System Modelling and Measurement Under the View of Design of Testability and Fault Diagnosis of Analog Circuits

Jigou Liu and Uwe Frühauf
Dresden University of Technology, Faculty of Electrical Engineering
E-mail: liu@iee. et.;

With the rapidly increasing complexity of electronic measuring systems, it is more necessary to test their analog circuits not only in the production but also in their application area, in order to ensure the system parameters and the reliability of measurements. In the present paper, a method is proposed to model analog circuits and systems for design of testability and fault diagnosis in measuring systems using three basic functions (Gu/u , Zi , Zo). In order to model complex circuits and systems, coupling models considering the interactions between the subcircuits and subsystems in frequency domain are derived by using a presented equivalent circuit. After the examinations concerning to modelling problems, a method is proposed to measure the basic functions with the help of a discrete Fourier-Series. The presented methods are used to analyse the testability especially for analog measuring circuits. Test matrix and testability condition are derived on the base of the modelling. The results are necessary to ensure build-in-self-test and calibration of electronic measuring systems, too.