An EMI Immune PAM4 Transmitter in 130 nm BiCMOS Technology

This paper presents the design of a PAM4 (pulse amplitude modulation) transmitter system, which demonstrates higher EMI (electromagnetic interference) immunity over traditional designs. The traditional PAM4 transmitter is investigated for the EMI effects. The proposed PAM4 transmitter uses a transimpedance amplifier (TIA) to isolate the effect of EMI on the PAM4 transmitter. TIA uses common mode feedback (CMFB), which minimises the variation caused in common mode voltage on the transmission line due to EMI injection. Simulation results show that the proposed PAM4 transmitter structure is able to maintain a minimum eye opening of 80 mV as per the standard IEEE802.3bs at a data rate of 12.5 Gbps. The proposed transmitter efficiently transmits the data in the presence of EMI with power of 5 mW and frequency ranging from 1 MHz to 1 GHz, whereas the traditional PAM4 transmitter exhibits complete loss of data in presence of EMI. This EMI immune PAM4 transmitter is designed in STMicroelectronics 130 nm BiCMOS technology.