Abstract: A flat ribbon cable having a controlled impedance and suitable for use at high data rates. The ribbon cable includes a plurality of conductors arranged side-by-side within an insulating material. The conductors include a first portion at each end having a generally circular cross-section, a center portion of generally rectangular cross-section in which the width is greater than the height and a transition portion at each end between the first portion and the second portion. A shield is disposed over selected ones of the plurality of conductors on at least one side of the ribbon cable. A drain wire is provided that is conductively coupled to the shield and may be disposed between the shield and insulating material. The drain wire is disposed over one of the conductors and may be conductively coupled to the conductor via use of a single contact of an insulation displacement connector that engages both the drain wire and the respective conductor.