Voltage-Driven Hall Plate Current Sensor for Stress-Stable Sensitivity
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Solution Overview
Problem
Existing Hall effect sensors experience sensitivity changes due to stress and temperature variations, leading to instability in magnetic field detection, particularly in current-driven Hall plate sensors, which require large die areas and high noise levels.
Innovation Solution
Implementing a voltage-driven Hall plate sensor with stress compensation using vertical and lateral epi resistors, current ratios, and trimming techniques to stabilize sensitivity, reducing noise and die area requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current-driven Hall plate sensor is used, then sensitivity can be maintained, but die area increases and noise levels increase
Solution Approach 1:
The patent replaces the current-driven mechanism with a voltage-driven mechanism. Instead of using a current source to drive the Hall plate (which requires large die area and generates noise), a voltage source is used to drive the Hall plate through a known resistance, eliminating the need for complex current mirroring circuits and reducing die area while maintaining sensitivity.
Solution Approach 2:
The patent changes the driving parameter from current to voltage. By applying a voltage drive to the Hall plate and using the relationship V=IR, the Hall voltage can be calculated without requiring precise current control, thereby reducing the complexity of the driver circuit and the associated die area.
2Measurement precision
If a current-driven Hall plate sensor is used, then sensitivity can be maintained, but noise levels increase
Solution Approach 1:
The patent replaces the current-driven mechanism with a voltage-driven mechanism. Instead of using a current source to drive the Hall plate (which requires large die area and generates noise), a voltage source is used to drive the Hall plate through a known resistance, eliminating the need for complex current mirroring circuits and reducing die area while maintaining sensitivity.
3Reliability
If temperature compensation is applied to Hall plate sensitivity changes, then sensitivity stability improves, but device complexity increases
Solution Approach 1:
The patent implements self-compensation by utilizing the inherent temperature dependence of the Hall plate resistance. The voltage-driven approach automatically compensates for temperature effects because the Hall voltage is derived from the voltage division across the Hall plate resistance, which naturally tracks temperature variations without requiring external compensation circuits.
Solution Approach 2:
The patent changes the driving parameter from current to voltage. By applying a voltage drive to the Hall plate and using the relationship V=IR, the Hall voltage can be calculated without requiring precise current control, thereby reducing the complexity of the driver circuit and the associated die area.
4Reliability
If stress compensation is applied to Hall plate sensitivity changes, then sensitivity stability improves, but device complexity increases
Solution Approach 1:
The patent implements self-compensation by utilizing the inherent temperature dependence of the Hall plate resistance. The voltage-driven approach automatically compensates for temperature effects because the Hall voltage is derived from the voltage division across the Hall plate resistance, which naturally tracks temperature variations without requiring external compensation circuits.
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 voltage-driven Hall plate sensor achieves lower noise and reduced die area, with sensitivity drift minimized to about 0.23% compared to current-driven sensors' 1.2%, providing stable magnetic field detection.
Implementation Method 1
Hall elements can be used for various sensing applications based on detecting magnetic field changes. A typical planar or horizontal Hall effect element is a four-terminal device for which a drive current (a DC current) is passed between two opposing ones of the four terminals and a differential voltage (AC or DC), responsive to a magnetic field (AC or DC), is generated between the other two opposing ones of the four terminals.
Implementation Method 2
The changes in sensitivity of the Hall effect element can result directly from temperature changes. However, the changes in sensitivity of the differential signal can also result from stresses upon a substrate on which the Hall effect element is disposed.
Data Source
AI summary
Methods and apparatus for a voltage driven Hall plate current sensor integrated circuit (IC) package that includes a die including a Hall plate with a lateral epi resistor. A gm amplifier receives an output voltage from the Hall plate and a front end amplifier receives an output of the gm amplifier. A compensation circuit compensates for stress on the die that affects a resistance of the Hall plate and includes a lateral epi resistor coupled to a constant current for compensating for piezoresistive stress in the Hall plate.