Z-axis TMR Sensor Dual-Coil Reset for Low Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic field sensors with Z-axis sensitivity require high power for flux guide reset operations, exceeding the voltage and power capabilities of devices like smartphones, making them unsuitable for mobile applications.
Innovation Solution
A magnetic field sensor design featuring a sense element, a flux guide, and two coils, where the coils are energized in specific modes to generate reset fields, reducing power consumption by allowing the sense element reset operation to occur independently of the flux guide reset, and utilizing a custom metal layer for efficient field generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single coil is used for both flux guide reset and sense element reset operations, then device complexity is reduced, but power consumption increases due to the need to generate large reset fields across all flux guides
Solution Approach 1:
The patent divides the single coil into two separate coils: a first coil positioned to generate reset fields across the flux guides, and a second coil positioned to generate reset fields across the sense element. This segmentation allows independent control of reset operations, enabling the second coil to reset the sense element without requiring the high-power operation needed for the first coil, thus reducing overall power consumption while maintaining device functionality.
2Reliability
If a large voltage overhead is applied to reset flux guides, then magnetization direction is properly set, but power consumption becomes too high for mobile device applications
Solution Approach 1:
The patent segments the reset operation into two independent phases using two separate coils. The first coil handles flux guide magnetization setting with appropriate high voltage when needed, while the second coil handles sense element reset with lower power requirements. This allows the system to achieve reliable magnetization stability in the flux guide without continuously applying high voltage overhead, as the second coil can operate independently at lower power levels.
Solution Approach 2:
The patent implements periodic reset operations where the first coil is activated to set flux guide magnetization direction, and the second coil is activated to reset the sense element. By separating these operations in time and using independent coils, the system can maintain reliable magnetization states without continuous high-power application, reducing average power consumption while ensuring magnetization stability when needed.
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 design reduces power requirements for Z-axis sensor reset operations, enabling stable and accurate magnetic field detection in mobile devices while extending battery life.
Implementation Method 1
drive circuitry configured, in a first reset mode, to energize both the first coil and the second coil to generate a first field about the first coil and a second field about the second coil, respectively, that combine to set a predetermined magnetization direction of the flux guide
Implementation Method 2
a flux guide arranged on the substrate and configured to direct a magnetic field perpendicular to the sense plane into the sense plane
Implementation Method 3
A Z-axis tunneling magnetoresistive (TMR) magnetic field sensor
Data Source
AI summary
An out-of-plane tunneling magnetoresistive (TMR) magnetic field sensor includes a sense element that defines a sense plane and a flux guide configured to direct a magnetic field perpendicular to the sense plane into the sense plane. The magnetic field sensor further includes a first coil arranged in a first plane, a second coil electrically insulated from the first coil and arranged in a spaced-apart second plane, and drive circuitry operatively connected to the first coil and the second coil. The drive circuitry in a first mode energizes the first and second coils to generate respective first and second fields that combine to set a magnetization of the flux guide. The drive circuitry in a second mode energizes only the first coil to generate the first field so as to set a magnetization of the sense element without changing the magnetization of the flux guide.