MEMORY DEVICE AND METHOD OF CONTROLLING READ LEVEL

摘要

PURPOSE: A memory device and a reading level controlling method are provided to adjust offset based on difference between the number of memory cells having the threshold value, included in each section of the memory device, and the threshold number, thereby providing a reading level optimized to the property of the memory cell varied according to time. CONSTITUTION: A memory cell array(110) comprises a plurality of memory cells. A counter(120) counts the number of memory cells having a threshold voltage which is included in a reference threshold voltage section among the memory cells. A first decision unit(130) compares the counted number with a threshold number. The first decision unit decides the setup state of a reading level based on the reference threshold voltage section. A second decision unit(140) creates a new reference threshold voltage section based on the comparison result. The first decision unit creates a digital code corresponding to the reading level.