HS-Links are designed for bidirectional point-to-point connections, each link consists of one signal in each direction. HS-Links use single-ended transmission over 50 Ohm matched impedance transmission lines. These can be implemented as controlled impedance tracks on a printed circuit board or as coaxial cables for connections between boards. The serial line signal is DC balanced, i.e. it has a constant DC component. This enables AC coupling to be used for improved common mode rejection and also allows a simple interface to standard fibre optic transceivers with pseudo ECL inputs and outputs, since the link uses a serial line swing of 800mV, which is centered between the positive power supply and ground.