Refresh techniques for memory data retention

摘要

A digital memory system (30) includes a memory cell (52), a bit line (50) and a charge integrity estimating module 35. The module is operative during a first mode of operation to detect whether a quantity of the charge stored in the memory cell lies within the first range of values or the second range of values, is operative during a second mode of operation to detect whether the quantity of the charge lies within a third range of values comprising a subset of the first range of values and is operative during a third mode of operation to detect whether the quantity of the charge lies within a fourth range of values comprising a subset of the second range of values.