Memory ECC Bit Flipping With Dynamic Soft-Bit Thresholds
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Solution Overview
Problem
Existing memory sub-systems face inefficiencies in error correction due to the susceptibility of bit-flipping algorithms to noise and lack of dynamic adjustment of bit flip thresholds, leading to suboptimal decoding efficiency and reliability.
Innovation Solution
A memory sub-system controller utilizes soft bits and match bits to determine dynamic bit flip thresholds during error correcting code operations, using a metadata table to adjust thresholds based on soft and match bit combinations, thereby improving decoding efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed bit flip thresholds are used in error correction, then device complexity is reduced, but decoding efficiency and reliability deteriorate due to inability to adapt to varying noise conditions
Solution Approach 1:
The patent implements dynamic bit flip thresholds that adapt during the decoding process based on the current state of the codeword and noise conditions, transforming the static threshold into a dynamic parameter that improves reliability without requiring complex external control mechanisms
Solution Approach 2:
The patent changes the threshold parameter based on the decoding state and noise characteristics, allowing the system to optimize its error correction performance by adjusting the bit flip threshold according to actual conditions rather than using a fixed value
2Productivity
If dynamic bit flip thresholds are implemented, then decoding efficiency and reliability are improved, but device complexity increases due to additional threshold adjustment mechanisms
Solution Approach 1:
The decoding system automatically adjusts its own bit flip thresholds based on internal state information and noise observations, eliminating the need for external control mechanisms and reducing overall system complexity while maintaining high decoding efficiency
3Adaptability or versatility
If static error correction thresholds are used, then ease of operation is maintained, but adaptability to different noise conditions deteriorates
Solution Approach 1:
The system uses feedback from the decoding process and noise observations to automatically adjust bit flip thresholds, achieving adaptability to different noise conditions while maintaining ease of operation through automated control rather than manual intervention
Data Source
AI summary
A soft input is obtained from a sense word corresponding to encoded host data read from the memory device and decoded using a parity-check matrix. A match array is maintained. Each iteration of an error correcting code operation a number of unsatisfied check nodes of a respective bit of the sense word is calculated for each bit of the sense word. A bit flip threshold from a threshold data structure is obtained based on a current iteration of the error correcting code operation, a soft bit associated with the respective bit, and a match bit associated with the respective bit. The respective bit is flipped based on the number of unsatisfied check nodes satisfying the bit flip threshold.