Sensor Interface Circuit Self-Testing for EMC Fault Detection

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Solution Overview

Problem

Existing sensor interface circuits in safety-critical applications, such as automotive systems, face challenges in reliably detecting common cause faults and electromagnetic compatibility (EMC) events, especially when sensors and interface chips use different manufacturing technologies.

Innovation Solution

A sensor interface circuit with at least two sensor inputs and two front-end circuits, equipped with a test circuit that applies a test input intermittently between sensor signal acquisitions to evaluate the correct functionality of the front-end circuits, thereby increasing the safety integrity level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two separate analog front-ends are used to increase safety level, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvesafety levelVSAvoidcomplexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines two separate analog front-ends into a single integrated circuit device, merging their functionality while maintaining separate signal paths. This integration reduces the overall device complexity and component count while preserving the redundancy needed for safety-critical applications.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single integrated circuit device performs multiple functions by incorporating both analog front-ends within it. This multi-functional approach allows the device to handle multiple sensor signals simultaneously while maintaining a compact structure, thereby improving reliability without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Device complexity

If monolithic integration of sensors and interface circuit is used, then device complexity is reduced, but adaptability worsens when different manufacturing technologies are required

Engineering Contradiction:

ImprovecomplexityVSAvoidadaptability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the integrated circuit into distinct functional blocks: a first analog front-end for a first sensor type and a second analog front-end for a second sensor type. This segmentation allows each front-end to be optimized for its specific sensor technology while maintaining overall integration, thus preserving adaptability across different manufacturing technologies.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions or blocks within the integrated circuit are designed with local quality variations to accommodate different sensor technologies. Each analog front-end is tailored to its specific sensor requirements, allowing the integrated device to adapt to multiple manufacturing technologies without compromising overall complexity.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If longer electrical connections are used to connect sensor chips with interface chip, then adaptability is improved, but reliability worsens due to EMC sensitivity

Engineering Contradiction:

ImproveadaptabilityVSAvoidreliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges the sensor chip and interface chip functions into a single integrated circuit device, eliminating the need for longer external electrical connections. This integration directly addresses the EMC sensitivity issue by removing vulnerable inter-chip connection paths while maintaining the adaptability to handle multiple sensor types within the unified device.

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If two completely diverse analog front-ends are used to reduce common cause faults, then reliability is improved, but device complexity and design effort double

Engineering Contradiction:

ImprovereliabilityVSAvoidcomplexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges two diverse analog front-ends into a single integrated circuit, combining their functionality while maintaining their distinct designs. This approach preserves the reliability benefits of diversity (reducing common cause faults) while avoiding the complexity increase that would result from using two separate physical devices.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated circuit is designed with universal capabilities to host multiple diverse front-ends within a single device structure. This multi-functional architecture allows the system to benefit from design diversity for reliability while maintaining a unified, manageable complexity level through integration.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12206428B2Sensor interfaces for functional safety applications

Publication Date: 2025.01.21 MELEXIS TECH NV

AI summary

A sensor interface circuit includes at least two sensor inputs and at least two front-end circuits to obtain sensor signal acquisitions from the at least two sensor inputs; a test circuit configured to test correct functionality of at least part of one of the front end circuits by applying a test input to the front end circuit under test, by reading a test output of the front end circuit, and by comparing the test output with an expected result thus obtaining at least one test result. The test input is applied intermittently between sensor signal acquisitions; a processing device is configured to compare the sensor signal acquisitions from the different sensor inputs and combine the comparison with the at least one test result to evaluate correct functionality of the sensor interface circuit.