Research On Virtual Test Technology About Mixed-signal Circuits

Mixed-signal(digital and analog)circuits are widely used in multimedia, the wireless network and the portable data system. There are some problems in present fault-diagnosis of mixed-signal circuits, such as difficulty in unifying the digital and analogue signal, poor efficiency, low automatization and so on. So the fault-diagnosis of mixed-signal circuits is a hotspot in the field of circuits testing.In this dissertation, the DES theory is used to analyse the testability of circuits, the virtual instrument technique is used in the fault diagnosis of mixed-signal circuits. The main work and contributions of the dissertation are summarized as follows:By deep research in Automatic Test System and fault-diagnosis of mixed-signal, a scheme was designed to realize the diagnosis by combining DES theory and the virtual instrument technique.A typical mixed-signal circuit was chosen, it's fault model was built up. The software Multisim was used to simulate the circuit so as to build up the fault dictionary. The Discrete Particle Swarm Optimization Algorithm was used to get the minimum test set of the circuit, and then a reduced fault dictionary could be attained.The structure of the hardware was designed. The experiment circuit was built on SC-2075, PCI DAQ device was used to acquire data to the software system. In this way, the speed of test could be improved and automatization of the test could be realized.The program of acquiring data was completed in the VI environment LabWindows/CVI, the program of analysis was also completed according to the reduced fault dictionary. It can be certified that it is feasible to carry out the fault-diagnosis of mixed-signal circuits by combining with DES theory and the virtual instrument technique.