Magnetic Field Sensor Compensation Circuit Using Matched Reference Resistor
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Solution Overview
Problem
Magnetic field sensing elements, particularly Hall semiconductor devices, suffer from low sensitivity to stress, poor compensation effects, and temperature inconsistency due to mechanical stress and different doped structures, leading to inaccurate output readings.
Innovation Solution
A compensation circuit and method involving a magnetic field sensing element with a reference resistor having a perpendicular current direction and matching doped structure, coupled with a processing module to calculate and adjust resistance values, and switching modules to vary current directions for enhanced compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If two groups of Hall devices with different doped structures are configured in the same plane to achieve mean compensation, then temperature consistency is improved, but manufacturing complexity increases and compensation effect deteriorates due to poor temperature consistency
Solution Approach 1:
The invention segments the compensation function into two independent parts: (1) Hall devices all with the same doped structure for magnetic field sensing, and (2) a separate reference resistor with matching doped structure for temperature compensation. This segmentation eliminates the conflict between different doped structures while maintaining temperature consistency through the matched reference resistor.
Solution Approach 2:
The reference resistor acts as an intermediary element that bridges the Hall devices and the compensation circuit. It is configured with the same doped structure as the Hall devices and experiences the same temperature variations, thereby providing an accurate reference for temperature compensation without directly interfering with the magnetic field sensing function.
2Measurement precision
If two groups of Hall devices are configured in the same plane with different current directions to achieve mean compensation, then compensation capability is improved, but mutual interference between current directions deteriorates the compensation effect
Solution Approach 1:
The invention extracts the compensation function from the Hall devices themselves and places it in a separate reference resistor. The Hall devices focus solely on magnetic field sensing with uniform current directions, while the reference resistor handles temperature compensation independently, eliminating mutual interference between different current directions.
Solution Approach 2:
The reference resistor is designed as a copy of the Hall device structure with the same doped regions and material composition, but configured to measure only temperature effects. This copying approach allows accurate temperature tracking without the complications of multiple current directions in the same plane.
3Measurement precision
If Hall devices are used for magnetic field sensing, then sensing function is achieved, but sensitivity to stress deteriorates due to susceptibility to mechanical stress
Solution Approach 1:
The invention changes the configuration parameter of the reference resistor to have the same doped structure as the Hall devices, ensuring that both experience identical stress effects. This allows the compensation circuit to accurately track and compensate for stress-induced variations while maintaining the Hall devices' magnetic field sensing capability.
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
Improves sensitivity to stress and temperature consistency by utilizing perpendicular current directions and matching doped structures, enabling accurate compensation for mechanical stress-induced errors.
Implementation Method 1
Hall semiconductor devices, which are mostly used for magnetic field sensing in general technology
Implementation Method 2
the resistor response layer has a first thickness and a first length, the first thickness and the first length satisfy a preset multiple relationship to make an average current in the reference resistor at least partially flow in a direction of the first thickness, and the direction of the first thickness is perpendicular to the first plane
Data Source
AI summary
Disclosed are a compensation circuit and compensation method for a magnetic field sensing element. The compensation circuit comprises a magnetic field sensing element, a reference resistor, a current source, and a processing module. The magnetic field sensing element comprises a sensing substrate, a sensing response layer, a sensing electrode, and a sensing doped region. An average current flows in a first plane. The reference resistor comprises a resistor substrate, a resistor response layer, a resistor electrode, and a resistor doped region. The average current at least partially flows in a direction of a first thickness. The direction of the first thickness is perpendicular to the first plane. The sensing response layer and the sensing doped region form a same doped structure as the resistor response layer and the resistor doped region. The compensation circuit provided in the present invention ensures the consistency of temperature and the stress sensitivity of compensation.