Vertical Differential Pair Routing in High Performance Ceramic Multi-chip Module Packages

We describe a methodology to route differential pairs in vertical layers in a high performance multi-chip module ceramic package. By matching the impedance of these vertical differential pairs to their conventional counterparts and adopting a power distribution topology that effectively isolates these pairs from noise aggressors, routing was improved by 17% and simultaneous switching noise decreased by 60%. The methods described in this paper were applied successfully in the design of an IBM ceramic multi-chip module (MCM) package with good electrical performance.