Probabilistic Wordline Refresh for DRAM Row Hammer Protection
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Solution Overview
Problem
Volatile memory devices like DRAM suffer from row hammering, where adjacent wordlines activated repeatedly cause unintended charge leakage in memory cells, leading to data damage.
Innovation Solution
A memory device with a row hammering protector that probabilistically performs additional refresh operations based on adjacent wordline activation counts, using a global probability table to determine when to issue row refresh commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional refresh operations are performed frequently to protect against row hammering, then data reliability is improved, but power consumption increases
Solution Approach 1:
The patent applies local quality by differentiating refresh operations between victim wordlines and aggressor wordlines. Victim wordlines receive enhanced refresh protection based on their susceptibility to row hammering, while aggressor wordlines follow standard refresh patterns. This localized approach ensures data reliability is improved where needed without unnecessarily increasing power consumption across the entire memory array.
Solution Approach 2:
The patent implements dynamics through probabilistic refresh operations that adapt to real-time conditions. The row hammering protector dynamically adjusts refresh probabilities based on detected row hammering attacks, transitioning from static fixed-interval refresh to dynamic condition-based refresh. This allows the system to maintain high reliability during attacks while reducing power consumption during normal operation.
2Reliability
If row hammering protection is implemented with frequent refresh operations, then data reliability is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary component called the row hammering protector that sits between the memory controller and the memory cell array. This mediator monitors for row hammering conditions and selectively triggers additional refresh operations only when needed, rather than implementing complex protection logic throughout the entire memory system. This modular approach improves reliability while minimizing added complexity.
Solution Approach 2:
The row hammering protector operates autonomously by self-monitoring for row hammering conditions and automatically triggering appropriate refresh operations without requiring complex external control logic. The system serves itself by detecting its own vulnerability states and responding accordingly, simplifying the overall device architecture while maintaining high data reliability.
3Loss of energy
If probabilistic refresh operations are used to reduce power consumption, then energy efficiency is improved, but the ability to detect and prevent row hammering may worsen
Solution Approach 1:
The patent implements feedback mechanisms where the row hammering protector continuously monitors memory access patterns and refresh operation effectiveness. Based on this feedback, the system dynamically adjusts refresh probabilities to maintain optimal balance between power consumption and row hammering protection. The feedback loop ensures that probabilistic operations remain effective at detecting and preventing row hammering attacks.
Solution Approach 2:
The patent applies preliminary action by performing refresh operations in advance before row hammering attacks can cause data corruption. The probabilistic refresh mechanism proactively protects vulnerable wordlines before damage occurs, ensuring that even if row hammering detection is not immediately certain, the preventive measure is already in place to maintain data reliability.
Data Source
AI summary
A memory device includes a memory cell array connected to a plurality of wordlines, and a row hammering protector including processing circuitry configured to probabilistically perform, based on an adjacent wordline activation count with respect to each of the plurality of wordlines during a first bank refresh period, an additional refresh operation with respect to each of the plurality of wordlines within a second bank refresh period after the first bank refresh period.