Patent ID: 8797114

Claim:
A printed circuit board comprising: a dielectric layer having a first surface and a second surface; first and second transmission lines formed on the one first surface of said dielectric layer and constituting a differential transmission path; and a ground conductor layer formed on the second surface of said dielectric layer, wherein said ground conductor layer is arranged to be opposite to at least part of said first transmission line and at least part of said second transmission line in a width direction of said first and second transmission lines with said dielectric layer sandwiched between said ground conductor layer and said first and second transmission lines, and a width W1 of said first transmission line, a width W2 of said second transmission line, a spacing S between said first transmission line and said second transmission line, and a width Wg of said ground conductor layer in an arbitrary cross section perpendicular to said first and second transmission lines satisfy a relationship of Wg<(W1+W2+S) and S≦0.8 Wg, and further satisfy a relationship of Wg/S≧2.00 and W1>2S and W2>2S.