Cable Backplane and Cable Cartridge

Overview

Cable backplane and cable cartridge systems are high-density copper interconnect assemblies that connect GPU nodes to switch nodes within AI scale-up racks via a midplane, replacing traditional PCB backplanes at high data rates. As lane speeds advance from 112G to 224G and beyond, the end-to-end copper cable solution has emerged as the preferred approach due to its superior signal integrity compared to rigid PCBs at frequencies above 50 GHz.

A cable cartridge system must address six engineering pillars: (1) system channel budget — meeting the ~24 dB bump-to-bump insertion loss target at 53 GHz for 224G PAM4; (2) robust mating interface — blind/brute-mate with shrouded pins to prevent damage; (3) signal integrity — minimal discontinuities and controlled impedance transitions; (4) system co-design and co-validation with OEM customers; (5) vertical integration of contacts, cable, and assembly; and (6) fast ramp — typically 3-month automation replication requirement.

A representative ORV3 cable cartridge 1024DP design uses 8U GPU nodes (2 pieces of 8P18C) and 9U switch nodes (4 pieces of 8P16C), with 1250 mm cable length. Future evolution to 448 Gbps copper cable backplane is expected to continue as the industry scales.