NONVOLATILE SEMI-CONDUCTOR MEMORY DEVICE AND METHOD FOR CALCULATING READ VOLTAGE NON-VOLATILE SEMICONDUCTOR MEMORY DEVICE

摘要

PURPOSE: A nonvolatile semiconductor memory device, a memory card thereof, a memory system thereof, and a read voltage estimation method thereof are provided to prevent data error due to the change of read voltage by estimating optimum read voltage through comparing data information during a program process and a read process. CONSTITUTION: A memory cell array(110) comprises a plurality of memory cells. A read voltage estimating unit(20) compares data information during a program process and a read process. The read voltage estimating unit estimates optimum read voltage by changing the read voltage based on the comparison result. A read voltage generating unit(10) generates a corresponding read voltage in response to a control signal of the read voltage estimating unit. A reference data storage unit stores the reference data drawn from program data.