Inverting charge pump

A charge pump comprising:

• a pair of pump capacitors connected between an input terminal and an output terminal each pump capacitor having first and second terminals;
• a first group of switches being controllable by a first control signal, two of the first group of switches being connected between the input terminal and the first terminal of each pump capacitor, and another two of the first group of switches being connected between the second terminal of each pump capacitor a reference terminal;
• and,
• a second group of switches being controllable by a second control signal, one of the second group of switches being connected between the first terminal of one pump capacitor and the reference terminal, a second one of the second group of switches being connected between the second terminal of one pump capacitor and the first terminal of the other pump capacitor, and a third one of the second group, of switches being connected between the second terminal of the other pump capacitor and the output terminal.

A method of producing an output voltage, -2V from an input voltage, V, wherein the output voltage is approximately twice a magnitude of an inverse of the input voltage the method comprising the steps of:

• connecting the input voltage, V to two pump capacitors, each pump capacitor being connected in parallel;
• charging the pump capacitors to the input voltage, V;
• reconnecting the pump capacitors in series with each other and connecting a hold capacitor in parallel with the reconnected series pump capacitors;
• and,
• connecting an output terminal between the hold capacitor and the pump capacitors.