Memory Systems With Adaptive Read-Voltage Error Correction
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Solution Overview
Problem
Existing memory devices face challenges in accurately determining optimal read voltages for memory cells, leading to read errors and inefficiencies in data retrieval.
Innovation Solution
A memory system and method that adjusts read voltages based on threshold voltage distributions to determine optimal read voltages, using a memory controller to offset default read voltages and perform read retry operations when necessary, with error correction and data recovery mechanisms.
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 read errors occur due to threshold voltage distribution variations
Solution Approach 1:
The patent performs preliminary actions by determining the offset direction of the optimal read voltage before actually adjusting the read voltage. This is done by analyzing threshold voltage distributions and comparing memory cell counts at different voltages. By preparing the offset direction determination in advance, the system can then quickly adjust the read voltage in the correct direction to improve read accuracy without excessive complexity
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring read operations and adjusting the read voltage based on the determined offset direction. The system uses feedback from threshold voltage distribution analysis to dynamically adjust the read voltage, ensuring high read accuracy while managing complexity through intelligent control algorithms
2Reliability
If the read voltage is adjusted to optimize read accuracy, then read errors are reduced, but the operation time increases due to voltage adjustment and retry processes
Solution Approach 1:
The patent determines the offset direction of the optimal read voltage in advance before performing read operations. By analyzing threshold voltage distributions and comparing memory cell counts at different voltages beforehand, the system prepares the necessary voltage adjustment information, enabling faster read operations without excessive retries and thus reducing time loss
Solution Approach 2:
The patent dynamically adjusts the read voltage based on the determined offset direction rather than using a fixed voltage. This dynamic adjustment allows the system to optimize read accuracy for current conditions while minimizing the number of retry operations needed, thereby reducing the overall time loss
Data Source
AI summary
Memory systems and methods of controlling thereof are disclosed. An example memory system includes a memory device and a memory controller. The memory device includes memory cells each being configured to be in one of data states. The memory controller is configured to: control the memory device to perform a single level read operation; in response to a first count of memory cells each having a threshold voltage less than a default read voltage being less than a first threshold, determine that an optimal read voltage has a positive offset relative to the default read voltage; and in response to the first count of memory cells each having a threshold voltage less than the default read voltage being greater than a second threshold larger than the first threshold, determine that the optimal read voltage has a negative offset relative to the default read voltage.