Analysis of radiated emission performance of various passive signal integrity improvement techniques

The impact of passive signal integrity (SI) improvement techniques on the radiated emission (RE) for different interconnections between digital devices is presented. In high speed digital integrated circuits, SI is no longer the only issue for desired functional performance. RE is also critical for the functional performance and for compliance with EMC standards. Hence, it is important to understand the impact of SI improvement techniques on the RE of digital circuits under realistic conditions. Four passive SI improvement techniques are considered here: series termination, parallel termination, Thévenin termination, and AC termination. Straight and L-shaped interconnections are investigated. Digital devices at the two ends of the interconnections are modeled by Input/Output Buffer Information Specification (IBIS) models. The RE evaluation results can help designers to select the appropriate SI improvement technique taking into account RE requirements.