Application and Feasibility of Ultra-Fine Coaxial Cable Bundles in PCIe Gen5/Gen6 High-Speed Interconnect

PCIe standards are rapidly advancing from Gen3's 8 GT/s to Gen5's 32 GT/s and into the high-speed stage of Gen6's 64 GT/s. With the significant increase in transmission speeds, there is a high requirement for channel loss, impedance control, and anti-interference capability. To maintain high-speed signal quality in compact spaces, engineers are beginning to focus on more flexible and shielded interconnect methods, among which ultra-fine coaxial cables (Micro Coax) have become a new choice for supporting high-speed interconnects due to their high shielding structure and flexible cabling capabilities.
This article will analyze from three perspectives: structural characteristics, high-speed challenges, and application feasibility.

The structural characteristics of extremely fine coaxial beam束
Extremely fine coaxial cable束 generally adopts AWG36～40 fine wire diameters, consisting of an inner conductor, insulation layer, shielding layer, and outer sheath. The coaxial structure provides excellent electromagnetic shielding effect, effectively reducing noise and crosstalk. Its flexible characteristics allow the cable束 to adapt to complex layouts, and it has advantages in space-limited or routing designs. The overall lightweight and small volume of the cable束 is suitable for the internal high-speed signal connection needs of miniaturized and high-density modules, providing a flexible path selection for high-speed transmission under stringent environmental conditions.

High-speed transmission challenges of PCIe Gen5/Gen6
As the link rate increases to 32-64 GT/s, channel loss and impedance consistency become key factors affecting system performance. High-speed transmission requires extremely low insertion loss, low reflection, and stable differential impedance. Any excessive bending or wire diameter variations may cause signal attenuation. Cross-talk, mode conversion, and noise coupling are also more pronounced when multiple channels work simultaneously, so the interconnect medium needs to have high-quality shielding capabilities and good electrical stability, and be matched with system equalization strategies to ensure eye diagram opening and bit error rate performance.

Section 3: Feasibility and Design Considerations of Micro Coax for PCIe
Extremely thin coaxial cable bundles have obvious advantages in high-speed shielding capabilities, low crosstalk, and flexible cabling, and can meet the high-speed transmission needs between boards or modules. Due to the thinner wire diameter, signal loss in the high-frequency band will be more sensitive, so it is necessary to shorten the cable bundle path as much as possible, avoid excessive bending, and ensure the stability and reliability of the shielding layer grounding design. During the design process, S parameter analysis, eye diagram simulation, and actual link testing are required to ensure that the overall channel still has controllable loss, low jitter, and high consistency under high-frequency conditions. The consistency of mass production, the stability of the cable bundle geometric structure, and the integrity of the shielding are also important factors that determine performance.

In general, ultra-fine coaxial cable assemblies have distinct advantages in structural flexibility, high shielding characteristics, and compatibility with high-density designs, making them a feasible interconnection solution for PCIe Gen5/Gen6. Under the premise of ensuring material quality, perfect shielding, consistent processing, and complete signal simulation verification, Micro Coax can meet the requirements for loss control and anti-interference in high-speed links, providing a reliable internal interconnection method for the next generation of high-speed equipment. Neglecting impedance control, loss management, and structural stability may lead to performance issues such as eye diagram contraction and error rate increase.

I amSuzhou Hui Cheng Yuan Electronic Technology, committed to the design and customization of high-speed cable harnesses and ultra-thin coaxial cables, providing customers with stable and reliable high-speed interconnection solutions. For inquiries or customization services, welcome to contactManager Yin: 18913280527 (WeChat same number)。