Output equivalent circuit model of digital IC for estimating emissions radiated from signal trace

摘要

The output model of a digital IC for calculating normal-mode emissions radiated from a signal trace was studied. It is confirmed that the difference of kinds and manufacturers of various digital ICs can be found by measuring normal-mode radiations from a signal trace driven by a digital IC such as TTL or CMOS. In order to calculate the difference of normal-mode emissions, it is proposed that the output equivalent circuit of the digital IC be modeled as a circuit consisting of a voltage source and an output resistor, and a method of obtaining them is presented. The validity of the output model of the digital IC is confirmed by the fact that the results of calculation using the output model of a digital IC agree very well with measured data.