Analog Memory Cell Data Retention During Power Loss
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Solution Overview
Problem
Power shut-offs negatively impact the storage reliability of analog memory cells, causing drift-related distortion and performance degradation due to the inability to identify and mitigate threshold voltage changes during disconnection from electrical power.
Innovation Solution
Implementing a method that re-programs data in non-volatile memory using a robust storage configuration before power shut-off, characterized by features such as reduced programming states, higher error correction capabilities, smaller programming step sizes, and improved interference cancellation, which are less sensitive to drift-related distortion, and then converts it back to the normal configuration when power is restored.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is stored using a first storage configuration with higher programming states during normal operation, then storage density and productivity are improved, but data reliability deteriorates during power shut-off periods due to drift-related distortion
Solution Approach 1:
The system dynamically switches between two storage configurations based on power availability. During normal operation, it uses a first storage configuration with higher programming states for better storage density. When power shut-off is detected, it switches to a second storage configuration with fewer programming states that is more robust against drift-related distortion, thereby maintaining data reliability during power loss events.
Solution Approach 2:
The invention changes the programming parameters of the memory cells by switching between different storage configurations. The first configuration uses a higher number of programming states for increased density, while the second configuration uses fewer states with larger voltage margins for improved reliability during power shut-off. This parameter switching allows the system to optimize for either density or reliability based on operational conditions.
2Reliability
If data is re-programmed using a second storage configuration with fewer programming states before power shut-off, then data reliability during shut-off is improved, but device complexity and processing time increase
Solution Approach 1:
The system performs preliminary action by detecting imminent power shut-off and proactively re-programming the data in the second storage configuration before the power is actually lost. This advance preparation ensures that the data is in a more reliable state to withstand the upcoming power shut-off period, preventing data loss without requiring complex real-time intervention during the actual power loss event.
Solution Approach 2:
The invention implements a feedback mechanism where the system monitors power availability and responds by switching storage configurations. When power shut-off is detected, the system triggers a re-programming operation that converts data from the first storage configuration to the second configuration, which is more suitable for retaining data during power loss. This feedback-driven approach automates the complexity management based on actual power conditions.
3Adaptability or versatility
If the system switches between different storage configurations, then adaptability to power conditions is improved, but processing time and operational complexity increase
Solution Approach 1:
The system performs the configuration switching as a preliminary action when power shut-off is detected, rather than attempting to switch configurations during the actual power loss event. This advance switching minimizes the time the system spends in a transitional state and ensures that the data is already in the appropriate configuration when power is lost, reducing overall processing time and operational complexity.
Data Source
AI summary
A method for data storage in a non-volatile memory includes storing data in the non-volatile memory using a first storage configuration while the non-volatile memory is supplied with electrical power. After storing the data, an indication is accepted, indicating that shut-off of the electrical power is imminent. Responsively to the indication and before the shut-off, at least some of the data is re-programmed in the non-volatile memory using a second storage configuration.