Memory Interference Compensation via Lookup Table Probability
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Solution Overview
Problem
In nonvolatile memory systems, real-time compensation for inter-cell interference during data read operations is challenging due to the difficulty in calculating the voltage compensation for interference caused by adjacent cells, leading to errors and reduced data reliability.
Innovation Solution
A memory system and method that determine a compensation value for data read from a victim cell by comparing read voltage levels of adjacent cells, using a lookup table to evaluate program states and perform bit flip operations based on probability thresholds to correct errors, thereby compensating for inter-cell interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time voltage compensation calculation is performed for inter-cell interference, then data reliability is improved, but device complexity and processing time increase
Solution Approach 1:
The patent performs preliminary characterization evaluation to create lookup tables that map program states of interfering cells to compensation values. This pre-computed data is stored and retrieved during actual read operations, eliminating the need for real-time complex calculations while maintaining high data reliability through accurate interference compensation.
2Measurement precision
If multiple reference voltages are used for soft decision read, then measurement precision is improved, but use of energy and processing time increase
Solution Approach 1:
The patent segments the read operation into two distinct phases: a hard decision read using a single reference voltage for fast data retrieval, and a soft decision read using multiple reference voltages for reliability assessment. This segmentation allows the system to achieve high measurement precision through soft decision reading while minimizing time consumption by using the faster hard decision read as the primary data acquisition method.
Data Source
AI summary
A memory system includes a memory device including a plurality of memory cells, and a controller configured to access the plurality of memory cells. The controller includes a data read block configured to read first data from one or more pages included in first memory cells, determine a target memory cell subject to a compensation based on the first data, and read second data from one or more pages of second memory cells adjacent to the target memory cell, and an equalizer configured to convert the second data into symbol interfering data, check a probability of the first data from a lookup table according to the symbol interfering data, and determine the compensation on the first data based on the probability.