TITLE:
Boundary Induced Inductive Delay in Transmission of Electromagnetic Signals
AUTHORS:
Yong Yang, Mingzhi Li, Yan Sun, Dongfei Pei, Shengyong Xu
KEYWORDS:
Wave Propagation; Computer Modeling and Simulation; Transmission Lines; High-Speed Techniques;Integrated Electronics
JOURNAL NAME:
Journal of Electromagnetic Analysis and Applications,
Vol.4 No.4,
April
24,
2012
ABSTRACT: When an electromagnetic signal transmits through a coaxial cable, it propagates at speed determined by the dielectrics of insulator between the cooper core wire and the metallic shield. However, we demonstrate here that, once the shielding layer of the coaxial cable is cut into two parts leaving a small gap, while the copper core wire is still perfectly connected, a remarkable transmission delay immediately appears in the system. We have revealed by both computational simulation and experiments that, when the gap spacing between two parts of the shielding layer is small, this delay is mostly determined by the overall geometrical parameters of the conductive boundary which connects two parts of the cut shielding layer. A reduced analytic formula for the transmission delay related with geometrical parameters, which is based on an inductive model of the transmission system, matches well with the fitted formula of the simulated delay. This above structure is analog to the situation that an interconnect is between two inter-modules in a circuit. The results suggest that for high speed circuits and systems, parasitic inductance should be taken into full consideration, and compact conductive packaging is favorable for reducing transmission delay of inter-modules, therefore enhancing the performance of the system.