Clock signal synchronization circuit, semiconductor memory device including clock signal synchronization circuit, and method of operating clock signal synchronization circuit

Abstract

A clock signal synchronization circuit includes a delay line configured to delay an input clock signal in response to a delay control signal to output an output clock signal, a replica circuit configured to delay the output clock signal to output a feedback clock signal, a phase detector configured to compare the input clock signal and the feedback clock signal with each other to detect a phase difference, and a delay control circuit configured to generate the delay control signal based on the phase difference. The replica circuit may delay the output clock signal based on an operation mode of a memory device to output the feedback clock signal.