Memory devices and methods using improved reference cell trimming algorithms for accurate read operation window control

摘要

A memory device is disclosed that includes a plurality of word lines and a plurality of memory cells operating in one of a plurality of modes and coupled to at least one of the word lines. The memory device also includes a plurality of reference lines and reference cells. Each reference cell corresponds to one of the operating modes, supplies a reference current for the corresponding mode, and is coupled to at least one of the reference lines. A reference cell current from a reference cell can also be compared to a target range and, if outside the target range, the voltage level on a corresponding reference line can be adjusted accordingly such that the reference current falls within the target range (i.e., reference current trimming).