PTAT Voltage Supervisor Circuit for Stable Low-Voltage Thresholds
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Solution Overview
Problem
Conventional voltage supervisors face challenges in maintaining temperature-insensitive threshold voltages, especially when operating below the bandgap voltage, leading to variations that can cause inaccurate monitoring of supply voltages and potential device damage.
Innovation Solution
A detection circuit utilizing a proportional to absolute temperature (PTAT) current generation circuit and a low-voltage comparator to generate a temperature-insensitive threshold voltage, ensuring accurate toggling at voltages below the bandgap voltage with a low temperature coefficient of less than ±1% over -40°C to 125°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage supervisors are used to monitor supply voltage, then power supply supervision function is provided, but threshold voltage varies with temperature causing inaccurate monitoring
Solution Approach 1:
The patent changes the operating parameters by using a PTAT current generation circuit that produces a current proportional to absolute temperature, and a low-voltage comparator that operates below the bandgap voltage. This parameter change enables the threshold voltage to remain stable across temperature variations while maintaining accurate monitoring capability.
Solution Approach 2:
The patent introduces a PTAT current generation circuit and a low-voltage comparator as intermediary components between the supply voltage and the monitoring function. These intermediaries process the voltage signal in a way that compensates for temperature effects, resulting in a temperature-insensitive threshold voltage.
2Adaptability or versatility
If threshold voltage is set below bandgap voltage for low-voltage operation, then power rail monitoring flexibility is improved, but temperature-induced threshold variation increases
Solution Approach 1:
The patent changes the operational parameters by deliberately setting the comparator threshold below the bandgap voltage level while using PTAT current to compensate for temperature effects. This allows the system to monitor multiple power rails with different voltage levels while maintaining threshold stability through the temperature-proportional current mechanism.
3Device complexity
If conventional detection circuits are used, then simple circuit structure is maintained, but threshold voltage variation over temperature exceeds acceptable limits
Solution Approach 1:
The patent introduces a PTAT current generation circuit as an intermediary element that adds minimal complexity to the detection circuit. This intermediary component generates a temperature-proportional current that compensates for threshold variations, achieving temperature-insensitive operation without significantly increasing overall circuit complexity.
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 provides a reliable and accurate temperature-insensitive threshold voltage, reducing threshold voltage variation by a factor of 10 compared to conventional supervisors, ensuring proper operation of digital and analog blocks across a wide temperature range.
Implementation Method 1
A detection circuit utilizing a proportional to absolute temperature (PTAT) current generation circuit and a low-voltage comparator to generate a temperature-insensitive threshold voltage
Data Source
AI summary
Methods, apparatus, systems and articles of manufacture are disclosed for temperature insensitive voltage supervisors. An example apparatus includes a PTAT generation circuit including an output terminal: a first resistor having a first terminal and a second terminal, a second resistor having a third terminal and a fourth terminal, the third terminal coupled to the second terminal at a first node, a first transistor including a base terminal coupled to the fourth terminal of the second resistor at a second node, and a first current terminal coupled to the fourth terminal of the second resistor, a comparator including, a first input terminal coupled to the output terminal of the PTAT generation circuit at a third node, a second input terminal coupled to the second terminal and third terminal, and a third resistor having a fifth terminal coupled to the third terminal and the second input terminal at a fourth node.