Memory Device Dynamic Refresh Rate Control for Row-Hammer Mitigation
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Solution Overview
Problem
Existing memory systems face challenges in efficiently performing target refresh operations to mitigate row-hammer phenomena, particularly in varying temperature conditions where the frequency of refresh management commands differs.
Innovation Solution
A memory device and system that adjust the refresh rate based on temperature by generating a refresh counting value from both external refresh management commands and internally generated target refresh commands, and using this value to set a target number for issuing internal target refresh commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refresh rate is increased to improve row-hammer mitigation, then the reliability against row-hammer attacks is improved, but the energy consumption and refresh overhead increase
Solution Approach 1:
The patent implements dynamic adjustment of the target refresh rate based on real-time temperature monitoring. The refresh rate is not fixed but adapts to changing thermal conditions, increasing when temperature rises (indicating higher row activation activity) and decreasing when temperature is stable or low. This dynamic approach optimizes the balance between row-hammer mitigation and energy consumption by applying refresh operations only when necessary.
Solution Approach 2:
The patent changes the refresh rate parameter according to temperature conditions. By monitoring temperature as an indicator of row activation intensity, the system adjusts the refresh rate parameter to match the actual stress on memory rows, thereby improving reliability when needed while reducing unnecessary refresh operations and energy consumption when the stress is low.
2Productivity
If the refresh rate is adjusted dynamically based on temperature, then the refresh efficiency is improved, but the control complexity increases
Solution Approach 1:
The patent employs a self-regulating mechanism where the memory device autonomously monitors its own temperature and adjusts its refresh rate accordingly. The temperature sensing circuit and control logic are integrated within the memory device itself, allowing it to self-manage the refresh operations without requiring complex external control systems. This self-service approach improves efficiency while keeping the added complexity contained within the device.
Solution Approach 2:
The patent implements a feedback loop where temperature information is continuously monitored and fed back to the refresh control logic. This feedback mechanism allows the system to automatically adjust the refresh rate based on actual thermal conditions, improving refresh efficiency without requiring complex predictive models or external intervention. The feedback-based control simplifies the overall system architecture compared to open-loop control schemes.
Data Source
AI summary
A memory device includes: a rate control circuit configured to: generate a refresh counting value based on a refresh management command and an internal target refresh command, and generate a rate control signal by comparing the refresh counting value with a target value corresponding to temperature information; and a target command issuing circuit configured to: set a target number according to the rate control signal, and issue the internal target refresh command whenever a number of inputs of a normal refresh command reaches the target number.