Abstract: A computer motherboard includes a motherboard substrate defining a CPU loading area and a CPU voltage regulator power supply layout area. The power supply layout area is equally divided into a number of phase regions, and each of the phase regions has a number of spaced circuit layers. The circuit layers in the phase regions are symmetrical about a central axis of the CPU loading area, and a difference between each two simulating impedances between an impedance center of each of the phase regions and a loading center of the CPU loading area is within 1%.

Abstract: A power supply conversion circuit includes a PWM chip and many sub-circuits. Each sub-circuit includes an inductor, a first capacitor connected to ground, a first resistor connected in series with the first capacitor to form a branch parallel to the inductor, a differential pair having a first differential signal trace and a second differential signal trace, a second resistor, and a second capacitor. The first trace is connected between the connection of the first resistor and the first capacitor and the PWM chip. The second resistor is connected between the connection of the first resistor and the inductor and the second capacitor. The second trace is connected between the connection of the second resistor and the second capacitor and the PWM chip. The ratios of the capacitances of each two second capacitors are the same as that of the lengths of the traces of each two corresponding differential pairs.

Abstract: A computer-based method and a computing device for checking signal transmission lines of a printed circuit board (PCB) layout are provided. The computing device identifies differential pairs in a currently run PCB layout according to an information file for the currently run PCB layout, checks whether any signal transmission line is routed between switching vias of each differential pair according to the information file for the currently run PCB layout, and displays a routing error window to display information of each misrouted signal transmission line.

Abstract: A power supply conversion circuit includes a PWM chip and many sub-circuits. Each sub-circuit includes an inductor, a first capacitor connected to ground, a first resistor connected in series with the first capacitor to form a branch parallel to the inductor, a differential pair having a first differential signal trace and a second differential signal trace, a second resistor, and a second capacitor. The first trace is connected between the connection of the first resistor and the first capacitor and the PWM chip. The second resistor is connected between the connection of the first resistor and the inductor and the second capacitor. The second trace is connected between the connection of the second resistor and the second capacitor and the PWM chip. The ratios of the capacitances of each two second capacitors are the same as that of the lengths of the traces of each two corresponding differential pairs.

Abstract: A computer motherboard includes a motherboard substrate defining a CPU loading area and a CPU voltage regulator power supply layout area. The power supply layout area is equally divided into a number of phase regions, and each of the phase regions has a number of spaced circuit layers. The circuit layers in the phase regions are symmetrical about a central axis of the CPU loading area, and a difference between each two simulating impedances between an impedance center of each of the phase regions and a loading center of the CPU loading area is within 1%.

Abstract: A printed circuit board with a quartz crystal oscillator includes a mounting area for receiving the quartz crystal oscillator, two first vias, and two second vias. A copper foil is arranged on the mounting area. Pins of the quartz crystal oscillator are inserted into the first vias. The second vias are connected to a ground layer of the PCB and communicate with the copper foil, for transmitting noise of the quartz crystal oscillator to the ground layer of the PCB.

Abstract: A printed circuit board with a quartz crystal oscillator includes a mounting area for receiving the quartz crystal oscillator, two first vias, and two second vias. A copper foil is arranged on the mounting area. Pins of the quartz crystal oscillator are inserted into the first vias. The second vias are connected to a ground layer of the PCB and communicate with the copper foil, for transmitting noise of the quartz crystal oscillator to the ground layer of the PCB.

Abstract: A electronic device for shielding electromagnetic interference (EMI) including a metal shield, a printed circuit board (PCB) having a ground layer, and a number of ground pads arranged at edges of the PCB and in electrical conductivity with the ground layer. The ground pads lies close to edges of the metal shield. During solder reflowing process, solder is laid on the ground pads, and a height of the solder is adjusted to meet spaces or gaps of the shield. When the PCB is placed into the shield, the solder on the ground pads is in electrical conductivity with the metal shield to eliminate spaces or gaps thereof. So the EMI coupling which causes EMI signals interfering with sensitive components is avoided.