Integrated Current Sensor Shielding for Noise-Coupled Conductors
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Solution Overview
Problem
Current sensors face performance issues due to noise coupling from current conductors, which affects the accuracy and reliability of the output signals.
Innovation Solution
Integration of a shield layer between the die and the 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 conductor to improve sensitivity, then 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, thereby allowing close positioning while maintaining accuracy
Solution Approach 2:
The space between the conductor and sensing element is segmented by introducing the shield layer, which divides the electromagnetic field interaction into distinct zones. This segmentation allows the sensing element to maintain close proximity to the conductor for high sensitivity while the shield layer absorbs or redirects noise interference
2Volume of moving object
If integration is performed to reduce size, then device size is reduced, but noise shielding becomes more difficult
Solution Approach 1:
The shield layer is nested within the integrated circuit structure, positioned between the conductor and sensing element in a compact arrangement. This nested configuration provides effective noise shielding while maintaining a small overall device footprint, as the shield layer utilizes the existing vertical space within the integrated package
Solution Approach 2:
The shielding approach transitions from horizontal spacing to vertical layering within the integrated circuit. By stacking the shield layer and sensing element in different vertical positions relative to the conductor, effective noise protection is achieved without increasing the lateral device footprint
3Object-affected harmful factors
If a shield layer is added to reduce noise, then noise shielding is improved, but device complexity increases
Solution Approach 1:
The shield layer is merged with existing circuit elements or packaging structures where possible, such as utilizing ground planes or existing metal layers in the integrated circuit. This merging approach provides noise shielding functionality without requiring completely separate additional components, thereby limiting the increase in device complexity
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 sensitivity and accuracy of the current sensor by minimizing the impact of external and internal noise sources.
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 is disposed between the die and the conductor to shunt this noise to ground... to shield the magnetic field sensing element and associated circuitry from external noise and internal noise
Implementation Method 3
some current sensors use a magnetic field sensing element in proximity to a current conductor. The sensing element can generate an output signal having a magnitude proportional to the magnetic field induced by a current that flows through the current conductor
Data Source
Figure 1~2
Figure 3
Figure 3A
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.