Magnetic Sensor Compensation Coil Switching for Low-Frequency Sensitivity
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Solution Overview
Problem
Existing magnetic sensors face challenges in detecting low-frequency magnetic fields with high sensitivity due to significant 1/f noise, and existing solutions require high current for modulation, leading to increased power consumption and heat generation.
Innovation Solution
A magnetic sensor design incorporating first and second compensation coils, switches, and a control circuit to modulate the detection-target magnetic field using on/off frequencies, reducing 1/f noise while minimizing the required current for modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetosensitive element is periodically saturated using a modulator to reduce 1/f noise, then the sensitivity for low-frequency magnetic field detection is improved, but the current consumption increases
Solution Approach 1:
The patent divides the compensation function into two separate coils: a first compensation coil for generating a canceling magnetic field and a second compensation coil for detecting the compensation current. This segmentation allows the detection function to be separated from the high-current generation function, enabling low-current operation while maintaining sensitivity.
Solution Approach 2:
The patent introduces a switch as an intermediary component that periodically connects and disconnects the first compensation coil from the magnetosensitive element. This switching mechanism enables periodic saturation modulation without requiring continuous high current flow, thus reducing overall current consumption while maintaining the ability to reduce 1/f noise.
2Object-affected harmful factors
If a large current is used to saturate the magnetosensitive element, then the 1/f noise is reduced, but heat generation increases
Solution Approach 1:
The patent employs periodic switching of the first compensation coil rather than continuous current flow. The control circuit periodically turns the switch on and off, creating periodic saturation cycles that reduce 1/f noise while allowing the system to operate at lower average current levels, thereby reducing heat generation.
Solution Approach 2:
The patent extracts the detection function into a separate second compensation coil that operates independently from the first compensation coil. This allows the detection of compensation current to occur without requiring the high current levels needed for saturation, separating the noise-reduction function from the high-power operation.
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 design effectively reduces 1/f noise in low-frequency regions, enhances sensitivity, and decreases current consumption and heat generation, achieving accurate output signals with reduced current flow.
Implementation Method 1
first and second compensation coils generating a canceling magnetic field based on an output signal from the magnetosensitive element
Implementation Method 2
a sensor chip having a magnetosensitive element
Data Source
AI summary
Disclosed herein is a magnetic sensor that includes sensor chip having a magnetosensitive element, first and compensation coils configured to generate a canceling magnetic field based on an output signal from the magnetosensitive element, a first switch connected in series to the first compensation coil, a control circuit configured to periodically turn on/off the first switch, and a detection circuit configured to detect a compensation current flowing through the second compensation coil.