Magnetic random access memory

A magnetic random access memory in which “0” data and “1” data are associated with resistance values of a non-magnetic layer of a magnetoresistive element, the resistance values being variable depending on orientation of magnetization of a magnetic free layer and a magnetic pinned layer which sandwich the non-magnetic layer, and current is let to flow to first and second write current paths, which are provided close to the magnetoresistive element and are separated from each other, thereby producing a composite write magnetic field, changing a direction of magnetization of the free layer, wherein the first write current path includes a channel region of an insulated-gate transistor that is disposed close to the free layer, and the transistor is controlled such that a channel current with a desired magnitude flows in the transistor.

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Magnetic memory device structure

Ferromagnetic elements for use with spin memories, logic devices and processing circuits include a geometry incorporating an asymmetry about one axis and in some instances one or more curved sections. Magnetic memory elements can be set out in an array such that convex and concave portions are also optimally arranged about magnetization axes.

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MRAM and data writing method therefor

In an MRAM having main and sub-structures, selecting transistors are arranged so as to meet the arrangement order of main word lines, sub-word lines and the selecting transistors. The selecting transistor is driven to cause a snap back phenomenon to occur. As a result, data can be written to a memory cell using a substrate current, not a channel current. Moreover, a data may be written into a selected memory cell by discharge the charge which is charged in the main and sub word lines corresponding to the memory cell.

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Three-terminal magnetostatically coupled spin transfer-based MRAM cell

A magnetic memory device for reading and writing a data state comprises at least three terminals including first, second, and third terminals. The magnetic memory device also includes a spin transfer (ST) driven element, disposed between the first terminal and the second terminal, and a readout element, disposed between the second terminal and the third terminal. The ST driven element includes a first free layer, and a readout element includes a second free layer. A magnetization direction of the second free layer in the readout element indicates a data state. A magnetization reversal of the first free layer within the ST driven element magnetostatically causes a magnetization reversal of the second free layer in the readout element, thereby recording the data state.

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Test terminal negation circuit for protecting data integrity

A test terminal negation circuit comprises a switch circuit which receives a test signal from a test terminal and outputs it in an asserted state as it is or in a predetermined negated state to a test object circuit, a test signal control circuit which controls an output signal of the switch circuit to be asserted or negated, a test mode signal generation circuit which generates a test mode signal which asserts the output signal of the switch circuit, and a negating signal generation circuit which can output a negating signal for forcing the output signal of the switch circuit into negated state and comprises an electrically rewritable nonvolatile memory element. When the test signal control circuit receives the negating signal, it does not assert the output signal of the switch circuit even it receives the test mode signal.

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Non-volatile memory architecture to improve read performance

A memory cell array is physically divided into an even number of sectors, with each pair of sectors sharing read circuitry. The outputs of the shared read circuitry are commonly connected to form data lines spanning the height of the array, which are input to global sense amplifiers. A two-stage sensing scheme is employed, with first stage and global sense amplifiers. The driving capability of the first stage sense amplifier can be used to decrease the time to charge or discharge the data lines, which reduces the total signal development time and consequently improves read performance. Granularity of the array can be adjusted by dividing groups and sub-groups of memory cells within a sector accordingly. In a read operation, the bit line in the opposite sector at the same column location is used as reference bit line, which greatly improves matching of bit line loading for the sensing.

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Bit switch voltage drop compensation during programming in nonvolatile memory

A method is provided of regulating a supply voltage for providing a bit line voltage in a semiconductor memory device where the bit line voltage is provided to memory cells in a bit line from the supply voltage through a bit switch. A bit line current provided to the memory cells is detected. The supply voltage is adjusted responsive to the deducted bit line current to at least partially compensate for a voltage drop across the bit switch where the voltage drop is dependent at least in part on the bit line current.

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Automatic programming time selection for one time programmable memory

A method of programming a memory includes the steps of attempting to program a bit at a designated address for a predetermined time; testing the bit to see if it has been programmed; increasing the predetermined time by approximately an order of magnitude; repeating the previous steps (until the bit at the designated address is programmed; and repeating all the previous steps by advancing the designated address until all bits in the memory are programmed.

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Circuit and method for reducing leakage current in a row driver circuit in a flash memory during a standby mode of operation

A row driver receives an input signal and a test mode signal, and is coupled to first and second voltage sources and has an output coupled to a word line. The row driver operates in an active mode responsive to the test mode signal going inactive to couple the output to either the first or second voltage source responsive to the input signal. The row driver operates in a standby mode responsive to the test mode signal going active to present a high impedance to the word line. A method includes detecting a first mode of operation of a memory device and floating at least some of the word lines when the first mode is detected. The memory device may be a flash memory device and the first mode may be a standby mode of operation of the flash memory device.

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Integrated circuit memory device with bit line pre-charging based upon partial address decoding

An integrated circuit memory device has an array of memory cells arranged in a plurality of rows and columns and a plurality of row lines and a plurality of column lines. Cells arranged in the same row are connected by a common row line, and cells arranged in the same column are connected by a common column line. Each cell in the array is addressed by an address signal which has a plurality of bits. A sense amplifier circuit is connectable to one or more of the plurality of column lines of the array. An address input terminal receives in series the plurality of bits of the address signal. Each of the column lines is connectable to a pre-charge voltage, in response to a read command. A decoder circuit receives the address signal and decodes the address signal as each of the plurality of bits is received and disconnects certain of the column lines to the pre-charge voltage in response to the decoding, and activates the sense amplifier circuit after all of the plurality of bits of the address signal are received.

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Method of determining voltage compensation for flash memory devices

The present invention determines or identifies programming variations for different groups within an array or memory device that properly program memory cells within the respective groups. Then, during programming operations for a given memory cell, programming voltages are applied according to the determined or identified programming variations for the group to which the given memory cell belongs. These adjusted programming variations facilitate successful programming of the particular memory cell.

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Comprehensive erase verification for non-volatile memory

Systems and methods in accordance with various embodiments can provide for comprehensive erase verification and defect detection in non-volatile semiconductor memory. In one embodiment, the results of erasing a group of storage elements is verified using a plurality of test conditions to better detect defective and/or insufficiently erased storage elements of the group. For example, the results of erasing a NAND string can be verified by testing charging of the string in a plurality of directions with the storage elements biased to turn on if in an erased state. If a string of storage elements passes a first test process or operation but fails a second test process or operation, the string can be determined to have failed the erase process and possibly be defective. By testing charging or conduction of the string in a plurality of directions, defects in any transistors of the string that are masked under one set of conditions may be exposed under a second set of bias conditions. For example, a string may pass an erase verification operation but then be read as including one or more programmed storage elements. Such a string can be defective and mapped out of the memory device.

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