A novel trench routing for next-generation high-speed serial buses beyond 10Gbps applications

Abstract

This work describes an innovative low-loss transmission line routing configuration, which enables improved channel margin in next-generation high-speed serial buses beyond 10Gbps applications. One such example is SuperSpeed Plus USB a.k.a. USB 3.1 Gen2. Ultimately, this novel routing when implemented in either substrate or printed circuit board (PCB) will extend platform length within the interconnect channel loss budget as stipulated by standard development body e.g. USB-IF specifications. This inventive routing provides huge benefit to original equipment manufacturer (OEM) in term of platform component removal (e.g. USB 3.1 re-timer that costs ∼$1) for high-speed differential links >10Gbps data transfer rates. These cost-adding repeaters would be indispensable under conventional routing for instance microstrip, stripline and dual-stripline for high-speed applications. The PCB trench routing aims to mitigate the existing and future challenges of next-gen multi-Gbps signaling, of which one of the platform length limitations is PCB interconnect loss. In this work, signaling analysis in 10Gbps USB 3.1 and 32Gbps SerDes applications have shown feasibility of yielding significant eye margin improvements i.e. up-to 30% voltage margin improvements, which also translates into ample board design flexibility with extended platform routing length.