Differential Thermistor Circuit for Stable Temperature Sensing
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Solution Overview
Problem
Traditional temperature measurement methods using thermistors suffer from significant measurement errors due to unstable power supply voltage and offset voltage, leading to inaccurate resistance calculations and temperature readings.
Innovation Solution
A temperature measurement circuit incorporating a differential amplifier and conversion circuit, which includes a calibration resistor and thermistor, employs a time-division sampling mechanism to isolate and measure offset, calibration, and temperature measurement voltages, allowing for accurate temperature signal extraction independent of power supply stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a thermistor is used to measure temperature with a simple circuit, then the device complexity is reduced, but the measurement precision deteriorates due to unstable power supply voltage and offset voltage
Solution Approach 1:
The measurement process is segmented into three distinct phases: offset voltage measurement (with input terminal unloaded), calibration voltage measurement (with calibration resistor connected), and temperature measurement voltage (with thermistor connected). This segmentation allows each voltage component to be measured and processed independently, eliminating the interference between them and improving measurement precision without significantly increasing overall circuit complexity.
Solution Approach 2:
The offset voltage and calibration voltage are measured in advance before the actual temperature measurement. By performing these preliminary measurements, the system establishes reference values that are used to compensate for power supply instability and amplifier offset, thereby improving the precision of the subsequent temperature measurement without requiring a more complex real-time measurement circuit.
2Device complexity
If traditional voltage measurement method is used, then the device complexity is low, but the measurement precision deteriorates due to the influence of unstable power supply voltage
Solution Approach 1:
The system uses the measured offset voltage and calibration voltage as feedback to compensate for power supply instability. By comparing the actual measured voltages with expected values and adjusting the resistance calculation accordingly, the system maintains high measurement precision even when the power supply voltage fluctuates, without requiring a more complex voltage regulation circuit.
Solution Approach 2:
The system changes the measurement parameters by measuring voltages at three different states (unloaded, calibration resistor connected, thermistor connected) rather than directly measuring resistance. This parameter transformation allows the system to eliminate the influence of power supply voltage instability on the resistance calculation, improving precision without increasing 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
This approach significantly reduces measurement errors by isolating the impact of unstable power supply voltage and offset voltage, resulting in more accurate temperature measurements.
Implementation Method 1
a thermistor is configured to convert a temperature signal of a measured object to a resistance signal
Data Source
AI summary
The present disclosure relates to the field of biometric parameter measurement, and in particular, to a temperature measurement circuit, a temperature measurement method, a temperature and light intensity measurement circuit, a temperature and light intensity measurement method, a chip, a module, and an electronic device. A temperature signal is obtained based on an output voltage of a differential amplifier circuit when a non-inverting input terminal of the differential amplifier circuit is unload, an output voltage of the differential amplifier circuit when the non-inverting input terminal of the differential amplifier circuit is connected to a calibration resistor, and the output voltage of the differential amplifier circuit when the non-inverting input terminal of the differential amplifier circuit is connected to a thermistor, which improves the accuracy of the temperature measurement.