US Patent 7737742 Delay locked loop

An integrated circuit includes a chain of delay elements, a first phase detector, and a controller. The chain of delay elements is configured to delay an input clock signal for providing an output clock signal phase shifted with respect to the input clock signal by a selected value. The first phase detector is configured to provide a common control signal to each delay element based on a phase difference between the input clock signal and a signal output from one of the delay elements to adjust a delay of each delay element. The controller is configured to provide an independent control signal to each delay element to individually adjust the delay of each delay element such that the delay of each delay element is equal.