Fault Modeling Methods For Analog Circuit Simulation

With the rapid development of large-scale integrated circuit technology, the reliability of circuits has gained more attentions. The importance of the PCB testing diagnostics is increasing obviously. Owing to the complexity and the continuousness of the analog behavior, the allowance of component parameter, it is more difficult to modeling the behavior of analog faults than digital faults, which act as a rather monotonous action and have had widely applicable fault models.This paper first presents the research development of the circuit fault simulation and fault modeling technology. Based on the theory of system modeling and considering that the fault models should describe the actual faults in analog circuits, this thesis gives a brief discussion on the analog circuit fault modeling related technology, and summarize the circuit fault modeling methods of different abstract levels.Subsequently, this paper proposes the analog behavioral fault modeling method in the actual fault simulation environment, which establishes models of the input/output behavior of faulty circuits based on transistor-level fault simulation, using the analog behavior modeling tool, and then a closed loop fault behavioral model is developed for a benchmark opamp circuit. The behavioral fault models can shorten the simulation time and reduce the storage costs before tests, and can be used in all Spice-like simulators directly. It is applicable to large scale components or circuit modules.Finally, this paper designs and implements of the analog circuit fault simulation module in the platform named "fault diagnosis software development environment". On the basis of the given simulator, the definitions of fault model and the specifications of fault injection are introduced. Since they are similar with Spice netlist syntax specifications, the fault models and fault injection statements can be explained by the simulator easily. Then the automated fault injection module and fault modeling module are accomplished, both of which are completed with two ways: graphics editing and text editing.