A printed circuit board (PCB) includes first and second signal layers sandwiching a dielectric layer therebetween and a first differential pair and a second differential pair each having a positive differential trace and a negative differential trace. The positive differential traces of the two differential pairs are disposed within the first signal layer. The negative differential traces of the two differential pairs are disposed within the second signal layer. The positive differential trace of the first differential pair is defined at the left side of the positive differential trace of the second differential pair. The negative differential trace of the first differential pair is defined at the right side of the negative differential trace of the second differential pair.