Self-turn-on temperature detector circuit
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Solution Overview
Problem
Conventional temperature detection circuits in integrated circuits face challenges in balancing power consumption, accuracy, and complexity, particularly in low-power modes where they must operate continuously, leading to reduced accuracy and increased power usage.
Innovation Solution
A self-activated temperature detector circuit using a compact current mirror circuit with a diode-connected bipolar junction transistor and a current conveyor configuration that remains inactive at low temperatures, automatically activating at high temperatures to detect junction temperature thresholds with ultra-low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional comparator circuits are used for temperature detection, then temperature monitoring function is provided, but power consumption increases continuously across all temperature ranges
Solution Approach 1:
The circuit transitions from a static always-on comparator to a dynamic self-activating structure that adapts its operation state based on temperature conditions. The bipolar transistor's base-emitter voltage naturally varies with temperature, automatically enabling the comparator only when the temperature threshold is approached, thus reducing power consumption while maintaining monitoring reliability.
Solution Approach 2:
The invention exploits the temperature-dependent parameter change of the bipolar transistor's base-emitter voltage (VEB) to control circuit activation. As temperature increases, VEB decreases, and this parameter change directly controls the switching behavior of the comparator, eliminating the need for external control signals and reducing continuous power consumption.
2Use of energy by moving object
If special low-power structures are used to generate reference voltage during low power modes, then power consumption is reduced, but accuracy of the generated reference voltage is reduced
Solution Approach 1:
The circuit uses the temperature-dependent characteristics of the bipolar transistor itself to generate the reference voltage, eliminating the need for separate low-power reference voltage generation circuits. The transistor's own VEB serves as the reference, providing both power savings and maintained accuracy through its inherent physical properties.
Solution Approach 2:
The bipolar transistor serves multiple functions simultaneously: it acts as both the temperature sensing element and the reference voltage source. This multi-functionality eliminates the need for separate reference voltage generation circuits, reducing overall power consumption while maintaining measurement accuracy through the transistor's well-characterized temperature-voltage relationship.
3Measurement precision
If unbalanced input MOS transistors are employed to create temperature-dependent input offsets, then temperature detection is achieved, but circuit complexity and fabrication difficulty increase
Solution Approach 1:
The invention extracts the temperature detection function from complex unbalanced MOS transistor structures and implements it using a simple balanced comparator with a bipolar transistor. By removing the need for unbalanced input structures, the circuit complexity is reduced while fabrication becomes easier, as standard balanced transistor pairs are used instead of requiring different channel doping concentrations.
Solution Approach 2:
The invention replaces the mechanical/fabrication-intensive approach of creating unbalanced MOS transistors with different doping concentrations with an electrical approach using the natural temperature-dependent voltage characteristics of bipolar transistors. This substitution simplifies the fabrication process while maintaining temperature detection capability.
4Reliability
If MOS transistor thermal parameters are used for temperature detection, then temperature monitoring is provided, but accuracy is reduced due to higher non-linear components and spread
Solution Approach 1:
The invention changes the physical parameter basis from MOS transistor thermal parameters (which exhibit high non-linearity and spread) to bipolar transistor base-emitter voltage (which has a well-known, linear temperature coefficient). This parameter change improves measurement precision while maintaining temperature monitoring reliability.
Solution Approach 2:
The invention uses the readily available and well-characterized bipolar transistor VEB temperature characteristic instead of relying on less predictable MOS transistor thermal parameters. This approach leverages a more stable and predictable physical phenomenon, improving accuracy without requiring complex calibration or compensation circuits.
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 continuous temperature monitoring with improved accuracy, minimal power consumption, and reduced area requirements, suitable for ultra-low-power applications like IoT devices, while maintaining high detection performance.
Implementation Method 1
compare a base-emitter voltage VEB produced by a PNP transistor with voltage reference signal
Data Source
AI summary
A low power temperature detection method, system, and apparatus sense when a temperature threshold is reached by connecting a current conveyor (111) with a startup bias circuit (112) having a first FET (P1) (connected to level shift a reference voltage to provide an input voltage VS1), a first diode-connected BJT (Q0) (connected to generate a base-emitter voltage based on the junction temperature), and a second FET (P2) (connected to level shift the base-emitter voltage), where the startup bias circuit (112) selectively connects the current conveyor (111) to ground to form a closed loop that is activated only when an emitter current at the first diode-connected BJT (Q0) enters a self-turned-on operation region, thereby activating the current conveyor to detect a temperature threshold being reached by the device junction temperature.