Simultaneous Improvement to Signal Integrity and Electromagnetic Interference in High-Speed Transmission Lines

Branched traces are strictly prohibited in the routing of printed circuit boards (PCBs) for high-speed data transfer, because they cause serious degradation of the signal integrity (SI) and excessive electromagnetic interference (EMI). If this strong design constraint can be removed, the number of degrees of freedom increases dramatically, and the operation speed in PCBs is expected to be improved significantly. In an attempt to overcome the SI degradation that occurs due to characteristic impedance mismatching, we previously proposed the bio-inspired segmental transmission line (STL), and we demonstrated its effectiveness. In this paper, we apply the STL to a branched trace for high-speed data transfer, and we use genetic algorithms to try to simultaneously improve its SI and EMI. Some branched STL prototypes are fabricated and evaluated, the results, which include eye diagrams and electromagnetic emission intensities, show a big improvement in SI and EMI in branched traces.