Quantitative Analysis of Ringing in a Controller Area Network With Flexible Data Rate for Reliable Physical Layer Designs

Signal distortion, called ringing, in a controller area network with flexible data rate (CAN-FD) causes asymmetry in propagation delay throughout a network, which is dependent on its physical bus design and becomes a critical issue in limiting the data rate. Thus, in this paper, the bus structure of a CAN-FD is investigated and a transfer function of ringing is modeled by considering the physical bus configuration and features of a controller area network transceiver. The effects of the main parameters of the physical bus, such as the stub line length and number of stub lines connected to a joint connector, are then quantitatively analyzed using the presented model. When a practical bus structure is considered, additional signal distortion owing to a neighboring connector in a physical bus is modeled and analyzed. These analytical results are confirmed experimentally. Their comparison shows that the presented model-based analysis can closely approximate the size and time response of ringing and the extent of bit time distortion. The presented model-based analysis facilitates reliable communication performance by estimating the ringing and resulting asymmetry of the propagation delay for a given physical bus design and, if necessary, adjusting the design.