Design of a High-Speed CAN FD Transmitter with Low Electromagnetic Interference

In order to meet the high speed demands of the CAN FD bus protocol and ensure reliable communication in complex electronic system environments, this research paper presents a design for a high-speed CAN bus transmitter that minimizes Electromagnetic Interference (EMI). The design achieves this by implementing a delay control output power tube switch, which effectively reduces the signal voltage slew rate. Additionally, a bias circuit is incorporated to provide a stable gate voltage to the power tube, thereby enhancing signal stability and reducing EMI emitted by the transmitter. Based on the 0.18 μm 60 V BCD process to complete the design and simulation, the simulation results show that, under the 5V power supply voltage, The output signal of the CAN transmitter meets the requirements of the CAN protocol, that is, the dominant level of CANH is about 3.56V and the hidden level is about 2.52V. The dominant level of CANL is about 1.48V and the implicit level is about 2.52V. The symmetry of the output signal is good, and meet the requirements of CAN FD bus protocol high speed. The output common-mode signal has good voltage symmetry, and the fluctuation of common-mode interference is 361 mV.