Wavelet based approach for analog filter fault detection

A method for analog filter fault detection based on wavelet transform of dynamic supply current (IDD) is presented. The pole/zero locations in the frequency response of analog filters shift due to change in component values with process variations. Wavelet transform of supply current can be a promising alternative to test frequency specification of analog filters, since it needs only one ac stimulus and is virtually unaffected by transistor threshold variation. Simulation results on the test circuit demonstrate that we can estimate pole/zero shift with less than 4% error using only one measurement, which requires about 14 measurements in the conventional technique.