Sensor Circuit Compensating Resistor Temperature Coefficient
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Solution Overview
Problem
Magnetic field sensors with resistance bridge circuits face challenges in temperature compensation of measurement sensitivity and offset voltage, particularly when supplied with constant current, leading to poorer thermal characteristics compared to voltage-fed sensors.
Innovation Solution
Incorporating a compensating resistor with a different temperature coefficient into the sensor circuit, connected either in parallel or series with the bridge circuit, to compensate for the negative temperature coefficients of measurement sensitivity and resistance, thereby stabilizing the measurement sensitivity and offset voltage over temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant current supply is used for the sensor bridge, then the sensor can operate with stable current, but the measurement sensitivity temperature coefficient becomes more negative due to the combination of negative TCR and negative TCSB_TMR
Solution Approach 1:
A compensating resistor is introduced as an intermediary element in parallel with the sensor bridge. This resistor has a positive temperature coefficient that compensates for the negative temperature coefficient effects in the constant current-fed bridge, thereby improving measurement precision while maintaining current stability.
2Device complexity
If the bridge circuit has negative temperature coefficients for both resistance and measurement sensitivity, then the components can be simplified, but the thermal characteristics become poorer
Solution Approach 1:
The temperature coefficient parameter of the total bridge resistance is changed by adding a compensating resistor with a different temperature coefficient. This modifies the thermal characteristics from poor (negative TCR) to improved (near-zero or positive TCR), while keeping the bridge circuit structure relatively simple.
3Device complexity
If no compensating resistor is used, then the circuit remains simple, but the offset voltage shifts with temperature due to measurement sensitivity changes
Solution Approach 1:
A compensating resistor serves as an intermediary element that specifically addresses offset voltage shifts. By having a different temperature coefficient, it counteracts the temperature-induced sensitivity changes that cause offset drift, thereby stabilizing the offset voltage without significantly 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
The compensating resistor effectively reduces the absolute value of the measurement sensitivity temperature coefficient, stabilizes the bridge voltage and output voltage over temperature, and improves the thermal characteristics of current-fed sensors to match those of voltage-fed sensors.
Implementation Method 1
at least one compensating resistor that is connected between the first connection (e.g., supply connection) and the second connection (e.g., ground connection), which is configured to compensate the temperature coefficient of measurement sensitivity (measurement sensitivity temperature coefficient) of the bridge circuit
Data Source
AI summary
The present disclosure relates to a sensor circuit, including a first connection, a second connection and a bridge circuit, which is connected between the first connection and the second connection, having a plurality of bridge resistors with a respective temperature coefficient. The bridge circuit has a measurement sensitivity and a temperature coefficient of measurement sensitivity and a bridge offset with a temperature coefficient of the bridge offset. The sensor circuit further includes at least one compensating resistor, which is connected between the first connection and the second connection, with a temperature coefficient that differs from the temperature coefficient of the bridge resistors.