DRAM Thermal Protection via Fine-Grain Temperature Estimation
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Solution Overview
Problem
Current thermal control mechanisms for DRAM chips rely on coarse-grained temperature measurements, leading to oscillations and undesirable user experiences due to audible fan speed changes, as they struggle to accurately manage temperature fluctuations within the fine granularity required for efficient heat dissipation.
Innovation Solution
A system that includes separate sensor circuits and a temperature estimation circuit using empirically-derived relationships to provide a finer grain temperature estimate, allowing for more precise control of memory requests and fan speeds, thereby reducing oscillations and improving thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If coarse-grained temperature measurements are used for thermal control, then device complexity is reduced, but temperature control precision deteriorates causing oscillations and audible fan speed changes
Solution Approach 1:
The temperature measurement system is segmented into multiple components: coarse-grained memory refresh codes from DRAM standards and fine-grained sensor circuit measurements. The temperature estimation circuit combines these segmented measurements to produce a comprehensive temperature estimate that achieves fine precision without requiring a completely complex measurement system.
Solution Approach 2:
The temperature estimation circuit acts as an intermediary that processes both coarse memory refresh codes and fine sensor measurements. It applies empirically-derived relationships to transform these inputs into an accurate fine-grained temperature estimate, mediating between simple and complex measurement approaches.
2Measurement precision
If fine-grained temperature measurements are implemented, then temperature control precision is improved, but device complexity increases
Solution Approach 1:
The system merges coarse memory refresh code data with fine sensor circuit measurements in the temperature estimation circuit. By combining these different granularity levels using empirically-derived relationships, the system achieves fine temperature measurement precision while leveraging existing simple components to avoid excessive complexity.
Solution Approach 2:
The temperature estimation circuit serves multiple functions: it processes coarse memory refresh codes, integrates fine sensor measurements, applies empirical relationships, and outputs controlled temperature estimates. This multi-functionality allows a single circuit to achieve fine precision without requiring separate dedicated systems for each function.
3Reliability
If self-protect circuitry is used to terminate DRAM operation at elevated temperatures, then DRAM reliability is improved, but system productivity deteriorates due to underruns in real-time sections
Solution Approach 1:
The thermal control circuit implements continuous feedback by monitoring fine-grained temperature estimates and dynamically adjusting memory request rates. When temperatures approach threshold levels, the system gradually reduces memory traffic to prevent thermal shutdown, maintaining productivity while ensuring reliability through proactive temperature management rather than reactive termination.
Solution Approach 2:
The system dynamically adjusts the memory request rate based on real-time temperature conditions. Instead of static operation or abrupt termination, the memory controller continuously modulates the rate of memory requests to maintain temperatures within safe operating margins, enabling adaptive balance between reliability and productivity.
Data Source
AI summary
A system includes one or more memory circuits and one or more sensor circuits that are separate from the memory circuits. A temperature estimation circuit estimates a temperature of the memory circuits based on sensor measurements from the sensor circuits and based on an empirically-derived relationship between the temperature and the sensor measurements. The temperature estimate is finer in granularity than a temperature indication provided by the memory circuits. For example, a given temperature indication value covers a range of 5 degrees Celsius, while the temperature estimate may be any integer temperature value or a decimal temperature value (e.g., to tenths or hundredths of degrees C.). A power control circuit in the system uses the temperature estimate to control a rate at which one or more agent circuits in the system generate memory requests to the memory circuit, which may control the temperature of the memory circuits.