Micro coaxial cables, with their excellent flexibility, shielding properties, and ultra-thin structure, have been widely used in lightweight electronic products such as smartphones, laptops, vehicle systems, and medical equipment. However, in these high-speed, high-frequency signal environments, in order to maintain signal integrity and reduce reflection and interference, "impedance matching" becomes a crucial technology that must be mastered.
What is impedance matching? Why is it so important?
In electronic devices, signals pass through multiple paths such as cables, connectors, PCB routing, and terminal modules.
If the impedance values of these paths are not consistent, reflections and echoes will occur at the impedance突变points, leading to reduced signal integrity, manifested as waveform distortion, decreased speed, and even communication failure. A simple analogy: just like water flow in a pipeline, if the pipeline suddenly becomes narrower or wider, water waves or backflow will occur at that point. The transmission of electronic signals is similar to this; when encountering discontinuous impedance, signal reflections will occur.
How to determine the impedance matching value?
Common signal transmission impedance standards include 50 Ω (single-ended) and 100 Ω (differential).
For example:
HDMI, USB, LVDS and other differential signals usually use 100 Ω;
RF signals are commonly used with 50 Ω.
The impedance of micro coaxial cable is usually designed to be 50 Ω, and it is mainly controlled by the conductor diameter, insulation layer thickness, and dielectric constant. Due to the extremely small diameter and precise structure of micro coaxial cable, it is more difficult to maintain impedance consistency compared to conventional coaxial cables, especially in the connector plug-in area where impedance突变 points are prone to form. Therefore, high-quality connectors and high-precision manufacturing processes are crucial.
How to achieve impedance matching?
To ensure the impedance consistency of the micro coaxial cable harness, the following aspects should be addressed:
Cable structural parameters control - including precise design of conductor diameter and dielectric material.
Connector terminal arrangement optimization - reduce the coupling between terminals and impedance突变.
Welding / crimping process consistency — ensure stable contact for each line.
Cable processing control — Reasonable bending radius and length allowance can effectively avoid impedance change.
It is worth mentioning that the I-PEX 20454-240T optimizes the terminal contact structure for high-frequency micro coaxial cable, effectively reducing impedance突变 points and significantly improving signal integrity.
Four, I-PEX 20454-240T connector introduction
• Series positioning: belongs to the I-PEX CABLINE®-VS series, complies with VESA standards, and is specially designed for high-frequency signal applications such as notebook display panels.
Interface specification: Support 20/30/40/50 pin multiple rows (the plug housing can be adapted).
• Transmission performance: Single channel speed up to 20 Gbps, compatible with high-speed protocols such as USB4 Gen3, Thunderbolt 4, PCIe Gen4, and eDP HBR3.
Cable compatibility: Compatible with AWG #38 ~ #46 ultra-fine coaxial cables, standard impedance 50 Ω, some models can provide 45 Ω.
Typical applications: notebook displays, in-car image modules, VR/AR headsets, medical imaging equipment, and other scenarios with extremely high requirements for space and signal.
With the popularity of high-definition displays, in-car electronics, and high-speed applications such as VR/AR, the impedance matching of micro coaxial cable with high-quality connectors becomes increasingly important. Choosing the I-PEX 20454-240T paired with professional cable assembly solutions not only reduces design and production risks but also significantly improves the signal integrity and long-term reliability of the product.
I am Kunshan Jie Kang Fu Precision Electronic, which has been focusing on the design and customization of high-speed signal cables and ultra-fine coaxial cables for a long time. We are committed to providing stable and reliable high-speed interconnect solutions for our customers. If you have any related needs or would like to learn more, please contact: Manager Zhang.
18913228573 (WeChat number).
