Flash Memory Soft-Value Generation for Reliable ECC Decoding

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Solution Overview

Problem

Flash memory devices rely on hard values for data readout, which are insufficient for error detection and correction, necessitating the generation of soft values to improve data reliability and ECC decoding.

Innovation Solution

A method and apparatus for generating soft values by setting memory read-related parameters, reading data multiple times, and using an arithmetic logic unit or converter to update and store these values, enabling effective ECC decoding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hard value readout is used in flash memory, then the device complexity is low and operation is simple, but error detection and correction capability is insufficient

Engineering Contradiction:

Improveerror detection and correction capabilityVSAvoidcomplexity of readout process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs multiple preliminary read operations with different read voltages before final data processing. By conducting these preliminary actions (reading at multiple voltage levels) beforehand, the system gathers sufficient information to generate accurate soft values for reliable error correction, while keeping the main processing logic relatively simple.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces soft values as an intermediary representation between hard readout values and error correction processing. These soft values encode reliability information and serve as a mediator that enables effective ECC decoding without requiring complex direct analysis of raw readout signals, thus improving reliability while managing complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If multiple iterations of data reading are performed, then soft value accuracy is improved, but reading time increases

Engineering Contradiction:

Improvesoft value accuracyVSAvoidreading time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs a predetermined number of read iterations (excessive action) to ensure sufficient soft value accuracy for reliable error correction. Rather than attempting to determine the exact minimum number of iterations needed, the system uses a fixed number of iterations that is sufficient to achieve the required precision, simplifying control while ensuring measurement accuracy.

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If soft value generation is implemented, then ECC decoding precision is improved, but computational complexity increases

Engineering Contradiction:

ImproveECC decoding precisionVSAvoidcomputational complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the parameter representation from hard binary values to soft values that encode reliability information. By transforming the data representation parameters (from simple 0/1 to multi-level soft values indicating confidence levels), the system enables more precise ECC decoding while managing computational complexity through efficient soft value generation and processing algorithms.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20110246855A1Method and Apparatus of Generating a Soft Value for a Memory Device

Publication Date: 2011.10.06 YEESTOR MICROELECTRONICS CO LTD

AI summary

A method and apparatus of generating the soft value for a memory device is disclosed. Memory read-related parameters are set, and data are read out of the memory device according to the set parameters. The data reading is performed for pre-determined plural iterations, thereby obtaining the soft value according to the read-out data and the set parameters.