Octagonal Hall Sensor DC Biasing Offset Reduction
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Solution Overview
Problem
Current Hall sensor systems face challenges in achieving high sensitivity and bandwidth while minimizing offset effects, particularly due to the complexity of integrating coils and the inefficiency of spinning techniques, which often result in reduced bandwidth and increased design complexity.
Innovation Solution
The use of an octagonal Hall sensor with a biasing/sensing method that avoids integrated coils and spinning techniques, employing a DC biasing approach and spatial averaging across two sensors on the same active area to reduce offset and enhance bandwidth, allowing for a simpler analog front-end design without the need for switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spinning techniques are used to reduce offset effects, then offset reduction is achieved, but bandwidth is reduced and measurement time increases
Solution Approach 1:
The Hall sensor is divided into multiple sensing regions (first and second sensing regions) with different orientations. Each region senses magnetic field components in different directions, allowing simultaneous offset cancellation and high-bandwidth measurement without requiring sequential spinning operations
Solution Approach 2:
The sensor structure is pre-configured with multiple sensing regions oriented at specific angles (e.g., 45 degrees) to each other. This preliminary geometric arrangement enables the sensor to inherently cancel offset effects through spatial averaging, eliminating the need for dynamic spinning operations during measurement
2Speed
If integrated coils are used to achieve high bandwidth, then bandwidth exceeds 1 MHz, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent removes the coils entirely from the sensor structure, relying solely on the Hall effect in a planar sensing element. This extraction of the coil component simplifies the device architecture while maintaining high bandwidth through the intrinsic response of the Hall sensor material
Solution Approach 2:
The mechanical/spinning system used for offset cancellation is replaced with a static geometric arrangement of multiple sensing regions. The offset cancellation function is achieved through the spatial configuration of the sensing elements rather than through dynamic mechanical rotation or complex coil arrangements
3Measurement precision
If spinning techniques are used for offset reduction, then offset values are reduced, but the number of measurement steps increases to four steps per measurement
Solution Approach 1:
The multiple sensing regions operate simultaneously and continuously, providing both offset-corrected signals and high-bandwidth response in real-time. The spatial averaging occurs continuously through the parallel operation of all sensing regions, eliminating the need for sequential measurement steps
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 achieves a significantly higher bandwidth (up to 50 times that of spinning readout) with low offset values (as low as 100 μT at 50 MHz), facilitating a competitive, low-cost, high-speed, and high-sensitivity Hall-based sensor arrangement suitable for applications like RF and automotive industries.
Implementation Method 1
a planar Hall sensing element configured to be exposed to a transverse magnetic field and to produce at least one Hall voltage indicative of said magnetic field when traversed by an electric current
Data Source
AI summary
A planar Hall sensing element includes a first pair of sensing electrodes mutually opposed in a first direction across the sensing element and a second pair of sensing electrodes mutually opposed in a second direction across the sensing element, with the second direction orthogonal to the first direction. A first pair of bias electrodes is mutually opposed in a third direction and a second pair mutually opposed in a fourth direction across the sensing element, the fourth direction orthogonal to the third direction. The third and fourth directions are rotated 45° with respect to the first and second directions so each sensing electrode is arranged between a bias electrode of the first pair and second pair. A DC bias current is supplied between the first and second pairs of bias electrodes. First and second Hall voltages are sensed at the first and second pairs of sensing electrodes.