Determining effective testability degree of analog circuits

The paper deals with the parametric fault diagnosis of linear analog circuits in the frequency domain. The testability degree, which is referred to as the total number of testable network parameters, is theoretically independent of nominal values of network parameters, the set of test frequencies and the fault detection method. However, practical results show that the effective testability determined numerically using the Singular Value Decomposition of sensitivity matrix (Jacobian) depends on the normalization of network parameters, frequency response measurement methods and a selected set of test frequencies. The differences between the theoretical and the practical testability degree will be discussed on a practical example of RC phase shifter filter.