Asymmetric, multi-conductor low-coupling structures for high-speed, high-density digital interconnects

Due to the increasing speeds of digital circuits and the small interline spacings, a full-wave analysis of multilayer, multiconductor structures is required to accurately predict the coupling and crosstalk on these structures. Using the spectral domain approach, it is shown that substrate compensation can be used for asymmetric coupled lines and symmetric multiconductor lines. Some of the characteristics of substrate compensated low-coupling structures were also investigated, showing that one substrate configuration can be used to reduce coupling and crosstalk with a variety of conductor configurations. It is concluded that, by designing high-speed interconnects with substrate compensation, it will be possible to achieve an extremely high density of signal conductors, using interline spacings of less than one center conductor width, while keeping crosstalk and coupling distortion to a minimum.<>