Magnetic Field Sensor Shared Path Amplifier Diagnostic Circuit
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Solution Overview
Problem
Magnetic field sensors often face manufacturing defects and faults during use, which can be difficult to detect with existing self-test capabilities, leading to incomplete test coverage and potential operational disruptions.
Innovation Solution
A magnetic field sensor design incorporating a diagnostic circuit and a dual-path analog-to-digital converter that processes both measured and diagnostic signals during separate time periods, allowing for effective fault detection and improved test coverage without interrupting sensor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-test circuitry is implemented in magnetic field sensors, then fault detection capability is improved, but test coverage remains incomplete due to inability to test certain circuits
Solution Approach 1:
A diagnostic signal is introduced as an intermediary test input that can be routed through the signal path to test circuits that normal magnetic field signals cannot reach. This diagnostic signal acts as a mediator that enables testing of amplifier and ADC circuits without requiring physical access to those components during normal operation.
Solution Approach 2:
The system dynamically switches between normal sensing mode and diagnostic test mode by controlling a switch that routes either magnetic field signals or diagnostic signals to the signal path. This dynamic reconfiguration allows the same hardware to serve dual purposes: normal operation and comprehensive testing.
2Reliability
If self-tests are performed during sensor operation, then continuous monitoring is improved, but performance degrades due to interruptions
Solution Approach 1:
Self-tests are performed periodically by alternating between sensing intervals and test intervals. During sensing intervals, the sensor operates normally to maintain productivity. During test intervals, diagnostic signals are injected to perform comprehensive testing. This periodic alternation ensures both continuous monitoring and maintained performance.
Solution Approach 2:
The system performs preliminary diagnostic testing during scheduled intervals before faults can disrupt normal operation. By proactively testing circuits periodically, the system can detect and report potential failures before they affect sensor performance during critical sensing operations.
3Difficulty of detecting and measuring
If dedicated test circuits are designed to test specific circuits, then test coverage is improved, but device complexity increases
Solution Approach 1:
The signal path components (amplifier, ADC, switches) are designed to be universal and handle both normal magnetic field signals and diagnostic test signals. This multi-functionality eliminates the need for separate dedicated test circuits, achieving comprehensive test coverage while maintaining relatively simple device architecture.
Solution Approach 2:
The testing functionality is merged with the normal sensing functionality by using the same signal path, amplifier, and ADC for both purposes. This consolidation achieves comprehensive test coverage without duplicating circuits, thereby reducing overall device complexity compared to having separate dedicated test paths.
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 enables comprehensive fault detection and reduced operational disruptions by processing diagnostic signals during non-overlapping time periods, enhancing the accuracy and effectiveness of self-tests in magnetic field sensors.
Implementation Method 1
Magnetic field sensors including a magnetic field sensing element, or transducer, such as a Hall Effect element
Implementation Method 2
an amplifier and an analog-to-digital converter for processing the measured magnetic field signal
Implementation Method 3
an amplifier and an analog-to-digital converter for processing the measured magnetic field signal
Data Source
AI summary
A magnetic field sensor comprises at least one magnetic field sensing element configured to generate a measured magnetic field signal responsive to an external magnetic field; a diagnostic circuit configured to generate a diagnostic signal, wherein the diagnostic signal is not dependent on a measured magnetic field; a signal path comprising an amplifier and an analog-to-digital converter for processing the measured magnetic field signal to generate a sensor output signal indicative of the external magnetic field during a measured time period and for processing the diagnostic signal during a diagnostic time period; and a switch coupled to receive the measured magnetic field signal and the diagnostic signal and direct the measured magnetic field signal to the signal path during the measured time period and direct the diagnostic signal to the signal path during the diagnostic time period.