Patent ID: 8384491

Claim:
A signal transmission apparatus comprising: a first ground sheet arranged in a first circuit layer of a printed circuit board (PCB); a second ground sheet arranged in a second circuit layer of the PCB; a third ground sheet arranged between the first and second circuit layers; and a differential pair comprising a first transmission line and a second transmission line parallel to the first transmission line, wherein the first transmission line is arranged between the first and third ground sheets, the second transmission line is arranged between the second and third ground sheets; wherein the first, second, and third ground sheets have the same electric potentials, and are parallel to a signal transmission direction of the differential pair, orthogonal projections of the first and second ground sheets superpose a border of the third ground sheet, the third ground sheet is formed by extending the border along the signal transmission direction, and a vertical distance between the first and second transmission lines is twice as much 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.