To simultaneously reduce the impedance and crosstalk of the PCB, the following methods can be considered:
Choosing the appropriate PCB material: Select a PCB material with a lower dielectric constant to reduce the impedance of the transmission line.
Optimizing the wiring: Reasonably set the wiring layer and the wiring spacing, reduce the length of parallel signals, shorten the spacing between the signal layer and the planar layer, increase the spacing between signal lines, and reduce the length of parallel signal lines (within the key length range). These measures can effectively reduce crosstalk.
Adopting shielding measures: Provide grounding enclosure for high-speed signals, but it should be noted that the grounding shielding may lead to an increase in the amount of wiring, making the originally limited wiring area more crowded, and at the same time, it will also increase the distributed capacitance of the signal, increase the impedance of the transmission line, and slow down the signal edge.
Conducting impedance matching: If the impedance at the near-end or far-end terminal of the transmission line matches the impedance of the transmission line, the amplitude of crosstalk can also be greatly reduced.
Setting different wiring layers: Setting different wiring layers for signals of different rates and reasonably setting the planar layer is also a good way to solve crosstalk.
Reducing the rate of change of the signal edge: When selecting devices, try to choose slow devices and avoid the mixed use of different types of signals, because the fast-transforming signal has a potential crosstalk hazard to the slow-transforming signal.
Adding termination matching: Under the condition that the high-speed signal line meets the requirements, adding termination matching can reduce or eliminate reflection, thereby reducing crosstalk.
Limiting the trace height: For microstrip transmission lines and stripline transmission lines, limiting the trace height within the required range above the ground plane can significantly reduce crosstalk.
Inserting a ground wire: Under the condition that the wiring space allows, inserting a ground wire between two lines with more severe crosstalk can play an isolation role, thereby reducing crosstalk.