NON-EQUAL THRESHOLD VOLTAGE RANGES IN MLC NAND

摘要

Memory devices adapted to process and generate analog data signals representative of data values of two or more bits of information facilitate increases in data transfer rates relative to devices processing and generating only binary data signals indicative of individual bits. Programming of such memory devices includes programming to a target threshold voltage range representative of the desired bit pattern. Reading such memory devices includes generating an analog data signal indicative of a threshold voltage of a target memory cell. Threshold voltage ranges of the memory cells have a larger range size for ranges that include lower threshold voltages and a smaller range size for ranges that include higher threshold voltages since program disturb is lower at higher threshold voltages.