A two stage charge pump circuit can perform either a two stage boosting operation or a single stage boosting operation. The charge pump circuit includes first, second and third gate transistors connected in series between first and second supply voltages, and a bypass transistor. A first booster stage includes a capacitor connected between the first and second gate transistors and a drive circuit. A second booster stage includes a capacitor connected between second and third gate transistors and the drive circuit. The third gate transistor is connected to an internal bus which provides an output voltage to other circuit elements connected to it. The bypass transistor is connected between the first booster stage and the internal bus.