Patent ID: 8516183

Claim:
A method of estimating a read level for a memory device, the method comprising: calculating a first information corresponding to at least one of information about a number of cells in the memory device having a particular logic level in data to be programmed and information about a number of cells having a particular cell state; storing the first information during a program operation; reading the data based on a threshold level that has been set, the threshold level defining at least one first state for cells having a voltage above the threshold level and at least one second state for cells having a voltage below the threshold level; calculating a second information about a number of cells in at least one state of the at least one first state and the at least one second state defined by the threshold level with respect to the read data; calculating a third information about a number of cells in the at least one state using a probability based on the first information; comparing the second information with the third information; and determining whether to change the threshold level according to a comparison result.