IBM CAS

IBM CAS Project: Improved Testing of VLSI Chips with Power Constraints

The elevated power dissipation during test has severe impact on test time, test reliability and product reliability, especially for high-performance processors like the Cell Processor. In the course of this project, new methods for test planning that take advantage of clock gating and power gating are developed.

10.2005 - 12.2009, IBM CAS-Project

Project Description

Built-in self test is a major part of the manufacturing test procedure for the Cell Processor. However, pseudo random patterns cause a high switching activity which is not effectively reduced by standard low power design techniques. If special care is not taken, the scan-speed may have to be reduced significantly, thus extending test time and costs.

 

cell-small

 

A test power reduction method for logic BIST is being developed which uses test scheduling, planning and scan-gating. In LBIST, effective patterns that detect additional faults are very scarce after a few dozens of scan cycles and often less than one pattern in a hundred detects new faults. In most cases, such an effective pattern requires only a reduced set of the available scan chains to detect the fault and all don't-care scan chains can be disabled, therefore significantly reducing test power.

 

stump-extended-small

 

Journals and Conference Proceedings

  1. 2007

    1. Verlustleistungsoptimierende Testplanung zur Steigerung von Zuverlässigkeit und Ausbeute. Michael E. Imhof; Christian G. Zöllin; Hans-Joachim Wunderlich; Nicolas Mäding and Jens Leenstra. In 1. GMM/GI/ITG-Fachtagung Zuverlässigkeit und Entwurf (ZuE’07), Munich, Germany, 2007, pp. 69--76.
    2. Scan Test Planning for Power Reduction. Michael E. Imhof; Christian G. Zoellin; Hans-Joachim Wunderlich; Nicolas Maeding and Jens Leenstra. In Proceedings of the 44th ACM/IEEE Design Automation Conference (DAC’07), San Diego, California, USA, 2007, pp. 521--526. DOI: https://doi.org/10.1145/1278480.1278614
  2. 2006

    1. BIST Power Reduction Using Scan-Chain Disable in the Cell Processor. Christian Zoellin; Hans-Joachim Wunderlich; Nicolas Maeding and Jens Leenstra. In Proceedings of the International Test Conference (ITC’06), Santa Clara, California, USA, 2006, pp. 1--8. DOI: https://doi.org/10.1109/TEST.2006.297695

Workshop Contributions

  1. 2008

    1. Reduktion der Verlustleistung beim Selbsttest durch Verwendung testmengenspezifischer Information. Michael E. Imhof; Hans-Joachim Wunderlich; Christian Zöllin; Jens Leenstra and Nicolas Maeding. In 20th ITG/GI/GMM Workshop “Testmethoden und Zuverlässigkeit von Schaltungen und Systemen” (TuZ’08), Wien, Austria, 2008, pp. 137--141.
  2. 2006

    1. BIST Power Reduction Using Scan-Chain Disable in the Cell Processor. Christian Zöllin; Hans-Joachim Wunderlich; Nicolas Maeding and Jens Leenstra. In 18th ITG/GI/GMM Workshop “Testmethoden und Zuverlässigkeit von Schaltungen und Systemen” (TuZ’06), Titisee, Germany, 2006, pp. 101--103.
Hans-Joachim Wunderlich (i.R.)
Prof. Dr. rer. nat. habil.

Hans-Joachim Wunderlich (i.R.)

Heading the Research Group Computer Architecture

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