Flash Memory Read Threshold Adjustment via Error Feedback
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Solution Overview
Problem
Non-volatile memory systems, such as flash memory, face challenges in optimizing read thresholds due to limited endurance and data retention issues, leading to read retry errors and inefficiencies in adjusting read thresholds, which hinder memory performance and data integrity.
Innovation Solution
A feedback mechanism is implemented to dynamically optimize read thresholds using read retry errors, selecting candidate voltages from recovered read failures to adjust read threshold values, thereby improving memory efficiency and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If read threshold adjustments are made in small increments, then the adjustment process becomes more precise and controlled, but the ability to optimize read thresholds is hindered and more adjustments are required
Solution Approach 1:
The patent implements a feedback mechanism where read retry errors are captured and analyzed to determine optimized read threshold values. The system uses the error information as feedback to adjust thresholds more effectively, breaking the trade-off between precision and efficiency by making informed adjustments based on actual performance data rather than relying solely on small incremental changes
Solution Approach 2:
The system dynamically changes read threshold parameters based on feedback from read retry errors. Instead of fixed small increments, the threshold values are adjusted according to the specific error patterns observed, allowing for larger and more targeted parameter changes that optimize performance without requiring numerous small adjustments
2Area of stationary object
If memory cell dimension is scaled to smaller dimensions, then capacity per unit area increases, but cell endurance and data retention are degraded
Solution Approach 1:
The system uses feedback from read retry errors to dynamically adjust read thresholds, compensating for the reduced reliability inherent in smaller memory cells. By continuously monitoring error rates and adjusting thresholds based on this feedback, the system maintains data integrity despite the physical limitations of scaled memory cells
Solution Approach 2:
The patent dynamically changes operational parameters (read thresholds) to compensate for the degraded reliability of scaled memory cells. By adjusting thresholds based on observed error patterns, the system adapts to the reduced endurance and retention characteristics of smaller cells, maintaining effective data storage capacity
3Reliability
If read retry operations are performed frequently, then data integrity is improved, but memory efficiency decreases and latency increases
Solution Approach 1:
The system performs preliminary analysis of read retry errors to identify patterns and determine optimized threshold values in advance. By pre-processing error information and determining optimal thresholds before actual read operations, the system reduces the need for frequent read retries, thereby improving efficiency while maintaining data integrity
Solution Approach 2:
The patent dynamically changes read threshold parameters based on error feedback to minimize the frequency of read retry operations. By optimizing thresholds to match actual memory conditions, the system achieves high data integrity with fewer retry operations, thus improving overall memory efficiency and reducing latency
Data Source
AI summary
A storage device with a memory may optimize the setting of a read threshold or read level. A feedback mechanism may be used responsive to there being a read retry error for providing the read threshold from the read retry. Specifically, recovery from a read failure can provide feedback information for dynamically optimizing read threshold values. Read threshold adjustments may occur each time there is a successful error recovery. The read threshold adjustment scheme may select one logical page or multiple logical pages from a recovered region. If a read threshold is found to be working, this threshold may be part of a feedback message to make an informed adjustment that optimizes the read threshold of other pages.