A printed circuit board (PCB) helps in the support and connection of electrical components. The design of a PCB becomes more complex as its pin density and frequency increase. A successful PCB design should follow some rules. For instance, the design should cut down the PCB's system noise and minimize its crosstalk.
Cutting Down on Crosstalk
Crosstalk results when there is a coupling of signals between parallel traces. PCB design that uses proper routing techniques and stacks up layers can help minimize this crosstalk. Layer stack up can be done using the proper layout, and by increasing the distance between the signal layers. Also, it is important to make sure that the signals have good-quality return paths and signal traces are spread out. Although there has been some progress in this direction, in general it is difficult to simulate crosstalk.
Signal Routing
Proper signal routing is another fundamental high-speed PCB design rule. Signal routing could be single-ended trace routing, which connects the source and the receiver. This sort of routing is used in routing that is not critical. Star routing is one method of signal routing in which the clock signal goes to all devices at the same time. In order to reduce any distortion, the path between the clock source and the devices should be matched. The loads should be similar in order to cut down on signal integrity issues. Differential signal routing is another routing technique.
Pre-Emphasis
Pre-emphasis is a technique that helps compensate for what is known as the "skin effect." Transmission media such as copper trace and coaxial cable tend to emphasize higher frequencies more than lower frequencies. The high-frequency current that flows on the surface of a conductor causes resistance to increase. If you apply the correct amount of pre-emphasis to a signal, it will have minimum distortion.
