US Patent 6920055 Charge pumping system and method

A charge pumping system capable of a forward operation mode and a reverse operation mode is provided. In forward operation mode the charge pumping system can step-up an input voltage at a ratio of ½:1 and can step-down the input voltage at a ratio of n:m where n and m are both integer values and n is equal to or greater than m. In reverse operation mode the charge pumping system can step-down the input voltage at a ratio of 1:½ and 1:1 and can step-up the input voltage at a ratio of p:q where p and q are both integer values and p is less than q.