Memory Controller Strong Error Information Management
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Solution Overview
Problem
As the storage capacity and number of bits per memory cell in flash memory increase, the narrow threshold voltage distributions lead to a higher number of errors, making error correction challenging, especially when strong errors occur, which can render data unreliable.
Innovation Solution
A memory controller that periodically or aperiodically monitors strong error information by collecting hard and soft decision data using different read levels, generates and updates strong error information, and uses this information for error correction, optimizing recovery algorithms and reducing data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the storage capacity and number of bits per memory cell are increased, then the storage capacity is improved, but the threshold voltage distribution interval becomes narrower leading to increased errors
Solution Approach 1:
The patent segments the error correction process by dividing memory cells into monitoring units and separately managing strong error information for each unit. This segmentation allows targeted error correction strategies for high-density storage regions, improving reliability without sacrificing storage capacity.
Solution Approach 2:
The patent performs preliminary action by proactively monitoring and collecting strong error information from memory cells before actual data read operations. This advance error detection and classification enables the system to prepare correction strategies in advance, improving data reliability in high-capacity storage configurations.
2Reliability
If hard decision information and soft decision information are collected using different read levels, then error correction capability is improved, but the time required for error recovery increases
Solution Approach 1:
The patent applies preliminary action by collecting and processing hard decision and soft decision information in advance during normal read operations. This pre-collected strong error information is stored and ready for immediate use when errors occur, enabling fast error recovery without requiring time-consuming re-reading operations.
Solution Approach 2:
The system implements self-service by maintaining its own strong error information database that automatically updates during normal operations. When errors occur, the system uses this pre-built information to self-correct without external intervention or time-consuming diagnostic procedures, reducing error recovery time while maintaining high correction capability.
3Reliability
If strong error information is monitored and updated periodically, then data reliability is improved, but the complexity of the memory controller increases
Solution Approach 1:
The patent reduces controller complexity by segmenting the monitoring function into discrete monitoring units with dedicated strong error information storage. Each monitoring unit independently tracks errors, allowing the controller to manage complexity through modular organization rather than centralized complex processing.
Solution Approach 2:
The monitoring system implements self-service by automatically collecting, processing, and updating strong error information during normal read operations without requiring additional controller intervention. This autonomous operation reduces the burden on the memory controller, maintaining data reliability while minimizing added complexity.
Data Source
AI summary
A method of operating a memory controller includes: collecting hard decision information based on data read from memory cells of a monitoring unit using a normal read level; collecting soft decision information based on data read from the monitoring unit using one or more offset read levels that are different from the normal read level; storing first strong error information determined based on the hard decision information and the soft decision information in a memory in the memory controller; and updating second strong error information determined for the monitoring unit in the memory after the first strong error information is stored. The second strong error information is used to correct an error in data read in response to a read request from a host.