The Research Of The Fault Detection And The Testability Of Mixed-signal Circuits

With the development of technology, especially micro-electronics, the density of LSK VLSI are increasing. This made the test of ICs more difficult, and the application of digital and analog mixed-signal circuits made the test much more difficult. The research of the testability and the fault detection of mixed-signal circuits is always a difficulty, and it is also one of the important research aspects. We should use new methods to solve this problem. A recently developed theory of discrete event system provides a uniform and effective treatment for digital and analog circuits.The main works are as follows:1) We made the mathematics model of mixed-signal circuits based on the DES theory to make the circuit states discrete. So we can unite the digital part and the analog part of the circuit to research the testability and the fault detection.2) We put up the experiments mainly based on the CPLD for the faults emulation on some typical digital circuits. And we built the transition function databases according to the faulty testing results.3) We programmed a demo's software of circuits' test and fault diagnosis on Borland C++ Builder. This software can realize these functions, such as judging the testability, getting the minimum test set, testing circuit quickly and making a fault diagnosis.4) In this paper, according to the transition function databases we got the minimum test set using the graph theory. And later we built the quick test databases and the fault diagnosis databases.