Memory Controller Optimal Read Voltage Determination
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Solution Overview
Problem
Existing storage devices face challenges in accurately determining optimal read voltages, leading to failed read operations due to incorrect error correction decoding, which affects data retrieval reliability.
Innovation Solution
A storage device and operating method that include a memory controller performing soft read operations using multiple soft read voltages based on a default read voltage, determining an optimal read voltage by counting memory cells within voltage intervals, and selecting the optimal voltage to improve data retrieval accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a default read voltage is used for reading memory cells, then the read operation is simple and fast, but the read operation may fail due to incorrect error correction decoding
Solution Approach 1:
The patent performs soft read operations using multiple soft read voltages before finalizing the read operation. By preliminarily reading memory cells with multiple voltages and counting threshold voltage distributions, the system prepares accurate information about memory cell states, which enables reliable error correction decoding in the subsequent final read operation using the determined optimal read voltage.
Solution Approach 2:
The patent changes the read voltage parameter dynamically by determining an optimal read voltage based on counted threshold voltage distributions from soft read operations. Instead of using a fixed default read voltage, the system adjusts the read voltage parameter according to the actual state of memory cells, thereby improving read operation reliability while managing complexity through intelligent parameter adaptation.
2Measurement precision
If multiple soft read voltages are used to determine optimal read voltage, then data retrieval reliability is improved, but the read operation time increases
Solution Approach 1:
The patent segments the read operation into distinct phases: soft read operations using multiple soft read voltages to gather threshold voltage distribution information, followed by optimal read voltage determination based on counting results, and finally the actual read operation using the determined optimal voltage. This segmentation allows the system to invest time only in voltage determination when needed, rather than always performing exhaustive multi-voltage reads.
Solution Approach 2:
The patent implements feedback by using the results of soft read operations (counted threshold voltage distributions) to determine the optimal read voltage for subsequent read operations. The system learns from the soft read results and adjusts the read voltage accordingly, creating a feedback loop that improves accuracy while avoiding redundant operations by using the determined optimal voltage in future reads.
Data Source
AI summary
A memory controller controlling a memory device including a plurality of memory cells includes a read operation controller performing a soft read operation on the plurality of memory cells by using a plurality of soft read voltages determined based on a default read voltage when a read operation for reading the plurality of memory cells by the default read voltage fails, and reading the plurality of memory cells by using an optimal read voltage determined according to a result of performing the soft read operation, and a read voltage setting circuit determining the optimal read voltage using voltage candidates being soft read voltages corresponding to at least two voltage intervals, among a plurality of voltage intervals determined according to the plurality of soft read voltages, the voltage candidates selected in ascending order of a number of memory cells having threshold voltages belonging to each of the plurality of voltage intervals.