Bulk current injection quantification of BroadR-Reach protocol based system by measurements and modeling

摘要

BroadR-Reach is a point-to-point Ethernet Physical Layer standard for automotive applications, allowing full-duplex communication between two devices over an unshielded twisted-wire pair (UTP) at 100 Mb/s. The high transmission speed in combination with the use of an unshielded harness makes compliance of the BroadR-Reach Ethernet with automotive Electromagnetic Compatibility requirements a challenging task. This paper investigates the main factors influencing the outcome of Bulk Current Injection (BCI) tests carried out on BroadR-Reach Ethernet channels. To this end, experimental measurements, circuit and electromagnetic simulation of a simplified test setup are exploited. The analysis allows putting in evidence the fundamental role played by line length, injection probe positioning, and imbalance affecting the terminal units, as well as the impedance discontinuities introduced when the UTP has to be interfaced with a shielded (untwisted) wire-pair (SWP) of the fiber optics converter electronics.