Three-Axis Hall Angle Sensor Using Complementary Hall Elements
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Solution Overview
Problem
Conventional three-axis Hall sensors face challenges in manufacturing complexity, high cost, sensitivity issues, and inaccuracies due to neglecting the influence of magnetic fields in other directions and N-well thickness changes during operation.
Innovation Solution
A three-axis Hall sensor design utilizing four horizontal and eight vertical Hall elements, with specific geometric configurations and connections, along with a transmission equation that accounts for magnetic field components in multiple directions and N-well thickness variations, achieving improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three identical horizontal Hall elements are used to measure three-dimensional magnetic field, then sensitivity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The sensor is segmented into two functional groups: horizontal Hall elements for measuring vertical magnetic field components and vertical Hall elements for measuring horizontal magnetic field components. This segmentation allows each element type to be optimized for its specific measurement function, simplifying the overall manufacturing process while maintaining high sensitivity for both orientations
Solution Approach 2:
The patent introduces vertical Hall elements (adding a dimensional orientation change) to complement the horizontal Hall elements. By utilizing vertical orientation elements, the system can measure horizontal magnetic field components that horizontal elements cannot detect, thereby achieving three-axis measurement capability without requiring three identical horizontal elements, thus reducing manufacturing complexity
2Ease of manufacture
If vertical Hall elements are used to measure horizontal magnetic field, then manufacturing cost is reduced, but sensitivity and accuracy deteriorate
Solution Approach 1:
The patent merges horizontal and vertical Hall elements into a unified three-axis measurement system. The horizontal Hall elements measure vertical magnetic field components with high sensitivity, while vertical Hall elements measure horizontal components. By combining these complementary measurement capabilities and integrating their outputs through coordinate transformation, the system achieves accurate three-axis measurement using cost-effective vertical elements for horizontal field detection
Solution Approach 2:
The patent introduces coordinate transformation as an intermediary computational process that bridges the gap between vertical Hall element measurements and horizontal magnetic field components. The transformation equations convert vertical element outputs into accurate horizontal field representations, thereby maintaining measurement precision while using cost-effective vertical elements
3Adaptability or versatility
If magnetic concentrator technology is used to convert horizontal magnetic field to vertical direction, then measurement capability is improved, but placement accuracy requirements increase
Solution Approach 1:
The patent extracts the magnetic field direction conversion function from physical magnetic concentrators and implements it through mathematical coordinate transformation. By removing the magnetic concentrator component entirely and using computational transformation of Hall element outputs, the system achieves the same measurement capability without the stringent placement accuracy requirements that physical concentrators would impose
4Device complexity
If N-well thickness change due to reverse bias PN junction is not considered, then device simplicity is maintained, but measurement accuracy deteriorates
Solution Approach 1:
The patent applies preliminary compensation by pre-characterizing the N-well thickness change effect and incorporating correction terms into the measurement equations. By accounting for this second-order effect in advance through modified transmission equations, the system maintains device simplicity while achieving high measurement accuracy through computational compensation rather than complex hardware modifications
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 an angle error of less than 0.3° between the magnetic field direction and the xy-plane, and less than 0.22° between the magnetic field projection on the xy-plane and the x-axis, with enhanced sensitivity and reduced power consumption.
Implementation Method 1
Single-axis Hall sensor is the oldest Hall sensor, and the single-axis Hall sensor can only measure one specific direction of the magnetic field
Data Source
AI summary
Disclosed is a three-axis Hall angle sensor with an accuracy of 0.3°. The sensor is mainly designed by means of finite element software and COMSOL Multiphysics. The present specification will be mainly performed in three steps. In the first step, a cross-shape horizontal Hall element for measuring the magnetic field in the vertical direction, that is, the direction z, is studied. The second section mainly studies a three-contact four-Hall vertical element for measuring the magnetic field in the directions x, y. The third part is to design the angle sensor. Compared with the horizontal Hall element, the vertical Hall element has a relatively large offset, therefore, four vertical Hall elements are used to measure the magnetic field in the horizontal direction, and two complementary vertical structures are used to eliminate the error when the magnetic field in the same horizontal direction is measured.