Charge pump circuit based on the sharing technique

A charge pump circuit based on the sharing technique was developed which reduces the chip area while improving the gain.The circuit can generate two negative high voltages by changing the serial/parallel connection between the two sub-charge pumps.The technique not only gives high quality voltage signals,but also reduces the chip size of the charge pumps by 50%.An additional circuit was designed to dynamically control the substrate bias of the PMOS transistors.Simulation results show that the charge pump gain is increased by 14%.This charge pump design is suitable for flash memory circuits which use two different negative high voltages for program and erase operations.