Self-referenced sense amplifier for spin torque mram
AssigneeEverspin Technologies, Inc.
InventorsThomas Andre, Syed M. Alam, Chitra Subramanian
Life of this patent
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Abstract
Circuitry and a method provide a plurality of timed control and bias voltages to sense amplifiers and write drivers of a spin-torque magnetoresistive random access memory array for improved power supply noise rejection, increased sensing speed with immunity for bank-to-bank noise coupling, and reduced leakage from off word line select devices in an active column.
Claims20
A method of operation of a spin-torque magnetoresistive memory that includes a plurality of magnetic bit cells, wherein each magnetic bit cell includes a magnetic tunnel junction device coupled to a first electrode of a select transistor, the method comprising:
- providing a word line voltage on a selected word line corresponding to a selected magnetic bit cell of the plurality of magnetic bit cells, wherein the selected word line is coupled to a control electrode of the select transistor for the selected magnetic bit cell;
- applying a read voltage across the magnetic tunnel junction device of the selected magnetic bit cell;
- storing a sample voltage resulting from applying the read voltage;
- after storing the sample voltage, applying a first write current through the magnetic tunnel junction device of the selected magnetic bit cell to write a first state in the selected magnetic bit cell;
- after applying the first write current:
- reapplying the read voltage across the magnetic tunnel junction device of the selected magnetic bit cell;
- while reapplying the read voltage, applying a programmable offset current, wherein there is a delay between reapplying the read voltage and applying the programmable offset current;
- and
- comparing an evaluation voltage with the sample voltage to determine a state for the selected magnetic bit cell, wherein the evaluation voltage results from applying the programmable offset current and reapplying the read voltage.
A method of operation of a spin-torque magnetoresistive memory, the method comprising:
- writing to a first register to set a programmable delay for a programmable offset current;
- applying a read voltage across a memory cell;
- storing a sample voltage resulting from applying the read voltage;
- after storing the sample voltage, applying a first write current through the memory cell to write a first state in the memory cell;
- after applying the first write current:
- reapplying the read voltage across the memory cell;
- applying the programmable offset current at a later time after reapplying the read voltage, wherein the programmable offset current is applied while the read voltage is being reapplied, and wherein the later time is determined from the programmable delay as set in the first register;
- and
- comparing an evaluation voltage with the sample voltage to determine a state for the memory cell, wherein the evaluation voltage results from reapplying the read voltage and applying the programmable offset current.
Dependencies are inferred from the claim text.