Integrated Silicon Solution Incorporated

Justin Kim

Seong Jun Jang

Geun-Young Park

A resistive memory device implements a selective refresh operation in which only memory cells with reduced sense margin are refreshed. In some embodiments, the selective refresh operation introduces a sense margin guardband so that a memory cell having programmed resistance that falls within the sense margin guardband will be refreshed during the read operation. The selective refresh operation is performed transparently at each read cycle of the memory cells and only memory cells with reduced sense margins are refreshed.

Resistive memory device implementing selective memory cell refresh

A method in a resistive memory device includes configuring two or more memory cells in a column of the array sharing the same bit line and the same source line to operate in parallel as a merged memory cell; programming the resistance of the merged memory cell in response to the write data, the resistance of the two or more resistive memory cells in the merged memory cell being programmed simultaneously; and reading the programmed resistance value of the merged memory cell, the programmed resistance of the two or more memory cells in the merged memory cell being read simultaneously.

Method for improving sensing margin of resistive memory

A resistive memory device incorporates a reference current generation circuit to generate a reference current for the sense amplifier that is immune to variation in the resistance of the reference resistive memory cells. In some embodiments, the reference current generation circuit uses reference resistive memory cells configured in the low resistance state only. The reference current generation circuit generates the reference current by combining a reference cell current and a bias current. The bias current is regulated by a feedback circuit in response to changes in the reference current to maintain the reference current at a substantially constant value and having a current value being an average of the cell currents for a resistive memory cell in the high resistance state and the low resistance state.

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Seongnam, South Korea

Justin Kim