Adaptive ECC Decoding in Memory Arrays for Speed-Accuracy Tradeoffs
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Solution Overview
Problem
High error rates in communication channels increase hardware complexity for error control code (ECC) encoding and decoding in memory devices, necessitating more efficient decoding methods to maintain performance.
Innovation Solution
Implementing ECC decoders in memory devices that selectively apply hard decision decoding or soft decision decoding based on error rates, with a control unit determining whether to perform additional read commands for soft decision decoding, and using internal and external decoders to iteratively adjust decoding processes and read voltages for improved accuracy and reduced decoding times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hard decision decoding is used, then decoding speed is improved, but decoding accuracy deteriorates
Solution Approach 1:
The system dynamically switches between hard decision decoding and soft decision decoding based on the error rate of read data. When error rate is high, soft decision decoding is applied for higher accuracy; when error rate is low, hard decision decoding is used for faster processing. This dynamic adaptation resolves the contradiction by making the decoding method flexible rather than fixed.
Solution Approach 2:
The system changes the decoding parameter (hard vs soft decision) based on the error rate condition. By monitoring the error rate and adjusting the decoding approach accordingly, the system optimizes both speed and accuracy for different operating conditions, resolving the inherent trade-off between these two parameters.
2Measurement precision
If soft decision decoding is used, then decoding accuracy is improved, but decoding time increases
Solution Approach 1:
The system dynamically selects the decoding method based on error rate conditions. Soft decision decoding is applied only when necessary (high error rate), while hard decision decoding is used for normal conditions. This dynamic selection achieves high accuracy when needed while minimizing decoding time in most cases.
Solution Approach 2:
Instead of always applying the more accurate but slower soft decision decoding, the system applies it partially - only when the error rate exceeds a threshold. For normal operating conditions, the faster hard decision decoding is sufficient, thus avoiding unnecessary time loss while maintaining adequate accuracy.
3Reliability
If concatenated encoder is used for high error rate channel, then error correction capability is improved, but hardware complexity increases
Solution Approach 1:
The system dynamically adjusts the decoding approach based on the actual error rate of read data rather than always using the full concatenated decoding structure. This allows the system to achieve necessary error correction capability only when high error rates occur, reducing hardware complexity for normal operating conditions.
Solution Approach 2:
The system changes the decoding parameter (hard vs soft decision) based on error rate conditions, allowing flexible error correction capability that adapts to channel conditions. This avoids the need for always-active complex concatenated decoding hardware, reducing overall device complexity while maintaining reliability when needed.
Data Source
AI summary
Memory devices and/or error control codes (ECC) decoding methods may be provided. A memory device may include a memory cell array, and a decoder to perform hard decision decoding of first data read from the memory cell array by a first read scheme, and to generate output data and error information of the output data. The memory device may also include and a control unit to determine an error rate of the output data based on the error information, and to determine whether to transmit an additional read command for soft decision decoding to the memory cell array based on the error rate. An ECC decoding time may be reduced through such a memory device.