AMR Angular Sensor Segment Balancing for Non-Uniform Field Accuracy
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Solution Overview
Problem
Integrated anisotropic magnetoresistive (AMR) angular sensors face errors when measuring non-uniform magnetic fields due to variations in magnetoresistive segments across the sensing area, leading to inaccurate angle estimation.
Innovation Solution
The design includes two sets of magnetoresistive segments oriented in parallel/anti-parallel configurations on opposite sides of a central point, with equal numbers of segments in each group, to balance the length-to-width ratio between 3 and 10, reducing shape anisotropy errors and increasing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple magnetoresistive segments are used in each resistor to increase sensing area, then the sensing area is increased, but measurement accuracy deteriorates due to errors from non-uniform magnetic fields
Solution Approach 1:
The sensor is divided into multiple discrete magnetoresistive segments (first segments 105 and second segments 110) arranged in specific patterns. Each segment responds to the magnetic field independently, and their combined response in bridge circuits provides accurate angle measurement while maintaining a distributed sensing area that averages out non-uniformities in the magnetic field
Solution Approach 2:
Different regions of the sensing area are assigned different functions through the segmented architecture. The first magnetoresistive segments are oriented in one direction while the second segments are oriented perpendicularly, allowing each segment to optimally detect magnetic field components in its specific orientation, thereby improving overall measurement accuracy across the entire sensing area
2Measurement precision
If magnetoresistive segments have low length-to-width ratios to reduce shape anisotropy error, then shape anisotropy error is reduced, but device area increases
Solution Approach 1:
Instead of using a single large magnetoresistive element with low length-to-width ratio, the sensor uses multiple smaller segments. Each segment can have optimized dimensions that balance shape anisotropy minimization with compact area, while the collective arrangement maintains the overall low length-to-width ratio characteristic for reduced shape anisotropy error
Solution Approach 2:
The patent transitions from considering only the in-plane dimensions (length and width) to incorporating the vertical dimension through thin-film deposition. The magnetoresistive segments are implemented as thin films with controlled thickness, allowing optimization of the length-to-width ratio in the plane while using the vertical dimension to achieve the desired low ratio without proportionally increasing the planar area
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 configuration enhances the accuracy of angle measurements for non-uniform magnetic fields by providing a balanced distribution of magnetoresistive segments, reducing the sensor area and fabrication costs while maintaining measurement precision.
Implementation Method 1
Each magnetoresistive segment has an ohmic resistance dependent on the orientation of the magnetic field relative to current flow through the magnetoresistive segment
Data Source
AI summary
An integrated AMR angular sensor includes a first sensor resistor and a second sensor resistor. The first sensor resistor and the second sensor resistor each has a plurality of magnetoresistive segments containing magnetoresistive material that are electrically coupled in series. The magnetoresistive segments of each sensor resistor are parallel/anti-parallel to each other. The magnetoresistive segments of the second sensor resistor are perpendicular to the magnetoresistive segments of the first sensor resistor. The first magnetoresistive segments are divided into a first group and a second group, which are disposed in a balanced distribution relative to a sensor central point of the integrated AMR angular sensor. Similarly, the second magnetoresistive segments are divided into a first group and a second group, which are disposed in a balanced distribution relative to the sensor central point.