Generally, this disclosure provides negative charge pump circuitry that is configured to supply a voltage that is less than a reference voltage (such as ground). The charge pump circuitry includes blocking circuitry that reduces or eliminates charge leakage so that a negative voltage may be developed at the output. The charge pump circuitry generally includes complimentary pairs of MOS switches that switch in a complimentary fashion according to charge developed on complimentary capacitors to provide a negative voltage power supply.