Methods and systems for locating a filament in a resistive memory device are described. In an example, a device can acquire an image indicating an occurrence of photoemission from the resistive memory device. The device can determine a location of the filament in a switching medium of the resistive memory device using the acquired image.

A resistive memory device includes word lines, first memory cells, second memory cells, bit lines, source lines, and a driver. The driver provides a forming voltage to the first memory cells and the second memory cells through the bit lines and the source lines in a forming process. A first connection length along the bit lines and the source lines between the first memory cells and the driver is longer than a second connection length along the bit lines and the source lines between the second memory cells and the driver. The forming process is performed to the first memory cells before the forming process is performed to the second memory cells. A first value of the forming voltage provided to the first memory cells is less than a second value of the forming voltage provided to the second memory cells.

A technique relates to biasing, using a control system, a crossbar array of resistive processing units (RPUs) under a midrange condition, the midrange condition causing resistances of the RPUs to result in a random output of low values and high values in about equal proportions. The control system reinforces the low values and the high values of the random output by setting the resistances of the RPUs to a state that forces the low values and the high values having resulted from the midrange condition. Reinforcing the low values and the high values makes the random output permanent even when the crossbar array of the RPUs is not biased under the midrange condition. The control system records a sequence of the low values and the high values of the random output responsive to reinforcing the low values and the high values of the random output.

Provided is a variable resistance random-access memory for suppressing degradation of performance by recovering a memory cell that fails. A variable resistance random-access memory of the disclosure includes a memory array, a row selection circuit, a column selection circuit, a controller, an error checking and correcting (ECC) circuit, an error bit flag register, and an error bit address register. The memory array includes a plurality of memory cells. The column selection circuit includes a sense amplifier and a write driver/read bias circuit. The error bit flag register stores bits for indicating presence/absence of an error bit in a write operation. The error bit address register stores an address of the error bit. The controller recovers the error bit when a predetermined event occurs.

A resistive random-access memory (ReRAM) cell includes a field-effect transistor (FET) and a resistive element. The FET having a gate port, a drain port, and a source port. The gate port is connected to a word-line (WL) of the ReRAM cell, the source port is connected to a bit-line (BL) of the ReRAM cell, and a first port of the resistive element is connected to the drain of the FET. A second port of the resistive element is connected to a source-line (SL) of the ReRAM cell. During reset operation SL is connected to a high-voltage and BL to a low-voltage. During set operation SL is connected to a low-voltage and BL to a high-voltage. Using this common source configuration overcomes the requirement for a wider FET width of the prior art so as to accommodate the current supply needed during reset operation, and avoids overstressing of the FET.

A variable resistance memory device includes: a memory cell including a first and second sub memory cell; and a first, second and third conductor. The first sub memory cell is above the first conductor, and includes a first variable resistance element and a first bidirectional switching element. The second sub memory cell is above the second conductor, and includes a second variable resistance element and a second bidirectional switching element. The second conductor is above the first sub memory cell. The third conductor is above the second sub memory cell. The variable resistance memory device is configured to receive first data and to write the first data to the memory cell when the first data does not match second data read from the memory cell.

The disclosed invention presents a self-tracking reference circuit that compensates for IR drops and achieves the target resistance state at different temperatures after write operations. The disclosed self-tracking reference circuit includes a replica access path, a configurable resistor network, a replica selector mini-array and a step current generator that track PVT variations to provide a PVT tracking level for RRAM verify operation.

The present invention relates to a method of operating memory cells, comprising reading a previous user data from the memory cells; writing a new user data and merging the new user data with the previous user data into write registers; generating mask register information, and wherein the mask register information indicates bits of the previous user data stored in the memory cells to be switched or not to be switched in their logic values; counting numbers of a first logic value and a second logic value to be written using the mask register information, respectively; storing the numbers of the first logic value and the second logic value into a first counter and a second counter, respectively; and applying a programming pulse to the memory cells according to the mask register information.

A memristor-based circuit includes a voltage generator that applies a series of voltage pulses to a memristor to progressively change the resistance of the memristor. A comparator: receives an input electrical value; receives an electrical value based on the resistance of the memristor; compares the received values; and, based on the comparison, enables the application of the voltage pulses to the memristor by the voltage generator until a defined condition is satisfied. This circuit can be used to enable the memristor to be programmed to a desired resistance value, such as for use as a non-volatile memory. It can also enable the resistance of one memristor to be replicated to another memristor. By counting the number of applied voltage pulses, the circuit can be used as an encoder or analog-to-digital converter. Other variants of the circuit enable construction of a decoder or digital-to-analog converter, and an authentication circuit.

The disclosed invention presents a self-tracking reference circuit that compensates for IR drops and achieves the target resistance state at different temperatures after write operations. The disclosed self-tracking reference circuit includes a replica access path, a configurable resistor network, a replica selector mini-array and a step current generator that track PVT variations to provide a PVT tracking level for RRAM verify operation.