Delay locked loop and semiconductor memory device

Abstract

The present invention provides a delay locked loop (DLL) that can complete the process of adjusting the delay of an internal clock signal within a predetermined execution period. The DLL includes a DLL control circuit and a delay line circuit. The DLL control circuit sets the delay amount based on the phase difference between an input clock signal and an output clock signal. The delay line circuit performs a delay operation on the input clock signal according to the delay amount, thereby generating the output clock signal. The delay line circuit includes a plurality of delay units, each delay unit includes at least one delay element, and one of the delay units includes a greater number of delay elements than another delay unit.