One-Sided Soft Reads for Flash Memory Latency Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flash memory systems face challenges in accurately reading data due to nonvolatile storage errors, which are not fully correctable by existing error correction techniques, and traditional soft reads increase latency significantly.
Innovation Solution
The implementation of one-sided soft reads, where additional read strobes are applied either above or below the expected reference read voltage, providing reliability information without significantly increasing latency, by determining the side of the read reference voltage based on error patterns and applying fewer read strobes compared to traditional soft reads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional soft reads are performed by applying additional read strobes above and below the reference voltage, then error correction reliability is improved, but read latency increases significantly
Solution Approach 1:
The patent extracts only the necessary soft read operations by determining error patterns from initial reads and applying additional read strobes only on the specific side (above or below reference voltage) where errors are detected, rather than performing reads on both sides as in traditional soft reads. This selective approach maintains error correction reliability while reducing the number of operations and latency.
Solution Approach 2:
The patent applies partial action by performing only the minimum necessary additional read operations based on detected error patterns. Instead of always performing complete soft reads with strobes on both sides, the system performs partial soft reads with strobes applied only where needed, reducing overall read latency while maintaining sufficient error correction capability.
2Reliability
If error correction techniques are applied to flash storage reads, then data accuracy is improved, but read operation latency increases
Solution Approach 1:
The patent uses feedback from initial read operations to detect error patterns and dynamically determines whether additional read strobes are needed and on which side to apply them. This feedback mechanism allows the system to apply error correction only when and where necessary, improving data accuracy without uniformly increasing latency for all read operations.
Solution Approach 2:
The patent makes the read operation dynamic by adapting the number and position of additional read strobes based on real-time error pattern detection. The system transitions from static traditional soft reads (always applying strobes on both sides) to dynamic one-sided soft reads (applying strobes only where errors are detected), optimizing the balance between data accuracy and read latency.
3Measurement precision
If multiple read strobes are applied to determine reliability information, then read accuracy is improved, but the complexity of the read operation increases
Solution Approach 1:
The patent extracts only the necessary reliability information by determining error patterns from initial reads and applying additional read strobes only on the specific side where errors are detected. This selective extraction of soft read operations reduces the number of read strobes required compared to traditional methods, improving read accuracy while reducing operational complexity.
Data Source
AI summary
One-sided soft reads can enable improved error-correction over regular reads without significantly increasing the latency for reads. In one example, a flash storage device includes an array of storage cells and a controller to access the array of storage cells. The controller is to perform at least one read of a storage cell to cause a read strobe to be applied at an expected read reference voltage and also cause one or more additional read strobes to be applied at voltages on only one side of the expected read reference voltage (e.g., which in some cases involves applying the additional one or more read strobes at a voltage with a slightly lower or higher magnitude than the magnitude of the expected read reference voltage). The controller can then provide a logic value and one or more bits indicating confidence or reliability of the logic value's accuracy based on an electrical response of the storage cell to the read strobe and the one or more additional read strobes.