Signal Integrity Analysis of PCIe Channel with Floating Board-to-Board Connectors in Automotive Infotainment System

In this paper, we analyzed signal integrity (SI) of peripheral component interconnect express (PCIe) channels in an infotainment system utilizing floating board-to-board (BtoB) connectors for automotive environments. The floating BtoB connector is designed to maintain reliable electrical performance at high frequencies, making it compatible with various I/O protocols. Thus, the floating BtoB connectors can be effectively used for PCIe interconnect between the CPU on the main board and the ECU on the daughter board. To accommodate numerous components, including connectors, packages, and chips within a single system, the placement of the ECU package varies across different scenarios. Accordingly, we explored PCIe channel configurations by altering the ECU package's position, both on top and bottom-side of the daughter board. By designing PCIe interconnects within the system, we conducted electromagnetic (EM) simulations to analyze differential insertion loss (DIL), considering the impact of routing paths containing floating BtoB connectors. To verify compatibility with PCIe, we achieved eye diagrams at 16 Gb/s via equalization. Finally, we suggest design guidance for the proposed system considering cost and SI.