A Schottky diode that is used to prevent the voltage at a particular point in a circuit from exceeding a predetermined value. The forward bias characteristic of a Schottky diode is such that in the conducting state the diode has an essentially constant small voltage drop across it. Carrier storage is negligible, leading to very fast switching between the ‘on’ and ‘off’ states of the diode. The most common application of Schottky clamps is in integrated logic circuits in which the bipolar transistors forming the logic gates are operated in saturation during part of the switching cycle. A Schottky diode connected across the base and collector prevents the collector-base voltage swinging too far in the forward direction and hence controls the depth of saturation of the transistor; the speed of operation of the gate is thus optimized.