Abstract: 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.

Abstract: 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.

Abstract: One embodiment of the differential sense amplifier of the present includes a pair of amplifier portions, each of which includes a reference branch and an amplifying branch. Each amplifier portion amplifies one input signal of the differential input signal applied to the differential sense amplifier by an amount related to the difference between the applied input signal and a reference signal established by the reference branch of the amplifier portion. The input signals are cross-coupled between the amplifier portions so that each input signal is applied to the reference branch of one amplifier portion and to the amplifying branch of the other amplifier portion. Separate reference nodes and reference signals are established for each amplifier portion. A change in the differential input signal creates correspondingly opposite changes in the magnitude of the reference signal and the input signal applied to the amplifying branch of both amplifier portions to provide greater gain and sensitivity.

Abstract: 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.