A circuit board including a board substrate having opposite first and second sides. The board substrate has a thickness measured along a z-axis that is perpendicular to the first and second sides. The circuit board also includes plated thru-hole (PTH) vias extending along the z-axis from the first side into the board substrate. The PTH vias are arranged to form multiple signal pairs. The circuit board also includes signal traces that are directly coupled to the PTH vias and extend perpendicular to the z-axis in the board substrate. The signal traces and the PTH vias are configured to transmit differential signals. The circuit board also includes ground columns that extend along the z-axis in the board substrate. The ground columns are distributed relative to the signal pairs to form shield arrays. Each of the shield arrays surrounds one of the signal pairs, wherein the ground columns comprise microvias.