Read circuit for magnetic memory array using magnetic tunnel junction devices
Patent 5793697 Issued on August 11, 1998. Estimated Expiration Date: February 18, 2017. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
365/230.07, Including magnetic element257/E45.001, SOLID-STATE DEVICES ADAPTED FOR RECTIFYING, AMPLIFYING, OSCILLATING, OR SWITCHING WITHOUT POTENTIAL-JUMP BARRIER OR SURFACE BARRIER, E.G., DIELECTRIC TRIODES; OVSHINSKY-EFFECT DEVICES, PROCESSES, OR APPARATUS PECULIAR TO MANUFACTURE OR TREATMENT THEREOF, OR OF PARTS THEREOF (EPO)365/66, Magnetic365/171Magnetic thin film
A sensing circuit reads the magnetic state of individual memory cells making up a nonvolatile magnetic random access memory (MRAM) array. Each memory cell is a magnetic tunnel junction (MTJ) element and a diode electrically connected in series. Each MTJ is formed of a pinned ferromagnetic layer whose magnetization direction is prevented from rotating, a free ferromagnetic layer whose magnetization direction is free to rotate between states of parallel and antiparallel to the fixed magnetization of the pinned ferromagnetic layer, and an insulating tunnel barrier between and in contact with the two ferromagnetic layers. The memory cells in the array are controlled by only two lines, and the write currents to change the magnetic state of an MTJ, by use of the write currents' inherent magnetic fields to rotate the magnetization of the free layer, do not pass through the tunnel barrier layer. The magnetic state of a memory cell is read by reducing the voltage on one of the lines while the voltage on the other line is clamped.
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February 18, 2017. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
