US Patent 7683700 Techniques of ripple reduction for charge pumps

A charge pump system for supplying an output voltage to a load is described. It includes a regulation circuit connected to receive the output voltage and derive an enable signal from it and multiple charge pump circuits connected in parallel to supply the output voltage. Each of the charge pump circuits is also connected to receive a clock signal and the enable signal. The system also includes one or more delay circuit elements, where a corresponding one or more, but less than all, of the charge pump circuits are connectable to receive the enable signal delayed by the corresponding delay circuit element.