Temperature Sensor Bias Circuit for Flicker Noise Reduction
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Solution Overview
Problem
Temperature sensor arrangements face limitations in long-term stability and accuracy due to low-frequency flicker noise in biasing currents, which is challenging to address with existing solutions that often require complex implementations and trade-offs in circuit size, power consumption, and complexity.
Innovation Solution
Incorporating a poly-resistor connected between the bandgap voltage generator and the semiconductor junction to reduce low-frequency flicker noise, along with a chopper amplifier and source follower output stage, which simplifies the design and reduces power consumption while improving linearity, eliminating the need for chopping methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chopping methods are used in the biasing current source to reduce flicker noise, then flicker noise is reduced, but circuit complexity and implementation difficulty increase
Solution Approach 1:
The patent extracts the flicker noise reduction function from the complex chopper-stabilized OTA and implements it through a simple poly-resistor connected between the bandgap voltage generator output and the semiconductor junction. This removes the need for chopping circuits while maintaining low flicker noise in the biasing current.
Solution Approach 2:
The patent changes the resistance parameter by using a poly-resistor with specific resistance value and noise characteristics. The poly-resistor provides a stable biasing current with low flicker noise, achieving the desired parameter change in current stability without adding circuit complexity.
2Measurement precision
If chopper-stabilized OTA is implemented to reduce flicker noise, then flicker noise is reduced, but power consumption increases
Solution Approach 1:
The patent removes the power-consuming chopper-stabilized OTA from the circuit and replaces it with a passive poly-resistor that consumes minimal power while achieving the same flicker noise reduction effect in the biasing current.
Solution Approach 2:
The patent uses a simple poly-resistor component that is inexpensive and consumes minimal power compared to the complex chopper-stabilized OTA. The poly-resistor provides a cost-effective and low-power solution for flicker noise reduction.
3Measurement precision
If chopping circuits are added to reduce flicker noise, then flicker noise is reduced, but area consumption increases
Solution Approach 1:
The patent extracts the flicker noise reduction function from the area-consuming chopping circuits and implements it through a compact poly-resistor that occupies minimal circuit area while maintaining the desired noise performance.
Solution Approach 2:
The patent uses the poly-resistor as a simplified copy of the complex chopper circuit functionality, achieving the same flicker noise reduction effect with a much smaller physical footprint in the circuit.
4Ease of manufacture
If conventional biasing current sources are used, then circuit implementation is straightforward, but flicker noise limits long-term stability
Solution Approach 1:
The patent introduces a poly-resistor as an intermediary component between the bandgap voltage generator and the semiconductor junction. This intermediary element provides a stable biasing current with low flicker noise, improving long-term stability while maintaining ease of implementation.
Solution Approach 2:
The patent changes the biasing current characteristics by using a poly-resistor with specific noise and stability parameters. This parameter change improves the long-term stability of the temperature sensor while keeping the implementation straightforward.
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 configuration significantly reduces flicker noise, enhances temperature measurement accuracy, and minimizes area and power consumption, achieving greater stability and linearity without additional complexity.
Implementation Method 1
the flicker noise at low frequency is greatly reduced in the sensor, which allows an accurate measurement of the temperature
Implementation Method 2
a bandgap voltage generator 8... V ref , which shall have ignorable temperature dependency
Implementation Method 3
the bipolar semiconductor junction 2... The resulted voltage, V be , has complementary to absolute temperature (CTAT) characteristics
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention concerns a temperature sensor arrangement (10). The temperature sensor arrangement (10) comprises: - a bandgap voltage generator (12), which is configured to provide an output voltage (Vbg); - at least one semiconductor junction (14) for temperature sensing, which is biased by a biasing current flowing through said semiconductor junction (14); wherein the arrangement (10) further comprises at least one poly-resistor (Rb3) which is connected between the output (23) of the bandgap voltage generator (12) and the semiconductor junction (14), thereby providing said biasing current from the bandgap voltage generator (12) to the semiconductor junction (14).