On-Chip Temperature Sensor for Dynamic DRAM Refresh Control
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Solution Overview
Problem
Integrated circuits, such as non-volatile memory devices and DRAM, face operational challenges due to temperature variations, which affect threshold voltages and refresh rates, leading to inefficiencies in programming, reading, and data integrity, as existing technologies lack effective temperature sensing mechanisms to adjust operations dynamically.
Innovation Solution
A temperature sensing circuit is developed, comprising a band-gap voltage reference circuit, amplifier, level generation circuit, and analog-to-digital converter, which generates a temperature-dependent voltage, allowing for precise temperature measurement and adjustment of refresh rates in memory devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If temperature sensing is implemented in integrated circuits, then operational efficiency and data integrity are improved, but device complexity increases
Solution Approach 1:
The temperature sensing circuit is integrated within the existing integrated circuit structure, combining temperature measurement functionality with the memory device. The circuit shares common components and substrate with the memory device, eliminating the need for separate external temperature sensors and reducing overall system complexity.
Solution Approach 2:
The temperature sensing circuit serves multiple functions: it monitors temperature for dynamic refresh rate adjustment, provides thermal compensation data for voltage threshold adjustments, and enables adaptive power management. This multi-functionality improves operational efficiency across multiple parameters simultaneously.
2Reliability
If fixed refresh rate is used for DRAM, then reliability is maintained, but energy consumption increases
Solution Approach 1:
The refresh rate is changed from a fixed value to a dynamic parameter that automatically adjusts based on real-time temperature measurements. The controller circuit modifies the refresh rate according to the sensed temperature, maintaining data integrity at high temperatures while reducing unnecessary refresh operations at lower temperatures to conserve power.
Solution Approach 2:
A feedback loop is established where the temperature sensing circuit continuously monitors the internal temperature and provides data to the controller circuit, which then adjusts the refresh rate accordingly. This closed-loop control ensures reliability is maintained when needed while optimizing energy consumption under varying thermal conditions.
3Measurement precision
If temperature compensation is implemented, then operational accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The temperature sensing function is segmented into distinct modular components: a temperature sensing circuit with specific transistors and resistors, an amplifier circuit for signal conditioning, and a controller circuit for processing. This segmentation allows each component to be optimized independently while maintaining overall manufacturing feasibility through standardized integration processes.
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
The solution enables accurate temperature monitoring within integrated circuits, optimizing operational voltages and refresh rates, thereby improving data integrity and reducing power wastage by adjusting operations based on actual temperature conditions.
Implementation Method 1
A temperature sensing circuit is developed, comprising a band-gap voltage reference circuit
Implementation Method 2
A temperature sensor circuit generates a voltage that varies linearly with temperature, and that indicates the temperature of the integrated circuit
Data Source
AI summary
A temperature invariant reference voltage and a temperature variant physical quantity, such as a voltage or current, are generated. The temperature variant physical quantity changes in response to a temperature of the integrated circuit. A temperature sensor circuit generates a voltage that is linearly dependent on the temperature. A level generator circuit generates 2n−1 voltage levels from the reference voltage. A comparator circuit, such as an analog-to-digital circuit, compares the voltage from the temperature sensor to the 2n−1 voltage levels to determine which level is closest. An n-bit digital output of the resulting level is proportional to the temperature of the integrated circuit.