Design of a CML Transceiver With Self-Immunity to EMI in 0.18- $\mu $ m CMOS

This paper presents the design of an integrated current mode logic (CML) transceiver system that demonstrates a superior robustness to electromagnetic interference (EMI). The effect of EMI on a typical CML transceiver has been investigated and the findings are addressed in the design of the proposed CML transceiver. The typical and proposed CML transceivers are compared experimentally for EMI-robustness using the direct power injection (DPI) method. The proposed CML transceiver system consistently maintains a sufficient differential eye opening retaining a minimum of 160 mV of the original 500 mV peak when EMI is not applied. This is unlike the typical transceiver where the differential eye opening is completely closed for EMI frequencies from 20 MHz to 700 MHz. In terms of bit error rate (BER) measurements, the typical transceiver yields a worst case result of 0.5 for EMI frequencies ranging from 400 MHz to 700 MHz and EMI amplitude of 5 V peak, whereas the proposed transceiver yields a worst case BER result of 0.035 in a narrow EMI frequency range around 200 MHz with the same amount of EMI amplitude. Both typical and proposed CML transceivers are fabricated using a standard 0.18 μm CMOS UMC process.