Memory Controller Suspend Offset Read Voltage Adjustment
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Solution Overview
Problem
Non-volatile memory devices, such as flash memory, face read errors due to widened or shifted threshold voltage distributions during suspend operations, which affect data reliability and require improved methods for reliable data read operations.
Innovation Solution
A memory controller method that identifies memory pages that have undergone suspend operations, determines a read offset level based on suspend operation information, and adjusts the read voltage to ensure reliable data retrieval by storing and using suspend flag and offset level information to control read operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If suspend operation is performed during program operation to handle higher priority data requests, then productivity is improved, but reliability deteriorates due to threshold voltage distribution changes
Solution Approach 1:
The memory controller stores suspend operation information (including suspend address, suspend count, and program time) in an internal buffer before performing the suspend operation. This preliminary recording allows the controller to retrieve and apply appropriate offset levels during subsequent read operations, ensuring data reliability even after suspend operations have disrupted the threshold voltage distribution.
Solution Approach 2:
The patent applies offset levels to read voltages based on the stored suspend operation information. By dynamically adjusting the read voltage parameters (applying different offset levels depending on suspend address, suspend count, and program time), the system compensates for threshold voltage distribution changes caused by suspend operations, thereby maintaining read operation reliability.
2Reliability
If read voltage is adjusted based on suspend operation information, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent introduces an internal buffer as an intermediary component that stores suspend operation information (suspend address, suspend count, program time). This buffer acts as a mediator between the suspend operation execution and the subsequent read operation voltage adjustment, simplifying the control logic by centralizing the storage and retrieval of critical parameters needed for reliable reads.
Solution Approach 2:
The memory controller preliminarily determines and stores the appropriate offset level in the internal buffer during the suspend operation based on the suspend address, suspend count, and program time. This preliminary determination eliminates the need for complex real-time calculations during read operations, reducing control logic complexity while maintaining reliability.
Data Source
AI summary
A read control method of a memory controller for controlling a memory device including a plurality of memory pages respectively connected to a plurality of word lines includes identifying a selected memory page connected to a selected word line among the plurality of memory pages has undergone a suspend operation, determining a read offset level of the selected memory page based on suspend operation information associated with the selected memory page according to a result of the identifying the selected memory page, and controlling a read operation of the memory device based on a read voltage associated with the read offset level that was determined.