Magnetic Sensor Sensitivity Compensation Using Feedback Gain Control
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Solution Overview
Problem
Magnetoresistive sensors suffer from sensitivity drift due to mechanical stress, temperature changes, and incomplete temperature compensation, which existing compensation methods fail to adequately address, particularly due to manufacturing-related fluctuations and reliance on statistical mean values.
Innovation Solution
A magnetic sensor apparatus that includes a magnetic field generating circuit, a magnetic field sensor circuit, an amplifier circuit, and a control circuit to adjust supply signal and/or gain, using techniques such as pseudo-random pilot signals and feedback loops to compensate for sensitivity drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional stress compensation methods using correlation coefficients are used, then compensation for mechanical stress drift is attempted, but manufacturing-related fluctuations and statistical mean values lead to insufficient accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the sensor output is continuously monitored and compared against a reference value. The control circuit adjusts the supply current to the sensor based on the deviation detected, creating a closed-loop system that automatically compensates for drift. This feedback approach eliminates reliance on statistical mean values and correlation coefficients, directly addressing manufacturing variations in real-time.
Solution Approach 2:
The patent changes the operating parameter (supply current) dynamically to compensate for sensitivity drift. By adjusting the supply current based on the measured sensor output deviation, the system maintains stable sensitivity despite manufacturing variations. This parameter change approach provides more accurate and reliable compensation compared to fixed correlation-based methods.
2Measurement precision
If temperature compensation is performed, then sensitivity drift due to temperature changes is reduced, but mechanical stress and moisture effects remain uncompensated
Solution Approach 1:
The patent creates a universal compensation mechanism that handles multiple types of drift (temperature, mechanical stress, moisture) through a single feedback loop. The control circuit adjusts the supply current based on the overall sensor output deviation, which encompasses all types of drift simultaneously. This multi-functional approach eliminates the need for separate compensation circuits for each stress type, providing comprehensive compensation with simpler architecture.
Solution Approach 2:
The sensor system performs self-compensation by monitoring its own output and automatically adjusting its operating parameters. The feedback mechanism enables the sensor to compensate for its own drift without external intervention, making the system adaptable to various environmental factors including temperature, mechanical stress, and moisture changes.
3Reliability
If multiple stress components are compensated for individually, then comprehensive stress compensation is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent merges multiple compensation functions into a single feedback loop that handles all types of stress and environmental effects simultaneously. Instead of implementing separate compensation circuits for each stress component, the system uses one control circuit that adjusts the supply current based on the overall sensor output deviation. This combining approach reduces device complexity while maintaining comprehensive compensation coverage.
Solution Approach 2:
The patent segments the compensation function by separating the sensing function from the compensation function. The sensor circuit remains simple and dedicated to sensing, while the compensation is handled by a separate control circuit that adjusts the supply current. This segmentation allows each component to remain simple while achieving comprehensive compensation through their coordinated interaction.
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 stabilizes sensor sensitivity, achieving low noise, high bandwidth, and high accuracy while reducing costs by compensating for lifetime drift and mechanical stress effects.
Implementation Method 1
Magnetoresistive effects are all effects that describe the change in an electrical resistance of a material by applying an external magnetic field. These include, in particular, the anisotropic magnetoresistive effect (AMR effect), the giant magnetoresistance (GMR effect), the colossal magnetoresistive effect (CMR effect), the magnetic tunnel resistance (TMR effect) and the planar Hall effect.
Implementation Method 2
According to some example implementations, the magnetic field sensor circuit includes at least one Hall sensor.
Implementation Method 3
The magnetic field generating circuit includes a current conductor for an electrical excitation current. For example, the current conductor and the magnetic field sensor circuit can be arranged on a common semiconductor chip.
Implementation Method 4
an amplifier circuit which is configured to amplify the sensor signal and to output an amplified sensor signal with an amplified signal amplitude
Data Source
AI summary
A magnetic sensor apparatus includes a magnetic field generating circuit which is configured to generate a magnetic field, a magnetic field sensor circuit which is configured to output a sensor signal in response to the magnetic field, which sensor signal has a signal amplitude dependent on a sensitivity of the magnetic field sensor circuit, an amplifier circuit which is configured to amplify the sensor signal and to output an amplified sensor signal with an amplified signal amplitude, and a control circuit which is configured to use a setting signal to set a supply signal of the magnetic field sensor circuit and/or a gain of the amplifier circuit such that the amplified signal amplitude corresponds to a target amplitude.