A New Test Point Selection Method for Analog Circuit

Abstract

A new method to select an optimum test point set in analog fault diagnosis is proposed in this paper. As the probability density of the circuit output approximately satisfies the normal distribution, an accurate way for determining the fault ambiguity gap is used to calculate the isolation probability of the faults. The proposed fault-pair isolation table derived from the mean and standard deviation values of node voltage can exactly represent the fault-pair isolation capability of the test points. The special test points that can uniquely isolate some particular fault pairs are selected first. This step can help to save the total cost of the computation time and even find the final solution directly. After removing the isolated fault pairs (rows) and the selected test points (columns), the size of the fault-pair isolation table could reduce dramatically. If more optimum test points are needed, the normalized fault-pair isolation probability values in the table are used to select the right test point that has the largest fault-pair isolation capability among all the candidate test points. Analog circuits' examples and the statistical experiments are given to demonstrate the feasibility and effectiveness of the proposed algorithm. The other reported algorithms are also used to do the comparison. The results indicate that the proposed algorithm has excellent performance in minimizing the size of the test point set. Therefore, it is a good solution and applicable to actual circuits and engineering practice.