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Easily Testable Iterative Logic Arrays

IP.com Disclosure Number: IPCOM000128370D
Original Publication Date: 1987-Dec-31
Included in the Prior Art Database: 2005-Sep-15
Document File: 21 page(s) / 63K

Publishing Venue

Software Patent Institute

Related People

Cheng-Wen W'u: AUTHOR [+4]

Abstract

Iterative logic arrays (ILA) are studied with respect to two testing problems. First, a variety of conditions are presented which, when met, guarantee an upper bound on the size of the test set for the ILA under consideration. Second, techniques are presented for designing optimally testable ILAs. The arrays that are treated are, in some cases, more general than those that have been reported by other researchers: They include multidimen-sional and inhomogeneous arrays. Octagonally-connected arrays, hexagonally-connected arrays, and bilateral arrays also are discussed. The presented results indicate that the characteristics of the individual cell functions (e.g., whether they are injective) are a good guide to the test complexity of the overall array. Matrix multiplication, as an example, is shown to have several different optimally testable implementations. The results are useful for combinational and pipelined arrays, and for certain systolic arrays.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Easily Testable Iterative Logic Arrays

Cheng-Wen W'u Peter R. Cappello

Department of Computer Science

September, EASILY TESTABLE ITERATIVE LOGIC ARRAYS

Cheng-Wen Wu and Peter R. Cappello

Department of Computer Science University of California Santa Barbara, CA 93106 August 28, 1987

ABSTRACT

Iterative logic arrays (ILA) are studied with respect to two testing problems. First, a variety of conditions are presented which, when met, guarantee an upper bound on the size of the test set for the ILA under consideration. Second, techniques are presented for designing optimally testable ILAs. The arrays that are treated are, in some cases, more general than those that have been reported by other researchers: They include multidimen-sional and inhomogeneous arrays. Octagonally-connected arrays, hexagonally-connected arrays, and bilateral arrays also are discussed. The presented results indicate that the characteristics of the individual cell functions (e.g., whether they are injective) are a good guide to the test complexity of the overall array. Matrix multiplication, as an example, is shown to have several different optimally testable implementations. The results are useful for combinational and pipelined arrays, and for certain systolic arrays.

INTRODUCTION

Advantages associated with ILA's, such as simplified design and layout, were known long before the advent of VLSI technology. This motivated research concerned with, among other things, ILA testing. Special advantages associated with combinational ILA's have been known j 1, 2, 3] since the 1950's. The suitability of ILA's to integrated circuit technology with respect to design and layout is not their only advantage. They often can be tested economically as well. In this paper, we discuss the testing of ILAs with combinational cells. DEFINITION: An ILA is unilateral when signals propagate in only 1 sense with respect to each axis. It is bilateral when signals propagate in both directions with respect to some axis. DEFTNrrION: An ILA is homogeneous when it consists of functionally identical cells, otherwise it is inhomogeneous.

t This work was supported by the Office of Naval Research under contracts N00014-84-K-0664 and N00014-85-K-0553. In this paper, and in the work to which we refer, certain assumptions are made. Assuvrnrlort 1: The circuit's behavior is invariant over time. That is, we are not testing for transient errors (e.g., due to a-particle interference). We also do not consider pattern- sensitivity or bridging among cells. To completely test an array, therefore, it suffices to verify the function of every cell in the array. Verifying a cell function involves generating input for the cell
(i.e., controlling the cell), and propagating faults from the cell (i.e., observing the cell). This

University of California at Santa Barbara Page 1 Dec 31, 1987

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Easily Testable Iterative Logic Arrays

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