Oscillation-based diagnosis by using harmonics analysis on analog filters

The Oscillation-Based Test (OBT) method converts the circuits under test (CUTs) into self-oscillating mode by changing CUT´s typology or adding feedback path(s). In traditional OBT, the frequencies and amplitudes of sinusoidal oscillation are used as fault features to build up the fault dictionary, which is capable of test but not diagnosis. This paper designs harmonic feedback path to enlarge the harmonics in oscillation, and then builds up fault dictionary to diagnose the analog faults and eliminate the deviation effects by membership functions. The simulation and PCB experiment results prove that the proposed method is both applicable and practical.