Flash Memory Controller for QLC Multi-Threshold Decoding
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Solution Overview
Problem
Existing flash memory devices, particularly those with quadruple level cell (QLC) technology, face inefficiencies in access control due to increased bit error rates and the inability of traditional sensing schemes to effectively manage high-level memory cells, leading to inefficient data retrieval and decoding processes.
Innovation Solution
A flash memory controller and method that includes a microprocessor and control logic circuit to analyze multi-bit information from flash memory modules, determining threshold voltage distributions for efficient decoding processes, allowing for the efficient retrieval of data from high-density storage arrangements by sending a single read command and obtaining both most significant bits (MSBs) and least significant bits (LSBs) to facilitate hard or soft decoding based on state balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional sensing schemes are used for reading data from QLC flash memories, then the memory device can operate with high storage density, but the bit error rate increases and data retrieval efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by performing multiple read operations at different voltage thresholds before final decoding. The controller reads data at multiple voltage levels (e.g., first threshold voltage, second threshold voltage) to obtain multiple bits of information per memory cell in advance, which are then used for more reliable decoding. This preliminary multi-threshold reading resolves the contradiction by gathering sufficient information upfront to maintain low error rates while preserving high storage density.
Solution Approach 2:
The patent implements feedback mechanisms where the controller analyzes the reliability of read data and adjusts subsequent read operations accordingly. Based on the detected bit error rates and decoding results, the system dynamically adjusts voltage thresholds and performs additional read operations when needed. This feedback loop ensures that data retrieval reliability is maintained even as storage density increases to QLC levels.
2Quantity of substance
If traditional sensing schemes are used for reading data from QLC flash memories, then the memory device can operate with high storage density, but the data retrieval efficiency and bandwidth consumption worsen
Solution Approach 1:
The controller performs preliminary read operations at multiple voltage thresholds to gather all necessary information in a coordinated sequence. By planning and executing multiple reads with different thresholds as a unified preliminary action, the system obtains complete multi-bit information per cell in one organized process, improving data retrieval efficiency compared to traditional sequential approaches while maintaining QLC storage density.
Solution Approach 2:
The patent merges multiple read operations into a coordinated sequence where information from different voltage thresholds is combined to form complete data. By merging the results of reads at first threshold voltage, second threshold voltage, and potentially additional thresholds, the system efficiently reconstructs the full multi-bit data stored in each QLC cell, improving overall retrieval efficiency while preserving high storage density.
3Measurement precision
If multiple read operations are performed to ensure accurate data retrieval, then data accuracy improves, but power consumption and operation time increase
Solution Approach 1:
The patent applies partial action by performing exactly the number of read operations needed based on the specific data retrieval requirements. The controller determines the minimum necessary read operations at different voltage thresholds to achieve the required accuracy, avoiding unnecessary additional reads. This selective approach maintains data accuracy while minimizing power consumption by performing only the essential multiple reads needed for QLC reliable retrieval.
4Measurement precision
If multiple read operations are performed to ensure accurate data retrieval, then data accuracy improves, but operation time increases
Solution Approach 1:
The controller executes multiple read operations at different voltage thresholds as a preliminary coordinated sequence before final decoding. By organizing these reads as preliminary actions with optimized timing and voltage sequencing, the system gathers all necessary accuracy information in advance, reducing the need for additional corrective operations later and minimizing total operation time while maintaining high data accuracy.
Solution Approach 2:
The patent maintains continuity of useful action by performing read operations at multiple voltage thresholds in a continuous optimized sequence rather than discrete separate operations. The controller seamlessly transitions between different threshold voltage reads, keeping the data retrieval process continuously active and efficient. This continuous multi-threshold reading approach improves data accuracy while reducing idle time and overall operation duration.
Data Source
AI summary
The present invention provides a method for accessing a flash memory module, wherein the flash memory module comprises at least one flash memory chip, each flash memory chip comprises a plurality of blocks, each block comprises a plurality of pages, and the method includes the steps of: sending a read command to the flash memory module to ask for data on at least one memory unit; receiving multi-bit information of a plurality of memory cells of the at least one memory unit from the flash memory module; and analyzing the multi-bit information of the plurality of memory cells to obtain a threshold voltage distribution of the plurality of memory cells for determining a decoding process.