Volatile Memory Self-Refresh Control Using Dynamic Rate Curves
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Solution Overview
Problem
Existing memory technologies lack the ability to dynamically adjust refresh rates based on various factors, such as the frequency of recent refresh operations, leading to potential data loss due to inflexible refresh rate curves.
Innovation Solution
Implementing a refresh control circuit that dynamically selects and applies different refresh rate curves based on factors like the number of refresh operations performed during a specified time period, allowing for more frequent refresh operations when few or no operations have been performed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed refresh rate curve is used, then the memory device structure is simple, but data loss risk increases due to inflexible refresh operations
Solution Approach 1:
The patent implements dynamic refresh rate adjustment by monitoring the number of recent refresh operations and selecting from multiple refresh rate curves (first, second, and third curves with different refresh intervals). The refresh control circuit dynamically switches between these curves based on real-time conditions, transforming the fixed refresh mechanism into an adaptive one that responds to operational history to prevent data loss while optimizing performance.
Solution Approach 2:
The patent employs feedback mechanisms where the refresh control circuit monitors the count of recent refresh operations and uses this information to determine which refresh rate curve to apply. This closed-loop feedback system adjusts refresh behavior based on actual operational state, ensuring data retention reliability by increasing refresh frequency when needed while avoiding unnecessary operations during stable periods.
2Reliability
If refresh operations are performed frequently, then data loss risk is reduced, but energy consumption increases
Solution Approach 1:
The patent dynamically adjusts refresh rate based on the number of recent refresh operations. When few or no refresh operations have been performed recently, the system uses a first refresh rate curve with longer intervals to conserve energy. When refresh operations become frequent, the system transitions to a second refresh rate curve with shorter intervals to maintain data retention, thus optimizing the balance between reliability and energy consumption through adaptive behavior.
Solution Approach 2:
The patent changes the refresh rate parameter based on operational conditions by selecting from multiple predefined refresh rate curves. The system monitors refresh operation counts and switches between curves with different refresh intervals, adjusting this critical parameter dynamically to minimize energy consumption while maintaining adequate data retention, avoiding both over-refreshing and under-refreshing scenarios.
Data Source
AI summary
Apparatuses, systems, and methods for dynamic self-refresh rate in volatile memory are disclosed. An example memory device determines a number of refresh operations performed between self-refresh exit and subsequent self-refresh entry, and the memory device determines a self-refresh rate based on the number of refresh operations. In some examples, the memory device selects a refresh rate curve from a plurality of refresh rate curves to determine the self-refresh rate. In some examples, the memory device selects a refresh rate curve for auto-refresh, which is applied to determine timing of self-refresh operations, when no refresh operations or few refresh operations were performed between the self-refresh exit and the subsequent self-refresh entry.