Multi-bit spin torque transfer magnetoresistive random access memory with sub-arrays
AssigneeQUALCOMM Incorporated
InventorsYu Lu, Xia Li
Life of this patent
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Abstract
A device includes a first magnetic tunnel junction (MTJ) element having a first read margin and a second MTJ element having a second read margin. The first read margin is greater than twice the second read margin. The device also includes an access transistor coupled between the first MTJ element and the second MTJ element. A gate of the access transistor is coupled to a word line. The first MTJ element, the second MTJ element, and the access transistor form a multi-bit spin torque transfer magnetoresistive random access memory (STT-MRAM) memory cell.
Claims30
A device comprising:
- a first magnetic tunnel junction (MTJ) element having a first read margin;
- a second MTJ element having a second read margin, the first read margin greater than twice the second read margin;
- an access transistor coupled between the first MTJ element and the second MTJ element, wherein a gate of the access transistor is coupled to a word line, and wherein the first MTJ element, the second MTJ element, and the access transistor form a multi-bit spin torque transfer magnetoresistive random access memory (STT-MRAM) memory cell;
- and
- circuitry configured to compare a sensed value of the STT-MRAM memory cell to a second value, the second value based on a comparison of the sensed value to a first value.
A method of operation of a device that includes an access transistor, a first magnetic tunnel junction (MTJ) element, and a second MTJ element, the method comprising:
- activating the access transistor, wherein the first MTJ element and the second MTJ element are responsive to the access transistor, wherein the first MTJ element has a first size, and wherein the second MTJ element has a second size that is greater than twice the first size;
- and
- determining a resistive state of the second MTJ element by:
- performing a first comparison of a sensed value to a first reference value;
- and
- performing a second comparison of the sensed value to a second reference value, wherein the second reference value is based on a result of the first comparison.
An apparatus comprising:
- first means for storing a first magnetic state, wherein the first means for storing has a first size;
- second means for storing a second magnetic state, wherein the second means for storing has a second size that is greater than twice the first size;
- means for coupling the first means for storing and the second means for storing, wherein the means for coupling is coupled to a word line, and wherein the first means for storing, the second means for storing, and the means for coupling form a multi-bit spin torque transfer magnetoresistive random access memory (STT-MRAM) memory cell;
- and
- means for comparing a sensed value of the STT-MRAM memory cell to a second value, the second value based on a comparison of the sensed value to a first value.
An apparatus comprising:
- a first magnetic tunnel junction (MTJ) sub-array formed by a plurality of first MTJ elements of a memory array;
- a second MTJ sub-array formed by a plurality of second MTJ elements of the memory array, wherein the first MTJ sub-array is configured to operate based on a first set of parameters for a first memory use and the second MTJ sub-array is configured to operate based on a second set of parameters for a second memory use that is different from the first memory use;
- and
- circuitry configured to compare a sensed value associated with an MTJ element of the plurality of second MTJ elements to a second value, the second value based on a comparison of the sensed value to a first value.
A non-transitory computer-readable medium storing instructions, which when executed by a processor of an apparatus, cause the processor to perform operations comprising:
- activating an aces transistor, wherein a first MTJ element and a second MTJ element at the apparatus are responsive to the access transistor, wherein the first MTJ element has a first size, and wherein the second MTJ element has a second size that is greater than twice the first size;
- and
- determining a resistive state of the second MTJ element by:
- performing a first comparison of a sensed value to a first reference value;
- and
- performing a second comparison of the sensed value to a second reference value, wherein the second reference value is based on a result of the first comparison.
Dependencies are inferred from the claim text.