DRAM Write Recovery Time Adjustment via Thermal Sensing
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Solution Overview
Problem
As DRAM technology scales below 20 nm, the write recovery time (tWR) increases due to increased resistance in data lines and sense amplifier circuitry, impacting CPU performance, with a potential 5% or more decrease in processor performance expected for a three-fold increase in tWR.
Innovation Solution
A memory system that tracks the temperature of DRAM chips and adjusts precharge timing on-the-fly, utilizing temperature-dependent write recovery (TC-tWR) to maintain shorter write recovery times by setting a write recovery parameter based on thermal states, allowing for auto-precharge operations independent of explicit precharge commands from a memory controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If DRAM technology scales to below 20 nm, then data transfer speed and capacity are improved, but write recovery time increases three to five times
Solution Approach 1:
The patent implements dynamic adjustment of write recovery time based on real-time temperature sensing. The system transitions from a static, fixed tWR value to a dynamic parameter that adapts to thermal conditions, allowing shorter recovery times when the memory device is warm and longer times when cold, thereby resolving the contradiction between scaling performance and recovery time requirements
Solution Approach 2:
The invention changes the write recovery time parameter based on temperature conditions. By sensing the thermal state of the memory device and adjusting tWR accordingly, the system optimizes performance across different operating conditions, maintaining fast data transfer while accommodating the increased recovery time inherent in scaled technologies
2Reliability
If write recovery time increases due to technology scaling, then data integrity is improved, but processor performance decreases by 5% or more
Solution Approach 1:
The system dynamically adjusts the write recovery time parameter based on real-time temperature sensing, transitioning from a conservative fixed value to an adaptive parameter that maintains data integrity while minimizing performance impact. This dynamic approach allows the system to achieve faster effective recovery times during normal warm operation
Solution Approach 2:
The patent implements a feedback mechanism where the memory device senses its own temperature and uses this information to adjust the write recovery time parameter. This closed-loop control ensures that data integrity requirements are met while optimizing processor performance by avoiding unnecessarily long recovery times
3Device complexity
If a fixed write recovery time is used for all temperature conditions, then system simplicity is maintained, but performance is degraded during cold startup conditions
Solution Approach 1:
The memory device performs self-diagnosis and self-adjustment by sensing its own temperature and automatically modifying its write recovery time parameter. This self-service approach eliminates the need for external temperature monitoring and control logic, maintaining system simplicity while enabling dynamic performance optimization
Solution Approach 2:
The invention changes the write recovery time parameter based on detected temperature conditions, allowing the system to adapt to different thermal states without adding significant complexity. The parameter adjustment is triggered by simple temperature threshold comparisons rather than complex control algorithms
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 improves CPU performance by maintaining shorter write recovery times at hotter temperatures during normal operation while accommodating colder startup conditions, ensuring compatibility with existing mechanisms like DDR specifications.
Implementation Method 1
thermal detection logic to detect a signal from a thermal sensor, the signal indicating a first temperature state of a memory resource
Data Source
AI summary
Techniques and mechanisms for determining a write recovery time of a memory device. In an embodiment, thermal detection logic detects a signal from a thermal sensor indicating a temperature state of a resource of the memory device. A value of a write recovery parameter is set based on the signal from the thermal sensor. In another embodiment, command logic generates a signal to precharge one or more cells of the memory device. The write recovery parameter is used by timer logic to control a timing of the signal to precharge the one or more cells.