The Practical Study Of PCB-Level Digital Circuits Fault Simulation

Along with the development of micro-electronics technology, more and more complicated and smaller digital circuit is getting widely used. Therefore, tests to digital circuit, especially the timely diagnoses in late using process, are more important progressively. At present, it becomes necessary how to effectively diagnose the PCB digital circuit. So the system of Automation Testing Generation and Testing Analysis (PATGTA) aimed to PCB is researched, the fault simulation for digital circuit is a part of PATGTA.This paper emphasizes the theory of fault simulation, and analyzes what should be taken into account when the theory is used. Based on these contents, the practical fault simulator aimed to PCB digital circuit is designed. In the meantime, this paper introduces an effective fault simulation method for a circuit with RAM. Finally, this paper discusses how to define multi-event fault simulation in the fault simulating for the scheduling circuit and the impact to fault simulation, and the author's own point is put forward in this paper.A parallel fault simulation method based on fault parallel is adopted in the practical fault simulator for PCB level digital circuit and in the system of PATGTA, it run according to coupling with the test generating in turns. During every pat testing code (as one testing frame) simulating process, three segments and many times simulation method is adopted.Three segments mean combination sequence-combination turns, many times mean that the two combination simulating can't stop until the state of circuit is stable. When sequence simulating, it is only to simulate the action of sequence function model according to there is pulse or not. During every segment simulating, normal simulation, multi-fault simulation and fault simulation are carried out by turns. In realization the means of transferring, the sub-procedure is used. This not only ensures the fault simulation precision, also complies with the actual circumstance, as well as strengthens system expansibility for...