Wavelet energy-based Mahalanobis distance metric for testing analog and mixed-signal circuits

In this paper a test method based on the wavelet transformation of the measured signal, be it supply current (I_PS) or output voltage (V_OUT) waveform, is presented. In the wavelet analysis, a Mahalanobis distance test metric is introduced utilizing information from the wavelet energies of the first decomposition level of the measured signal. The tolerance limit for the good circuit is set by statistical processing data obtained from the fault-free circuit. Simulation comparative results on a benchmark circuit for testing both hard faults and parametric faults are presented showing the effectiveness of the proposed testing scheme.