Simtek Corporation

Microchip Technology Inc.

Christian E Herdt

Albert Weiner

Paul Fredrick Ruths

Daryl G Dietrich

John Roger Gill

Steven H Cliadakis

David A Kamp

Klaus J Dimmler

The invention relates to a NAND stack EEPROM that with random programming capability. In one embodiment, dynamic program inhibit is used to achieve random programming the memory cells within a NAND stack.

NAND stack EEPROM with random programming capability

The invention relates to a non-volatile, static random access memory (nvSRAM) in which there are at least two, non-volatile memory cells associated with each SRAM memory cell. The non-volatile memory cells are capable of being programmed with whatever bit of information is present in the SRAM at two different times. In one embodiment, the non-volatile memory cells are capable of being randomly programmed, i.e., programmed in any order. Further, the bits of data programmed into the non-volatile memory cells can be recalled in any order, i.e., randomly recalled.

nvSRAM with multiple non-volatile memory cells for each SRAM memory cell

The invention relates to a non-volatile, static random access memory (nvSRAM) device that is capable of high speed copying of the data in the static random access portion of the device into the non-volatile portion of the device after the detection of possible loss of power. This is accomplished by preparing the non-volatile portion for receiving a bit of data from the SRAM portion before the possible loss of power is detected, i.e., pre-arming the device. In one embodiment, the pre-arming is accomplished by erasing the non-volatile portion during the time when the power supply is stable and data can be transferred between the SRAM portion and the exterior environment. In another embodiment, pre-arming is accomplished by erasing the non-volatile portion immediately after power has been provided to the device and data from the non-volatile portion has been copied into the SRAM in a recall operation. Another aspect of the invention provides for the decoupling of the erase and store operations. This facilitate, for example, the erase of the data in the non-volatile portion of the nvSRAM without a subsequent copying of data in the SRAM portion into the non-volatile portion.

Non-volatile, static random access memory with high speed store

The invention relates to a non-volatile, static random access memory (nvSRAM) device that addresses the consequence of a manufacturing defect that occasionally occurs during mass production of the nvSRAM device and if not addressed, reduces the yield of the production process. The consequence of the defect is termed a store disturb because the execution of a store operation in a defective nvSRAM causes the bit of data retained in the SRAM portion and, in some cases, the nv portion of the nvSRAM to be instable or corrupted. The present invention provides an nvSRAM device in which the controller provides modified signals to the nvSRAM memory portion of the device that address the store disturb phenomena and, as a consequence, improve the yield of the manufacturing process.

Non-volatile, static random access memory with store disturb immunity

A semiconductor memory device is disclosed that provides replacement of defective main memory portions with operational redundant memory portions. The device includes fuse circuitry that comprises both nonvolatile and volatile memory portions. Because the fuse circuitry includes a volatile memory portion in addition to a nonvolatile memory portion, additional functionality may be achieved by the fuse circuitry. For example, the volatile portion of the fuse circuitry allows the retention of the nonvolatile portion of the circuitry to be tested using standard testing techniques. In addition, the volatile memory portion provides a way for easily utilizing unused redundant memory. In one embodiment of the present invention, a semiconductor memory device is provided that uses nvSRAM cells as the main storage element in the main memory area, the redundant memory area, and in the fuse circuitry.

Memory with electrically erasable and programmable redundancy

The present invention provides a non-volatile, static random access memory (nvSRAM) cell with a current limiting feature that prevents current that is provided to the cell or array of cells during a recall operation in which information is transferred from the non-volatile portion of the cell or array to the static random access memory portion of the cell or array from reaching a point that would be detrimental to the cell or array. The current limiting device is located between the nvSRAM cell or array of cells and ground. In one embodiment, the current limiting device includes a variable resistance and a device for modulating the resistance so that the resistance is high at the beginning of a recall operation and decreases thereafter.

Non-Volatile, static random access memory with current limiting

The present invention provides a computer memory device having a sleep mode characterized by extremely low current consumption and relatively large turn on delay. The invention includes circuitry for disabling current sinking elements internal to said device in response to a sleep signal. In one embodiment, the invention includes circuitry for disconnecting the bit lines and memory cell loads of a nonvolatile static random access memory (nvSRAM) array from a source of power in response to a sleep signal. This embodiment is capable of first transferring the data stored in a volatile portion of the array to a nonvolatile portion of the array before entering sleep mode to prevent loss of the data.

Semiconductor memory device having a sleep mode

A non-volatile random access memory (NVRAM) cell of condensed size employs a pair of programmable threshold voltage devices, e.g. MNOS (metal nitride oxide semiconductor), SNOS (silicon nitride oxide semiconductor), SONOS (silicon oxide-nitride-oxide semiconductor) or floating gate transistors, in which different threshold voltage levels are established in accordance with the data signal levels existing on the data nodes of a flip flop, when the volatile data is stored in the programmable devices. During recall of the non-volatile stored data to the data nodes of the flip flop, the programmable devices actively conduct current to the data nodes to set the flip flop in the same state that existed when the data was stored. Power is supplied to the flip flop independently of the power supplied to the programmable devices. A single polysilicon conductor forms gates of transistors which connect the programmable devices to the data nodes and the gates of the flip flop transistors. A load device for each data node is integrated in the single polysilicon conductor. A dynamic program inhibit capability is achieved in each programmable device during the store operation, by applying a series of programming signal pulses.

Non-volatile RAM with integrated compact static RAM load configuration

Faster access time is achieved in a NAND stack ROM by eliminating depletion mode decode transistors, thus reducing column capacitance. Horizontal ground straps of diffusion are eliminated to reduce chip area by running virtual ground lines vertically through the array. Adjacent columns are tied to alternating sense amplifiers utilizing a simple multiplexer connected to the virtual ground lines.

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Monument, CO, United States of America

Christian E Herdt