With the continuous development of high-definition monitors, laptops, in-car equipment, and camera module products towards thinness and high speed, micro coaxial cable (micro coaxial cable) has gradually become an ideal choice for high-speed signal transmission. However, in practical applications, when multiple micro coaxial cables are arranged in parallel, problems such as crosstalk, radiation interference (EMI), and signal integrity degradation often arise. This article will introduce the key techniques for EMC optimization in such applications, helping products pass electromagnetic compatibility tests smoothly.
What is EMC (Electromagnetic Compatibility)?
In electronic design, EMC (Electromagnetic Compatibility) refers to the ability of a device to operate normally in a specific electromagnetic environment without causing excessive interference to other devices.
EMC mainly includes two aspects:
EMI (Electromagnetic Interference): Electromagnetic noise emitted by the equipment itself, which may interfere with the surrounding electronic systems.
• EMS (Electromagnetic Susceptibility, Electromagnetic Interference Resistance): The ability of the equipment to resist external electromagnetic interference.
Common EMC problems with parallel wiring of multi-core Micro Coaxial Cable
When multiple micro-coaxial cables are arranged in parallel, the following electromagnetic compatibility risks may occur:
Interference (Crosstalk)
Common-mode noise superposition
The overall radiation exceeds the standard.
Signal reflection leads to intersymbol interference (ISI).
Especially in high-speed signal transmission such as MIPI D-PHY, C-PHY, USB 3.0, and PCIe, EMC issues are more prominent.
Three, Full Analysis of EMC Processing Techniques
Maintain reasonable spacing
When laying out multiple micro coaxial cables, it is best to maintain a spacing of at least twice the cable diameter to reduce electromagnetic coupling. If space is limited, you can use interleaved wiring or layered routing to reduce the risk of crosstalk.
Strengthen overall shielding of the harness
Add an overall woven shielding layer to the side-by-side cables and ensure reliable connection with the device housing or grounding plane, forming a 360°all-around shielding structure. This measure can effectively suppress electromagnetic leakage and significantly reduce radiation interference.
Optimize grounding design
The shielding layer of a micro coaxial cable should adopt a single-point grounding or low-impedance multi-point grounding method to avoid the generation of common-mode interference due to ground loops.
Reasonably arrange the signal line order
Wiring can be followed by the following strategies:
High-frequency sensitive signals (such as MIPI Clock) should be routed on separate lines.
High-frequency lines and low-frequency lines are arranged in sections;
Avoid crossing, twisting, and excessively long parallel paths.
⑤ Use EMC absorbing material
For areas with strong radiation or high test sensitivity, EMI absorber can be attached to the outer layer to achieve local suppression of electromagnetic leakage and improve the pass rate of EMC testing.
In the parallel application of multiple micro coaxial cables, EMC design is crucial. By maintaining a reasonable spacing, optimizing the shielding structure, scientifically grounding, reasonably arranging the wiring order, and using absorbent materials as assistance, the risk of crosstalk and radiation can be effectively reduced, ensuring the stability and reliability of the product in a high-speed transmission environment.
We have been focusing on the design and customization of high-speed cable harnesses and ultra-thin coaxial cable harnesses for a long time, committed to providing stable and reliable high-speed interconnection solutions. If you have any related needs or want to learn more, please contact: Manager Zhang.
18913228573 (WeChat number)。
