-mode filter. The disclosed dual-spiral common-mode filters can replace both conventional patterned ground structure (PGS) filters used for radio-frequency interference mitigation and the cutouts often used in the reference plane of a PCB to mitigate impedance mismatches due to DC blocking capacitors. Also disclosed herein are methods of making PCBs that include dual-spiral common-mode filters.

A structure of serpentine transmission line includes a first transmission line and a second transmission line. The first transmission line includes a first line segment, a second line segment and a third line segment. The second transmission line includes a fourth line segment, a fifth line segment and a sixth line segment. The first line segment, the second line segment, the fourth line segment and the fifth line segment extend along a first direction and have a first line width. The third line segment extends along a second direction and is connected to the first line segment and the second line segment. The sixth line segment extends along the second direction and is connected to the fourth line segment and the fifth line segment. Both the third line segment and the sixth line segment have a second line width. The second line width is greater than the first line width.

A stacked, multi-layer transmission line is provided. The stacked transmission line includes at least a pair of conductive traces, each conductive trace having a plurality of conductive stubs electrically coupled thereto. The stubs are disposed in one or more separate spatial layers from the conductive traces.

This document describes techniques, apparatuses, and systems utilizing a high-isolation transition design for differential signal ports. A differential input transition structure includes a first layer and a second layer made of a conductive metal and a substrate positioned between the first and second layers. The second layer includes a first section that electrically connects to a single-ended signal contact point and to a first contact point of a differential signal port. The first section includes a first stub based on an input impedance of the single-ended signal contact point and a second stub based on a differential input impedance associated with the differential signal port. The second layer includes a second section that electrically connects to a second contact point of the differential signal port and to the first layer through a via housed in a pad. The second section includes a third stub associated with the differential input impedance.

A transmission line structure for transmitting radio signals includes a first transmission line, a first ground region, and a second transmission line. The first transmission line is arranged on a first layer of a circuit board. The first transmission line includes a first signal line and a second signal line. The first ground region is arranged between the first and second signal lines. The first and second signal lines do not contact the first ground region. The second transmission line is arranged on a second layer of the circuit board, and the second layer is different from the first layer. The second transmission line does not contact the first transmission line, and the second transmission line interleaves with the first signal line, the second signal line and the first ground area.

In photonic integrated circuits implemented in silicon-on-insulator substrates, non-conductive channels formed, in accordance with various embodiments, in the silicon device layer and/or the silicon handle of the substrate in regions underneath radio-frequency transmission lines of photonic devices can provide breaks in parasitic conductive layers of the substrate, thereby reducing radio-frequency substrate losses.

Provided are a printed circuit board configured to achieve reduction in impedance of a differential transmission line extending in a stacking direction, and an optical module. The printed circuit board includes a stacking-direction differential transmission line extending in the stacking direction, including: a differential signal via pair including a first signal via and a second signal via; and a plurality of conductor plate pairs each including a first conductor plate expanding outward from the first signal via, and a second conductor plate expanding outward from the second signal via. With respect to a perpendicular bisector of a center-of-gravity line segment connecting centers of gravity of the first and second signal vias, in each of the plurality of conductor plate pairs, centers of gravity of contours of the first and second conductor plates are located on inner sides of the centers of gravity.

A circuit board includes a dielectric substrate, a signal line and a pair of ground wires. The dielectric substrate includes a base and an elevated platform protruding from an upper surface of the base. The signal line is conformally disposed on the dielectric substrate and includes a first segment disposed on an upper surface of the elevated platform, a second segment extending on the upper surface of the base, and a third segment disposed on a sidewall of the elevated platform and connecting the first segment and the second segment. The pair of ground wires are disposed on the dielectric substrate and are spaced apart from the signal line. A projection of the second segment of the signal line on the upper surface of the base partly overlaps projections of the pair of ground wires on the upper surface of the base.