Flash Memory Error Recovery Using Modified Reference Voltages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for reading data from flash memory, particularly Multi-Bit Cells, face errors due to threshold voltage drift, leading to longer read and write times and lower reliability, with current error correction techniques being slow and inefficient as they require repeated writing operations to correct errors.
Innovation Solution
A method that involves reading data bits from flash memory cells, attempting error correction, and re-reading using modified reference voltages until successful correction is achieved, without rewriting the data, and storing successful reference voltages for subsequent reads, allowing for faster error recovery without the need for repeated writing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If repeated writing operations are used to correct errors in flash memory, then error correction can be achieved, but read and write times increase and reliability decreases
Solution Approach 1:
The patent extracts the error correction process from the writing operation. Instead of rewriting data to correct errors, the system separates error detection and correction into a standalone reading process that uses modified reference voltages. This allows error correction without requiring repeated write cycles, thereby reducing time loss while maintaining reliability.
Solution Approach 2:
The patent implements feedback by using the results of error correction to adjust subsequent reading operations. When errors are detected and corrected using modified reference voltages, the system feeds back this information to optimize future reads, reducing the need for repeated writing operations and improving overall efficiency.
2Reliability
If traditional error correction techniques are used, then data integrity can be maintained, but the process becomes slow and inefficient
Solution Approach 1:
The patent applies preliminary action by pre-establishing multiple reference voltages at different levels before reading operations. This allows the system to quickly identify and correct errors by comparing readings against these pre-prepared reference levels, avoiding the need for slow, iterative writing-based correction processes and significantly improving error correction speed while maintaining data integrity.
3Reliability
If multiple reading attempts with modified reference voltages are made, then error correction success rate improves, but reading time increases
Solution Approach 1:
The patent applies dynamics by making the reference voltage selection adaptive rather than static. The system dynamically chooses which reference voltages to use based on the actual reading results and error patterns detected. This allows the system to achieve high error correction success rates by intelligently selecting the most effective reference voltages, while minimizing unnecessary reading attempts and reducing overall reading time.
Data Source
AI summary
Methods, devices and computer readable code for reading data from one or more flash memory cells, and for recovering from read errors are disclosed. In some embodiments, in the event of an error correction failure by an error detection and correction module, the flash memory cells are re-read at least once using one or more modified reference voltages, for example, until a successful error correction may be carried out. In some embodiments, after successful error correction a subsequent read request is handled without re-writing data (for example, reliable values of the read data) to the flash memory cells in the interim. In some embodiments, reference voltages associated with a reading where errors are corrected may be stored in memory, and retrieved when responding to a subsequent read request. In some embodiments, the modified reference voltages are predetermined reference voltages. Alternatively or additionally, these modified reference voltages may be determined as needed, for example, using randomly generated values or in accordance with information provided by the error detection and correction module. Methods, devices and computer readable code for reading data for situations where there is no error correction failure are also provided.