Magnetic Field Sensor Using Multiple CVH Elements for High-Speed Angle Detection
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Solution Overview
Problem
Magnetic field sensors using CVH elements face limitations in sampling rate and angular resolution, particularly when sensing rapidly rotating magnetic fields, leading to inaccurate direction identification and low resolution.
Innovation Solution
A magnetic field sensor design incorporating multiple CVH elements with aligned maximum response axes, utilizing sequence switches and processing circuits to combine signals and generate an x-y angle signal, enabling higher sampling rates and improved angular resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single CVH element is used to sense magnetic field direction, then the sensor structure is simple, but the sampling rate is limited and angular resolution is low
Solution Approach 1:
The patent divides the sensing function into multiple independent CVH elements (first CVH element and second CVH element) with different orientations. Each element processes magnetic field information independently, allowing parallel sampling that doubles the effective sampling rate without requiring a single complex element to perform all functions.
Solution Approach 2:
The patent combines the output signals from multiple CVH elements through signal processing circuits that integrate information from both elements. The processing circuit combines signals to generate enhanced angle information, achieving higher sampling rates and resolution by merging data from multiple simpler elements rather than using one complex element.
2Measurement precision
If vertical Hall elements are arranged in a circular pattern to sense magnetic field direction, then angle detection is achieved, but DC offset variations among elements degrade measurement precision
Solution Approach 1:
The patent uses multiple CVH elements that are essentially copies of the same sensing structure, each oriented differently. By having multiple identical elements with known offset characteristics, the system can compensate for DC offset variations through signal processing that references the expected behavior of identical elements, rather than relying on a single element with unknown offset.
Solution Approach 2:
The processing circuit employs feedback mechanisms to compensate for DC offsets by continuously monitoring the output signals from multiple CVH elements and adjusting the angle calculation accordingly. The system uses the known geometric relationships between elements to feedback-correct offset errors in real-time, maintaining measurement precision despite hardware variations.
3Speed
If sequential sampling of vertical Hall elements is performed to identify magnetic field direction, then angle information is obtained, but the sampling rate is constrained by electronic circuit speed
Solution Approach 1:
The patent segments the sampling process across multiple CVH elements that can be read in parallel or with overlapping sequences. By distributing the sampling task across multiple elements rather than sequentially reading all elements of a single element, the effective sampling rate increases without requiring each individual element to be read at extremely high speeds.
Solution Approach 2:
The patent employs periodic sampling patterns where multiple CVH elements are sampled in a coordinated sequence. The processing circuit uses periodic reference signals to synchronize the sampling of multiple elements, allowing high-speed angle detection by periodically refreshing information from multiple elements in a predictable pattern that simplifies timing and increases effective sampling rate.
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 allows for accurate direction sensing of rapidly rotating magnetic fields with enhanced resolution, improving the sensor's ability to identify magnetic field angles with increased precision and speed.
Implementation Method 1
A vertical Hall element tends to be responsive to magnetic field parallel to a surface of a substrate on which the vertical Hall element is formed
Data Source
AI summary
A magnetic field sensor for sensing a direction of a magnetic field in an x-y plane, can include a first plurality of magnetic field sensing elements operable to generate a first plurality of magnetic field signals and a second plurality of magnetic field sensing elements operable to generate a second plurality of magnetic field signals. The magnetic field sensor can also include at least one sequence switches circuit operable to select ones of the first plurality of magnetic field signals and to select ones of the second plurality of magnetic field signals. The magnetic field sensor can also include a processing circuit operable to combine the selected ones of the first plurality of magnetic field signals and the selected ones of the second plurality of magnetic field signals to generate at least one sequential signal and to process the at least one sequential signal to generate an x-y angle signal indicative of a direction of the magnetic field in the x-y direction. An associated method is described.