Patent ID: 7864573

Claim:
A method for data storage in analog memory cells, the method comprising: defining a nominal level of a physical quantity to be stored in the analog memory cells for representing a given data value; writing, at a first time, the given data value to the analog memory cells in first and second groups of the analog memory cells, which have respective first and second programming responsiveness such that the second programming responsiveness is different from the first programming responsiveness, by applying to the analog memory cells in the first and second groups respective, different first and second patterns of programming pulses that are selected so as to cause the analog memory cells in the first and second groups to store respective levels of the physical quantity that fall respectively in first and second ranges of the levels, such that the first range is higher than the nominal level and the second range is lower than the nominal level; and at a second time, subsequent to the first time, reading the given data value from the analog memory cells in the first and second groups.