Patent ID: 8099652

Claim:
A method of reading a cell of a non-volatile memory, the cell having a threshold window demarcated by a first set of (L−1) reference thresholds into a first set of L bands, with L being an integer >1, and the cell having being programmed with a threshold among one of the L bands, said method comprising: setting a second set of (L+M−1) reference thresholds for demarcating the threshold window into a second set of (L+M) bands, with M being an integer >0, the reference thresholds of the second set being distributed non-uniformly in the threshold window with higher density around locations that coincide with the reference thresholds of the first set, and wherein the first set of reference thresholds is not a subset of the second set; and reading the cell by locating the band in the second set containing the programmed threshold.