Automated synthesis of configurable two-dimensional linear feedback shifter registers for random/embedded test patterns

A new approach to optimize a configurable two-dimensional (2-D) linear feedback shift registers (LFSR) for both embedded and random test pattern generation in built-in self-test (BIST) is proposed. This configurable 2-D LFSR based test pattern generator generates: 1) a deterministic sequence of test patterns for random-pattern-resistant faults, and then 2) random patterns for random-pattern-detectable faults. The configurable 2-D LFSR test generator can be adopted in two basic BIST execution options: test-per-clock (parallel BIST) and test-per-scan (serial BIST). Experimental results of test-per-clock BIST for benchmark circuits show with the configurable scheme the number of flip-flops of 2-D LFSR is reduced by 79%. The average number of faults detected by configurable 2-D LFSR is 9.27% higher than the conventional LFSR. Experimental results of test-per-scan BIST for benchmark circuits demonstrate the effectiveness of the proposed technique in which high fault coverage can be achieved.