Dedicated circuitry on supported device(Cyclone IV, Stratix IV, Stratix V) family devices that helps to prevent reflections and maintains signal integrity, and as a result, improves signal integrity. The OCT circuitry provides differential termination for differential I/O standards, such as LVDS and LVPECL. OCT simplifies board design by minimizing the number of external termination resistors required. Termination can be placed inside the package, eliminating small stubs that can still lead to reflections. Stratix IV, and Stratix V devices provide both series and differential termination.