Memory Bank Refresh Scheduling for Usage-Based Disturbance Mitigation
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Solution Overview
Problem
As processors and memory devices operate more quickly together, electromagnetic coupling between adjacent memory cells increases, leading to interference (crosstalk) and voltage fluctuations that cause memory errors, especially in larger memory devices with constrained timing resources for refreshes, necessitating efficient utilization of timing resources to mitigate usage-based disturbance.
Innovation Solution
Implementing a usage-based-disturbance circuit at a local-bank level with a refresh control circuit at a global-bank level to detect conditions and efficiently schedule mitigation strategies using available timing resources, supported by a mitigation decision circuit that prioritizes mitigation actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If processors and memory devices operate more quickly together, then performance is improved, but electromagnetic coupling between adjacent memory cells increases causing interference and voltage fluctuations
Solution Approach 1:
The memory device is divided into multiple banks, and each bank is further divided into smaller units that can be independently controlled. This segmentation allows the system to apply mitigation strategies locally to affected banks rather than globally, reducing the impact of electromagnetic coupling while maintaining high-speed operation in unaffected areas.
Solution Approach 2:
Different mitigation strategies are applied to different banks based on their specific usage patterns and disturbance levels. The system monitors each bank individually and applies refresh or mitigation operations only where needed, creating local quality variations in the approach to electromagnetic interference management.
2Reliability
If mitigation strategies are applied to reduce usage-based disturbance, then memory reliability is improved, but timing resources are consumed
Solution Approach 1:
Instead of applying mitigation strategies to all memory banks continuously, the system applies partial action only to banks that exhibit usage-based disturbance patterns. The mitigation is excessive only where needed, leaving other banks operating without interference, thus conserving timing resources while maintaining reliability where necessary.
Solution Approach 2:
The system dynamically changes operational parameters such as refresh timing and mitigation strategy selection based on real-time monitoring of usage patterns. When usage-based disturbance is detected, parameters are adjusted to apply mitigation; when not detected, parameters return to normal high-speed operation, optimizing the balance between reliability and timing resource consumption.
3Reliability
If refresh operations are performed to mitigate usage-based disturbance, then memory errors are reduced, but available timing resources for other operations are constrained
Solution Approach 1:
The system performs preliminary monitoring of usage patterns to identify banks that will require mitigation before actual disturbance occurs. By detecting usage-based patterns early, the system can schedule refresh operations in advance during low-utilization periods, preventing errors without significantly impacting productivity during high-demand operations.
Solution Approach 2:
Instead of continuous refresh operations, the system implements periodic monitoring and mitigation based on detected usage patterns. Refresh operations are triggered periodically when specific usage conditions are met, rather than continuously, allowing memory operations to proceed at full productivity unless and until disturbance patterns emerge.
4Productivity
If local-bank-level scheduling is implemented, then timing resource utilization is improved, but device complexity increases
Solution Approach 1:
The control functionality is segmented and distributed to individual bank-level controllers rather than centralized. Each bank controller independently monitors its own usage patterns and schedules mitigation operations, reducing the complexity of any single control unit while improving overall timing resource utilization through localized decision-making.
Solution Approach 2:
Each memory bank is equipped with self-monitoring and self-scheduling capabilities that allow it to autonomously detect usage-based disturbance patterns and initiate appropriate mitigation strategies without external intervention. This self-service approach reduces the complexity of external control circuitry while maintaining high timing resource utilization through decentralized intelligence.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the risk of memory errors by efficiently utilizing timing resources without increasing cost or die size, ensuring reliable operation of memory devices.
Implementation Method 1
electromagnetic coupling between adjacent memory cells increases, leading to interference (crosstalk) and voltage fluctuations
Data Source
AI summary
Apparatuses and techniques for local-bank-level scheduling enhancement of usage-based-disturbance mitigation based on global-bank-level control are described. To enable efficient utilization of timing resources, a memory device includes a refresh control circuit implemented at a global-bank level of the memory die and a mitigation decision circuit implemented at a local-bank level of the memory die. The refresh control circuit determines currently available timing resources for mitigating usage-based disturbance and generates a control signal to pass this information to the mitigation decision circuit. The mitigation decision circuit schedules the mitigation actions to efficiently utilize the currently available timing resources and ensure that different conditions associated with usage-based-disturbance are mitigated in order of priority. In this manner, available timing resources are efficiently utilized to decrease a risk of the memory device being subjected to usage-based disturbance. Furthermore, these techniques can be performed without significantly increasing cost or die size.