Analog Memory Cell Re-Read Using Suspect ECC Bits
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Solution Overview
Problem
Existing data retrieval methods from analog memory cells involve multiple read operations, which increase the number of operations and information volume, limiting data retrieval speed, especially when ECC decoding is performed in a separate device and results are transferred over a limited-bandwidth interface.
Innovation Solution
The method involves initially reading storage values from analog memory cells using a certain threshold, identifying suspect values that may cause ECC decoding failure, re-reading these values using different thresholds, and transferring only the re-read results to the ECC decoder for re-decoding, thereby reducing the volume of information transferred and focusing on suspect values that affect decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple read operations are performed to ensure accurate data retrieval from analog memory cells, then data accuracy is improved, but the number of operations and information volume increase, limiting data retrieval speed
Solution Approach 1:
The patent extracts and identifies only the suspect storage values that may cause ECC decoding failure, rather than processing all read values. By isolating and re-reading only these suspect values, the system maintains data accuracy while significantly reducing the volume of data that requires multiple read operations and transfer over the interface.
Solution Approach 2:
The patent segments the data retrieval process into distinct phases: initial read, ECC decoding attempt, identification of suspect values, and targeted re-read of only those suspect values. This segmentation allows the system to perform multiple read operations selectively rather than uniformly across all data, improving overall retrieval speed while maintaining accuracy.
2Adaptability or versatility
If ECC decoding is performed in a separate device with transfer over limited-bandwidth interface, then system modularity is improved, but the volume of information transferred limits data retrieval speed
Solution Approach 1:
The patent extracts only the suspect storage values that require re-reading and transfers only these extracted values over the interface to the separate ECC decoding device. This dramatically reduces the volume of information transferred over the limited-bandwidth interface compared to transferring all read values, while maintaining the benefits of modular system architecture.
3Reliability
If re-read operations are performed on all memory cells, then data accuracy is improved, but the number of operations increases significantly
Solution Approach 1:
The patent identifies and extracts only the suspect storage values that may cause ECC decoding failure, and performs re-read operations exclusively on these extracted suspect values rather than on all memory cell values. This selective approach maintains data accuracy by addressing potential errors while minimizing the time loss associated with re-read operations.
Solution Approach 2:
The patent applies partial action by performing re-read operations on only a subset (the suspect values) of the total memory cell values, rather than performing excessive re-read operations on all values. This partial approach is sufficient to maintain data accuracy while significantly reducing the time required for re-read operations.
Data Source
AI summary
A method for data storage includes storing data, which is encoded with an Error Correction Code (ECC), in a group of analog memory cells by writing respective first storage values to the memory cells in the group. After storing the data, respective second storage values are read from the memory cells in the group, and the read second storage values are processed so as to decode the ECC. Responsively to a failure in decoding the ECC, one or more of the second storage values that potentially caused the failure are identified as suspect storage values. Respective third storage values are re-read from a subset of the memory cells that includes the memory cells holding the suspect storage values. The ECC is re-decoded using the third storage values so as to reconstruct the stored data.