Low Transition-Generalized Linear Feedback Shift Register Based Test Pattern Generator Architecture for Built-in-Self-Test

Problem statement: In Built-In Self-Test (BIST), test patterns are generated and applied to the Circuit-Under-Test (CUT) by on-chip hardware; minimizing hardware overhead is a major concern of BIST implementation. In pseudorandom BIST architectures, the test patterns are generated in random nature by Linear Feedback Shift Registers. This normally requires more number of test patterns for testing the architectures which need long test time. Approach: This study presents a novel test pattern generation technique called Low-Transition Generalized Linear Feedback Shift Register (LT-GLFSR) and it was also called Bipartite GLFSR. Intermediate pattern (Bipartite technique) inserted in between consecutive test patterns generated by GLFSR was called LT-GLFSR technique which was enabled by a non overlapping clock scheme. Low-transition generalized linear feedback shift registers (LT-GLFSR), was used in a circuit under test to reduce the average and peak power during transitions. LT-GLFSR pattern generator would generate patterns with higher degree of randomness and high correlation between consecutive patterns would have efficient area implementation. LT-GLFSR did not depend on circuit under test and hence it could be used for both BIST and scan-based BIST architectures. Results/Conclusion: Simulation results show that this technique has reduction in power consumption and high fault coverage with minimum number of test patterns. The results also show that it reduces the peak and average power consumption during test for ISCAS’89 bench mark circuits.