TMR Sensor Interdigitated Flux Concentrators
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Solution Overview
Problem
Manufacturing high-sensitivity single-chip linear magnetic field sensors is challenging due to the need for precise magnetization alignment of pinned layers and poor sensitivity and linearity of existing bridge magnetoresistive sensors.
Innovation Solution
A TMR high-sensitivity single-chip push-pull bridge magnetic field sensor design utilizing interdigitated soft ferromagnetic flux concentrators to convert X magnetic fields into oppositely directed Y magnetic fields, enhancing sensitivity and linearity by alternately arranging TMR magnetoresistive sensing elements within the interdigitated structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If push-pull bridge magnetoresistive sensor is used, then magnetic field sensitivity is improved, but manufacturing complexity increases due to requiring local programming of magnetization alignment directions
Solution Approach 1:
A magnetic shielding layer is introduced as an intermediary component between the external environment and the pinned layers of the magnetoresistive sensing elements. This shielding layer passively establishes the required opposite magnetization alignment directions in the pinned layers without requiring complex local programming techniques, thus achieving high magnetic field sensitivity while simplifying the manufacturing process.
2Ease of manufacture
If referenced bridge magnetoresistive sensor is used, then manufacturing is simplified, but sensitivity is reduced to half of push-pull bridge
Solution Approach 1:
The sensor design employs asymmetric configuration where the magnetoresistive sensing elements are arranged in a push-pull bridge structure with opposite magnetization directions in adjacent arms. This asymmetric arrangement enables the sensing elements to respond differentially to magnetic field changes, achieving full push-pull sensitivity while maintaining manufacturing simplicity through the use of identical sensing element structures that only differ in their magnetization orientation.
3Ease of manufacture
If referenced bridge magnetoresistive sensor is used, then manufacturing is simplified, but output linearity deteriorates
Solution Approach 1:
The magnetic shielding layer is strategically positioned and configured with specific geometric characteristics to create localized magnetic field distributions that enhance the linearity of the sensor output. The shielding layer's structure is optimized to ensure uniform magnetic field coupling with the sensing elements across the sensing region, thereby improving output linearity while maintaining the simplicity of the overall manufacturing process.
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 design achieves high magnetic field sensitivity and good linearity with a simple structure and low power consumption, effectively addressing the limitations of existing sensors.
Implementation Method 1
Interdigitated soft ferromagnetic flux concentrators are used to implement conversion of an X magnetic field into a −Y magnetic field and a +Y magnetic field that have identical sizes and opposite directions in interdigitated gaps
Implementation Method 2
comb-shaped soft ferromagnetic flux concentrators located on the substrate
Implementation Method 3
TMR magnetoresistive sensing elements in the gaps have identical magnetic multi-layer film structures and Y-axis sensitive directions
Data Source
AI summary
A magnetic field sensor comprises a substrate and two comb-shaped soft ferromagnetic flux concentrators with an interdigitated structure formed on the substrate. The concentrators comprise N and N−1 rectangular comb teeth and corresponding comb seats wherein N is an integer greater than 1. Gaps are formed between the comb teeth of one concentrator and the comb seat of the other concentrator in an X direction. Adjacent comb teeth in a +Y direction form 2m−1 odd space gaps and 2m even space gaps. Here, m is an integer greater than zero and less than N. Push and pull magnetoresistive sensing element strings are located respectively in the odd space gaps and the even space gaps, and are electrically interconnected into a push-pull bridge. The magnetization alignment directions of the ferromagnetic pinned layer of the magnetic sensing element strings are Y direction.