Assessment of digital integrated circuit electromagnetic emission based on radiated power evaluation

This paper deals with the assessment of digital integrated circuit (IC) electromagnetic emission (EME), and concentrates on the specific aspect of EME of long external wiring, driven by IC input-output pins. In particular, the contribution of single IC pins is investigated by analyzing the structure composed of an IC output driver connected via a microstrip line to a receiver. A transmission-line model is used, and an approach based on the concept of radiated power is applied to the characterization of single-pin IC EME in terms of external-wiring radiation effects. By the analysis of typical driver-wiring configurations, it is shown that the spectrum of the driver output current is the quantity of interest, and that the use of wiring with smaller characteristic impedance leads to larger radiated power. The use of a specific test setup (IEC 61967-4-150-Ω direct coupling method) for the experimental assessment of single pin IC emissions is also considered. Frequency-dependent setup effects are experimentally ascertained via a scattering parameter characterization, and definition of suitable circuit functions. An estimate of the degree of correlation between voltage measurements foreseen by the test procedure and the total power radiated by the loading network of an IC driver is derived