ADAPTIVE REFERENCE TUNING FOR ENDURANCE ENHANCEMENT OF NON-VOLATILE MEMORIES

摘要

A wear leveling technique is employed in a memory device so that the cycling history of a memory block is represented by the cycling history of a representative memory cell or a small number of representative memory cells. A control logic block tracks the cycling history of the one or more representative memory cells. A table tabulating the predicted shift in an optimal value for a reference variable for a sensing circuit as a function of cycling history is provided within the memory device. Prior to sensing a memory cell, the control logic block checks the total number of cycling in the one or more representative memory cells and adjusts the value for the reference variable in the sensing circuit, thereby providing an optimal value for the reference variable in the sensing circuit for each sensing cycle of the memory device.

主权项

1. A method of operating a memory device, said method comprising:
providing a memory device comprising a plurality of memory cells, a sensing circuit, a memory controller comprising a wear leveling circuit, a control logic block, and a look-up table; randomizing location of data written into said plurality of memory cells employing said wear leveling circuit; determining an estimated number of cycling for said plurality of memory cells by counting a total number of cycling for at least one memory cell; providing said estimated number of cycling to said look-up table, wherein said look-up table returns a value for a variable reference parameter that corresponds to said estimated number of cycling to said sensing circuit; and determining, employing said sensing circuit and said returned value for said variable reference parameter, a state of a selected memory cell among said plurality of memory cells.