Memory Controller Scrambling and ECC for NAND Read Errors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonvolatile memory devices, such as NAND-type flash memory devices, face reliability issues due to cell-to-cell interference and high error rates, particularly in multi-level cell structures, which necessitate the use of error correction codes to ensure data integrity.
Innovation Solution
An error correction apparatus comprising a scrambler, ECC encoder, ECC decoder, and descrambler is implemented to randomize data, perform ECC encoding and decoding, and restore the original bit array sequence, thereby reducing noise effects and correcting errors in read data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-level cell (MLC) techniques are used to increase integration density, then the number of bits stored per cell increases, but cell-to-cell interference occurs and data errors increase
Solution Approach 1:
The patent applies preliminary action by performing scrambling operations on data before it is written to the memory device. The scrambler randomizes the data patterns in advance, preventing the formation of continuous same-level signals that cause noise effects. This preliminary randomization ensures that even when MLC techniques are used to increase bits per cell, the resulting cell-to-cell interference and data errors are minimized because the data patterns written to adjacent cells are randomized and less likely to cause interference.
2Manufacturing precision
If advanced process techniques are used to reduce minimum feature size, then integration density increases, but reliability of the memory device degrades
Solution Approach 1:
The patent applies preliminary action by implementing scrambling operations before data writing. The scrambler randomizes data patterns in advance, converting continuous same-level signals into randomized patterns. This preliminary processing compensates for the reliability degradation caused by advanced process techniques by ensuring that even with reduced minimum feature sizes, the actual data patterns stored are less susceptible to manufacturing variations and interference.
Solution Approach 2:
The patent applies feedback by using randomness checkers that monitor the scrambled data and generate control signals based on the randomness level. The system continuously checks the randomness of scrambled data and adjusts scrambling operations accordingly. This feedback mechanism ensures that even when advanced process techniques introduce variability, the system can detect and compensate for patterns that might lead to errors, thereby maintaining reliability despite reduced feature sizes.
3Quantity of substance
If nonvolatile memory devices with narrow read margin are used, then data storage capacity increases, but error rate increases due to difficulty in recognizing data differences
Solution Approach 1:
The patent applies preliminary action by scrambling data before writing to the memory device. This randomization prevents continuous same-level patterns that would be particularly problematic for memory devices with narrow read margins. By ensuring that data patterns are randomized in advance, the system reduces the likelihood of storing patterns that are difficult to distinguish during reading, thereby compensating for the narrow read margin while maintaining high storage capacity.
Solution Approach 2:
The patent applies feedback through randomness checkers that monitor data patterns and generate control signals to adjust scrambling operations. This feedback ensures that data patterns suitable for storage in devices with narrow read margins are selected and randomized appropriately, making it easier to recognize data differences during reading while preserving the high storage capacity enabled by multi-level cell structures.
Data Source
AI summary
An error correction apparatus may be provided. The error correction apparatus may be configured to perform a scrambling operation before an error correction code (ECC) operation is performed.