Delay control circuit, semiconductor memory device, and delay control method

Abstract

Provided is a delay control circuit that can prevent an N-value detection sequence performed by the delay control circuit from exceeding a specific period. The delay control circuit includes: a DLL control circuit that sets a delay amount; a delay line circuit that performs a delay operation; and an N-value detection circuit that receives an input clock signal and an output clock signal and is configured to perform a pre-N-value detection operation. The pre-N-value detection operation includes detecting the number of delayed clock cycles from the input clock signal to the output clock signal as the number of pre-delayed clock cycles before a delay operation is performed. In response to that the number of pre-delayed clock cycles is not greater than a specific value, the DLL control circuit changes the delay amount so that the delay line circuit performs the delay operation in a fast mode.