Charge Pump

A charge pump is a circuit that uses switches, diodes, and capacitors to generate a supply voltage that exceeds the limits of what are possible using passive components.  A positive charge pump can generate an output supply above the positive input supply rail while a negative (or inverting) charge pump can generate an output supply rail below the negative (or ground) input supply rail.  These circuits are used in many applications but are often used to drive the gates of transistors that are used as switches to connect power rails together.  A charge pump IC requires the external capacitors to generate a pumped voltage rail, which enables quick integration into a design.