Lessons learned in high frequency data transmission design: ATLAS strips bus tape

Requirements of HEP experiments lead to highly integrated systems with many electrical, mechanical and thermal constraints. A complex performance optimisation is therefore required. High-speed data transmission lines are designed using copper-polyimide flexible bus tapes rather than cable harnesses to minimise radiation length. Methods to improve the signal integrity of point-to-point links and multi-drop configurations in an ultra-low-mass system are described. FEA calculations are an essential guide to the optimisation of a tape design which supports data rates of 640 Mbps for point-to-point links over a length of up to 1.4 m, as well as 160 Mbps for multi-drop configuration. The designs were validated using laboratory measurements of S-parameters and direct bit error ratio tests.