Printed circuit board

A printed circuit board (PCB), comprising a ground layer, a first layer above the ground layer, a second layer below the ground layer, two differential mode signal lines, and a connector footprint comprising a first bonding pad arranged on the first layer, a second bonding pad arranged on the first layer, a first signal via defined in a central location bounded by the first bonding pad and extending through the first layer, the ground layer, and the second layer, a second signal via defined in a central location bounded by the second bonding pad and extending through the first layer, the ground layer, and the second layer, a plurality of first ground vias extending through the first bonding pad, the first layer, the ground layer, and the second layer, and a plurality of second ground vias extending through the second bonding pad, the first layer, the ground layer, and the second layer, wherein the plurality of first and second ground vias are electrically connected to the ground layer, the two differential mode signal lines each comprise a first part extending from a corresponding one of the first and second signal vias toward the other one of the first and second signal vias, and a second part extending substantially perpendicularly from a distal end of the first part opposite to the corresponding one of the first and second signal vias, the first and second parts are both arranged on the second layer, the distal ends of the first parts are apart from each other, the ground layer defines a first slot surrounding one of the plurality of first ground vias located adjacent to the first part and at a side bounded by the first and second parts of a corresponding one of the two differential mode signal lines, a second slot surrounding one of the plurality of second ground vias located adjacent to the first part and at a side bounded by the first and second parts of the other one of the two differential mode signal lines, and a first connection slot communicating between the first slot and the second slot, and a projection of the first connection slot on the second layer is substantially perpendicular to the second parts of the two differential mode signal lines.