Abstract:
Phase change memory devices, systems, and associated methods are provided and described. Such devices, systems, and methods manage and reduce voltage threshold drift of a phase change memory device comprising a select device SD and a phase change memory element PM, by at least reducing the threshold voltage drift of the select device SD, to increase read accuracy of phase change memory.
Abstract:
The invention has involved the development of a method for reading a resistive memory cell that has two electrodes spaced apart from one another by an ion-conductive resistive material and that can be transferred from a stable state having a relatively high resistance value (high resistive state, HRS) to a stable state having a relatively low resistance value (low resistance state, LRS) by applying a write voltage. According to the invention, reading involves a read voltage being applied as a read pulse, wherein the number of ions driven through the ion-conductive resistive material during the pulse is set by means of the level and duration of the pulse such that, on the basis of the state for forming an electrically conductive path through the ion-conductive resistive material, they suffice at least until the onset of a flow of current through this path and hence for the transition to a metastable state VRS (volatile resistance state) with a reduced resistance value and a prescribed relaxation time for the return to the HRS state, but not for the transition to the LRS state. This ensures that the memory cell is always back in the same state after reading as before reading. This renders particularly memory elements that consist of two memory cells in reverse-connected series being nondestructively readable without this diminishing the possibility of producing large arrays from these memory elements.
Abstract:
Some embodiments include methods of reading memory cells. The memory cells have a write operation that occurs only if a voltage of sufficient absolute value is applied for a sufficient duration of time; and the reading is conducted with a pulse that is of too short of a time duration to be sufficient for the write operation. In some embodiments, the pulse utilized for the reading may have an absolute value of voltage that is greater than or equal to the voltage utilized for the write operation. In some embodiments, the memory cells may comprise non-ohmic devices; such as memristors and diodes.
Abstract:
Methods, systems, and devices for drift mitigation with embedded refresh are described. A memory cell may be written to and read from using write and read voltages, respectively, that are of different polarities. For example, a memory cell may be written to by applying a first write voltage and may be subsequently read from by applying a first read voltage of a first polarity. At least one additional (e.g., a second) read voltage-a setback voltage-of a second polarity may be utilized to return the memory cell to its original state. Thus the setback voltage may mitigate a shift in the voltage distribution of the cell caused by the first read voltage.
Abstract:
A disclosed example to reduce a threshold voltage drift of a selector device of a memory cell includes providing an applied voltage to the selector device of the memory cell, the applied voltage being less than a threshold voltage of the selector device, and reducing the threshold voltage drift of the memory cell by maintaining the applied voltage at the selector device for a thresholding duration to activate the selector device.
Abstract:
In one example in accordance with the present disclosure a memristor device is described. The device includes an active memristor to be set to one of a plurality of states. The device also includes a state controller to program the state of the active memristor. The state defines a current-voltage relationship for the active memristor. The state controller also sets an operating point for the active memristor around which an input signal oscillates. The resistance of the active memristor defines an amplitude modulation of the input signal and the reactance of the active memristor defines a phase delay of the input signal.
Abstract:
In one embodiment, a non-volatile memory is controlled in a selectable read mode in response to commands from a processor. Selectable read modes may include a default read memory mode, for example, and a performance read memory mode having a shorter read pulse and a reduced read latency than the default read memory mode, for example. In one embodiment, the performance read memory mode may also have refresh operations at an increased frequency compared to that of the default read mode. Other aspects and advantages are described.
Abstract:
Embodiments of the present disclosure describe read and write operations in phase change memory to reduce snapback disturb. In an embodiment, an apparatus includes read circuitry to apply a read voltage to a phase change memory (PCM) cell, setback circuitry to apply a setback pulse to the PCM cell in response to the application of the read voltage, wherein the setback pulse is a shorter set pulse performed for a first period of time that is shorter than a second period of time for a regular set pulse that is configured to transition the PCM cell from an amorphous state to a crystalline state, sense circuitry to sense, concurrently with application of the setback pulse, whether the PCM cell is in the amorphous state or the crystalline state. Other embodiments may be described and/or claimed
Abstract:
An example device in accordance with an aspect of the present disclosure includes a first module, a second module, and a third module. The first module is coupled to an element whose status is to be determined, and the first module is to receive an input current that increases over time. The second module is to perform a temporal derivative of a voltage across the element. The third module is to provide an output signal based on a current behavior of the element, according to a change in voltage as a function of a change in current.
Abstract:
The present disclosure relates to mitigating read disturb in a cross-point memory. An apparatus may include a memory controller configured to select a target memory cell for a memory access operation. The memory controller includes a sense module configured to determine whether a snap back event occurs during a sensing interval; and a write back module configured to write back a logic one to the memory cell if a snap back event is detected.