Heated Voltage Reference Circuit for Low-Voltage Temperature Stability
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Solution Overview
Problem
Traditional voltage reference circuits face challenges in achieving high precision and performance due to sensitivity to power supply noise, device noise, leakage currents, and circuit element mismatch, especially at low supply voltages below 1.0V, and are unable to compensate for temperature variations effectively.
Innovation Solution
A voltage reference circuit that stabilizes local temperature using a heater device and feedback loop, generating voltages with different temperature coefficients and adjusting them to equilibrium at a target temperature, allowing operation at very low supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional bandgap reference circuits are used, then reference voltage can be generated, but they cannot operate at supply voltages below 0.9V due to insufficient voltage to bias bipolar junction transistors
Solution Approach 1:
The patent replaces the mechanical/electrical biasing requirement of traditional bandgap circuits with a thermal field approach. By using a heater device to actively control the temperature of the reference circuit, the system can operate at low supply voltages (down to 0.65V) because the thermal energy compensates for the insufficient electrical bias voltage, allowing the circuit to function reliably in low-voltage environments where traditional designs would fail.
Solution Approach 2:
The patent changes the operating parameter from voltage-based biasing to temperature-based control. By maintaining the circuit at an elevated temperature (e.g., 100°C) through active heating, the reference voltage becomes stable even at supply voltages as low as 0.65V. This parameter transformation allows the circuit to bypass the fundamental limitation of traditional bandgap references that require minimum supply voltage for proper transistor biasing.
2Device complexity
If open-loop voltage reference circuits are used, then circuit complexity is reduced, but precision is severely degraded due to sensitivity to power supply noise, device noise, leakage currents, and circuit element mismatch
Solution Approach 1:
The patent implements a feedback mechanism where the temperature of the reference circuit is actively monitored and controlled through a heater device. This feedback loop compensates for temperature variations and environmental disturbances, maintaining precise reference voltage output even though the electrical circuit itself remains relatively simple and open-loop. The thermal feedback provides the necessary stability without requiring complex electrical feedback circuits.
Solution Approach 2:
The patent introduces temperature as an intermediary parameter between the power supply and the reference voltage output. By controlling the temperature of the reference circuit through a heater, the system mediates the relationship between the low-voltage power supply and the precision reference output, isolating the reference generation from the noisy power supply environment and achieving high precision without complex electrical feedback.
3Device complexity
If voltage reference circuits operate without temperature compensation, then circuit complexity is reduced, but temperature variations cause significant precision degradation
Solution Approach 1:
The patent employs thermal feedback control where a heater device is controlled based on the temperature of the reference circuit. This feedback mechanism actively maintains a constant temperature (e.g., 100°C) despite external temperature variations, ensuring precise reference voltage output without requiring complex electrical temperature compensation circuits. The thermal feedback provides straightforward temperature stabilization.
Solution Approach 2:
The patent transforms the temperature compensation problem from an electrical parameter adjustment task to a thermal control task. By actively heating the reference circuit to a controlled elevated temperature and maintaining it there through thermal feedback, the system achieves temperature stability and precision without the need for complex electrical compensation networks, PTAT/CTAT voltage generation, or other traditional temperature compensation techniques.
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 circuit achieves precise reference voltages with no temperature curvature and local temperature stabilization, operating at supply voltages as low as 0.65V, while being insensitive to noise and mismatch, thus ensuring high precision and performance.
Implementation Method 1
a heater device, wherein the heater device is configured to generate heat in response to being controlled by the control signal
Implementation Method 2
the one or more circuit components comprise diodes and/or transistors, and the first and the second voltage are forward voltage drops across the respective devices
Data Source
AI summary
In an embodiment a voltage reference circuit includes one or more circuit components configured to generate a first voltage and a second voltage, wherein the first voltage has a first temperature coefficient and the second voltage has a second temperature coefficient that is different from the first temperature coefficient, an adjustment circuit configured to generate an adjusted voltage as product of the first voltage and an adjustment factor, wherein the adjusted voltage is designed to equal the second voltage in an equilibrium at a target temperature, a control device configured to provide a control signal based on a difference between the adjusted voltage and the second voltage, a heater device configured to generate heat in response to being controlled by the control signal, wherein the heater device is thermally coupled to the one or more circuit components thereby providing a feedback loop configured for establishing the equilibrium at the target temperature and an output terminal configured to provide a reference voltage as a function of the first voltage or the second voltage.