Abstract: A printed circuit board (PCB) includes a power layer and a signal layer. A signal line is arranged on the signal layer. A power via extends through the power layer and the signal layer, and is electrically connected to the power layer and the signal layer. A number of through holes is defined in the PCB, through the power layer and the signal layer, and arranged between the signal line and the power via. The through holes are insulated from the power via. The inside wall of the power via is made of conductive material.

Abstract: An equalizer for compensating transmission losses of electronic communication signals includes a circuit board and a compensation module. The compensation module includes a pair of input pins, a pair of output pins, and at least two resistors. When a signal transmitted by the circuit board is received by the input pins, a first portion of the signal is directly output from the output pins, a second portion of the signal is reflected by the first resistor and transmitted back to the output pins to output, and a third portion of the signal is reflected by the second resistor and transmitted back to the output pins to output, such that output of the equalizer applies two stages of compensation.

Abstract: An equalizer includes a first delay module, a second delay module, a first amplitude module, a second amplitude module, and a combining unit. The first delay module receives a first signal and delays the first received signal for a preset period, and the first amplitude module transfers the first delayed signal to transmit a first weighted signal with a first peak amplitude. Similarly, the second delay module receives the first delayed signal and delays the second received signal for the preset period, and the second amplitude module transfers the second delayed signal to transmit a second weighted signal with a second peak amplitude. The combining unit combines an input signal and the first and the second weighted signals together to generate an equalized signal.

Abstract: An enclosure of an electronic device includes a ventilation plate. The ventilation plate is a grid including a number of crisscrossed connection bars and a number of through holes defined by the connection bars. A tab is formed at each of the connection bars bounding each of the through holes. The tabs are substantially angled from a plane of the grid to elongate a path electromagnetic signals must travel to pass through the ventilation plate. The enclosure with the shields can shield the electronic device from EMI.

Abstract: An exemplary port reducing method is for removing unselected ports of an original S-parameter file and generating an optimized S-parameter file. The method controls a display unit to display a user interface to receive commands from a user in response to user operation; the commands comprise a calling command, a selecting command, and an executing command. The method obtains the original S-parameter file in response to the calling command Next, the method determines which of the ports of the original S-parameter file are unselected in response to the selecting command, and connects each unselected port to the ground through one terminal impedance. The method then generates an optimized S-parameter file that comprises only the selected ports in response to the executing command.

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 Marchand balun circuit includes a Marchand balun, an unbalanced matching circuit, and a balanced matching circuit. The Marchand balun includes an unbalanced terminal, and two balanced terminals. The unbalanced matching circuit includes a first and the second impedances which are connected between the unbalanced terminal and ground in series, and a first resistor which is connected between ground and a connection node of the first and the second impedances. The balanced matching circuit includes a third and a fourth impedances which are connected between one balanced terminal and ground in series, a fifth and a sixth impedance which are connected between the other balanced terminal and ground in series, a second resistor which is connected between ground and a connection node of the third and the fourth impedances, and a third resistor which is connected between ground and a connection node of the fifth and the sixth impedances.

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: 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. A vertical distance between the first and second transmission lines is twice as each of a vertical distance from the first ground sheet to the first transmission line and a vertical distance from the second ground sheet to the second transmission line.

Abstract: An enclosure of an electronic device includes a plate. The plate defines a number of through holes. Each through hole has a pair of tabs connected to each other and with the through hole. Each pair of tabs are slantingly bent towards an inside of the enclosure. The enclosure with the shields can shield the electronic device from electro-magnetic interference.

Abstract: In a method for analyzing a signal group delay of a printed circuit board (PCB) using a computing device, the computing device connects to a signal measuring device that measures S-parameters from a pair of data signal line and clock signal line of the PCB. The method analyzes a differential loss coefficient of the data signal line and the clock signal line based on the S-parameters, and calculates a first signal delay of the data signal line and a second signal delay of the clock signal line according to the differential loss coefficient. The method further analyzes a signal group delay of the PCB according to the first signal delay and the second signal delay, and displays the signal group delay on a display device if the signal group delay does not satisfy a PCB design specification.

Abstract: A printed circuit board includes a signal layer and a ground layer adjacent to the signal layer. The signal layer includes a pair of differential transmitting lines. The ground layer includes a common mode filter formed by hollow spiral patterns in the ground layer. The common mode filter includes two filter portions respectively arranged at opposite sides of a projection of the pair of differential transmitting lines onto the ground layer. Hollowed areas of the two filter portions are bridged by a void.

Abstract: An enclosure includes a plate. The plate defines a number of through holes. A hollow shield extends from the edges bounding each through hole. A top side of the shield opposite to the plate is smaller than a bottom side of the shield which is connected to the edges of the through hole. The enclosure can better shield electromagnetic interference (EMI) from the electronic device.

Abstract: A printed circuit board (PCB) with compound via includes a substrate and a pair of through holes passing through the substrate. The substrate includes a signal layer which is the top layer of the substrate, a first reference layer adjacent to the signal layer, and a second reference layer not adjacent to the signal layer. A first and a second pair of pads are mounted on the signal layer. Each of the through holes extends through the first pair of pads such that the through hole and the first pair of pads jointly form a compound via. A first reserved opening is formed on the first reference layer and corresponds to the first and the second pair of pads and the compound via. A second reserved opening is formed on the second reference layer and surrounds the through hole thereon.

Abstract: An exemplary high speed data storage system includes hard disks, a first control panel, a second control panel and a midplane interconnected between each of the first and second control panels and the hard disks. Each of the first and second control panels includes a control chip and a connector. First and second printed circuit wires corresponding to the hard disks are layered on the first and second control panels for electrically connecting the control chip with the connector, respectively. The first printed circuit wires of the first control panel and the second printed circuit wires of the second control panel are arranged symmetrically with respect to each other, and an order of stacking circuit layers of the first printed circuit wires of the first control panel is the reverse of an order of stacking of circuit layers of the second printed circuit wires of the second control panel.

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 first signal layer, a second signal layer, and a dielectric layer sandwiched between the first signal layer and the second signal layer. The first signal layer includes two pads. The second signal layer includes two conducting pieces connected to two signal traces. The shape and material of the pads are the same as the shape and material of the conducting pieces. The projections of the pads on the second signal layer are overlapping with the conducting pieces.

Abstract: A printed circuit board includes a signal layer and a ground layer adjacent to the signal layer. The signal layer includes a pair of differential transmission lines. The ground layer includes a first void, a second void, a third void, and a common mode filter. The first void and the second void are respectively arranged at opposite sides of a projection of the pair of differential transmission lines on the ground layer, and are bridged with the third void. The common mode filter includes a first filter portion positioned in the first void, and a second filter portion positioned in the second void. Each of the first and second filter portions includes a number of coils arranged side by side along a direction parallel to the projection of the pair of differential transmission lines.

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: A method of testing a printed circuit board (PCB) acquires test points from a wiring diagram of the PCB. Frequency domain tested items for each test point and a standard value of each frequency domain tested item are preset. A distance between a preset fiducial point and each test point is computed to create a testing order of the test points according to the distances. The frequency domain tested items of each test point are computed according to the testing order. A pass or a failure of each test point is displayed according to a determination of if each of the computed frequency domain tested items within the corresponding standard value, and a test result of the PCB is output according to the passes or the failures.