Read Voltage Adjustment via Syndrome Weight Comparison
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Solution Overview
Problem
Non-volatile memory devices face challenges in accurately reading data due to variations in threshold voltage states caused by data retention and program disturb conditions, leading to bit errors during read operations.
Innovation Solution
The system updates a set of read voltages based on error correction coding (ECC) related information by generating multiple trial sets of read voltages, using ECC information to select optimal voltage values that minimize bit errors, and iteratively adjusts these voltages to refine the accuracy of data reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple bits are stored in each flash memory cell to increase storage density, then storage capacity is improved, but read accuracy deteriorates due to threshold voltage variations
Solution Approach 1:
The patent dynamically adjusts read voltages as a parameter to optimize read accuracy. By varying the read voltage based on syndrome weight comparisons and ECC information, the system adapts to threshold voltage variations in multi-bit stored cells, resolving the contradiction between high storage density and accurate reading.
2Ease of operation
If read voltages are fixed to simplify the reading process, then ease of operation is improved, but bit error rate increases
Solution Approach 1:
The patent transitions from fixed read voltages to dynamic read voltage adjustment. The system continuously monitors ECC information and syndrome weights, then adjusts read voltages in real-time to minimize bit errors, maintaining operational simplicity while significantly improving reliability.
Solution Approach 2:
The patent implements a feedback mechanism where ECC information and syndrome weights are used to adjust read voltages. The system uses the outcome of read operations (error detection) to refine subsequent read voltage selections, creating a closed-loop system that reduces bit error rates.
3Measurement precision
If multiple trial sets of read voltages are tested to improve read accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing optimal read voltage candidates based on historical ECC data and syndrome weight patterns. This allows the system to quickly select appropriate read voltages without performing complex real-time analysis, reducing operational complexity while maintaining high accuracy.
Data Source
AI summary
A method performed at a data storage device includes adjusting a first read voltage and a second read voltage to form sets of read voltages. First representations of data are read from a logical page in the non-volatile memory according to the sets of read voltages. The first representations of the data correspond to multiple values of the first read voltage and the second read voltage. The first representations of the data are stored in a memory and second representations of the data are generated based on the first representations. A value of the first read voltage is selected based on syndrome weights corresponding to the second representations.