A circuit board has an edge connector with signal traces. The signal traces are formed on a dielectric layer of the circuit board. A reference trace is formed within the dielectric layer or on another surface of the dielectric layer. Parameters of the reference trace are adjusted to set an impedance of a single-ended signal trace or a differential impedance of two adjacent signal traces.

An insulation film has a first surface and a second surface opposite to each other and has a first portion and a second portion extending in a direction opposite to each other from a central portion. The optical subassembly is connected to the flexible printed circuit board at the central portion with the stem opposed to the second surface. The flexible printed circuit board curves with the second surface at least the central portion facing outward. The printed circuit board intervenes between edges of the first portion and the second portion and is connected to the flexible printed circuit board. The first portion and the second portion of the flexible printed circuit board curves in a shape to avoid mutual contact and three-dimensionally intersect with each other, and the first portion and the second portion on the second surface are opposed to the printed circuit board.

A circuit board has an electrical circuit and a connector that is attached to the circuit board. The connector has metal contacts. A housing of the connector has an embedded reference metal layer that is disposed under a single-ended metal contact or differential metal contacts. The reference metal layer sets the impedance of the single-ended metal contact or the differential metal contacts.

A signal transmission circuit includes a printed circuit board including a surface layer including a signal transmission path that transmits a signal, a signal line through hole that connects the signal transmission path with a signal layer arranged in an inner layer of the printed circuit board, a ground layer of the inner layer of the printed circuit board that forms a return current transmission path for the signal transmission path, and a ground through hole that is connected to the ground layer adjacent to the signal line through hole. A ground pattern including ground areas disposed with a certain distance therebetween and a side ground area connected with at least one end side of the ground areas is disposed at positions of both sides of the signal transmission path. The ground through hole is disposed to connect the ground pattern with the ground layer.

A display device includes a display panel, a data driver which transmits a data voltage to the display panel, a first flexible printed circuit board attached to the display panel and including an input side wiring electrically connected to the data driver, a first printed circuit board (PCB) electrically connected to the input side wiring to transmit a high-speed driving signal to the data driver, and a metal tape overlapping the input side wiring in a plan view and attached on the first flexible printed circuit board, where a part of the metal tape overlapping the input side wiring in the plan view defines an opening.

An optical module includes a photoelectric device and a flexible printed circuit board. The flexible printed circuit board includes an insulating substrate with a first surface and a second surface, a first wiring pattern on the first surface, and a second wiring pattern on the second surface. The first wiring pattern includes a signal line with a signal terminal portion at a tip and a signal-line portion narrower than the signal terminal portion, the first wiring pattern including a pair of ground pads at positions sandwiching the signal-line portion, at least part of the pair of ground pads avoiding being adjacent to the signal terminal portion. The second wiring pattern includes a ground plane overlapping with the signal-line portion and being connected to the pair of ground pads, the second wiring pattern including a signal pad connected to the signal terminal portion.

An electronic device and associated methods are disclosed. In one example, the electronic device can include an assembly having asymmetrically situated conductors. In selected examples, the assembly includes a ground plane, a central shield portion, a first side shield portion on a. first side, a second side shield portion on a second side, a first conductor asymmetrically situated between the central shield portion and the first side shield portion, a second conductor asymmetrically situated between the central shield portion and the second side shield portion, and dielectric within the assembly.

A transmission line includes a substrate, a high-frequency signal transmission line, a differential signal transmission line, and a power supply line. The substrate is insulating, extends in a predetermined direction, and internally includes each of the high-frequency signal transmission line, the differential signal transmission line, and the power supply line. The power supply line and the high-frequency signal transmission line are in parallel or substantially in parallel to each other, and the differential signal transmission line is between the power supply line and the high-frequency signal transmission line.

A semiconductor device comprises a wiring substrate and a semiconductor chip. In the wiring substrate, a plurality of micro-elements each comprised of a stacked structure including a power supply pattern and a ground pattern is arranged at a predetermined interval. In each of the plurality of micro-elements, the power supply pattern is formed in a wiring layer located one layer above or one layer below a wiring layer in which the ground pattern is formed. A power supply potential is to be supplied to the power supply patter, and a ground potential is to be supplied to the ground patter.

A printed circuit board includes an electrical component including a signal terminal, and a printed wiring board on which the electrical component is mounted. The printed wiring board includes a signal line connected to the signal terminal. The signal line includes a first line portion, a second line portion, a third line portion, and a fourth line portion disposed continuously in this order. The signal terminal is joined with the fourth line portion such that the signal terminal and the fourth line portion form an integral structure. A second characteristic impedance of the second line portion is lower than a first characteristic impedance of the first line portion. A third characteristic impedance of the third line portion is higher than the first characteristic impedance. A fourth characteristic impedance of the integral structure formed by the fourth line portion and the signal terminal is lower than the first characteristic impedance.