A charge pump includes an intermediate node capacitively coupled to receive a first clock signal oscillating between a ground and positive supply voltage, the intermediate node generating a first signal oscillating between a first and second voltage. A level shifting circuit shifts the first signal in response to a second clock signal to generate a second signal oscillating between first and third voltages. A CMOS switching circuit includes a first transistor having a source coupled to an input, a second transistor having a source coupled to an output and a gate coupled to receive the second signal. A common drain of the CMOS switching circuit is capacitively coupled to receive the first clock signal. When positively pumping, the first voltage is twice the second voltage and the third voltage is ground. When negatively pumping, the first and third voltages are of opposite polarity and the second voltage is ground.