Methodology using OBIST for detecting parametric with single and multiple catastrophic faults in an analog integrated circuit

A technique for fault diagnosis using oscillation based built-in self-test (OBIST) is presented in this paper. The method is used to detect parametric, single as well as multiple catastrophic faults in analog circuits of mixed signal IC. In this method the circuit under test (CUT) is converted to an oscillator and the output pulses are measured to test the circuit. For most of the catastrophic faults the variation in number of pulses is large and they are detected easily. The pulses are counted for lesser time to detect these faults. If catastrophic faults are present the chip is rejected without checking for parametric faults. Upon passing catastrophic fault test, the chip has to undergo rigorous process of testing parametric faults. Usefulness of this method is verified for various active filters and simulation results on second order Butterworth low pass filter (LPF) circuits with cutoff frequencies 10–50 kHz in the steps of 10 kHz are discussed.