ABSTRACT
At the simplest level, a pair of differential lines comprises two transmission lines such that the current flowing along one line is equal to the current flowing in the opposite direction along the second line. Informally then, the resultant current flowing along the pair is zero. Equivalently, the transmitted voltage on one of the pair is 180 degrees out of phase with the voltage of the other line. Thus, each line acts as the ground for its counterpart, and in this sense, they have a common self-referencing ground.
