Patent ID: 7616035

Claim:
A locked loop comprising: a phase detector for providing an up output signal and a down output signal; a charge pump comprising: pull-up circuitry that comprises a current source and a controlled transistor having a gate adapted for connection to the up output signal for being controlled thereby, the pull-up circuitry connected between a positive voltage supply and an output node of the charge pump; pull-down circuitry that comprises a current source and a controlled transistor having a gate adapted for connection to the down output signal for being controlled thereby, the pull-down circuitry connected between a ground voltage supply and the charge pump output node; a reference current source for controlling the current in the current sources of the pull-up and pull-down circuitries; an operational amplifier having two inputs and an output, and the operational amplifier configured to reduce phase error, one of the inputs of the operational amplifier connected to the charge pump output node; and 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.