Smart Logic Built in Self-Test in SOC

Abstract

DFT (Design for Testability) is a methodology of testing for manufacturing defects in a chip. DFT consists of scan, ATPG (Automatic test pattern generation) methodologies and the BIST (Built in self-test) methods. This paper explores ATPG for pattern generation and LBIST (Logic built-in self-test) for testing. LBIST is explored and tested using pseudorandom test pattern generation. The fault list created for undetected faults are dumped into ATPG and fault specific test patterns are generated. These patterns detect the random pattern resistant faults (which are undetected by pseudorandom testing patterns). Further, a smart compression algorithm is defined to compress the pattern which can be stored inside the chip for LBIST testing, with no added memory overhead, and the minimum extra hardware (which only comprises of combinational logic). The proposed algorithm has been reviewed and analyzed and it has been found that the fault coverage achieved is 86.01%.