Flash Memory Read Threshold Compression for Storage Efficiency
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Solution Overview
Problem
Flash memory devices face increased read errors due to threshold voltage distribution changes over time, requiring frequent adjustments of read thresholds, which is impractical for embedded systems with limited storage capacity.
Innovation Solution
A method to generate and store a compressed representation of reference read thresholds, allowing for efficient calculation and application of optimal read thresholds during flash memory operations, reducing the need for extensive storage of individual read threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual read threshold values are stored for each row and P/E cycle, then read accuracy is improved, but storage requirements increase significantly
Solution Approach 1:
The patent creates a compressed representation (copy) of the read threshold information that captures the essential characteristics without storing every individual threshold value. This compressed copy is then used to reconstruct or estimate the actual read thresholds needed for accurate reading operations, thereby reducing storage requirements while maintaining read accuracy.
Solution Approach 2:
The patent transforms the read threshold information from its original form (individual threshold values for each row and P/E cycle) into a compressed parameter representation. By changing the parameters from raw threshold values to compressed statistical or predictive parameters, the storage requirements are significantly reduced while the essential information is preserved for accurate read operations.
2Reliability
If read thresholds are frequently adjusted to account for retention and P/E cycle effects, then read reliability is improved, but system complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing compressed read threshold information that anticipates future read operations. This preliminary compressed representation allows the system to quickly reconstruct or estimate appropriate read thresholds without performing complex real-time calculations, thereby improving read reliability while managing system complexity.
Solution Approach 2:
The patent enables the flash memory system to self-adjust read thresholds using the stored compressed information. The system automatically reconstructs or estimates the necessary read thresholds based on the compressed representation and current operational conditions (such as P/E cycle count), reducing the need for external intervention or complex control mechanisms.
3Quantity of substance
If compressed representation is used to reduce storage, then storage efficiency is improved, but calculation complexity increases
Solution Approach 1:
The patent segments the read threshold information into manageable components that can be efficiently compressed and reconstructed. By dividing the threshold data into distinct segments (such as per-row or per-block compressed representations), the system reduces storage requirements while keeping the reconstruction calculations manageable and localized to specific segments rather than requiring processing of all threshold data simultaneously.
Data Source
AI summary
A method comprising: generating or receiving read threshold information indicative of multiple read thresholds values that were applied when reading multiple flash memory cells that belong to multiple rows of a flash memory module; and generating a compressed representation of reference read thresholds to be applied during future read operations of the flash memory cells in response to the read threshold information.