Stray-Field-Immune Angle Sensor With Vertical Hall Pairs
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Solution Overview
Problem
Magnetic field sensors are adversely affected by stray magnetic fields, which compromise their accuracy in detecting intended magnetic fields.
Innovation Solution
A sensor design featuring vertical Hall element pairs oriented at specific angles relative to a substrate's reference crystal orientation, positioned to cancel out stray magnetic fields by differential signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field sensors are used to detect magnetic fields, then magnetic field detection capability is achieved, but accuracy is adversely affected by stray magnetic fields
Solution Approach 1:
The sensor divides the detection function into multiple vertical Hall elements arranged in pairs at different orientations (e.g., 0° and 90°) relative to the substrate. Each element pair independently measures magnetic field components, allowing the system to segment the total magnetic field into orthogonal components that can be processed to eliminate stray field effects.
Solution Approach 2:
Each vertical Hall element is oriented with a specific sensitivity direction (local quality) relative to the substrate crystal orientation. The first element in each pair has a sensitivity axis at a first angle, while the second element has a sensitivity axis at a second angle, creating localized measurement capabilities that when combined provide stray field immunity.
2Reliability
If vertical Hall element pairs are used with specific orientations, then immunity to stray fields is improved, but device complexity increases
Solution Approach 1:
Multiple vertical Hall elements are merged into integrated pairs on a single substrate, with each pair containing elements at complementary orientations. The elements are electrically connected through common terminals, combining their outputs to achieve stray field immunity while maintaining a compact, integrated structure rather than separate discrete components.
Solution Approach 2:
The vertical Hall element pairs serve multiple functions: they detect magnetic field components in different directions, provide redundant measurement capability, and collectively achieve stray field rejection. The same basic element structure is reused in different orientations, providing universal functionality across multiple measurement axes.
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 sensor achieves improved accuracy and immunity to stray fields, enabling precise detection of intended magnetic fields.
Implementation Method 1
Magnetic field sensors employ a variety of types of magnetic field sensing elements, for example, Hall effect elements
Data Source
AI summary
A sensor, comprising: a substrate having a reference crystal orientation and a plurality of vertical Hall element pairs that are formed on the substrate. Each vertical Hall element pair includes: (i) a respective first vertical Hall element that is oriented at a respective first angle relative to the reference crystal orientation of the substrate and (ii) a respective second vertical Hall element that is oriented at a respective second angle relative to the reference crystal orientation of the substrate. The substrate has a rectangular shape, and each of the vertical Hall element pairs is disposed in a different respective corner of the substrate.