A Comprehensive Analysis of Multi-lane MIPI Signal Interference: How to Improve Transmission Stability with Extremely Thin Coaxial Cables

In high-speed interface design, the simultaneous transmission of multi-lane MIPI signals is often required, which is very common in smartphone camera modules, AR/VR display modules, and industrial camera systems. However, as the number of channels increases, issues such as crosstalk, EMI (electromagnetic interference), and impedance discontinuity will be significantly amplified, ultimately leading to noise in the image, reduced resolution, and even unstable operation of the link. So, how can engineers effectively deal with these challenges?

Optimize wiring and topology structure
In an early project, we encountered a typical crosstalk problem: multiple MIPI signals were routed in parallel on the PCB, resulting in severely distorted waveforms. Later, by increasing the routing spacing, adjusting the layer structure, and avoiding excessively long parallel routing, the problem was significantly improved. Especially, maintaining consistent differential pair spacing was very significant for improving signal integrity. This experience also indicates that in MIPI high-speed design, a reasonable routing topology is often the first line of defense.

Two, Introducing Shielding and Ultra-Fine Coaxial Cable
Relying solely on PCB optimization is sometimes not enough, especially in the connection parts between modules and mainboards. We have tried using extremely thin coaxial cables (Micro Coaxial Cable) for signal transmission, whose shielding layer can not only effectively reduce cross-talk between channels but also significantly enhance the ability to resist external EMI. This solution is quite mature in multi-channel MIPI camera modules.
In addition, shielding structure and grounding design are equally critical. In practice, we have found that adopting a multi-point grounding strategy can effectively cut off interference paths and prevent "cross-talking" phenomena between different channels.

Three, Impedance Control and Interface Matching
The MIPI interface has very strict requirements for impedance matching. In a long-distance transmission test we once conducted, serious signal reflection was found due to the mismatch between the connector and cable impedance. Subsequently, we switched to I-PEX connectors with more precise impedance matching and added matching resistors at the driver end, and only then was signal integrity restored. For longer distance applications, retimers or equalization chips can be introduced for compensation to further stabilize the transmission performance.

Comprehensive design from a systemic perspective
Multi-lane MIPI signal interference issues are often not caused by a single factor but rather the result of systematic coupling. During the design phase, several key aspects should be considered comprehensively:
4.1 Interface Standard and Protocol Selection
4.2 PCB routing rules and impedance control
4.3 Reasonable Applications of Ultra-fine Coaxial Cable (Micro Coax)
4.4 Shielding Layer and Grounding Design
Matching degree between connector and circuit.
Only by systematically integrating these links can the stable and reliable transmission of high-speed signals truly be achieved.

The handling of multi-lane MIPI signal interference not only tests the ability of circuit design but also the level of system architecture. From wiring, shielding to interface selection, every detail may determine the final image quality and stability. Practice has proven that introducing ultra-fine coaxial cables and other high-performance cable solutions often plays a decisive role in key stages.
I amSuzhou Huichengyuan ElectronicsFocusing on the research and development, as well as customization, of high-speed signal cable harnesses and ultra-thin coaxial cable harnesses, we are committed to providing customers with high-stability and high-reliability high-speed interconnection solutions. If you are looking for a better signal cable harness solution, please feel free to contact us:Manager Yin 18913280527 (WeChat number same)。