Magnetic Sensor Thermal Compensation Circuit
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Solution Overview
Problem
Magnetic sensors employing Magnetic Tunnel Junctions face accuracy issues due to thermally induced variations in sensitivity, with output drift of up to 5% across a significant temperature range (-40° C. to +155° C., necessitating effective thermal compensation.
Innovation Solution
A compensation circuit is integrated with a magnetic sensor and a temperature sensor to compute and apply a temperature compensation signal, using a gain variation computation block, multiplier, adder, and bridge amplifier to produce a temperature-compensated output signal, reducing thermal-induced variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If magnetic sensors operate over a wide temperature range, then the sensor's adaptability is improved, but thermally induced sensitivity variations increase
Solution Approach 1:
The patent implements a feedback mechanism where the temperature sensor continuously monitors the ambient temperature and feeds this information to the compensation circuit. The compensation circuit then adjusts the magnetic sensor's output signal based on the temperature feedback, creating a closed-loop system that automatically compensates for thermal drift and maintains measurement precision across wide temperature ranges.
Solution Approach 2:
The patent changes the electrical parameters of the magnetic sensor circuit dynamically based on temperature conditions. The compensation circuit modifies the bias voltage, gain, or other circuit parameters as functions of temperature, allowing the system to adapt its operating characteristics to compensate for thermally induced sensitivity variations while maintaining wide temperature range operation.
2Measurement precision
If thermal compensation is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the temperature sensing function and compensation function into an integrated circuit architecture. The temperature sensor and compensation circuit are combined in a way that shares common components such as signal processing paths and power supply, reducing the overall complexity compared to having separate compensation systems. This integration approach maintains high measurement precision while minimizing the increase in device 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 solution effectively reduces the Temperature Coefficient of Sensitivity by a factor of 10, substantially eliminating the 5% error range across the sensor's operating temperature, thereby enhancing the accuracy of magnetic sensor outputs.
Implementation Method 1
Magnetic sensors utilize Magnetic Tunnel Junctions (MTJs), which under appropriate circumstances, act as Tunnel Magneto Resistance (TMR) sensors. A TMR sensor experiences a change in its resistance in the presence of an ambient magnetic field.
Implementation Method 2
A temperature sensor produces an ambient temperature signal
Data Source
AI summary
A circuit has a magnetic sensor that produces an uncompensated magnetic sensor output signal. A temperature sensor produces an ambient temperature signal. A compensation circuit is connected to the magnetic sensor and the temperature sensor. The compensation circuit is configured to add a computed temperature compensation signal to the uncompensated magnetic sensor output signal to produce a magnetic sensor temperature compensated output signal that reduces thermally induced variation of the uncompensated magnetic sensor output signal.