A delay locked loop includes a pulse generator, a delay unit, a phase detector and a control unit. The pulse generator generates a pulse signal and a determination signal according to an input clock signal. The delay unit delays the pulse signal according to a digital control signal to generate a delayed pulse signal. The phase detector detects a time delay of the delayed pulse signal according to the determination signal to generate a detection result. The control unit generates a digital control signal according to the detection result to control the delayed pulse signal by a delay amount.