Hall Magnetic Switch Reference Voltage Tuning for Symmetric Detection
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Solution Overview
Problem
Magnetic switches, particularly those using Hall elements, face challenges in maintaining symmetric magnetoelectric conversion characteristics due to offset voltages and magnetic offsets, which can lead to phase and duty ratio shifts in output pulse signals, affecting the performance of brushless direct current (BLDC) motors and magnetic body detection mechanisms.
Innovation Solution
A semiconductor device with a magnetic switch configuration that includes a Hall element, a switch circuit, an amplifier, a comparator, and a latch circuit, which uses a reference voltage circuit to adjust the comparator reference voltage based on control signals, allowing for optimal adjustment of the magnetic offset and improving the symmetric property of magnetoelectric conversion characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-way drive spinning current method is used to eliminate offset voltages, then offset voltage elimination is improved, but symmetric property of magnetoelectric conversion characteristic deteriorates when absolute value of offset voltage differs between current drive directions
Solution Approach 1:
The patent applies preliminary action by adjusting the comparator reference voltage before magnetic field detection to compensate for magnetic offsets. The reference voltage adjustment circuit pre-calculates and applies the necessary voltage adjustment based on detected magnetic offset conditions, ensuring symmetric magnetoelectric conversion characteristics are established before actual measurement begins. This prevents the asymmetry that would otherwise occur during two-way drive spinning current operation.
Solution Approach 2:
The patent changes the parameter of comparator reference voltage to compensate for magnetic offsets. By dynamically adjusting the reference voltage level based on the detected magnetic offset conditions, the system maintains symmetric magnetoelectric conversion characteristics even when offset voltages differ between current drive directions. This parameter change allows the system to adapt to varying offset conditions while preserving measurement symmetry.
2Stability of the object's composition
If hysteresis width is set to prevent chattering of output signal, then signal stability is improved, but magnetic offset increases causing asymmetric sensitivity between magnetic poles
Solution Approach 1:
The patent changes the comparator reference voltage parameter to compensate for magnetic offsets introduced by hysteresis. By adjusting the reference voltage based on detected magnetic offset conditions, the system maintains accurate threshold detection despite the presence of hysteresis width. This allows the hysteresis to continue providing signal stability while the reference voltage adjustment corrects any resulting asymmetry in magnetic pole sensitivity.
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 effectively corrects the influence of magnetic offsets on the operating and returning points, enhancing the symmetric property of magnetoelectric conversion characteristics and reducing variations in detection distances, thereby improving the accuracy and reliability of magnetic field detection.
Implementation Method 1
A Hall element is used for various applications as a magnetic sensor because the Hall element can detect a position and an angle in a non-contact manner.
Data Source
AI summary
A semiconductor device includes a magnetic switch provided on a semiconductor substrate. The magnetic switch includes: a Hall element, first and second power supply terminals; a current source driving the Hall element; a switch circuit switching a differential output voltage supplied from two electrodes of the Hall element to a first or second state based on a control signal supplied from a control terminal; an amplifier amplifying a signal from the switch circuit; a reference voltage circuit generating a reference voltage based on a reference common mode voltage and a control signal; a comparator receiving an output signal of the amplifier and the reference voltage; and a latch circuit latching an output voltage of the comparator. The reference voltage of the reference voltage circuit is controlled by switching from a reference value to a voltage with a high or low adjustment value according to the output voltage of the comparator.