Design for diagnosability of linear digital filters using time-space expansion

Fault diagnosis in digital signal processing (DSP) circuits is very important for debugging circuit prototypes and chips and for identifying manufacturing process related problems. In this paper, we address the problem of diagnosing failures in digital filters. It is assumed that the circuit response obtained during off-line testing of digital filters is to be used for fault diagnosis. The tests applied to the filter consist of input data patterns generated by a standard test pattern generation algorithm. We propose a design for diagnosability procedure, based on time space expansion of a digital filter, which allows one circuit node in addition to the normal filter output to be externally observable for diagnosability purposes. The diagnosis is performed by measuring the error magnitudes at the observable circuit nodes at different times during application of the test sequence