What type of low-capacity TVS is needed for a 400G high-speed port on a data center switch?

The data center switch's 400G high-speed port signal rate reaches 56Gbps. PAM4 has stringent requirements for the parasitic capacitance of ESD devices, requiring <0.15pF to maintain a -3dB bandwidth >35GHz. The solution uses EASTTEC's ESDULC3V3D9B ultra-low capacitance TVS (Vrwm=3.3V, typical junction capacitance 0.12pF@1MHz, clamping voltage 7V, response time <0.5ns) connected in parallel to the differential line to ground. This device has an SOD923 package and a parasitic inductance of <0.3nH. Combined with a CMZ20212A-900T common-mode inductor (90Ω@100MHz) to suppress common-mode transients, the measured 400G port ESD ±8kV contact discharge eye diagram template margin >25%, bit error rate <10⁻¹², meeting the IEEE 802.3bs standard.