Integrated Silicon Solution Incorporated

Other

Seong Jun Jang

Geun-Young Park

Justin Kim

A memory device incorporates a chip enable protection circuit implementing a secured chip enable method providing a passcode protected enable scheme with secure chip disable for the memory device. The passcode can be programmed at manufacturing or programmed by the user. Memory device access is enabled by receiving the correct passcode and memory device access is denied when the wrong passcode is entered. Furthermore, the secured chip enable method implements secure chip disable where the memory device is disabled in response to receiving wrong passcodes repeatedly for a maximum number of tries.

Secured chip enable with chip disable

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 circuit for detecting a signal transition on an input signal includes a mirror delay circuit and an input blocking circuit to prevent signal glitches or undesired signal pulses from being passed to the output signal node, thereby preventing signal distortions from being detected as a valid signal transition. The input transition detection circuit generates stable and correct transition detection pulses having a consistent pulse width.

Glitch free input transition detector

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.

Reference current generation in resistive memory device

Glitch-free input transition detector

Method and apparatus for producing paper powder from paper-like sheet material by initially corrugating the sheet material so as to stiffen it and thereafter while so stiffened repeatedly impacting it so as to pulverize it into powder.

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San Jose, CA, United States of America

Seong Jun Jang