High-speed PCB design and routing method to solve signal crosstalk

1. The unwanted noise voltage signal generated by the interaction of electromagnetic fields between signals is called signal crosstalk. Crosstalk beyond a certain value may lead to misaction and cause the system to fail to work properly. Next, PCB design company Electronics shares the method of high-speed PCB design and wiring to solve signal crosstalk.When possible, reduce the conversion rate of the signal along the device, usually in the device, while meeting the design specification, try to choose a slow device, and avoid the mixed use of different kinds of signals, because the fast conversion signal has potential crosstalk danger to the slow transformation signal.

2. Adopt shielding measuresProviding packet ground for high speed signal is an effective way to solve crosstalk problem. However, covering the ground can lead to an increase in the amount of wiring, making the already limited wiring area more crowded. In addition, to achieve the desired purpose of ground shielding, the ground point spacing on the ground is critical, generally less than twice the length of the signal change along the length. At the same time, the ground wire will also increase the distribution of the signal, so that the transmission line impedance is increased, and the signal is slowed down.

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3. Reasonable setting of layers and wiring

Reasonable setting of wiring layer and wiring spacing, reducing parallel signal length, shortening the distance between signal layer and plane layer, increasing signal line spacing, reducing parallel signal line length (within the critical length range), these measures can effectively reduce crosstalk. Four, set up different wiring layers

It is also a good way to solve crosstalk by setting different wiring layers for signals of different rates and setting plane layers reasonably.

4. Impedance matching

If the impedance of the near or far end of the transmission line matches the impedance of the transmission line, the magnitude of the crosstalk can also be greatly reduced.

The purpose of crosstalk analysis is to quickly find, locate and solve crosstalk problems in PCB implementation. General simulation tools and the environment in the simulation analysis and PCB wiring environment are independent of each other, after the end of the wiring crosstalk analysis, get the crosstalk analysis report, deduce the new wiring rules and rewiring, and then analysis and correction, so that the design is more repeated.

Through the simulation analysis, we can see that the actual crosstalk results are different, and the difference is large. Therefore, a good tool should not only be able to analyze crosstalk, but also be able to apply crosstalk rules for wiring. In addition, the general wiring tool is limited to physical rule drive, the control of crosstalk wiring can only be restricted by setting line width and line spacing, as well as the maximum parallel line length and other physical rules. The signal integrity analysis and design tool set ICX can support the real sense of electrical rules-driven wiring, and its simulation analysis and wiring are completed in one environment. During the simulation, electrical rules and physical rules can be set, and signal integrity elements such as overshot and crosstalk can be automatically calculated while wiring, and the wiring can be automatically corrected according to the calculation results. This wiring speed is fast, and it really meets the actual electrical performance requirements.