Based On The Characteristics Of The Analog Signal Modeling And Software Implementation

Testability is a design characteristic of the product, which the state of the products can be determined timely and accurately, and its internal fault is isolated. With the development of electronic technology, the complexity of circuit system and difficulties of test are increasing, testability is more and more important. But the existing modeling methods of circuit testability are very complex, and are easily influenced by human factors. Therefore, to solve these problems, this paper focuses on the analog circuit testability design;mainly studied on the circuit fault automatic simulation, multi-signal modeling, dependency matrix generation technology and test point optimization, etc. And then built an automatic simulation and modeling software platform of the analog circuit. Specific contents are as follows:In order to solve the problem that the fault model is difficult to determine in the circuit design, the multi-signal modeling method based on multi-feature is proposed in the paper. This method can extract the different features (including time domain features, frequency domain features, statistical features, and wavelet features, etc) as the fault features for the multi-signal modeling of analog circuit, make the modeling more efficient and accurate.An optimum test signal set optimization approach is proposed to reduce the number of test and the cost of test. The test optimization algorithm is improved on the inclusion method, it finds the optimum test signal set via choosing the most influential features from the several tests based on the dependant matrix, attain to isolate the most fault components via the least tests. The rationality of this algorithm is also evaluated by the testability index.A multi-signal modeling software platform of the analog circuit is developed, and it is successfully integrated into the main software of "the software of testability for design and analysis". In the software platform, an algorithm is designed to obtain the initial voltage of the circuit via calling the Pspice simulation engine automatically; the fault extraction algorithms and the test optimization algorithm are achieved by Matlab; all the algorithms are integrated into multi-signal modeling software platform based on VC operation platform.Some examples in this paper are used to illustrate the practicability of multi-signal modeling platform. Furthermore, in order to prove the superiority of the multi-signal modeling algorithm based on multi-features, using typical low-pass filter circuit as an example, its index analysis result is used to compare with that of the authorized testability design software TEAMS, the results indicate, when both the fault detection ratios are100%, the fault isolation ratio of automatic modeling is100%, but th-e fault isolation ratio of manual modeling is only69.08%, so we can know the multi-si gnal automatic modeling of analog circuits is the better one.