Superfine coaxial cable bundle diameter selection guide: Signal frequency and performance matching

As electronic devices develop towards slimming down and high-speed performance, camera modules, display interfaces, and high-speed storage have increasingly high requirements for internal high-speed interconnection. Extremely fine coaxial cables (micro coax) have become a common choice for scenarios such as laptops, tablets, industrial cameras, and medical equipment due to their small size, good shielding, and high flexibility. However, the matching of wire diameter is crucial for signal integrity and transmission performance; an incorrect choice can lead to signal reflection, eye diagram collapse, and increased crosstalk. Therefore, reasonably determining the wire diameter is a key link in ensuring high-speed transmission performance.

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Signal frequency and wire diameter correspondence

The line diameter of extremely thin coaxial cables should be selected based on the frequency and rate of the applied signal. In high-speed scenarios (≥1GHz or rate ≥2Gbps), too thick a line diameter will increase parasitic capacitance, while too thin a diameter will result in conductor loss. Generally, an outer diameter of 0.25~0.35mm is recommended, with impedance controlled within 50Ω single-ended or 100Ω differential range. In medium-to-high-speed scenarios (several hundred MHz to 1GHz, rate 1~2Gbps), such as MIPI D-PHY or LVDS interfaces, the line diameter can be appropriately selected as 0.3~0.5mm to balance flexibility and low loss. For low-speed scenarios (<500MHz, rate <1Gbps), a 0.4~0.6mm outer diameter can be used to reduce DC resistance and improve stability.

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The key considerations behind wire diameter selection

When determining the diameter of extremely fine coaxial cable束，multiple factors need to be considered. Firstly, signal integrity is the core indicator, and the cable diameter directly affects the characteristic impedance, which in turn affects the eye diagram opening and jitter performance. Secondly, under high frequencies, the loss of the dielectric and conductor is significant, and a too small diameter of the cable will increase signal attenuation. Furthermore, miniaturized equipment has strict requirements for flexibility and wiring space, and a small diameter of the cable is helpful to adapt to narrow spaces. At the same time, process tolerances are also critical; the finer the cable diameter, the higher the processing difficulty and consistency requirements, which must be fully considered in the design.

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Typical Applications and Practice Strategies

In practical applications, the selection of the wire diameter for extremely fine coaxial cable bundles needs to be combined with specific interfaces and signal rates. Camera modules (MIPI CSI) typically use cable bundles with an outer diameter of 0.3~0.4mm to balance speed and flexibility; display interfaces (eDP, HDMI, USB3.x) are suitable for an outer diameter of 0.25~0.35mm under 1~5Gbps; for master control and high-speed storage (UFS, PCIe) with higher speeds, strict requirements are placed on wire diameter accuracy and impedance control, usually with an outer diameter of about 0.25mm. By reasonably matching the wire diameter, designers can balance signal integrity, flexibility, and manufacturing feasibility at different speeds and frequencies.

The selection of wire diameter in extremely thin coaxial cables directly affects signal integrity, transmission loss, and mechanical reliability in high-speed signal internal interconnections. High-frequency applications tend to favor smaller wire diameters and strict impedance control, while medium-to-low-speed applications can relax requirements slightly, focusing more on stability and process consistency. In design, engineers need to consider signal frequency, rate, flexibility, and process tolerances comprehensively to ensure the stability and reliability of the cable in a high-speed environment.

I am[Suzhou Huichengyuan Electronic Technology],Long-term focus on the design and customization of high-speed cable harnesses and extremely thin coaxial cables, committed to providing customers with stable and reliable high-speed interconnection solutions. If you have relevant needs or want to learn more, please contact Manager Zhang:18913228573 (WeChat number)。