Nonvolatile Memory Read Voltage Update
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Solution Overview
Problem
Non-volatile memory devices, such as flash memory devices, experience errors in reading stored data due to changes in threshold voltages over time, leading to inaccuracies in data retrieval.
Innovation Solution
Updating reference voltages based on error counts by comparing the original reference voltages with modified reference voltages, selecting the voltage with the smallest error count to create an updated set of reference voltages, which reduces read errors and maintains data accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference voltages are updated based on error counts, then reading accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback by monitoring read errors and using this information to update reference voltages. The controller counts errors associated with each reference voltage and uses this feedback to determine which reference voltages to update, creating a closed-loop system that continuously improves reading accuracy based on actual performance data.
Solution Approach 2:
The patent changes the parameters of the reference voltages themselves by selecting updated reference voltages that differ from the original set based on error count analysis. This parameter change directly addresses the drift in threshold voltages that causes reading errors, allowing the system to adapt to changing memory characteristics over time.
2Measurement precision
If reference voltages are updated frequently, then reading accuracy is improved, but processing latency increases
Solution Approach 1:
The patent applies partial action by updating only certain reference voltages based on error counts rather than updating all reference voltages uniformly. The controller selectively identifies which reference voltages have the highest error counts and updates only those, reducing the processing overhead while still improving overall reading accuracy.
Solution Approach 2:
The system dynamically changes the update frequency and scope of reference voltages based on observed error patterns. Rather than following a fixed update schedule, the patent adapts the updating process to actual performance needs, updating reference voltages only when error counts indicate it would be beneficial.
3Measurement precision
If error counting and comparison is performed for all reference voltages, then reading accuracy is improved, but processing time increases
Solution Approach 1:
The patent extracts or isolates the most problematic reference voltages by identifying those with the highest error counts. Rather than processing all reference voltages equally, the system focuses computational resources on the subset of reference voltages that are causing the most reading errors, thereby improving accuracy efficiently.
Solution Approach 2:
The patent applies local quality by treating different reference voltages differently based on their individual error characteristics. Each reference voltage is evaluated and updated independently based on its specific error count, allowing the system to optimize each reference voltage locally rather than applying a uniform approach to all.
Data Source
AI summary
A method includes, in a data storage device that includes a non-volatile memory, reading first data values from memory elements of the non-volatile memory using a set of reference voltages that includes a first reference voltage, and determining a first error count associated with the first reference voltage. The method includes reading second data values from the group of memory elements using a set of modified reference voltages that includes a modified first reference voltage, and determining a modified error count associated with the modified first reference voltage. The method includes updating the set of reference voltages to include the first reference voltage or the modified first reference voltage based on a comparison of the error count to the modified error count.