US Patent 7570116 Output stage

An output stage, comprising a first transistor operable to pull a voltage at an output node towards a first voltage, and a rechargeable energy store having a potential difference between first and second terminals wherein the rechargeable energy store is arranged to be controllably connected between the output node and a second voltage supply such that the voltage at the output node can be driven to a voltage outside of a range defined between the first and second voltages.