APPARATUS FOR GENERATING DATA MASKING SIGNAL OF SYNCHRONOUS DRAM AND ITS METHOD, ESPECIALLY USING DATA STROBE SIGNAL

摘要

PURPOSE: An apparatus for generating a data masking signal of a synchronous DRAM and its method are provided to remove data transmission time by generating a signal to mask data input using a data strobe signal in a semiconductor memory device. CONSTITUTION: The first counting unit(130) detects a rising/falling edge of a data strobe signal during a period when write information is activated to high, and performs counting in response to the detection result. The second counting unit(150) detects a rising/falling edge of a clock signal during a period when the write information is activated to high, and performs counting in response to the detection result. An exclusive OR gate unit(140) performs an exclusive OR operation of the output of the first counting unit and the output of the second counting unit, and outputs the exclusive OR operation result as a comparison signal. And the first AND gate unit(170) performs an AND operation of the comparison signal and the detection result of the rising/falling edge of the clock, and outputs the OR operation result as a data masking signal.