Delay Chain Fault Detection Using Stage-Based Delay Measurement
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Solution Overview
Problem
Existing delay circuits face challenges in detecting delay faults, particularly due to the need for additional components like flip-flops and difficulties in distinguishing between acceptable and unacceptable delay variations, which can lead to incorrect fault detection.
Innovation Solution
A delay circuit comprising a first delay module, a delay measurement unit, and a fault judge unit that measures and compares delay amounts across different stages to determine if a delay fault exists, allowing for accurate detection without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flip flop is added to detect delay faults, then fault detection capability is improved, but device complexity increases
Solution Approach 1:
The delay circuit performs self-diagnosis by using its own internal delay stages to generate test signals and detect faults without requiring external flip-flops or additional detection components. The circuit monitors its own delay performance through built-in measurement mechanisms.
Solution Approach 2:
The delay stages serve dual purposes: they function as signal processing elements for normal delay operations and simultaneously act as test signal generators for fault detection. This multi-functionality eliminates the need for separate detection components.
2Measurement precision
If delay amount variance is considered, then measurement precision is improved, but difficulty of detecting and measuring increases
Solution Approach 1:
The system applies a predetermined threshold for delay amount that is intentionally set to accommodate normal variance while still detecting actual faults. This partial action approach filters out minor variations without missing significant defects.
Solution Approach 2:
The fault detection mechanism changes the parameter being measured from absolute delay time to delay time difference or deviation from expected range. This parameter transformation allows the system to distinguish between acceptable variance and actual faults more easily.
Data Source
AI summary
A delay circuit includes a first delay module, a delay measurement unit and a fault judge unit. The first delay module has a first delay circuit with at least one delay stage. The delay measurement unit is used for measuring a first delay amount and a second delay amount of the first delay chain respectively corresponding to a first number and a second number of delay stages. The fault judge unit is used for determining if the first delay chain has delay faults or not according to the first and second delay amounts.