Magnetoresistive Angle Sensor with 180-Degree Chip Rotation
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Solution Overview
Problem
Existing magnetic sensors for non-contact measurement of rotation angles face challenges such as excessive size, inadequate sensitivity, dynamic range, cost, and reliability, particularly in integrating with semiconductor devices and achieving high sensitivity for low-cost mass production.
Innovation Solution
A dual-axis single-package magnetoresistive rotation sensor design using pairs of MTJ or GMR sensor chips with one chip rotated 180 degrees relative to the other, forming a push-pull full-bridge configuration within a standard semiconductor package, which enhances output signal and compensates for temperature changes and process variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MTJ sensor chips are used to achieve high sensitivity and small size, then measurement precision and device miniaturization are improved, but manufacturing complexity and packaging difficulty increase
Solution Approach 1:
The sensor system is divided into separate functional modules: MTJ sensor chips for magnetic field detection, lead frame for mechanical support and electrical connection, and encapsulant for protection. This segmentation allows each component to be optimized and manufactured independently using standard semiconductor processes, reducing overall packaging complexity while maintaining high sensitivity.
Solution Approach 2:
The lead frame serves multiple functions simultaneously: providing mechanical support for the MTJ chips, establishing electrical connections through wire bonds, enabling thermal management, and facilitating package sealing. This multi-functionality reduces the need for additional components and simplifies the overall packaging structure.
2Ease of manufacture
If MTJ sensor chips are integrated using standard semiconductor fabrication processes, then manufacturing cost is reduced, but yield and process matching difficulty increase
Solution Approach 1:
The MTJ sensor chips are pre-fabricated and tested using standard semiconductor fabrication processes before final assembly. This preliminary manufacturing and characterization allows for early detection of process variations and defects, enabling binning and matching of chips to ensure high yield in the final assembled sensors while maintaining cost-effectiveness.
Solution Approach 2:
The invention utilizes standard semiconductor fabrication parameters and materials that are well-established in the industry. By working within proven process parameter ranges and using commercially available MTJ chip technologies, the manufacturing cost is reduced while reliability is maintained through proven process compatibility.
3Measurement precision
If bridge sensor configuration is used to compensate temperature changes, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The bridge configuration uses asymmetric arrangement of MTJ chips with different pinned layer magnetization directions to achieve temperature compensation. By strategically positioning chips with opposite magnetic polarities in the bridge circuit, the design exploits the asymmetric response to temperature variations to cancel out drift effects, improving precision without requiring complex additional compensation circuits.
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 provides high-accuracy, low-cost magnetic angle sensors with improved sensitivity and resistance to ambient temperature changes, effectively addressing yield issues and integration challenges in mass production.
Implementation Method 1
magnetoresistive sensor chips... provide a non-contact measurement of rotation angle
Implementation Method 2
magnetic field sensors used in combination with a permanent magnet
Data Source
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AI summary
A single package magnetoresistive angle sensor for use in measuring rotation angle of a magnet is disclosed. The magnetoresistive angle sensor comprises a pair of magnetoresistive sensor chips, wherein one of the chips is rotated by 180-degree rotation relative to the other. The magnetoresistive sensor chips are attached to a standard semiconductor package lead frame to form a single-axis push-pull full-bridge sensor. Each of the magnetoresistive sensor chips comprises a pair of magneto resistance sensor arms. Each magnetoresistive sensor arm comprises one or more GMR or MTJ sensor elements. The GMR of MTR sensor elements utilize a pined layer. The element blocks of the magnetoresistive sensor electrically are interconnected and connected to the package leads by wirebonding. The magnetoresistive angle sensor can be packaged into various standard semiconductor package designs. Also, provided is a dual-axis push-pull full-bridge magnetoresistive angle sensor comprised of two pairs of magnetoresistive sensor chips.