Single-chip Full-bridge Magnetic Field Sensor
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Solution Overview
Problem
Existing magnetic sensors face challenges such as excessive size, inadequate sensitivity, and high cost, particularly in achieving high sensitivity and yield for low-cost mass production, especially when integrated with semiconductor devices.
Innovation Solution
A single-chip referenced full-bridge magnetic field sensor is developed, utilizing two reference arms and two sensing arms spatially interleaved and electrically interconnected to form a Wheatstone bridge, with MTJ or GMR magnetoresistive elements, where the relative resistance is adjustable by varying the number of elements and utilizing permanent magnets at different angles to optimize linear response, and incorporating a magnetic shield and antiferromagnetic or permanent magnet layers for enhanced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate evaluation circuits are used for each magnetic field sensor element, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines four separate magnetic field sensor elements (sensitive to x, y, z components and magnitude) into a single integrated sensor unit that shares common structural components. The evaluation circuit is designed to process signals from all four elements through a unified architecture, merging previously separate evaluation functions into one integrated circuit that can simultaneously evaluate multiple sensor elements, thereby reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The evaluation circuit is designed with multi-functional capabilities to handle different sensor element types (anisotropic magnetoresistive, tunnel magnetoresistive, or magnetic resonance sensors) and different measurement modes (vector components and magnitude) through a single unified circuit architecture. This universal design allows the same circuit to perform multiple evaluation functions without requiring separate dedicated circuits for each sensor element.
2Device complexity
If a unified evaluation circuit is used for multiple sensor elements, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The unified evaluation circuit is segmented into distinct functional modules, each responsible for evaluating specific sensor element types or measurement modes. The circuit can selectively activate appropriate evaluation paths depending on which sensor elements are present or which measurements are required, maintaining precision by providing dedicated processing paths while keeping the overall circuit unified and integrated.
Solution Approach 2:
The evaluation circuit incorporates dynamic switching capabilities that allow it to adapt its configuration based on the specific sensor elements being used and the measurement requirements. The circuit can dynamically route signals through appropriate processing paths and adjust its evaluation algorithms to maintain optimal measurement precision for different sensor types and measurement modes within a single unified architecture.
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 solution achieves excellent temperature stability, low offset voltage, and voltage symmetry, enabling efficient magnetic field detection while being compatible with standard semiconductor manufacturing processes.
Implementation Method 1
The magnetic field sensor elements are based on anisotropic magnetoresistive, tunnel magnetoresistive, or magnetic resonance sensing
Implementation Method 2
The magnetic field sensor elements are based on anisotropic magnetoresistive, tunnel magnetoresistive, or magnetic resonance sensing
Implementation Method 3
for example, in the form of a magnetic field sensor element arranged in a Wheatstone bridge
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention discloses a single-chip referenced full-bridge magnetoresistive magnetic-field sensor. The single-chip sensor is a Wheatstone bridge arrangement of magnetoresistive sensing elements and reference elements. The sensing elements and reference elements are formed from either magnetic tunnel junctions or giant magnetoresistive materials. The sensitivity of the reference and sensor elements is controlled through one or a combination of magnetic bias, exchange bias, shielding, or shape anisotropy. Moreover, the bridge output is tuned by setting the ratio of the reference and sensor arm resistance values to a predetermined ratio that optimizes the bridge output for offset and symmetry. The single-chip referenced-bridge magnetic field sensor of the present invention exhibits excellent temperature stability, low offset voltage, and excellent voltage symmetry.