Design Strategy for Step-Up Charge Pumps With Variable Integer Conversion Ratios

Method in identifying all possible configurations of 2-phase charge pumps giving an integer conversion ratio with a fixed number of flying capacitors is presented. A systematic strategy is proposed to design an integrated charge pump as an example with a variable gain of 6times and 7times in a standard 0.35-mum CMOS process using only 4 flying capacitors. Conduction loss is considered and minimized. Measurement results verified the validity of the design methodology