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VLSI Design
Volume 2 (1994), Issue 3, Pages 223-231

A Quadratic Programming Approach to Estimating the Testability and Random or Deterministic Coverage of a VLSl Circuit

Math and Computer Science, University of Nebraska, Omaha 68182, Nebraska, USA

Received 29 September 1992; Revised 9 March 1993

Copyright © 1994 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The testability distribution of a VLSI circuit is modeled as a series of step functions over the interval [0, 1]. The model generalizes previous related work on testability. Unlike previous work, however, we include estimates of testability by random vectors. Quadratic programming methods are used to estimate the parameters of the testability distribution from fault coverage data (random and deterministic) on a sample of faults. The estimated testability is then used to predict the random and deterministic fault coverage distributions without the need to employ test generation or fault simulations. The prediction of fault coverage distribution can answer important questions about the “goodness” of a design from a testing point of view. Experimental results are given on the large ISCAS-85 and ISCAS-89 circuits.