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Measuring Activity in a Random Adaptive Test System

IP.com Disclosure Number: IPCOM000077660D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Schurmann, HD: AUTHOR

Abstract

Activity is ordinarily measured in the process of determining weights in a random-adaptive test system, by examining only the outputs of each gate. When a pattern is applied to a nonlinear integrated circuit in such a system, only one input is allowed to change state at a time. For each input pattern, the number of gate outputs switching is credited to that particular input. The number of such output gate switchings is accumulated over the entire set of test patterns. From this accumulation, a set of adaptive weights for each input is determined by mapping the vector into a predetermined value.

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Measuring Activity in a Random Adaptive Test System

Activity is ordinarily measured in the process of determining weights in a random-adaptive test system, by examining only the outputs of each gate. When a pattern is applied to a nonlinear integrated circuit in such a system, only one input is allowed to change state at a time. For each input pattern, the number of gate outputs switching is credited to that particular input. The number of such output gate switchings is accumulated over the entire set of test patterns. From this accumulation, a set of adaptive weights for each input is determined by mapping the vector into a predetermined value.

In this method, the final set of adaptive weights takes into consideration all of the relevant information regarding the dynamics of the flow of signals through the integrated circuit. The final set of adaptive weights reflects the correlation between the number of faults to be detected and the input sensitizing combinations, and the setting of gate outputs. It thus assigns a realistic set of weights to the input pins.

An input sensitizing combination for a gate is a set of input signal levels, such that it results in an incorrect gate output level in the presence of a fault. Thus, with a three input AND gate, only four of the eight possible input combinations can detect a fault. In this method, the activity of the circuit is measured. The number of gate outputs that change state from a logic "0" to a logic "1" or vice ve...