| 摘要 |
Methods of operating memory devices include determining a threshold voltage drift of two or more reference memory cells of the memory device programmed to only a subset of data states of the memory device and, using the determined threshold voltage drift of the two or more reference memory cells, estimating a threshold voltage drift of one or more user data memory cells programmed to a data state of the memory device that is mutually exclusive to the subset of data states of the memory device. Apparatus include memory devices having an array of memory cells having one or more user data memory cells and two or more reference memory cells, and control circuitry configured to maintain locations and initial programmed threshold voltages of the two or more reference memory cells corresponding to only a subset of data states of the memory device.
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