A General Model for Integrated Circuit Susceptibility Prediction

The major results of this study may be summarized as follows. First, a simple model is adequate for the estimation of the susceptibility of integrated circuit systems. This model does not differ in any respect from the equivalent model that one would use to calculate the susceptibility of a vacuum tube circuit. Only the numerical values of the parameters differ. Second, it is apparent from the results that, at least at the present state of the art, the dimensions of the integrated circuits themselves are so small that they may be ignored in comparison with the connections in susceptibility calculations. Finally, since the susceptibility depends chiefly on the dimensions of the interconnections between circuits (at least when the power level is held constant), it can be stated that the more compactly packaged a system is the less susceptible it is likely to be. The fields to which the circuits are exposed can be greatly reduced by proper application of shielding. We have made some susceptibility estimates for a digital computer which included the shielding effect of the cabinet. We have not been able to verify this estimate because of the large field strength required over the test volume. We also feel that additional study of the effects of tuned circuits, electromechanical filters, and other components not considered in this work should be performed. A more detailed discussion of the complete study is contained in Ref. 1.