Monolithic Sensor Self-Diagnostics Using Distinct Signal Paths
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Solution Overview
Problem
Conventional magnetic sensor systems with a single-channel analog main signal path struggle to meet Safety Integrity Level (SIL) standards, leading to increased costs and complexity when using redundant sensors, as they fail to adequately cover safety requirements in safety-critical applications.
Innovation Solution
A monolithic integrated circuit sensor system with a primary sensor and a secondary sensor, each having distinct signal paths, where the secondary sensor is less accurate, slower, and noisier, allowing for self-testing and fault detection without significant additional hardware, thereby meeting SIL standards while reducing costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-channel analog main signal path is used in magnetic sensor systems, then device complexity is reduced, but reliability and safety compliance (SIL standards) deteriorate
Solution Approach 1:
The signal processing function is segmented into two distinct signal paths: a first signal path with high measurement precision and a second signal path with lower measurement precision. This segmentation allows the system to meet SIL safety requirements through redundancy while maintaining manageable complexity by using different precision levels for different functions.
Solution Approach 2:
Different parts of the signal processing system have different quality characteristics. The first signal path is optimized for high precision measurement, while the second signal path is optimized for safety monitoring and self-test functions. This local differentiation of quality enables the system to achieve both performance and safety goals without uniform high complexity throughout.
2Reliability
If two identical redundant magnetic field sensors are used to meet SIL requirements, then reliability improves, but cost increases
Solution Approach 1:
Instead of using two identical sensors, the system changes the parameters of the second signal path to have lower measurement precision compared to the first signal path. This parameter differentiation allows the second path to serve as a sufficient safety monitor without requiring full sensor redundancy, thereby reducing the quantity of high-precision sensors needed while still meeting SIL requirements.
3Ease of manufacture
If a secondary sensor with lower precision is added for self-testing, then cost efficiency improves, but measurement precision deteriorates
Solution Approach 1:
The measurement function is segmented into two precision levels. The first signal path handles high-precision measurement requirements, while the second signal path handles safety monitoring and self-test functions with lower precision requirements. This segmentation allows the system to use cost-effective lower-precision components for safety functions without compromising the overall measurement precision needed for primary operation.
Solution Approach 2:
Instead of creating a full precision copy of the first signal path for redundancy, the system creates a simplified copy with lower precision that is sufficient for safety monitoring purposes. This partial copying approach reduces manufacturing costs while maintaining adequate safety monitoring capability for meeting SIL standards.
Data Source
AI summary
Embodiments relate to systems and methods for sensor self-diagnostics using multiple signal paths. In an embodiment, the sensors are magnetic field sensors, and the systems and/or methods are configured to meet or exceed relevant safety or other industry standards, such as SIL standards. For example, a monolithic integrated circuit sensor system implemented on a single semiconductor ship can include a first sensor device having a first signal path for a first sensor signal on a semiconductor chip; and a second sensor device having a second signal path for a second sensor signal on the semiconductor chip, the second signal path distinct from the first signal path, wherein a comparison of the first signal path signal and the second signal path signal provides a sensor system self-test.