Calibrated RTD Measurement Circuit for Temperature Drift Compensation
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Solution Overview
Problem
Existing resistance temperature detector (RTD) systems face accuracy issues due to temperature drift and mismatched current sources, which affect the reliability of temperature measurements.
Innovation Solution
A calibrated measurement circuit that includes a reference resistor and advanced current switching functionality to determine a calibration factor, reducing the impact of temperature drift and current mismatch by measuring voltages across the RTD and reference resistor in different configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a RTD sensor is used to measure temperature, then temperature measurement capability is provided, but measurement accuracy deteriorates due to temperature drift and current source mismatch
Solution Approach 1:
The patent applies parameter changes by performing measurements at multiple current levels (first current and second current) and using multiple measurement configurations. By varying the excitation current parameters and measuring at different states, the system can calculate a calibration factor that compensates for temperature drift and current mismatch effects, thereby improving measurement accuracy and reliability
Solution Approach 2:
The patent implements feedback through the calibration process where measurement results from multiple configurations are used to calculate a calibration factor. This calibration factor is then applied to correct subsequent measurements, creating a feedback loop that continuously improves measurement accuracy by compensating for drift and mismatch effects
2Measurement precision
If advanced current switching and reference resistor measurements are implemented, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by using the same ADC and current sources for multiple purposes: measuring both the RTD sensor and the reference resistor, and performing measurements at different current levels. This multi-functional approach allows accurate calibration without requiring completely separate measurement circuits, thereby limiting the increase in device complexity
Solution Approach 2:
The patent uses the reference resistor as an intermediary element to establish a known reference measurement. By measuring the reference resistor at the same current levels as the RTD sensor, the system can calculate a calibration factor that mediates the effects of current mismatch and temperature drift, improving accuracy without requiring complex direct 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 accurate and reliable temperature measurements by eliminating offset errors and temperature drift, enhancing the precision of RTD systems and reducing measurement errors.
Implementation Method 1
a temperature-dependent resistor, whereby a voltage across a temperature-dependent resistor is measured and corresponds to its resistance, so that resistance further corresponds to the then-existing temperature to which the resistor is exposed
Implementation Method 2
circuitry for measuring a first voltage across the circuit element in response to the first current; circuitry for measuring a second voltage across the circuit element in response to the second current
Data Source
AI summary
A calibrated measurement circuit, with a first node, a second node, a circuit element coupled between the first node and the second node, and a reference circuit element. The calibrated measurement circuit also comprises circuitry for directing a first current and a second current between the first node and the second node and to the reference circuit element. The calibrated measurement circuit also comprises circuitry for measuring voltage across the circuit element in response to the first and second currents, and circuitry for measuring voltage across the reference circuit element in response to the first and second currents. A calibration factor is also determined for calibrating measured voltages across the circuit element, in response to a relationship between the first voltage, the second voltage, and the reference circuit element.