1. The wiring between two adjacent layers must adhere to the principle of vertical wiring; otherwise, it will lead to crosstalk between the lines and increase EMI radiation. In summary, adjacent wiring layers should follow horizontal and vertical wiring directions, with vertical wiring helping to mitigate crosstalk between lines.
2. **Rule 6: Topological Structure Rules in High-Speed PCB Design**
In high-speed PCB design, controlling the characteristic impedance of the circuit board and designing the topological structure under multi-load conditions directly impact the product’s success or failure. The figure illustrates a daisy-chain topology, which is generally effective at lower frequencies, such as a few MHz. For high-speed PCB design, it is recommended to use a star-shaped symmetrical structure on the backend.
3. **Rule 7: Resonance Rule for Trace Length**
Verify whether the length of the signal line and the frequency of the signal create resonance, meaning when the length of the trace is an integer multiple of one-quarter of the signal wavelength, resonance occurs. This resonance will emit electromagnetic waves and cause interference.
4. **Rule 8: Return Path Rules**
All high-speed signals must have a reliable return path. Ensure that the return path for high-speed signals, such as clocks, is as short as possible. Otherwise, it will significantly increase radiation, with the radiation level being proportional to the area enclosed by the signal path and the return path.
5. **Rule 9: Decoupling Capacitor Placement Rules for Devices**
Proper placement of decoupling capacitors is crucial. Incorrect placement will negate their decoupling effect. The principle is to position them close to the power supply pins and minimize the area enclosed by the power traces and ground connections of the capacitor.