Memory Read Threshold Control for Reliable Soft-Decoding Throughput

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Solution Overview

Problem

Existing data storage systems face challenges in maintaining readout reliability and throughput due to the degradation of memory cells over time, which affects the accuracy and efficiency of error correction and data retrieval.

Innovation Solution

The system adjusts the interval between read thresholds for soft decoding schemes to optimize error correction capabilities and compression rates, allowing for adaptive switching between hard and soft decoding based on error levels and stress conditions, thereby maintaining high reliability and throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the interval between read thresholds is reduced to improve soft decoding capability, then error correction capability is improved, but compression rate decreases and readout throughput is reduced

Engineering Contradiction:
Improveerror correction capabilityVSAvoidreadout throughput
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts the interval between read thresholds based on real-time error rate monitoring. When error rates are low, a larger interval is used to maximize compression rate and throughput. When error rates increase, the interval is reduced to improve soft decoding capability. This dynamic adaptation resolves the contradiction by making the system flexible rather than fixed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of read threshold interval based on stress conditions and error levels. By monitoring memory cell degradation and error rates, the system adjusts this critical parameter to optimize the tradeoff between decoding reliability and readout throughput under different operating conditions.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If soft decoding scheme is used to improve error correction capability, then reliability is improved, but bandwidth consumption increases due to uncompressed confidence levels

Engineering Contradiction:
Improvedecoding capabilityVSAvoidbandwidth consumption
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential information from confidence levels by compressing them before transmission. Instead of sending all confidence level data, the system applies compression algorithms to retain only the most critical error correction information, thereby reducing bandwidth consumption while maintaining soft decoding capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A compression module acts as an intermediary between the soft decoding process and the communication channel. This intermediary component compresses confidence levels before transmission and decompresses them at the receiver, enabling efficient bandwidth utilization while preserving the soft information needed for error correction.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If read threshold interval is adjusted to maximize compression rate, then readout throughput is improved, but soft decoding capability deteriorates

Engineering Contradiction:
Improvereadout throughputVSAvoidsoft decoding performance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system implements feedback by monitoring decoding success rates and error patterns, then using this information to adjust the read threshold interval. When decoding performance degrades, the feedback loop triggers a reduction in interval size to restore soft decoding capability, creating a self-regulating system that adapts to maintain optimal performance.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS11556416B2Controlling memory readout reliability and throughput by adjusting distance between read thresholds
Publication Date: 2023.01.17 APPLE INC
  • US11556416B2 patent drawing
  • US11556416B2 patent drawing
  • US11556416B2 patent drawing

AI summary

An apparatus for data storage includes an interface and a processor. The interface is configured to communicate with a memory device that includes (i) a plurality of memory cells and (ii) a data compression module. The processor is configured to determine a maximal number of errors that are required to be corrected by applying a soft decoding scheme to data retrieved from the memory cells, and based on the maximal number of errors, to determine an interval between multiple read thresholds for reading Code Words (CWs) stored in the memory cells for processing by the soft decoding scheme, so as to meet following conditions: (i) the soft decoding scheme achieves a specified decoding capability requirement, and (ii) a compression rate of the compression module when applied to confidence levels corresponding to readouts of the CWs, achieves a specified readout throughput requirement.