Memory Controller Read Fail Control Circuit Abnormal Voltage Distribution
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Solution Overview
Problem
Memory controllers face challenges in accurately reading data from memory cells with abnormal threshold voltage distributions, leading to failed read operations and subsequent error correction decoding failures.
Innovation Solution
A memory controller with a read fail control circuit that performs an assist read operation to determine optimal read voltages and an error correction code (ECC) engine to decode data using these voltages, while detecting abnormal threshold voltage distributions to prevent redundant error correction attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error correction decoding operations are performed on all read failures, then data recovery reliability improves, but processing time and computational resources are wasted on unrecoverable abnormal distributions
Solution Approach 1:
The patent performs a preliminary determination of threshold voltage distribution characteristics before executing error correction decoding operations. The read fail control circuit analyzes read-related information to identify whether the abnormal distribution is recoverable, thereby avoiding unnecessary decoding operations on unrecoverable cases and reducing wasted processing time.
Solution Approach 2:
The patent implements a feedback mechanism where the read fail control circuit continuously monitors read operation results and threshold voltage distribution characteristics. Based on this feedback, the system dynamically decides whether to proceed with error correction decoding or terminate the operation, optimizing the balance between data recovery reliability and processing efficiency.
2Measurement precision
If optimal read voltages are determined through assist read operations, then data reading accuracy improves, but additional operation time is required
Solution Approach 1:
The assist read operation is performed in advance to determine optimal read voltages before the actual data reading operation. This preliminary action ensures that the subsequent read operation uses optimized voltages for improved accuracy, while the time cost is incurred only once during the preliminary determination phase.
Solution Approach 2:
The system performs assist read operations selectively based on detected abnormal threshold voltage distributions, rather than on every read operation. This partial application of the voltage optimization process reduces the overall time overhead while maintaining accuracy improvements for the critical cases where abnormal distributions are present.
3Productivity
If abnormal threshold voltage distributions are detected and processed differently, then unnecessary decoding operations are prevented, but system complexity increases
Solution Approach 1:
The read fail control circuit is designed to perform multiple functions: normal read operations, assist read operations for voltage determination, threshold voltage distribution analysis, and error correction coordination. This multi-functional approach consolidates complexity into a single control unit rather than requiring separate dedicated circuits for each function.
Solution Approach 2:
The read fail control circuit acts as an intermediary between the read operation circuit and the error correction code engine. It receives read-related information, determines threshold voltage distribution characteristics, and based on this analysis, decides whether to forward data to the ECC engine or terminate the operation, thereby simplifying the overall system architecture through intelligent mediation.
Data Source
AI summary
Provided herein may be a memory controller and an operating method thereof. The memory controller may include: a read fail control circuit configured to perform, when the read operation fails, an assist read operation of determining optimal read voltages to be used to read the selected memory cells, and determine whether a threshold voltage distribution of the selected memory cells is an abnormal distribution based on read-related information obtained by the read operation and the assist read operation; and an error correction code (ECC) engine configured to perform an ECC decoding operation on hard decision data obtained by reading the selected memory cells using the optimal read voltages based on whether the threshold voltage distribution of the selected memory cells is the abnormal distribution.