On-Chip Safety Area Checker Without Replica Test Circuits
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Solution Overview
Problem
Existing test circuitry for safety areas in integrated circuit chips is inefficient due to the complexity and area consumption of stimuli circuits and replicated safety areas, which are necessary for fault detection and verification in high-safety integrity level applications like vehicle transmission controllers.
Innovation Solution
An integrated circuit chip design with a safety area isolated by deep trench isolation, generating fault signals from digital and analog signals, and a safety area checker circuit that verifies proper operation without the need for a replica safety area or complex stimuli circuits, using comparison circuits and OR logic to generate error check signals for immediate fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stimuli circuit and result checker are used to verify safety circuits, then fault detection capability is improved, but circuit complexity and area consumption increase
Solution Approach 1:
The patent extracts only the essential checking functionality from a complete replica safety area, implementing a simplified checker circuit that monitors safety circuit outputs without requiring full replication of safety area components. This selective extraction maintains fault detection capability while dramatically reducing circuit complexity and area consumption.
Solution Approach 2:
The patent uses a simplified copying approach by replicating only the output checking logic rather than the entire safety area. The checker circuit copies the essential monitoring functions needed to verify safety circuit operation, eliminating the need for complete duplication of safety area components and reducing overall system complexity.
2Reliability
If a stimuli circuit is used to generate test inputs for safety circuits, then fault detection capability is improved, but area consumption increases
Solution Approach 1:
The checker circuit is designed to perform multiple functions: it monitors safety circuit outputs, detects faults, and generates error signals all within a single compact unit. This multi-functionality eliminates the need for separate stimuli generation circuits and result checking circuits, reducing overall chip area while maintaining comprehensive fault detection capability.
Solution Approach 2:
The patent merges the stimuli generation, safety circuit operation, and result checking functions into an integrated checker system. By combining these previously separate functions into a unified circuit block, the patent achieves efficient fault detection with minimal area consumption on the chip.
3Reliability
If safety circuits are replicated to enable fault detection, then fault detection capability is improved, but area consumption increases
Solution Approach 1:
The patent extracts only the essential monitoring and comparison functions from a complete safety area replica, implementing a compact checker circuit that uses minimal resources. This selective extraction approach enables fault detection without requiring full replication of safety area components, thereby reducing chip area consumption while maintaining detection capability.
Data Source
Figure 1A~1C
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AI summary
Disclosed herein is a single integrated circuit chip including main logic (11) that operates a vehicle component such as a valve driver. Isolated from the main logic within the chip is a safety area (12') that operates to verify proper operation of the main logic (11). A checker circuit (16') within the chip outside of the safety area serves to verify proper operation of the checker circuit. The checker circuit (16') receives signals from the safety circuit and uses combinatorial logic circuit to verify from those signals that the check circuit is operating properly.