An apparatus for controlling slew rate is coupled to two adjustable voltage rails. The output of the apparatus is coupled to the gate of a switching element. By employing two adjustable voltage rails, the slew rate of the switching element is proportional to the voltage difference between the first adjustable rail and the second adjustable rail. The slew rate control apparatus can be applied to a variety of switching elements including N channel Field Effect Transistors (NFETs), P channel Field Effect Transistors (PFETs), current mode logic circuits and level shifter circuits.