Patent ID: 7514972

Claim:
A differential charge pump, comprising: a current steerer comprising: first and second output terminals for outputting a differential current; first and second input terminals, the first input terminal receiving a source current, the second input terminal receiving a sink current; a differential control for steering the source and sink currents to the first and second output terminals; and a common mode regulator comprising: first and second resistances each having a first and a second terminal, the first terminal of the first and second resistances coupled together, the second terminal of the first and second resistances respectively coupled to the first and second output terminals of the current steerer; and a voltage driver coupled to the first terminal of the first and second resistances, the voltage driver establishing a common mode voltage that drives the first and second output terminals of the current steerer to the common mode voltage, wherein the voltage driver is an inverter having an input terminal, an output terminal and a supply terminal, the inverter being coupled to a supply voltage at the supply terminal, the input terminal of the inverter being coupled to the output terminal of the inverter so as to output the common mode voltage at the output terminal of the inverter, and the common mode voltage having a voltage level associated with a switching threshold of the inverter.