Micron Technology, Inc.
Self-adaptive read voltage adjustment using directional error statistics for memories with time-varying error rates

Abstract:

A processing device in a memory system determines a first error rate associated with a first number of bits written to the memory device as a first logical value and erroneously read as a second logical value and corresponding to a first range of a plurality of write-to-read delay times and a second error rate associated with a second number of bits written to the memory device as the second logical value and erroneously read as the first logical value and corresponding to the first range of the plurality of write-to-read delay times. The processing device further determines whether a ratio of the first error rate to the second error rate satisfies a first threshold criterion, and responsive to the ratio of the first error rate to the second error rate not satisfying the first threshold criterion, adjusts a read voltage level associated with the first range.