NON-VOLATILE MEMORY AND METHODS WITH READING SOFT BITS IN NON UNIFORM SCHEMES

摘要

Non-volatile memory has a threshold of the programmed cells within any of the voltage band of the first set of one divided by the contrast threshold of the first set that spans the threshold window. Cells to provide additional soft bits for error correction are read out in much more degradation with respect to the contrast threshold of the second set. Contrast threshold of the second set to give more degraded in the specified area are arranged to be non-uniformly distributed on the threshold window. At the same time it is to be conductive so a simple algorithm and a reading circuit and a bit by bit soft systematically using a minimum of data latches are read into the read group. This is a contrast threshold of the first set must be a subset of the second set, and the resultant soft bits are achieved by mitigating the requirements that must be distributed symmetrically with respect to a hard bit.;