SEMICONDUCTOR MEMORY DEVICE HAVING CONFIGURATION OF SELECTING DESIRED DLL CLOCK, IN WHICH DESIRED DLL CLOCK IS SELECTED ACCURATELY

摘要

PURPOSE: A semiconductor memory device having a configuration of selecting a desired DLL clock is provided to select a DLL(Delay Locked Loop) clock corresponding to a desired external clock accurately, even though a cycle time is short. CONSTITUTION: The semiconductor memory device(510) comprises a clock port(512) and a control signal port(514) and an address port(516) and a data input/output port(518) and a data strobe signal input/output port(520). The clock port receives external clock signals(EXTCLK,EXTZCLK) and a clock enable signal(CKE). The address port receives address signals and bank address signals. A clock buffer(522) generates internal clock signals(CLK,ZCLK) and outputs it to a control signal buffer(524) and an address buffer(526) and a DLL circuit(400). A row decoder(544) selects a row in a memory cell array(510) according to a row address(XA). A column decoder(546) selects a column in the memory cell array according to a column address(CA). An output circuit(500) comprises a data latch and P/S conversion circuit(536) and an output driver(530).