Disclosed herein is a memory cell. The memory cell may act both as a combined selector device and memory element. The memory cell may be programmed by applying write pulses having different polarities. Different polarities of the write pulses may program different logic states into the memory cell. The memory cell may be read by read pulses all having the same polarity. The logic state of the memory cell may be detected by observing different threshold voltages when the read pulses are applied. The different threshold voltages may be responsive to the different polarities of the write pulses.

Methods, systems, and devices for accessing a multi-level memory cell are described. The memory device may perform a read operation that includes pre-read portion and a read portion to access the multi-level memory cell. During the pre-read portion, the memory device may apply a plurality of voltages to a plurality of memory cells to identify a likely distribution of memory cells storing a first logic state. During the read portion, the memory device may apply a first read voltage to a memory cell based on performing the pre-read portion. The memory device may apply a second read voltage to the memory cell during the read portion that is based on the first read voltage. The memory device may determine the logic state stored by the memory cell based on applying the first read voltage and the second read voltage.

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.

Sensing memory cells can include: applying a voltage ramp to a group of memory cells to sense their respective states; sensing when a first switching event occurs to one of the memory cells responsive to the applied voltage ramp; stopping application of the voltage ramp after a particular amount of time subsequent to when the first switching event occurs; and determining which additional memory cells of the group experience the switching event during the particular amount of time. Those cells determined to have experienced the switching event responsive to the applied voltage ramp are sensed as storing a first data value and those cells determined to not have experienced the switching event responsive to the applied voltage ramp are sensed as storing a second data value. The group stores data according to an encoding function constrained such that each code pattern includes at least one data unit having the first data value.

A method for reading memory cell, comprising the steps of applying a first read voltage to a plurality of memory cells, detecting first threshold voltages exhibited by the plurality of memory cells in response to application of the first read voltage, based on the first threshold voltages, associating a first logic state to one or more cells of the plurality of memory cells, applying a second read voltage to the plurality of memory cells, wherein the second read voltage has the same polarity of the first read voltage and a higher magnitude than an expected highest threshold voltage of memory cells in the first logic state, detecting second threshold voltages exhibited by the plurality of memory cells in response to application of the second read voltage, based on the second threshold voltages, associating a second logic state to one or more cells of the plurality of memory cells, applying a third read voltage to the plurality of memory cells, wherein the third read voltage has the same polarity of the first and second read voltages and is applied at least to a group of memory cells that, during the application the second read voltage, have been reprogrammed to an opposite logic state, detecting third threshold voltages exhibited by the plurality of memory cells in response to application of the third read voltage, and based on the third threshold voltages, associating one of the first or second logic state to one or more of the cells of the of the plurality of memory cells. A related circuit, a related memory device and a related system are also disclosed.

Disclosed herein is a memory cell including a memory element and a selector device. Data may be stored in both the memory element and selector device. The memory cell may be programmed by applying write pulses having different polarities and magnitudes. Different polarities of the write pulses may program different logic states into the selector device. Different magnitudes of the write pulses may program different logic states into the memory element. The memory cell may be read by read pulses all having the same polarity. The logic state of the memory cell may be detected by observing different threshold voltages when the read pulses are applied. The different threshold voltages may be responsive to the different polarities and magnitudes of the write pulses.

A phase change (PCM) memory device that includes a PCM and a resistance-capacitance (RC) circuit. The PCM has one or more PCM properties, each PCM property has a plurality of PCM property states. As the PCM property states of a given property are Set or Reset, the PCM property states each produce an incremental change to a property level of the respective/associated PCM property, e.g., PCM conductance. The incremental changes to property level of the PCM memory device are in response to application of one or more of a pulse number of voltage pulses. The RC circuit produces a configuring current that flows through the PCM in response to one or more of the voltage pulses. The configuring current modifies one or more of the incremental changes to one or more of the property levels so that the property level changes lineally with respect to the pulse number. The PCM memory device has use in a synapse connector, e.g., in a memory array. The memory array can be used to store and/or read memory values associated with one or more of the property levels. The memory values can be used as weighting values in a neuromorphic computing application/system, like a neural network.

A memory device can include a plurality of memory cells including a first group of memory cells and a second group of memory cells programmed to a predefined logic state. The plurality of memory cells includes a memory controller configured to apply a reading voltage to at least one selected memory cell of the first group during a reading operation, apply the reading voltage to the memory cells of the second group, and responsive to the logic state of at least one memory cell of the second group being assessed to be different from the predefined logic state perform a refresh operation of the memory cells of the first group by applying a recovery voltage higher than the reading voltage to assess the logic state thereof and reprogramming the memory cells of the first group to the logic state assessed with the recovery voltage.

A method includes: applying a first signal to memory cells in a memory device, to adjust resistance values of the memory cells; after applying the first signal, applying a second signal to the memory cells other than a first memory cell in the memory cells, to further adjust the resistance values of the memory cells other than the first memory cell. A memory device is also disclosed herein.

Methods, systems, and devices for accessing a multi-level memory cell are described. The memory device may perform a read operation that includes pre-read portion and a read portion to access the multi-level memory cell. During the pre-read portion, the memory device may apply a plurality of voltages to a plurality of memory cells to identify a likely distribution of memory cells storing a first logic state. During the read portion, the memory device may apply a first read voltage to a memory cell based on performing the pre-read portion. The memory device may apply a second read voltage to the memory cell during the read portion that is based on the first read voltage. The memory device may determine the logic state stored by the memory cell based on applying the first read voltage and the second read voltage.