Temperature Measurement Circuit with Dual Sensor Failure Detection
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Solution Overview
Problem
Existing temperature measurement systems require multiple temperature sensors and a logic unit for majority voting, leading to increased circuit complexity and susceptibility to common cause failures, making it difficult to detect sensor failures effectively.
Innovation Solution
A temperature measurement circuit using a combination of a resistive element-based temperature sensor and a ring oscillator-based temperature sensor, with a comparator to compare their results, allowing for detection of sensor failures without increasing circuit scale and mitigating common cause failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three or more temperature sensors and a logic unit for majority voting are used, then temperature measurement reliability is improved, but circuit complexity and scale are increased
Solution Approach 1:
The patent extracts the voting logic from a complex logic unit and implements it through a simple comparator that compares temperature values directly. By removing the need for a dedicated logic unit and reducing the sensor count to two, the circuit complexity is significantly reduced while maintaining the reliability benefits of redundant sensing.
Solution Approach 2:
The patent uses two different temperature sensor types (resistive element-based and ring oscillator-based) as copies of temperature measurement functionality. This diverse copying approach allows comparison of results from different sensing mechanisms, enabling failure detection without requiring three identical sensors and their associated voting logic.
2Reliability
If three or more temperature sensors are used for majority voting, then failure detection capability is improved, but the number of components and circuit scale are increased
Solution Approach 1:
The patent extracts the failure detection function from a multi-sensor majority voting system and implements it through a simpler comparison mechanism using only two sensors. The comparator directly identifies failures by detecting discrepancies between the two sensor readings, eliminating the need for three or more sensors.
Solution Approach 2:
The patent changes the sensing parameter diversity by using two different temperature sensing mechanisms (resistive element and ring oscillator) instead of three identical sensors. This parameter diversification enables effective failure detection through comparison while reducing the total component count.
3Measurement precision
If identical temperature sensors are used for majority voting, then measurement consistency is improved, but susceptibility to common cause failures is increased
Solution Approach 1:
The patent introduces asymmetry by using two different temperature sensor types with different operating principles (resistive element-based sensor and ring oscillator-based sensor). This asymmetric configuration ensures that a common cause failure affecting one sensor type is unlikely to affect the other, thereby mitigating the risk of common cause failures while maintaining measurement consistency through comparison.
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
Enables accurate temperature measurement and failure detection with reduced circuit complexity, using only two sensors and eliminating the need for a logic unit for majority voting, thereby reducing the risk of common cause failures.
Implementation Method 1
a first temperature sensor which measures a temperature using a temperature detection unit including a resistive element
Implementation Method 2
a second temperature sensor which measures a temperature using a ring oscillator
Data Source
AI summary
It is possible to detect a failure in a temperature sensor while preventing enlarging of a circuit scale. A temperature measurement circuit 10 includes temperature sensors 20 and 30, and a comparator 40. The temperature sensor 20 includes a temperature detection unit 21 including a resistive element, a resistance value of which varies in accordance with temperature changes, and an AD converter which converts a voltage of the temperature detection unit 21 into a temperature digital value D1. The temperature sensor 30 includes a ring oscillator 31 which oscillates at a cycle that is temperature dependent, and generates a digital value D2 based on an oscillating signal output by the ring oscillator 31. The comparator 40 compares the temperature digital values D1 and D2, and outputs a signal indicating whether the temperature sensor 20 is normal or not based on a comparison result.