Increasing scan compression by using X-chains
US7958472B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 2008 |
| Grant date | Jun 7, 2011 |
| Priority date | — |
| Expiry date | Aug 28, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/318547
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
To increase scan compression during testing of an IC design, an X-chain method is provided. In this method, a subset of scan cells that are likely to capture an X are identified and then placed on separate X-chains. A configuration and observation modes for an unload selector and/or an unload compressor can be provided. The configuration and observation modes provide a first compression for non-X-chains that is greater than a second compression provided for X-chains. ATPG can be modified based on such configuration and observation modes. This X-chain method can be fully integrated in the design-for-test (DFT) flow, requires no additional user input, and has negligible impact on area and timing. Test generation results on industrial designs demonstrate significantly increased compression, with no loss of coverage, for designs with high X-densities.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.