SEMICONDUCTOR MEMORY DEVICE HAVING DELAY LOCKED LOOP(DLL) CIRCUIT WHICH CAN OPERATE IN HIGH FREQUENCY DURING BURN-IN TEST AND METHOD FOR OPERATING DELAY LOCKED CIRCUIT THEREOF

摘要

PURPOSE: A semiconductor memory device having a delay locked loop(DLL) circuit which can operate in a high frequency and a method for operating the delay locked loop circuit are provided to enable the whole operation by generating a clock having an enough speed to operate the delay locked loop normally without regard to a clock frequency provided from the external. CONSTITUTION: The delay locked loop circuit comprises a ring oscillator(202) enabled by a burn-in mode signal(BURNIN). Output signals(CLK,CLKB) of the ring oscillator are inputted clock pads(220,221) via fuse stages(210,211), and the clock pads are connected to the delay locked loop circuit. The clock pads are set as a CTM pad and a CTMN pad which receives a CTM signal and a CTMN signal from the external. The CTMN signal has an inverted phase of the CTM signal. The delay locked loop circuit generates an internal clock signal operating internal circuit blocks by inputting the CTM signal and the CTMN signal. A DLL control signal generation circuit(204) generates signals(S1',S2') controlling the delay locked loop circuit in response to a power-up signal(VCCHB), a burn-in mode signal(BURN-IN) and signals(S1,S2) provided to drive the delay locked loop circuit in the prior logic circuit.