DRAM Refresh Rate Control via Temperature Change Rate Sensing
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Solution Overview
Problem
Current DRAM technologies consume excessive power due to coarse-grain temperature sensing, leading to unnecessary frequent refreshes, especially when temperature hot spots are not accurately detected, resulting in increased power consumption and heat generation.
Innovation Solution
Implementing multiple temperature sensors in close proximity to DRAMs and an integrated circuit, allowing for a more granular temperature change rate measurement, which adjusts the refresh rate accordingly, reducing power consumption by eliminating unnecessary refreshes when temperature change is low.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single coarse-grain temperature sensor is used in DRAM, then the device complexity is reduced, but the measurement precision of temperature is insufficient leading to inaccurate hot spot detection
Solution Approach 1:
The patent divides the temperature sensing function into multiple segments by implementing several temperature sensors at different locations within the DRAM device. This segmentation allows each sensor to monitor specific regions, collectively providing comprehensive and precise temperature coverage without requiring a single complex sensor system
Solution Approach 2:
The patent introduces temperature sensor readings as intermediary data that mediates between the physical temperature condition and the refresh rate control decision. The refresh controller uses these intermediary temperature measurements to dynamically adjust refresh rates, creating a feedback loop that optimizes power consumption while maintaining data integrity
2Reliability
If refresh rate is increased to account for hot spots and temperature margin, then data integrity is maintained, but power consumption increases due to unnecessary frequent refreshes
Solution Approach 1:
The patent implements dynamic refresh rate adjustment where the refresh rate is not fixed but continuously adapts based on real-time temperature sensor readings. The refresh controller dynamically modifies the refresh rate within a range, increasing it when hot spots are detected and decreasing it when temperatures are stable, thereby optimizing the balance between data integrity and power consumption
Solution Approach 2:
The patent changes the refresh rate parameter based on temperature conditions. Instead of using a static refresh rate, the system adjusts this critical parameter dynamically according to measured temperature values, allowing the DRAM to operate at lower refresh rates (and thus lower power) when conditions permit, while maintaining reliability when needed
3Reliability
If temperature margin is applied to account for potential hot spots, then reliability is improved, but the refresh rate becomes higher than actually required when hot spots do not exist
Solution Approach 1:
The patent implements a feedback mechanism where temperature sensor readings continuously feed back to the refresh controller, which then adjusts the refresh rate accordingly. This closed-loop feedback system eliminates the need for excessive conservative margins by providing real-time information about actual temperature conditions, allowing the system to operate efficiently without unnecessary overhead
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 reduces power consumption by optimizing refresh rates based on actual temperature conditions, ensuring data integrity while minimizing power usage, especially in portable devices where battery life is a concern.
Implementation Method 1
the integrated circuit includes multiple temperature sensors. A thermal controller may read the sensors and determine a rate of change of the temperature
Implementation Method 2
DRAM memory cells store data as electrical charge on a capacitor, and are subject to leakage of the charge over time
Data Source
AI summary
In an embodiment, a memory controller in an integrated circuit may generate refreshes for one or more DRAMs coupled to the integrated circuit according to a refresh rate. The integrated circuit may include one or more temperature sensors. A rate of change of the temperature may be determined from the temperature sensors. If the rate is greater than a threshold, the memory controller may generate refreshes according to a refresh rate specified by the DRAMs. If the rate is less than the threshold, the memory controller may generate refreshes at a reduced refresh rate.