Abstract: An enclosure of an electronic device includes a plate. The plate defines a number of through holes. A number of shields extend from the plate corresponding to the through holes. Each shield extends outwards from the outer surface of the plate, surrounding and partly covering a corresponding through hole. The enclosure with the shields can shield the electronic device from EMI.

Abstract: An enclosure includes a plate. The plate defines a number of through holes. A first shield extends from an edge bounding each through hole. A second shield extends from the edge bounding each through hole, opposite to the first shields. Each through hole is partially covered by a corresponding first shield and a corresponding second shield. The enclosure with the shields can shield the electronic device from electromagnetic interference.

Abstract: An electronic device includes a multi-frequency antenna. The multi-frequency antenna includes a ground portion, a support body, a radiation portion, and a strap. The ground portion defines a gap, and two grooves communicating with the gap and located at opposite ends of the gap. The radiation portion resists against a sidewall bounding the gap, and is connected to the strap. The radiation portion is accommodated in the gap and substantially coplanar with the ground portion. The radiation portion defines a slot. The support body is located in the gap and on the radiation portion, to support the strap.

Abstract: A compensation method compensates for a length offset between a first transmission line and a second transmission line of a differential signal transmission. The compensation method includes calculating a transmission speed of a first signal in the first transmission line, measuring lengths of the first and second transmission lines, calculating a transmission time of the first signal in the first transmission line, and calculating a relationship between permittivity values of the first and second transmission lines. The compensation method further changes the permittivity values of the first and second transmission lines according to the relationship.

Abstract: An exemplary FPCB includes a signal layer having a differential pair consisting of two transmission lines arranged therein, a ground layer, and a dielectric layer lying between the signal layer and the ground layer. Two sheets made of conductive materials are respectively arranged at opposite sides of the differential pair, and both connected to ground. The sheets are apart from and parallel to the transmission lines. The ground layer has a void defined therein, and the void is located under the two transmission lines.

Abstract: A printed circuit board (PCB) includes a differential pair having a first differential trace and a second differential trace, a first via having an upper cap and a lower cap, and a second via having an upper cap and a lower cap. The first differential trace includes a first segment and a second segment, the second differential trace includes a third segment and a fourth segment. The first and the third segments are electrically coupled to the upper caps of the first and the second vias respectively. The second and the fourth segments are electrically coupled to the lower caps of the first and the second vias respectively. The first and the third segments extend from corresponding upper caps in different directions, the second and the fourth segments extend from corresponding lower caps in different directions.

Abstract: A printed circuit board includes a first signal layer, a second signal layer, a plurality of transmission lines respectively including first segments laid in parallel on the first signal layer and second segments laid in parallel on the second signal layer, and a plurality of vias, each via connecting the first segment with the second segment of a corresponding transmission line. One of the plurality of transmission lines has the first segment positioned in the middle of an array defined by the first segments of the plurality of transmission lines, and a second segment positioned in an outmost position of an array defined by the second segments of the plurality of transmission lines. The printed circuit board reduces the possibility of false action of electronic components coupled to transmission lines, which is caused by the crosstalk between transmission lines.

Abstract: A printed circuit board includes a number of signal layers, a number of ground layers, a first transmission line, a second transmission line, a first via, and a second via. The first transmission is located on one of the number of signal layers. The second transmission line is located on another of the number of signal layers. The first and second vias pass through the printed circuit board. The first via is electrically coupled to the first and second transmission lines, and is isolated from the number of ground layers. The second via is electrically coupled to one or more of the number of ground layers, and is isolated from the other of the number of ground layers to increase an inductance, thus compensating capacitive nature of an open stub and improving signal integrity.

Abstract: A printed circuit board includes a layer. A layer of copper is covered on a surface of the layer. A through hole passes through the printed circuit board. A number of thermal engravings are defined in the layer around the through hole. Each thermal engraving is a groove defined in the surface of the layer, without covered with the layer of copper. The number of thermal engravings are not in contact with each other.

Abstract: A performance evaluation system for a multiple-input multiple-output (MIMO) antenna system receives simulation parameters from an input device, and simulates a MIMO antenna system accordingly. A method, also provided, further evaluates performance of the simulated MIMO antenna system when a series of radio frequency (RF) signals are transmitted through the MIMO antenna system, and displays a performance analysis result of the MIMO antenna system on a display device for evaluation of the performance of the simulated MIMO antenna system.

Abstract: A signal transmission apparatus includes a first ground layer, a second ground layer and a band pass filter. The band pass filter includes a first transmission line positioned in a void defined in the first ground layer and a second transmission line positioned in a void defined in the second ground layer. Each of the first transmission line and the second transmission line includes a coil with a plurality of turns spirally extending in the same plane, a gasket extending from the coil and located in the center of the coil, and a signal terminal extending from extremity of the coil. According to employing the band pass filter, the signal transmission apparatus has filtering function, therefore, quality of signals transmitted through the signal transmission apparatus is improved.

