Abstract: 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.

Abstract: A non-volatile memory device includes a two-dimensional array of non-volatile memory cells where a first portion of memory cells being configured as an one-time-programmable memory area; a bypass read-out circuit configured to sense a signal level on a bit line in response to a memory cell in the one-time-programmable memory area being selected and to generate a first signal indicative of the signal level on the bit line; and a trim data latch circuit having an input terminal configured to receive the first signal. The trim data latch circuit is configured to store a signal related to the first signal as a trim data value and to provide trim data value to circuitry of the non-volatile memory device. The trim data value may be applied to adjust a signal level of the circuitry of the non-volatile memory device.

Abstract: A non-volatile memory device includes a sector pass/fail indicator circuit configured to store a pass/fail indicator for each sector in a first block of memory cells. The pass/fail indicator has a first value indicating the respective sector has failed erase verification and has a second value indicating the respective sector has passed erase verification. The sector pass/fail indicator circuit set the respective pass/fail indicators to the second value for one or more sectors in the first block after the respective sectors pass erase verification following a previous block erase operation of the first block. The first block is subjected to subsequent block erase operation where only word lines associated with the sectors having a pass/fail indicator having the first value are biased to the first bias voltage level.

Abstract: 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.

Abstract: 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.

Abstract: A flash memory device uses a pair of parallely connected NMOS transistors with different voltage ratings to generate the reference current for the sense amplifier used in the read out operations. The reference current thus generated is temperature compensated with zero or near-zero temperature coefficient. In some embodiments, the pair of parallely connected NMOS transistors includes a high voltage NMOS transistor and a low voltage NMOS transistor or NMOS transistors with different gate oxide thicknesses.

Abstract: A memory device using error correction code (ECC) implements a memory array parallel read-write method to reduce the storage overhead required for storing ECC check bits. The memory array parallel read-write method stores incoming address and data into serial-in parallel-out (SIPO) address registers and write data registers, respectively. The stored data are written to the memory cells in parallel when the SIPO registers are full. ECC check bits are generated for the block of parallel input data stored in the write data registers. During the read operation, a block of read out data corresponding to the read address are read from the memory cells in parallel and stored in read registers. ECC correction is performed on the block of read out data before the desired output data is selected for output.

Abstract: 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.

Abstract: 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.

Abstract: A method in a memory device implementing error correction includes setting an error correction event register to a first value; assessing a memory location in the first memory array in response to a memory address; retrieving stored memory data from the assessed memory location in the first memory array and retrieving error correction check bits corresponding to the assessed memory location from the second memory array; checking the retrieved memory data for bit errors using the retrieved check bits; in response to a bit error being detected in the retrieved memory data, generating corrected memory data using the retrieved check bits and asserting an error correction event signal; and in response to the error correction event signal being asserted, setting the error correction event register to a second value.

Abstract: A non-volatile memory device incorporates a write buffer within a multi-level column decoder to enable multiple memory cells associated with a single write driver to be written in parallel. In this manner, in a non-volatile memory such as a flash memory that performs batch write operation, a group of data bits for a single I/O can be written to the memory cells at a time, thereby reducing the number of write cycles required for writing a block of program data and increasing the speed of write operation.

Abstract: A non-volatile memory device includes a two-dimensional array of non-volatile memory cells where a first portion of memory cells being configured as an one-time-programmable memory area; a bypass read-out circuit configured to sense a signal level on a bit line in response to a memory cell in the one-time-programmable memory area being selected and to generate a first signal indicative of the signal level on the bit line; and a trim data latch circuit having an input terminal configured to receive the first signal. The trim data latch circuit is configured to store a signal related to the first signal as a trim data value and to provide trim data value to circuitry of the non-volatile memory device. The trim data value may be applied to adjust a signal level of the circuitry of the non-volatile memory device.

Abstract: A flash memory device uses a pair of parallely connected NMOS transistors with different voltage ratings to generate the reference current for the sense amplifier used in the read out operations. The reference current thus generated is temperature compensated with zero or near-zero temperature coefficient. In some embodiments, the pair of parallely connected NMOS transistors includes a high voltage NMOS transistor and a low voltage NMOS transistor or NMOS transistors with different gate oxide thicknesses.

Abstract: A flash memory device employs a low current auto-verification programming scheme using multi-step programming voltage and cell current detection. The low current auto-verification programming scheme performs programming of memory cells by the application of programming voltages in step increments. For each programming pulse, the cell current of the memory cell is sensed to determine when the memory cell is programmed. The programming pulse is terminated when the cell current decreases below a reference current level.

Abstract: A non-volatile memory device includes a control circuit configured to perform a block erase operation including a block erase cycle and an erase verify cycle on a block of memory cells. The control circuit is configured to perform the erase verify cycle by storing a last verify address for each sector of the block of memory cells, verifying each memory cell in a sector starting from the last verify address for the sector until a memory cell has failed erase verification in that sector, storing the memory cell address of the failed memory cell as the last verify address for that sector, skipping the erase verification for the remaining memory cells in that sector, and continuing the erase verify cycle at a last verify address for the next sector.

Abstract: A non-volatile memory device includes a sector pass/fail indicator circuit configured to store a pass/fail indicator for each sector in a first block of memory cells. The pass/fail indicator has a first value indicating the respective sector has failed erase verification and has a second value indicating the respective sector has passed erase verification. The sector pass/fail indicator circuit set the respective pass/fail indicators to the second value for one or more sectors in the first block after the respective sectors pass erase verification following a previous block erase operation of the first block. The first block is subjected to subsequent block erase operation where only word lines associated with the sectors having a pass/fail indicator having the first value are biased to the first bias voltage level.

Abstract: A non-volatile memory device includes a sector pass/fail indicator circuit configured to store a pass/fail indicator for each sector in a first block of memory cells. The pass/fail indicator has a first value indicating the respective sector has failed erase verification and has a second value indicating the respective sector has passed erase verification. The sector pass/fail indicator circuit set the respective pass/fail indicators to the second value for one or more sectors in the first block after the respective sectors pass erase verification following a previous block erase operation of the first block. The first block is subjected to subsequent block erase operation where only word lines associated with the sectors having a pass/fail indicator having the first value are biased to the first bias voltage level.

Abstract: A method to trim a reference voltage source formed on an integrated circuit includes configuring the integrated circuit in a test mode; providing a power supply voltage and a trim code sequence to the integrated circuit where the power supply voltage is provided by a precision reference voltage source; generating a target voltage on the integrated circuit using the power supply voltage; generate a reference voltage using the reference voltage source formed on the integrated circuit; applying one or more trim codes in the trim code sequence to the reference voltage source to adjust the reference voltage; comparing the reference voltage generated based on the trim codes to the target voltage; asserting a latch signal in response to a determination that the reference voltage generated based on a first trim code is equal to the target voltage; and storing the first trim code in response to the latch signal being asserted.

Abstract: 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.

Abstract: A regulator for regulating the output from a high-voltage pump, Vpump, to provide a regulated load voltage, Vpp, to a load in MOSFET integrated circuits. The regulator includes a MOSFET switch which when enabled in a first state connects Vpp to the integrated circuit voltage level, Vcc, and which when disabled in a second state allows Vpp to be driven to levels greater than Vcc. The regulator includes a multipath control circuit for controlling the switch state and for controlling Vpp. A first current path, Iramp, controls the rise-time parameters of Vpp and a second current path, Idis, controls the fall-time parameters of Vpp. The rise-time parameters and the fall-time parameters are separately controlled.