25Gbps Automotive Ethernet ECU PCB: MDI Design Implementation and Insertion Loss Characterization

Physical Layer (PHY) Signal Integrity (SI) aspects of an Automotive Ethernet communication channel are characterized using Radio Frequency (RF) parameters. With increasing Automotive Ethernet data rates, communication channel signal attenuations (i.e., Insertion Loss (IL)) are significantly worsened. At 25Gbps data rate, the communication in cars faces various electrical limits and all components (i.e., segments) of the communication channel have to be optimized in order to reach the expected performance requirements. One such component is the Electronic Control Unit (ECU) Printed Circuit Board (PCB) Media Independent Interface (MDI). Consequently, for such high-speed links, ECU PCB electrical and material properties have an impact on the overall IL. Considering the stringent Automotive Ethernet channel electrical requirements, this study proposes and characterizes ECU PCB MDI design concepts for a 25Gbps in-vehicle Ethernet connectivity. Furthermore, the design concepts are manufactured on test boards to characterize the corresponding MDI signal IL budget. The characterizations are conducted using RF test bench measurement and a defined simulation approach. Lastly, in relation to test bench measurements, this study investigates and characterizes to what extent simulations can serve as either an alternative or a coexisting option for in-vehicle 25Gbps MDI IL characterizations, validations, and qualifications.