Efficient linear feedback shift register design for pseudo exhaustive test generation in BIST

Pattern generation is the most important module in a BIST. Out of many test pattern generators (TPG) explored for BIST, linear feedback shift registers (LFSR) are widely used due to their ability to produce highly random patterns. Various improvements over the basic forms of LFSR are available. In the current study, the selection of an appropriate LFSR for a given benchmark circuit is analyzed. It is done by considering various factors such as selection of characteristic polynomial and seed to obtain high fault coverage, minimize invalid patterns, area overhead and time taken to generate the patterns.