Using algebraic signatures to compress built-in self test on a chip

Chip functionality testing can greatly benefit from a Built In Self-Test (BIST). The Self-Test Using MISR and Parallel Shift Register Sequence Generator (STUMPS) architecture uses a compression technique to generate a set of test patterns, to submit them to the circuit undergoing testing, and to compare the output with that of a “gold” (known to be good circuit) by loading and comparing the contents of a Multiple Input Shift Register (MISR). We propose to use algebraic signatures as the comparison signature implemented by the MISR. As we will see, the MISR is still basically a Linear Feedback Shift Register (LFSR), but can now be made to guarantee to discover one or up to k output discrepancies, where k is a very small number that determines the length of the MISR register. The construction of the algebraic signature register is generic and only the comparison value needs to be programmed.