Fault detection of analog circuits by using transient output voltage

With the rapid development of integrated circuits technology, fewer and fewer circuit nodes are accessible for analog fault detection. In this research, the transient output voltage of analog circuits was used for fault detection. The circuits was stimulated by a transient signal source. It's transient output voltage was measured and analyzed. Then we extracted the features of this signal. Principal component analysis was used to combine these features and detect faults of circuits-under-test. The main advantages of this method is the single test point. Only the transient output voltage signal is measured for practical application. As an example, the proposed method was used for fault detection of the signal filtering and amplifying circuit, which was used in the ultrasonic liquid-level sensor. And we compare the results with those using other methods. From the comparing results, we can see that the proposed method have a higher fault detection accuracy.