TESTABLE DESIGN OF DIGITAL SUMMATION THRESHOLD LOGIC ARRAY FOR SYNTHESIS OF SYMMETRIC FUNCTIONS

H. Rahaman, D.K. Das, and B.B. Bhattacharya

Keywords

Symmetric Boolean functions, path-delay faults, design-for-testability

Abstract

A new cellular array is introduced for synthesizing totally symmetric Boolean functions. The cellular structure uses only 3-input, 3-output AND–OR cells, and is fully path-delay fault testable. It is an improved version of the classical digital summation threshold logic array used earlier in logic design [1]. It admits a universal test set of length 2n that detects all single stuck-at faults, where n is the number of input variables. The proposed design is useful in view of the fact that two-level realizations of most of the symmetric functions are known to be path-delay untestable. Experiments on several circuits demonstrate that the structure offers less area and fewer number of paths compared to earlier delay testable proposals.

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