On-Chip Coil Layout for TMR Sensor Pillar Stimulation
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Solution Overview
Problem
Conventional magnetic field sensors face challenges in generating a magnetic field that effectively stimulates all TMR pillars, particularly due to the need for external fields to verify pinning and compensate signal path distortions, which can be inefficient and require additional metal layers.
Innovation Solution
The integration of an on-chip coil routed under TMR elements generates a lateral magnetic field parallel to the pinning direction, eliminating the need for extra metal layers and allowing for efficient stimulation of TMR elements without affecting differential output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external magnetic fields are used to verify pinning and compensate signal path distortions, then measurement precision is improved, but device complexity increases due to additional metal layers and external field generation requirements
Solution Approach 1:
The patent combines the functions of pinning verification and signal path distortion compensation into the same on-chip coil structure. The coil is integrated within the TMR sensor chip itself, merging what would traditionally require separate external field generation systems and multiple metal layers into a single integrated component that performs multiple measurement functions.
Solution Approach 2:
The on-chip coil acts as an intermediary element that generates magnetic fields locally within the TMR sensor area. This intermediary structure eliminates the need for direct external field application and complex external wiring, providing a controlled magnetic field environment through an integrated intermediate component.
2Reliability
If conventional external field generation methods are used, then all TMR pillars can be stimulated, but loss of energy increases due to high voltage requirements and large coil resistance
Solution Approach 1:
The magnetic field generation is localized to the specific area where TMR pillars are located. The on-chip coil is positioned directly over the TMR array, creating a concentrated magnetic field precisely where needed. This local field generation eliminates the energy losses associated with large external coils and high voltage requirements, as the field is generated in-situ with minimal resistance.
Solution Approach 2:
The patent transitions from external three-dimensional field generation to integrated planar field generation on the chip surface. By routing coil traces in metal layers above or within the TMR structure, the magnetic field is generated in a different spatial dimension (planar integration vs. external volumetric generation), reducing the path length and resistance for current flow.
3Adaptability or versatility
If additional metal layers are added for coil routing, then magnetic field generation capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The on-chip coil structure serves multiple functions: it generates magnetic fields for pinning verification, compensates for signal path distortions, and stimulates all TMR pillars. By making the coil structure multi-functional, the patent reduces the need for additional specialized metal layers and structures, thereby lowering manufacturing precision requirements while maintaining field generation 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
This approach reduces coil resistance and voltage requirements, enabling consistent field generation within the TMR area, enhancing sensitivity and reducing wafer costs while maintaining sensitivity measurements.
Implementation Method 1
an on-chip coil routed under the TMR elements configured to conduct current for generating a magnetic field to stimulate the TMR elements
Data Source
AI summary
Methods and apparatus for a magnetic field sensor IC package having groups of arrays of TMR elements each having a pinning direction. An on-chip coil is routed under the TMR elements to conduct current for generating a magnetic field to stimulate the TMR elements. The device may be configured to sense changes in an applied magnetic field.