Hall Sensor Asymmetry Compensation via Resistance Ratio
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Solution Overview
Problem
Hall effect devices often suffer from asymmetry issues due to manufacturing processes, leading to magnetic cross-talk, which affects their accuracy in detecting magnetic fields, particularly causing sensitivity to unintended magnetic field components.
Innovation Solution
A sensor cross-talk compensation system is developed, including a semiconductor substrate with a vertical Hall sensor element and an asymmetry detector. The asymmetry detector has a conductivity type with a specific doping concentration and multiple detector contacts, allowing for resistance ratio measurement to compensate for asymmetry, generating a compensated measurement signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard manufacturing processes are used for Hall effect devices, then production efficiency is maintained, but asymmetries are introduced leading to magnetic cross-talk
Solution Approach 1:
The patent applies preliminary action by measuring the asymmetry characteristics of the Hall sensor element before final operation and pre-calculating compensation factors based on these measurements. The compensation factors are stored and applied during subsequent measurements to counteract the asymmetry effects, thereby preventing magnetic cross-talk from degrading measurement accuracy.
Solution Approach 2:
The patent changes the measurement parameters by introducing asymmetry measurement signals in addition to the standard magnetic field measurement signals. By measuring resistance values under different current directions and calculating asymmetry factors from these parameter variations, the system identifies and compensates for manufacturing-induced asymmetries that cause magnetic cross-talk.
2Reliability
If asymmetry compensation is implemented, then magnetic cross-talk is reduced, but device complexity increases
Solution Approach 1:
The patent implements feedback by measuring the actual asymmetry characteristics of each Hall sensor element, calculating compensation factors based on these measurements, and applying the calculated factors to correct subsequent measurements. This closed-loop feedback approach automatically compensates for manufacturing variations without requiring complex hardware modifications, thereby reducing magnetic cross-talk while limiting the increase in device complexity to software/algorithms processing.
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 system effectively reduces magnetic cross-talk by accurately detecting and compensating for asymmetries, enhancing the device's sensitivity to intended magnetic field components and reducing unwanted sensitivity to orthogonal components.
Implementation Method 1
a vertical Hall sensor element disposed in the semiconductor substrate, wherein the vertical Hall sensor element is configured to generate a first sensor signal in response to a first magnetic field impinging thereon
Implementation Method 2
a resistance ratio measurement circuit configured to determine a ratio between a first resistance and a second resistance, wherein the first resistance is a resistance between a first pair of detector contacts of the at least three detector contacts and the second resistance is a resistance between a second pair of detector contacts of the at least three detector contacts
Data Source
AI summary
A sensor cross-talk compensation system includes a semiconductor substrate having a first main surface and a second main surface opposite to the first main surface; a vertical Hall sensor element disposed in the semiconductor substrate, the vertical Hall sensor element is configured to generate a sensor signal in response to a magnetic field impinging thereon; and an asymmetry detector configured to detect an asymmetric characteristic of the vertical Hall sensor element. The asymmetry detector includes a detector main region that vertically extends into the semiconductor substrate from the first main surface towards the second main surface and is of a conductivity type having a first doping concentration; and at least three detector contacts disposed in the detector main region at the first main surface, the at least three detector contacts are ohmic contacts of the conductivity type having a second doping concentration that is higher than the first doping concentration.