Techniques for high speed (>100MHz) high density PCB design
In designing high-speed, high-density PCB, crosstalk (crosstalk, interference) is really a special consideration because it has a major impact on timing (timing) and signal integrity (signal integrity). Here are a few points to note:
The size of the line spacing. The distance usually seen is two times the line width. Simulation can be used to know the influence of line spacing on timing and signal integrity, and the minimum tolerable spacing is found. Different chip signals may have different results.
Select the proper termination mode.
Avoid moving up and down the two adjacent lines in the same direction, and even the line just up and down overlap, because this crosstalk than the same layer adjacent to the line is still larger.
Use blind via (blind/buried) to increase the line area. But the cost of making PCB boards increases. In practice, it is difficult to achieve full parallel and equal length, but try to do as much as possible.
In addition, differential termination and common mode termination can be reserved to mitigate the impact on timing and signal integrity.