A Formal Approach to On-Line Monitoring of Digital VLSI Circuits: Theory, Design and Implementation

This work is concerned with the development of algorithms and CAD tools for the design of digital circuits with on line monitoring capability. The Theory of Fault Detection and Diagnosis available in the literature on Discrete Event Systems has been adopted for on-line detection of stuck-at faults in Digital Circuits. Efficient computational techniques to deal with very large state spaces based on Ordered Binary Decision Diagrams and Abstraction have been proposed. Based on these a CAD tool has been developed that can provide a fully automated flow for design of circuits with on-line test capability without the requirement of any modification to the core. The tool can handle generic digital circuits with cell count as high as 15,000 and having the order of 2500 states. This is believed to be an improvement of an order of magnitude over results presented in the literature. This methodology enables the designer to tradeoff fault coverage and detection latency against area and power overhead. The design flow using the CAD tool developed is described and results for design of on-line detectors for various ISCAS89 benchmark circuits are provided. The methodology is further validated by design, fabrication, and testing of an ASIC in 0.18 μ technology.