Windowed MRAM sensing scheme

Memories using any type of on-chip magnetic memory elements (often known as MRAM) sometimes suffer from unstable magnetic domains within the memory bits. These states may occur because of improper bit manufacturing techniques or transient magnetic fields generated on or off chip. In many cases these errors are actually correctable if this unstable domain situation can be detected. In any traditional sensing method that only detects 1 or 0 states, these unstable states usually increase the soft-error-rate (SER) in that they reduce the bit related signal although the bits may still function to some degree. In other cases, these domain instabilities may render a bit unusable. In either case, if this situation is not detected it could easily result in erroneous memory operation. We have developed a Windowed Sensing Scheme described here to address this problem, which allows bits with unstable domains to be detected during reading. It also allows for improved sensing error rate by identifying read cycles with inadequate signal size caused for example by external noise