Analysis and design of low loss differential transmission line structures for high speed applications

Recent work by Intel [1,2] has shown that it is possible to reduce the loss of transmission lines through innovative routing. The “vertical trench” proposed in Intel's work [1,2] showed a 20% reduction in the differential insertion loss. In this work a detailed discussion on the reasons why this novel routing approach can reduce the loss of the differential lines as well as analysis on the design variables of and their effects on the performance of a differential transmission line employing the vertical trench is undertaken. It is also shown through simulation that similar improvements in the differential insertion loss can be obtained through simply increasing the thickness of the of metal for the differential pair.