Memory with separate read and write paths
A memory unit includes a giant magnetoresistance cell electrically coupled between a write bit line and a write source line. The giant magnetoresistance cell includes a free magnetic layer. A magnetic tunnel junction data cell is electrically coupled between a read bit line and a read source line. The magnetic tunnel junction data cell includes the free magnetic layer. A write current passes through the giant magnetoresistance cell to switch the giant magnetoresistance cell between a high resistance state and a low resistance state. The magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by magnetostatic coupling with the giant magnetoresistance cell, and be read by a read current passing though the magnetic tunnel junction data cell.
1. A memory unit comprising:
a giant magnetoresistance cell electrically coupled between a write bit line and a write source line, a write current passing through the giant magnetoresistance cell switches the giant magnetoresistance cell between a high resistance state and a low resistance state; and
a magnetic tunnel junction data cell electrically coupled between a read bit line and a read source line, the magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by magnetostatic coupling with the giant magnetoresistance cell, and be read by a read current passing through the magnetic tunnel junction data cell;
wherein the read bit line and the write bit line is separately addressable and the read source line is separately addressable from the write source line and a write transistor is electrically coupled between the write source line and the giant magnetoresistance cell, and a read transistor is electrically coupled between the read source line and the magnetic tunnel junction data cell; and
the giant magnetoresistance cell is spaced apart from the magnetic tunnel junction data cell a distance sufficient to prevent magnetostatic coupling between the giant magnetoresistance cell and the magnetic tunnel junction data cell, and the memory unit further comprises bridge of magnetic dots at least partially extending between the giant magnetoresistance cell and the magnetic tunnel junction data cell that provides magnetostatic coupling between the giant magnetoresistance cell and the magnetic tunnel junction data cell.
2. A memory unit according to claim 1 , wherein the magnetic tunnel junction data cell comprises a free magnetic layer separated from a pinned magnetic layer by an oxide barrier layer and the giant magnetoresistance cell comprises a free magnetic layer separated from a pinned magnetic layer by a non-magnetic electrically conducting layer, and the free magnetic layer of the magnetic tunnel junction data cell is adjacent to the free magnetic layer of the giant magnetoresistance cell, and the pinned magnetic layer of the magnetic tunnel junction data cell is not adjacent to the pinned magnetic layer of the giant magnetoresistance cell.
3. A memory unit according to claim 1 , wherein the giant magnetoresistance cell is electrically connected to a write transistor and the write transistor is electrically connected to a write word line, and the magnetic tunnel junction data cell is electrically connected to a read transistor and the read transistor is electrically connected to a read word line.
4. A memory unit according to claim 1 , wherein the giant magnetoresistance cell has a first free magnetic layer volume and the magnetic tunnel junction data cell has a second free magnetic layer volume, and the second free magnetic layer volume is less than the first free magnetic layer volume.
5. A memory unit according to claim 1 , wherein the giant magnetoresistance cell and the magnetic tunnel junction data cell are separated from each other.
6. A memory array comprising two or more memory units according to claim 1 arranged and configured in an array.