Vertical Hall Element Offset Cancellation via Adjustable Drive Currents
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Solution Overview
Problem
Vertical Hall elements used for magnetic field detection often generate offset voltage due to manufacturing variations, making it difficult to achieve accurate offset cancellation using the spinning current method.
Innovation Solution
A semiconductor device with two vertically arranged Hall elements, each driven by separate power sources, allowing for independent adjustment of drive currents to match their characteristics and improve offset cancellation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the spinning current method is used with multiple vertical Hall elements to remove offset voltage, then offset cancellation is achieved, but manufacturing variations cause unequal resistance in current paths reducing cancellation accuracy
Solution Approach 1:
The patent introduces adjustable drive current parameters for each Hall element to compensate for manufacturing variations. By independently controlling the drive current magnitude for each vertical Hall element, the system can equalize the effective resistance in current paths despite physical variations, thereby achieving accurate offset cancellation
Solution Approach 2:
The patent implements a feedback mechanism where the output signals from multiple Hall elements are processed to detect offset voltage, and this information is used to adjust the drive currents. The control unit monitors the combined output and modifies individual drive currents to minimize offset, creating a closed-loop system that compensates for manufacturing variations
2Measurement precision
If separate drive power sources are provided for each vertical Hall element to compensate for characteristic variations, then offset cancellation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent employs a control unit that performs multiple functions: it manages the drive currents for each Hall element, processes the output signals, detects offset voltage, and adjusts currents accordingly. This multi-functional approach consolidates what would otherwise require separate dedicated circuits for each function, reducing overall device complexity while maintaining the benefits of separate drive power sources
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 enables high-accuracy offset cancellation by compensating for characteristic variations between the Hall elements, reducing the need for additional circuit adjustments and allowing for the addition of a hysteresis characteristic to the output voltage.
Implementation Method 1
A Hall element is capable of detecting position or angle without contact as a magnetic sensor... there have also been proposed various magnetic sensors that use a vertical Hall element configured to detect a magnetic field component parallel to the semiconductor substrate surface (horizontal magnetic field)
Data Source
AI summary
The semiconductor device includes a first vertical Hall element provided in a first region of a semiconductor substrate, and including a first plurality of electrodes arranged at predetermined intervals on a first straight line, a second vertical Hall element provided in a second region of the semiconductor substrate different from the first region, and including a second plurality of electrodes of the same number as that of the first plurality of electrodes, the second plurality of electrodes being arranged at the predetermined intervals on a second straight line parallel to the first straight line, a first drive power source configured to drive the first vertical Hall element, and a second drive power source configured to drive the second vertical Hall element and provided separately from the first drive power source.