A Multi-Mode Scannable Memory Element for High Test Application Efficiency and Delay Testing

  • Authors:
  • E. S. Sogomonyan;A. D. Singh;M. Goessel

  • Affiliations:
  • Institute of Control Sciences, Russian Academy of Sciences Profsojuznaja ul. 65, 11 78 06 Moscow, Russia. egorsog@online.ru;Department of Electrical Engineering Auburn University, AL36849, USA. adsingh@eng.auburn.edu;Fault-Tolerant Computing Group, Institute of Informatics at the University of Potsdam, PSF 60 15 53, 14415 Potsdam, Germany. mgoessel@mpag-inf.uni-potsdam.de

  • Venue:
  • Journal of Electronic Testing: Theory and Applications
  • Year:
  • 1999

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Abstract

This paper introduces a new multi-mode scannable memory element whichallows pseudorandom testing to be integrated with scan in sequentialcircuits without the need of any design changes. As in the case ofscan, the new element is used in place of regular flip-flops in thedesign library. Concurrent with normal operation, the design canaccumulate a signature of the state variables in the scan-registerconfigured as a multiple input signature analyzer (MISA). Thusvirtually complete state observability is achieved without the need ofscanning-out the state for each test-input. The pseudorandom states ofthe MISA can also be utilized as state inputs in pseudorandom testing.In this way, most faults are covered in a pseudorandom, “test perclock” mode. Only a few random pattern resistant faults require scan,greatly reducing test application time. Pseudorandom delay testing ofthe true normally active circuit paths is also possible. Two-patterntests are supported. Finally, we show that the new memory element canalso be used for fault-tolerant design.