Low overhead output response compaction in RAS architectures

Scan design causes high switching activity during testing which results in high power dissipation. Therefore, an alternative scheme, termed Random Access Scan (RAS, initially proposed by Ando during the early 80´s) has regained interest due to its low power consumption. RAS-based schemes result in considerable reduction in power dissipation; furthermore they have been shown to compare favorably to scan based schemes with respect to hardware overhead. Response compaction in RAS architectures is typically performed using Multiple-Input Shift Register (MISR) structures. In this work we propose a response compaction scheme for RAS architectures which, compared to the utilization of MISR structures, results in lower hardware overhead and lower time required to capture the responses.