Multichip module structures for minimising crosstalk effects in high-speed applications

Remarkable progress has been made in electronic systems while reducing the cost and power and simultaneously increasing the reliability by attaching unpackaged ICs directly to a high density-wired substrate. This multichip technology offers significant advantages like the reduction in interchip wiring length and associated loading effects. Multichip modules are gaining importance gradually for high-speed applications in satellite communications, LAN and radio paging networks. The dense interconnection system and the multilayer nature of the MCM structure introduces limitations on the system performance at high-speed operations, since the nearby conductors develop electromagnetic coupling and a crosstalk voltage. This voltage has to be controlled for better and proper functioning of the circuit ahead. The authors have developed practical MCM structures which result in minimum crosstalk voltages in the nearby interconnects. A number of different crosstalk minimisation techniques are presented with a few numerical examples. The proposed negative shielding concept for multilayered structures is also presented