Compression solution

The latest manufacturing processes allow huge numbers of gates to be designed into a chip, but this is resulting in huge test pattern sizes. Meanwhile, shrinking geometries are introducing new defect mechanisms. Alongside this is a trend for companies to use scan test for yield improvement. In order to meet growing demand for scan test compression, Greg Aldrich, director of marketing for Mentor’s Design for Test products, said: “Test data compression is an enabling technology, allowing additional patterns to be added to maintain test quality.” Aldrich pointed to two factors in TestKompress Xpress: the ability to compress more directions into one test pattern and the ability to handle X states better. “As designs get bigger, you have to deal with more unknown states,” he noted. This is enabled by a patented Xpress compactor, which combines embedded test data selection circuitry with advanced software control. Because test patterns can be smaller and more highly compressed, test times are shorter and throughput is higher.