Integrated Current Sensor Shielding for Noise-Coupling Reduction
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Solution Overview
Problem
Current current sensors face performance issues due to noise coupling from current conductors, which affects the accuracy and reliability of the sensors.
Innovation Solution
Integration of a shield layer between the die and the current conductor in the current sensor to shunt noise to ground, thereby reducing parasitic capacitance and noise coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing element is positioned close to the current conductor to improve sensitivity, then the sensitivity is improved, but voltage noise is capacitively coupled from the conductor to the sensing element causing inaccurate response
Solution Approach 1:
A shield layer is introduced as an intermediary component between the current conductor and the sensing element. This shield layer is positioned closer to the conductor than the sensing element, creating a physical barrier that reduces parasitic capacitance and prevents voltage noise from coupling to the sensing element, while allowing the sensing element to maintain its close proximity for high sensitivity
Solution Approach 2:
The space between the current conductor and the sensing element is segmented into distinct regions by introducing the shield layer. This segmentation creates separate zones: one between the conductor and shield for noise management, and another between the shield and sensing element for magnetic field sensing, thereby resolving the conflict between proximity and noise coupling
2Volume of moving object
If integration of the current sensor into an IC package is implemented to reduce size, then the device size is reduced, but voltage noise coupling from the conductor adversely impacts performance
Solution Approach 1:
The shield layer is positioned in the vertical dimension (z-axis) between the conductor and sensing element, rather than increasing horizontal spacing. This vertical segmentation allows the sensor to maintain a compact IC package footprint while effectively reducing parasitic capacitance and noise coupling through the introduced shielding dimension
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 shield layer effectively reduces noise interference, enhancing the accuracy and reliability of the current sensor by minimizing the impact of parasitic capacitance and transient events.
Implementation Method 1
the die and the current carrying conductor can form two plates of a parasitic capacitor. This capacitance can lead to the coupling of electrical, voltage, or electrical transient noise from the conductor to the die during large transient (dV/dt) events on the conductor
Implementation Method 2
The shield layer may include an aperture (or other features to enable high frequency magnetic fields to reach the sensing element) to reduce eddy currents
Data Source
AI summary
Systems and methods described herein are directed towards integrating a shield layer into a current sensor to shield a magnetic field sensing element and associated circuitry in the current sensor from electrical, voltage, or electrical transient noise. In an embodiment, a shield layer may be disposed along at least one surface of a die supporting a magnetic field sensing element. The shield layer may be disposed in various arrangements to shunt noise caused by a parasitic coupling between the magnetic field sensing element and the current carrying conductor away from the magnetic field sensing element.