Abstract:
A method of reading a memory device that includes a memory cell that stores data of at least two bits includes determining whether a cell resistance level is no greater than a threshold resistance level. If the cell resistance level is smaller than or equal to the threshold resistance level, then the data is read based on a first factor that is inversely proportional to the cell resistance level. If the cell resistance level is greater than the threshold resistance level, then the data is read based on a second factor that is proportional to the cell resistance level.
Abstract:
A method of operating a resistive memory device having a plurality of word lines and a plurality of bit lines includes selecting one or more first memory cells connected to a first bit line, selecting one or more second memory cells connected to a second bit line, and simultaneously performing a reset write operation on the first and second memory cells using a first write driver.
Abstract:
In operating a resistive memory device including a number of memory cells, a write pulse is applied to each of the plurality of memory cells such that each of the memory cells has a target resistance state between a first reference resistance and a second reference resistance higher than the first reference resistance. The resistance of each of the memory cells is read by applying a verify pulse to each of the plurality of memory cells. A verify write current pulse is applied to each of the memory cells that has resistance higher than the second reference resistance, and a verify write voltage pulse is applied to each of the memory cells that has resistance lower than the first reference resistance.
Abstract:
Provided are a resistive memory device and a method of the resistive memory device. The method of operating the resistive memory device includes performing a pre-read operation on memory cells in response to a write command; performing an erase operation on one or more first memory cells on which a reset write operation is to be performed, determined based on a result of comparing pre-read data from the pre-read operation with write data; and performing set-direction programming on at least some memory cells from among the erased one or more first memory cells and on one or more second memory cells on which a set write operation is to be performed.
Abstract:
Provided are a resistive memory device including a plurality of memory cells, and a method of operating the resistive memory device. The resistive memory device includes a sensing circuit connected to a first signal line, to which a memory cell is connected, the sensing circuit sensing data stored in the memory cell based on a first reference current; and a reference time generator for generating a reference time signal that determines a time point when a result of the sensing is to be output, based on the first reference current.
Abstract:
A nonvolatile memory device, which has an improved read reliability through a refresh operation, and a memory system, are provided. The nonvolatile memory device includes a resistive memory cell, a reference resistor corresponding to the resistive memory cell, a reference sense amplifier electrically connected to the reference resistor and configured to change a transition time of an output value of the reference resistor, and a refresh request signal generator configured to output the refresh request signal for the resistive memory cell when the transition time of an output value of the reference resistor is in a preset refresh requiring period.
Abstract:
A method of programming memory cells of a resistive memory device includes; applying a first current pulse to each of the plurality of memory cells; applying a second current pulse that increases by a first difference compared to the first current pulse to each of the plurality of memory cells to which the first current pulse is applied; and applying a third current pulse that increases by a second difference compared to the second current pulse to each of the plurality of memory cells to which the second current pulse is applied, wherein the first through third current pulses non-linearly increase, and the second difference is greater than the first difference.
Abstract:
Resistive memory driving methods are provided. The methods may include applying an operating voltage set according to a mode of operation to a selected word line among the plurality of word lines and a selected bit line among the plurality of bit lines within a line delay period.
Abstract:
Provided is a nonvolatile memory device using a resistance material and a method of driving the nonvolatile memory device. The nonvolatile memory device comprises a resistive memory cell which stores multiple bits; a sensing node; a clamping unit coupled between the resistive memory cell and the sensing node and provides a clamping bias to the resistive memory cell; a compensation unit which provides a compensation current to the sensing node; a sense amplifier coupled to the sensing node and senses a change in a level of the sensing node; and an encoder which codes an output value of the sense amplifier in response to a first clock signal. The clamping bias varies over time. The compensation current is constant during a read period.
Abstract:
An operating method for a resistive memory device includes; applying a bias control voltage to a memory cell array of the resistive memory device, measuring leakage current that occurs in the memory cell array in response to the applied bias control voltage to generate a measuring result, generating a control signal based on the measuring result, and adjusting a level of the bias control voltage in response to the control signal.