How to choose a high-speed image transmission interface: a comprehensive comparison of HDMI, USB, and micro coax

In the design of high-speed image transmission, engineers often need to choose between HDMI, USB, and extremely thin coaxial cables (micro coax). Although they all seem capable of transmitting image signals, there are essential differences among them in terms of positioning, structure, bandwidth capacity, and application scenarios. To ensure that the system runs stably and reliably at full bandwidth, it is not only about "whether it can transmit" but also about "whether it is suitable for your design."

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The positioning of the three transmission methods is completely different.

1. HDMI is the most commonly used interface standard for traditional display devices, aimed at TVs, projectors, monitors, and other equipment. It is characterized by maturity and strong compatibility, and is a commonly used solution for external device display.

USB especially USB 3.x, USB4, and Thunderbolt is a universal high-speed transmission platform that can transmit video, data, power, and control signals simultaneously, and is the core interface form for interconnection of modern computing devices.

The ultra-fine coaxial cable (micro coax) is a physical transmission medium rather than a standard interface. It relies on precise impedance control, good anti-interference ability, and flexible structure, making it suitable for internal high-speed differential signal connections in camera modules, eDP screen lines, VR/AR devices, etc. It is an important solution for professional-level high-speed interconnects.

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Bandwidth and Signal Integrity: The advantages of micro coax are often undervalued

From the perspective of protocol standards:

• HDMI 2.1 has a bandwidth of up to 48Gbps, supporting 8K high frame rate images.

• USB4 / Thunderbolt up to 40Gbps, supporting mixed video and data transmission.

But the bandwidth capability of micro coax is equally strong. As a high-speed transmission medium, it can carry various high-speed differential signals such as MIPI, eDP, PCIe, and USB4. With the help of coaxial shielding structure and stable impedance consistency, it has lower loss, lower crosstalk, and higher signal integrity in short-distance transmission, making it the preferred choice for internal interconnection of many high-end devices.

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Section 3: Differences in Distance, Interference Resistance, and Practical Applications

HDMI and USB are more suitable for medium to long-distance transmission, generally stable at 1 to 3 meters. Beyond this distance, active cables or repeaters are usually required to enhance the signal.
micro coax is designed for short-distance high-speed connections (usually within a few centimeters). In high-speed image links, the shorter the path, the lower the loss and interference, so micro coax has a great advantage in internal connections of cameras, display modules, and VR/AR. It is superior to traditional cables in terms of EMI suppression, bending ability, and spatial adaptability, and is suitable for compact structure, high-speed, and low-latency system design.

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High-speed image transmission does not have a universal solution; only the best choice suitable for different system requirements.
HDMI and USB are more suitable for external connections and general expansion; micro coax is suitable for internal high-speed transmission, space-limited environments, and applications with extremely high requirements for signal integrity. If the goal is high resolution, low latency, low error rate, and short transmission distance, micro coax often performs better than standard interface cables. The key to engineering optimization is not the interface name, but a deep understanding of signal, structure, and system details.

I am[Suzhou Hui Cheng Yuan Electronic Technology],Long-term focused on the design and customization of high-speed cable harnesses and ultra-fine coaxial cables, committed to providing customers with stable and reliable high-speed interconnect solutions. If you have any related needs or want to learn more, please contact Manager Zhang :18913228573 (WeChat number)。