Using Coaxial Ground Full-touch Structure to Reduce Far-end Crosstalk in PCIe5 High-speed Connectors

With the continuous increase of data transmission speed, the problem of far-end crosstalk (FEXT) of high-speed connectors has gradually become a significant challenge that restricts the performance of communication systems. This paper proposes a full-contact return path design to mitigate the FEXT. By improving the return path distance, the stripping of the ground layer of the coaxial line is directly connected with the metal spacer in the hollow of the full-contact connection. Thus, the current return path flows between the coaxial and the metal spacer, which shortens the return path of high-frequency current. At the same time, to the entire coaxial conductive layer as the ground, FEXT can be further reduced by expanding the grounding area to constrain the signal. Simulations with the commercial software HFSS show the FEXT decreases by 6 dB from DC to 20 GHz compared to a return path design without complete contact. Besides, the time domain results are also simulated. Compared with the return path design without complete contact, the coaxial ground full-touch structure reduces peaks in FEXT voltage compared to the return path design. Therefore, it can be demonstrated that the coaxial ground full-touch structure can be adopted to mitigate the FEXT in high-speed connectors, further improving the signal quality and reliability in modern communication systems.