ISSN:
1573-0727
Keywords:
design for testability
;
path delay fault model
;
testability preserving transformations
;
testability inproving transformations
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
Notes:
Abstract Several synthesis for path delay fault (PDF) testability approaches are based on local transformations of digital circuits. Different methods were used to show that transformations preserve or improve PDF testability. In this paper we present a new unifying approach to show that local transformations preserve or improve PDF testability. This approach can be applied to every local transformation and in contrast to previously published methods only the subcircuits to be transformed have to be considered. Using our new approach we are able to show in a very convenient way that the transformations which are already used in synthesis tools preserve or improve PDF testability. We present further transformations which preserve or improve testability. We show that a transformation, claimed to preserve PDF testability, in fact, does not do so. Moreover, the testability improving factor which is a unit of measurement for the quality of testability improving transformations is introduced. Additionally, we present the capabilities of SALT (system forapplication oflocaltransformations), which is a general tool for application of a predefined set of local transformations. The implementation of SALT is described and it is shown how the isomorphism of a “pattern to be searched” and a “matched subcircuit” can be weakened to allow the application of local transformations more frequently. Finally, we confirm the theoretical part of this paper by experimental results obtained by application of the examined local transformations to several benchmark circuits. The effect of these transformations (and combinations of different types of transformations) on PDF testability, size and depth of the transformed circuits is examined and encouraging results are presented. For example, a reduction of up to 90% can be observed for the number of untestable paths.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00995312
Permalink
