Flash Memory Parameter Calibration via Dynamic Grouping
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Solution Overview
Problem
Flash memory devices face increased overhead due to unintentional shifts in threshold voltages of memory cells, leading to read errors and the need for dynamic shifting of read levels, especially with multiple read requests, which complicates data retrieval and storage.
Innovation Solution
A storage device with a parameter calibration function that measures threshold voltage distributions across memory units, determines distribution variations, and dynamically groups memory units to adjust operation parameters, reducing the need for frequent read voltage recalibration and minimizing read errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read level is dynamically shifted to prevent read errors caused by threshold voltage shifts, then read reliability is improved, but overhead increases
Solution Approach 1:
The memory units are divided into multiple groups based on their threshold voltage distribution characteristics. Each group is assigned a common read level, reducing the number of read levels needed compared to treating each memory unit individually. This segmentation approach maintains read reliability while reducing overhead.
Solution Approach 2:
The patent implements dynamic grouping where memory units are reorganized into groups based on their threshold voltage distribution characteristics. This dynamic adjustment allows the system to adapt to changing conditions and maintain optimal read reliability without requiring individual read level adjustments for every memory unit.
2Measurement precision
If read level is dynamically shifted for each memory unit, then read accuracy is improved, but operation time increases
Solution Approach 1:
By segmenting memory units into groups with similar threshold voltage characteristics and assigning common read levels to each group, the patent reduces the total number of read level adjustments needed. This maintains read accuracy for grouped units while significantly reducing operation time compared to individual adjustments.
Solution Approach 2:
The patent merges multiple memory units with similar characteristics into single groups that share common read levels. This combining approach maintains the precision needed for accurate reads while reducing the overall number of operations required, thereby decreasing operation time.
3Reliability
If multiple read requests are processed with individual read level adjustments, then read reliability is maintained, but system complexity increases
Solution Approach 1:
The patent creates groups of memory units that can be processed with common read levels, making the read operation more universal. This approach allows multiple read requests to be handled efficiently by applying group-level read levels rather than requiring complex individual adjustments for each memory unit, thus maintaining reliability while reducing system complexity.
Data Source
AI summary
An operating method of a storage device includes a controller: receiving read data from a non-volatile memory; measuring a plurality of threshold voltage distributions respectively corresponding to a plurality of memory units of the non-volatile memory, based on the received read data; measuring a distribution variation between the plurality of memory units, based on the measured plurality of threshold voltage distributions; dynamically determining operation parameters for the non-volatile memory, based on the measured distribution variation; and transmitting, to the non-volatile memory, an operate command, an address, and at least one operation parameter corresponding to the address.