A storage device that avoids unauthorized access attributable to a snapback when simultaneously accessing a plurality of memory cells includes a plurality of first wires extending in a first direction, a plurality of second wires extending in a second direction, and a plurality of memory cells at a position where any of the plurality of first wires and any of the plurality of second wires intersect each other. A first driving unit supplies a first voltage having any of a positive polarity and a negative polarity or a zero potential to each of the plurality of first wires. A second driving unit supplies a second voltage with a different polarity from the first voltage to any one of the plurality of second wires intersecting a first wire to which the first voltage is supplied and supplies a zero potential to a remainder of the plurality of second wires.

An embodiment method for programming a differential type phase-change memory device comprises, in a first time interval, programming a direct memory cell or the respective complementary one pertaining to a first programming driver by means of a current between SET and RESET; and, in the same first time interval, simultaneously programming a direct memory cell or the respective complementary one pertaining to a second programming driver by means of the same current between SET and RESET. The method further comprises, in a second time interval, programming the other direct memory cell or the respective complementary one pertaining to the first programming driver by means of the other current between SET and RESET; and, in the same second time interval, simultaneously programming the other direct memory cell or the respective complementary one pertaining to the second programming driver by means of the same other current between SET and RESET.

Concurrent access of multiple memory cells in a cross-point memory array is disclosed. In one aspect, a forced current approach is used in which, while a select voltage is applied to a selected bit line, an access current is driven separately through each selected word line to concurrently drive the access current separately through each selected memory cell. Hence, multiple memory cells are concurrently accessed. In some aspects, the memory cells are accessed using a self-referenced read (SRR), which improves read margin. Concurrently accessing more than one memory cell in a cross-point memory array improves bandwidth. Moreover, such concurrent accessing allows the memory system to be constructed with fewer, but larger cross-point arrays, which increases array efficiency. Moreover, concurrent access as disclosed herein is compatible with memory cells such as MRAM which require bipolar operation.

Techniques are provided for accessing two memory cells of a memory tile concurrently. A memory tile may include a plurality of self-selecting memory cells addressable using a row decoder and a column decoder. A memory controller may access a first self-selecting memory cell of the memory tile using a first pulse having a first polarity to the first self-selecting memory cell. The memory controller may also access a second self-selecting memory cell of the memory tile concurrently with accessing the first self-selecting memory cell using a second pulse having a second polarity different than the first polarity. The memory controller may determine characteristics of the pulses to mitigate disturbances of unselected self-selecting memory cells of the memory tile.

A synapse memory system includes: synapse memory cells provided at cross points of axon lines and dendrite lines, each synapse memory cell being associated with nonvolatile random-access memory (NVRAM), each synapse memory cell being configured to store a weight value according to an output level of a write signal; a write portion configured to write the weight value to each synapse memory cell, the write portion including a write driver and an output controller, the write driver being a digital driver configured to output the write signal to a subject synapse memory cell, the output controller being configured to control the output level of the write signal of the write driver; and read drivers configured to read the weight value stored in the synapse memory cells.

An optically gated transistor (OGT) device that may be used as a selector device for one or more variable resistive memory devices. The OGT device isolates the one or more variable resistive memory devices when the OGT is not optically activated. The amount of current conducted by the OGT device is dependent on an intensity of light optically applied to the OGT device. The OGT device includes alternating layers of germanium selenide (GeSe) and GeSe plus an additional element deposited on a substrate. The OGT device includes only two electrodes connected to the alternating layers deposited on the substrate. The OGT device may generate an amplified electrical signal with respect to the magnitude of a received optical signal. The OGT device may be used to generate an optical signal having a different wavelength than the wavelength of a received optical signal.

Methods, systems, and devices for a modified write voltage for memory devices are described. In an example, the memory device may determine a first set of memory cells to be switched from a first logic state (e.g., a SET state) to a second logic state (e.g., a RESET state) based on a received write command. The memory device may perform a read operation to determine a subset of the first set of memory cells (e.g., a second set of memory cells) having a conductance threshold satisfying a criteria based on a predicted drift of the memory cells. The memory device may apply a RESET pulse to each of the memory cells within the first set of memory cells, where the RESET pulse applied to the second set of memory cells is modified to decrease voltage threshold drift in the RESET state.

Methods, systems, and devices that support techniques for programming self-selecting memory are described. Received data may include a first group of bits that each have a first logic value and a second group of bits that each have a second logic value. The first and second group of bits may be stored in a first set of memory cells and a second set of memory cells, respectively. A first programming operation for writing the second logic value to both the first and second set of memory cells and verifying whether the second logic value is written to each of the first set of memory cells, the second set of memory cells, or both may be performed. A second programming operation may write the first logic value to either the first set of memory cells or the second set of memory cells based on a result of the verification.

A variable resistance memory device includes plural first, second, and third conductors, plural memory cells, and a write circuit. Each memory cell is between one first conductor and one third conductor, and includes a first sub memory cell and a second sub memory cell. The first sub memory cell is between the one first conductor and one second conductor, and includes a first variable resistance element and a first bidirectional switching element. The second sub memory cell is between the one second conductor and the one third conductor, and includes a second variable resistance element and a second bidirectional switching element. The write circuit applies a first potential to the first and third conductors of a selected memory cell, a second potential to the second conductor of the selected memory cell, and a third potential to the first and third conductors of non-selected memory cells.

Provided are a device comprising a bit cell tile including at least two memory cells, each of the at least two memory cells including a resistive memory element, and methods of operating an array of the memory cells, each memory cell including a resistive memory element electrically coupled in series to a corresponding first transistor and to a corresponding second transistor, the first transistor including a first gate coupled to a corresponding one of a plurality of first word lines and the second transistor including a second gate coupled to a corresponding one of a plurality of second word lines, each memory cell coupled between a corresponding one of a plurality of bit lines and a corresponding one of a plurality of source lines. The methods may include applying voltages to the first word line, second word line, source line, and bit line of a memory cell selected for an operation, and resetting the resistive memory element of the memory cell in response to setting the selected bit line to ground.