SPIN-TRANSFER TORQUE MEMORY NON-DESTRUCTIVE SELF-REFERENCE READ METHOD
First Claim
1. A method of non-destructive self-reference reading a spin-transfer torque memory unit, comprising:
- applying a first read current through a magnetic tunnel junction data cell and forming a first bit line read voltage, the magnetic tunnel junction data cell having a first resistance state;
storing the first bit line read voltage in a first voltage storage device;
applying a second read current thorough the magnetic tunnel junction data cell having the first resistance state and forming a second bit line read voltage, the first read current being less than the second read current;
storing the second bit line read voltage in a second voltage storage device; and
comparing the stored first bit line read voltage with the stored second bit line read voltage to determine whether the first resistance state of the magnetic tunnel junction data cell was a high resistance state or low resistance state.
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Abstract
A spin-transfer torque memory apparatus and non-destructive self-reference read schemes are described. One method of self-reference reading a spin-transfer torque memory unit includes applying a first read current through a magnetic tunnel junction data cell and forming a first bit line read voltage and storing the first bit line read voltage in a first voltage storage device. The magnetic tunnel junction data cell has a first resistance state. Then the method includes applying a second read current thorough the magnetic tunnel junction data cell having the first resistance state and forming a second bit line read voltage and storing the second bit line read voltage in a second voltage storage device. The first read current is less than the second read current. Then the stored first bit line read voltage is compared with the stored second bit line read voltage to determine whether the first resistance state of the magnetic tunnel junction data cell was a high resistance state or low resistance state.
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Citations
20 Claims
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1. A method of non-destructive self-reference reading a spin-transfer torque memory unit, comprising:
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applying a first read current through a magnetic tunnel junction data cell and forming a first bit line read voltage, the magnetic tunnel junction data cell having a first resistance state; storing the first bit line read voltage in a first voltage storage device; applying a second read current thorough the magnetic tunnel junction data cell having the first resistance state and forming a second bit line read voltage, the first read current being less than the second read current; storing the second bit line read voltage in a second voltage storage device; and comparing the stored first bit line read voltage with the stored second bit line read voltage to determine whether the first resistance state of the magnetic tunnel junction data cell was a high resistance state or low resistance state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of self-reference reading a spin-transfer torque memory unit, comprising:
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applying a first read current through a magnetic tunnel junction data cell and forming a first bit line read voltage, the magnetic tunnel junction data cell having a first resistance state; storing the first bit line read voltage in a first capacitor; applying a second read current thorough the magnetic tunnel junction data cell having the first resistance state and forming a second bit line read voltage, the first read current being less than the second read current; storing the second bit line read voltage in a second capacitor and a third capacitor, the second capacitor and the third capacitor are electrically connected in series; and comparing the stored first bit line read voltage with the stored second bit line read voltage, and if the first bit line read voltage is substantially the same as or less than the stored second bit line read voltage, then the first resistance state is determined to be a low resistance state, and if the first bit line read voltage is greater than the stored second bit line read voltage, then the first resistance state is determined to be a high resistance state. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A spin-transfer torque memory apparatus comprising:
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a magnetic tunnel junction data cell comprising a ferromagnetic free layer and a ferromagnetic reference layer separated by a oxide barrier layer, the magnetic tunnel junction data cell electrically between a bit line and a source line, the magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by passing a polarized write current through the magnetic tunnel junction data cell; an adjustable current driver electrically coupled to the bit line, the adjustable current driver configured to provide a provide a first read current and a second read current through the magnetic tunnel junction data cell; a first voltage storage device electrically coupled to the bit line and configured to store a first bit line voltage formed by the first read current; a second voltage storage device electrically coupled to the bit line and configured to store a second bit line voltage formed by the second read current; a third voltage storage device electrically coupled to the bit line and configured to store a second bit line voltage formed by the second read current, the second voltage storage device and the third voltage storage device are electrically connected in series; and a differential sense amplifier electrically coupled to the first voltage storage device and electrically coupled to an intermediate node electrically between the second voltage storage device and the third voltage storage device, the differential sense amplifier configured to compare the first bit line voltage with the second bit line voltage. - View Dependent Claims (19, 20)
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Specification