A novel scan architecture for power-efficient, rapid test

Scan-based testing methodologies remedy the testability problem of sequential circuits; yet they suffer from prolonged test time and excessive test power due to numerous shift operations. The high density of the unspecified bits in test data enables the utilization of the test response data captured in the scan chain for the generation of the subsequent test stimulus, thus reducing both test time and test data volume. The proposed scan-based test scheme accesses only a subset of scan cells for loading the subsequent test stimulus while freezing the remaining scan cells with the response data captured, thus decreasing the scan chain transitions during shift operations. The experimental results confirm the significant reductions in test application time, test data volume and test power achieved by the proposed scan-based testing methodology.