A semiconductor memory device includes a memory cell array having a first group of main blocks, a second group of main blocks and redundancy blocks replacing the first group of main blocks or the second group of main blocks, a repair logic suitable for enabling a replacement signal when one or more of the second group of main blocks are defective, a control logic suitable for generating an address for the second group of main blocks in response to a dedicated command for access to one or more of the second group of main blocks, and an address decoder suitable for selecting one or more of the redundancy blocks based on the address for the second group of main blocks when the replacement signal is enabled.

Semiconductor memory device and method of operating the same

A method for operating a memory (28) that includes a plurality of analog memory cells (32) includes storing data in the memory by writing first storage values to the cells. Second storage values are read from the cells, and a Cumulative Distribution Function (CDF) of the second storage values is estimated. The estimated CDF is processed so as to compute one or more thresholds. A memory access operation is performed on the cells using the one or more thresholds.

Adaptive Estimation of Memory Cell Read Thresholds

A NAND controller for interfacing between a host device and a flash memory device (e.g. a NAND flash memory device) fabricated on a flash die is disclosed. In some embodiments, the presently disclosed NAND controller includes electronic circuitry fabricated on a controller die, the controller die being distinct from the flash die, a first interface (e.g. a host-type interface, for example, a NAND interface) for interfacing between the electronic circuitry and the flash memory device, and a second interface (e.g. a flash-type interface) for interfacing between the controller and the host device, wherein the second interface is a NAND interface. According to some embodiments, the first interface is an inter-die interface. According to some embodiments, the first interface is a NAND interface. Systems including the presently disclosed NAND controller are also disclosed. Methods for assembling the aforementioned systems, and for reading and writing data using NAND controllers are also disclosed.

NAND flash memory controller exporting a NAND interface

An indicia-reading system is provided that incorporates a hybrid approach to decoding indicia such as barcodes. An indicia-capturing subsystem acquires information about indicia within the indicia-capturing subsystem's field of view. An indicia-decoding module decodes indicia information acquired by the indicia-capturing subsystem. The indicia-decoding module includes a primary, basic signal processor for initially decoding indicia information, and a secondary, advanced signal processor for decoding indicia information that is not decoded by the primary, basic signal processor.

Hybrid system and method for reading indicia

A method for decoding a plurality of flash memory cells which are error-correction-coded as a unit, the method comprising providing a hard-decoding success indication indicating whether or not hard-decoding is at least likely to be successful; and soft-decoding the plurality of flash memory cells at a first resolution only if the hard-decoding success indication indicates that the hard-decoding is not at least likely to be successful.

Flash memory apparatus and methods using a plurality of decoding stages including optional use of concatenated BCH codes and/or designation of “first below” cells

To store a plurality of input bits, the bits are mapped to a corresponding programmed state of one or more memory cells and the cell(s) is/are programmed to that corresponding programmed state. The mapping may be many-to-one or may be an “into” generalized Gray mapping. The cell(s) is/are read to provide a read state value that is transformed into a plurality of output bits, for example by maximum likelihood decoding or by mapping the read state value into a plurality of soft bits and then decoding the soft bits.

Multi-bit-per-cell flash memory device with non-bijective mapping

Data bits to be encoded are split into a plurality of subgroups. Each subgroup is encoded separately to generate a corresponding codeword. Selected subsets are removed from the corresponding codewords, leaving behind shortened codewords, and are many-to-one transformed to condensed bits. The final codeword is a combination of the shortened codewords and the condensed bits. A representation of the final codeword is decoded by being partitioned to a selected subset and a plurality of remaining subsets. Each remaining subset is decoded separately. If one of the decodings fails, the remaining subset whose decoding failed is decoded at least in part according to the selected subset. If the encoding and decoding are systematic then the selected subsets are of parity bits.

Method and device for multi phase error-correction

A plurality of logical pages is stored in a MBC flash memory along with corresponding ECC bits, with at least one of the MBC cells storing bits from more than one logical page, and with at least one of the ECC bits applying to two or more of the logical pages. When the pages are read from the memory, the data bits as read are corrected using the ECC bits as read. Alternatively, a joint, systematic or non-systematic ECC codeword is computed for two or more of the logical pages and is stored instead of those logical pages. When the joint codeword is read, the logical bits are recovered from the codeword as read. The scope of the invention also includes corresponding memory devices, the controllers of such memory devices, and also computer-readable storage media bearing computer-readable code for implementing the methods.

Method of error correction in MBC flash memory

A multi-level flash memory cell is read by comparing the cell's threshold voltage (111, 110, 101, 100, 011, 010, 001, 000) to a plurality of integral reference voltages (Vmin, V1, V2, V3, V4, V5, V6, V7, and Vmax) and to a fractional reference voltage (V0.5, V1.5, V2.5, V3.5, V4.5, V5.5, V6.5, and V7.5). Multi-level cells of a flash memory are programmed collectively with data and redundancy bits at each significance level, preferably with different numbers of data and redundancy bits at each significance level. The cells are read collectively, from lowest to highest significance level, by correcting the bits at each significance level according to the redundancy bits and adjusting the bits of the higher significance levels accordingly. The adjustment following the correction of the least significant bits is in accordance with comparisons of a cell's threshold voltages to fractional reference voltages.

Methods of increasing the reliability of a flash memory

A device for storing data includes a nonvolatile memory and a controller and/or circuitry that randomize original data to be stored in the memory while preserving the size of the original data, that store the original data in the memory, and that, in response to a request for the original data, retrieve, derandomize and export the original data without authenticating the requesting entity. A system for storing data includes a first nonvolatile memory and a processor that similarly stores data in the first nonvolatile memory by executing driver code stored in a second nonvolatile memory. ECC encoding is applied either before or after randomizing; correspondingly, ECC decoding is applied either after or before derandomizing.

Idan Alrod

Papers

Multi-bit-per-cell flash memory device with non-bijective mapping

Method and device for multi phase error-correction

Method of error correction in MBC flash memory

Methods of increasing the reliability of a flash memory

Flash memory device and system with randomizing for suppressing errors