Temperature Threshold Detection Circuit Using Stable PTAT Reference
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Solution Overview
Problem
Conventional temperature threshold detection circuits for electronic devices, such as lasers, are not reliable and suffer from precision issues due to signal variations, often requiring complex and costly circuitry to mitigate signal drift, leading to inaccurate or missed temperature threshold detections.
Innovation Solution
An integrated circuit with a temperature-independent voltage generator circuit that produces a constant voltage by summing a voltage proportional to absolute temperature and a complementary voltage, using a resistive voltage divider bridge and comparator circuit to generate a reference voltage, which compensates for undesirable variations, ensuring precise and reliable temperature threshold detection with a simple and economical design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature detection circuits are used, then the device can detect temperature, but the detection precision deteriorates due to signal drift and variations
Solution Approach 1:
The patent changes the parameter of voltage generation by using a temperature-independent voltage generator that produces a constant voltage (e.g., 1.25V) regardless of temperature variations. This constant voltage is then used to generate a reference voltage through a resistive divider, ensuring that the reference voltage remains stable and comparable across different temperatures, thereby improving detection precision and reliability.
Solution Approach 2:
The patent introduces a constant voltage as an intermediary element between the power supply and the reference voltage generation. This constant voltage acts as a stable reference point that is immune to temperature-induced variations in power supply voltage, allowing the resistive divider to generate a reliable reference voltage that accurately represents the temperature threshold.
2Reliability
If complex circuitry is added to reduce signal drift, then the detection reliability improves, but the device complexity increases
Solution Approach 1:
The temperature-independent voltage generator is designed to automatically compensate for power supply variations without requiring external calibration or adjustment circuits. The generator inherently produces a constant voltage output despite changes in input voltage or temperature, eliminating the need for additional complex drift-compensation circuitry while maintaining high detection reliability.
3Device complexity
If conventional voltage generation is used, then the circuit is simple, but the voltage varies with temperature causing detection inaccuracies
Solution Approach 1:
The patent transforms the temperature-dependent voltage parameter into a temperature-independent constant voltage parameter. By designing a voltage generator that maintains a fixed output voltage (e.g., 1.25V) across the operating temperature range, the circuit achieves both simplicity and accuracy, as the constant voltage eliminates the need for complex temperature compensation while ensuring precise threshold detection.
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 solution provides precise and reliable temperature threshold detection, reducing inaccuracies and the need for complex circuitry, allowing for effective protection against temperature-related risks in electronic devices, with experimental measurements showing an inaccuracy of only 2.7°C for a temperature threshold of -15°C.
Implementation Method 1
a voltage proportional to the absolute temperature and a voltage complementary to the absolute temperature
Implementation Method 2
the reference voltage can, at least partially, compensate for any undesirable variations in the constant voltage with temperature
Implementation Method 3
a resistive voltage divider bridge configured to generate a reference voltage equal to a fraction of the voltage constant with temperature
Implementation Method 4
a comparator circuit configured to compare the voltage proportional to the absolute temperature with the reference voltage
Data Source
Figure 1
Figure 2~3
AI summary
Integrated circuit comprising a temperature-independent voltage generator (BG) circuit configured to generate a constant voltage with temperature (VBG) by summing a voltage proportional to absolute temperature (VPTAT) and a voltage complementary to absolute temperature (VCTAT), and a temperature threshold detection (DET) circuit comprising a resistive voltage divider bridge (RS1, RS2) configured to generate a reference voltage (VREF) equal to a fraction of the constant voltage with temperature (VBG) and a comparator circuit (COMP) configured to compare the voltage proportional to absolute temperature (VPTAT) with the reference voltage (VREF).