Abstract: An AC coupling receiver circuit for use in a communication system comprises a comparator connected to transmission lines forming a twisted pair wire, through AC coupling capacitors, and a non-linear element connected between the transmission lines at a position close to the comparator with respect to the capacitors. When positive and negative pulses are respectively applied to the transmission lines, the voltages of the transmission lines are respectively increased and decreased to bring the non-linear element to a substantially cut-off state, thus causing the comparator output to be inverted. As the positive and negative pulses decay, the comparator output is again inverted, thus effectng signal transmission. During the application of pulses, the charge stored in the capacitors is quickly discharged through the non-linear element, whereby fluctuation of the received threshold voltage resulting from the stored charge can be eliminated even if pulse inputs are continuous.