Patent ID: 7893737

Claim:
A charge pump comprising: pull-up circuitry that comprises a current source and a controlled transistor having a gate adapted for connection to a first input signal for being controlled thereby, the pull-up circuitry connected between a positive voltage supply and a charge pump output node; pull-down circuitry that comprises a current source and a controlled transistor having a gate adapted for connection to a second input signal for being controlled thereby, the pull-down circuitry connected between a ground voltage supply and the charge pump output node, the first and second input signals being derived from up and down signals, respectively; a reference current source for controlling a current in the current sources of the pull-up and pull-down circuitries; an operational amplifier having two inputs and an output, the operational amplifier configured to reduce phase error, one of the inputs of the operational amplifier connected to the charge pump output node; a startup circuit to establish a predetermined voltage level at the charge pump output node during startup; and a capacitor connected to the charge pump output node.