A New LFSR Reseeding Scheme via Internal Response Feedback

Reseeding techniques have been adopted in BIST to enhance fault detect ability and shorten test application time for integrated circuits. In order to achieve complete fault coverage, previous reseeding methods often need large storage space to store all required seeds. In this paper, we propose a new LFSR reseeding technique that employs the internal net responses of the circuit itself as the control signals to change the states of the LFSR. A novel test architecture containing a net selection logic module and an LFSR with some inversion logic is presented that can generate all required seeds on-chip in real time without any external or internal storage requirement. Experimental results on ISCAS benchmark circuits show that the presented technique can achieve 100% stuck-at fault coverage in a short test time by using only 0.23-2.36% of internal nets for reseeding control.