Dll circuit and semiconductor device having the same

Abstract

A DLL circuit comprising: delay circuits which output first and second delayed clock signals obtained by delaying the reference clock signal by a delay times selected according to control signals; an interpolation circuit which interpolates a phase difference between the delayed clock signals to output an internal clock signal; an output circuit which generates a predetermined signal; a dummy output circuit which has the same transmission characteristics as the output circuit and outputs a feedback clock signal having the same phase as the predetermined signal; a phase comparison circuit which compares phases of the reference clock signal and the feedback clock signal; delay control circuits which controls the control signals in a direction where both phases are equal; wherein the delay time of the second delayed clock signal is larger than the first delayed clock signal by an amount equivalent to one cycle of the reference clock signal.