Reference plane of integrated circuit packages

An apparatus including an integrated circuit including a plurality of devices and signal circuitry coupled to the plurality of devices, and a package substrate including a first surface coupled to the integrated circuit, a second surface having a plurality of externally accessible contact points coupled to the signal circuitry, and a continuous layer of conductive material coupled to a reference signal of the integrated circuit and disposed over an area of the second surface and electrically isolated from the contact points.