抄録
The authors proposed a new method for grouping of relevant and equivalent inputs of a logical circuit by making use of input-output correlation function. Pseudorandom M-sequences are applied to a logical circuit and their outputs are observed. The crosscorrelation function between the input and output gives us the information on the logical circuit whether it is faulty or not. And the grouping of inputs by relevant and equivalent inputs gives us the structure of a logical circuit under test, and it is possible to estimate the faulty part by comparing the input grouping of faulty logical circuit and that of normal one. Of course these input grouping can also be estimated from truth table. But the authors show that the grouping method by use of correlation function is far advantageous over the truth table method when we admit small percentage of error. For example, it is possible to reduce the number of correlation functions needed to calculate these input grouping from 1.07×109 to only 465 in case of 30 inputs logical circuit if 1% error is admitted. This method of grouping of relevant and equivalent inputs of a logical circuit would be very useful in a fault diagnosis of logic boards.
