Redundant magnetic tunnel junctions in magnetoresistive memory

摘要

Memory cells in a spin-torque magnetic random access memory (MRAM) include at least two magnetic tunnel junctions within each memory cell, where each memory cell only stores a single data bit of information. Access circuitry coupled to the memory cells are able to read from and write to a memory cell even when one of the magnetic tunnel junctions within the memory cell is defective and is no longer functional. Self-referenced and referenced reads can be used in conjunction with the multiple magnetic tunnel junction memory cells. In some embodiments, writing to the memory cell forces all magnetic tunnel junctions into a known state, whereas in other embodiments, a subset of the magnetic tunnel junctions are forced to a known state.

主权项

1. A magnetoresistive memory comprising:
a memory cell that stores a single data bit, the memory cell including:
a first magnetic tunnel junction having a first resistance; anda second magnetic tunnel junction having a second resistance, wherein the first and second magnetic tunnel junctions are coupled in series; and access circuitry coupled to the memory cell, wherein the access circuitry is configured to determine the single data bit stored in the memory cell based on a sum of the first and second resistances.