Transformerless impedance matching networks for automotive power line communication

The automotive industry is constantly looking for ways of improving vehicles fuel economy, reliability, and reducing cost of manufacturing and maintenance. As a result, vehicle manufacturers have looked into power line communication (PLC) technology as a possible solution. However the nature of a vehicles power lines such as extremely low impedances, time varying channel characteristics, and noise make it difficult for modems to provide reliable communication. Extensive research is being conducted to improve communication reliability over power line networks. One of the areas being studied is impedance matching. This paper examines previous impedance matching methods proposed for PLC and proposes a transformerless matching network. The transformerless topology allows for reduction in modem PCB size and for possible integration in a modem IC. Simulations are conducted on the proposed matching network to determine its ability to provide matches to impedances found on the vehicle power line. The noise characteristics of the matching network are also examined to determine the impact the circuit will have on the modem.