Breaking the Test Application Time Barriers in Compression: Adaptive Scan-Cyclical (AS-C)

Scan compression technology innovation has broken out into solving the data volume problem keeping the test application time gains relatively constant over the generations of technologies. While data volume reductions are important there is a need to take the test application time gains to the next level as it has a direct impact to the cost of test. In this paper an enhancement to combinational compression is described that relies on increasing the encoding bandwidth for aggressive test application time targets. An architecture is described that adds very little area overhead to a combinational compression architecture by reusing the internal scan chains of the design for encoding bandwidth for a set of the test patterns.