Abstract: A printed circuit board includes a first layer, a second layer, a number of vias each passing through the first and second layers, and a number of transmission lines. Each transmission line is connected between bonding pads of the two of the number of vias to form a helical-shaped transmission path by the vias and the transmission lines. As a result, the printed circuit board can generate inductive effect.

Abstract: A signal transmission apparatus used in a printed circuit board (PCB). The apparatus includes a differential pair composed of two transmission lines arranged side by side in the PCB. The differential pair includes a filter section arranged therein to filter noise of transmission signals of the differential pair. The filter includes a number of section pairs connected in series. Each section pair includes two sections arranged in the two transmission lines symmetrically. Every two adjacent sections are different in line width. A distance between the two transmission lines, and the line width of each of the sections are predetermined according to desired frequency bandwidth, and desired frequency response of the differential pair.

Abstract: A signal transmission apparatus includes two circuit layers. First and second ground sheets each has a rectangular area are arranged in the two circuit layers respectively. A third ground sheet is arranged between the two circuit layers. A differential pair includes a transmission line arranged between the first and third ground sheets and a transmission line arranged between the second and third ground sheets. The first to third ground sheets have same electric potential. Projections of the two rectangular areas on a surface where the third ground sheet in only have one common border with the third ground sheet. The third ground sheet is formed by extending the common border along a signal transmission direction. The differential pair includes a number of section pairs each composed of two sections arranged in the two transmission lines symmetrically. Every two adjacent section pairs are equivalent to a capacitor and an inductor.

Abstract: A signal transmission apparatus includes two circuit layers. First and second ground sheets are arranged in the two circuit layers respectively. A third ground sheet is arranged between the two circuit layers. A differential pair includes a transmission line arranged between the first and third ground sheets and a transmission line arranged between the second and third ground sheets. The first to third ground sheets have same electric potential. Projections of the first and second ground sheets on the third ground sheet superpose a border of the third ground sheet. The third ground sheet is formed by extending the border along a signal transmission direction.

Abstract: An overdrive topology structure for transmission of a RGB signal includes a signal sending terminal, a signal receiving terminal, and a transmission line to transmit the RGB signal from the signal sending terminal to the signal receiving terminal. The transmission line is divided into a number of section transmission lines. A node is formed between every two section transmission lines. An impedance of a first section transmission line approaching to the signal sending terminal is less than an impedance of a second section transmission line approaching to the first section transmission line to overdrive the RGB signal at a first node between the first and second section transmission lines. At least one node except the first node is grounded via a resistor. An equivalent resistance of the resistor is equal to a resistance of the first resistor.

Abstract: An electronic device includes a multi-frequency antenna. The multi-frequency antenna includes a ground portion, a support body, a radiation portion, and a strap. The ground portion defines a gap, and two grooves communicating with the gap and located at opposite ends of the gap. The radiation portion resists against a sidewall bounding the gap, and is connected to the strap. The radiation portion is accommodated in the gap and substantially coplanar with the ground portion. The radiation portion defines a slot. The support body is located in the gap and on the radiation portion, to support the strap.

Abstract: A high-frequency module includes an antenna, an impedance matching circuit, and a transmission wire. The transmission wire is connected between the antenna and the impedance matching circuit. The transmission wire includes a dielectric layer, a signal layer, and two ground layers. The signal layer and the ground layers are located on the dielectric layer. The ground layers are located at opposite sides of the signal layer respectively. A space is formed between a signal and each ground layer.

Abstract: A printed circuit board (PCB) includes a power layer, a ground layer, a through hole, and a conductor. The through hole goes through the power layer and the ground layer. The conductor includes a hollow columnar main body and an extending portion. The main body is formed in a bounding wall of the through hole, and is conductively connected to one of the power layer and the ground layer, and insulated from the other one of the power layer and the ground layer by an insulation area. The extending portion extends out from the circumferential surface of the main body. The extending portion extends into the insulation area and is insulated from the other one of the power layer and the ground layer, to increase an area of the power layer facing the ground layer.

Abstract: A compensation method compensates for a length offset between a first transmission line and a second transmission line of a differential signal transmission. The compensation method includes calculating a transmission speed of a first signal in the first transmission line, measuring lengths of the first and second transmission lines, calculating a transmission time of the first signal in the first transmission line, and calculating a relationship between permittivity values of the first and second transmission lines. The compensation method further changes the permittivity values of the first and second transmission lines according to the relationship.