Modern digital circuits can be up to GHz and rise time is within 50ps. At such a rate, the negligence on the PCB design trace is even one foot, and the resulting voltage, delay and interface problems will not only be limited to this line, but will also affect the entire board and Adjacent boards.
Radiated EMI interference can come from an undirected source and an unintentional antenna. Conductive EMI interference can also come from a source of radiated EMI interference or caused by some board components. Once your board receives conductive interference, it resides in the PCB trace of the application circuit. Some common sources of radiated EMI interference include the components discussed in previous articles, as well as on-board switching power supplies, cables and switches, or clock networks.
How to define differential pairs in the schematic
Many people think that the work of PCB Layout is very boring. Every day, thousands of wires are routed to the board, and various packages are repeated, and the work of pulling the wires is repeated. However, designers must make trade-offs between various design rules, taking into account performance, cost, process and other aspects, but also notice that the layout of the board is neat and tidy, not as simple as it seems, and requires more wisdom. Let's talk about developing some good work habits during design, which will make your design more reasonable, easier to produce, and better.
The main parasitic components generated by board layout are resistors, capacitors, and inductors. When switching from a circuit diagram to an actual board, all parasitic components have a chance to interfere with circuit performance. When a system mixes digital and analog components, careful routing is key to the success of the board. In particular, digital traces that are often close to high-impedance analog traces will cause severe coupling noise, which can only be avoided by keeping the two traces at a distance. This article quantifies the toughest board parasitic components, board capacitors, and lists the performance examples that can be clearly seen on the board.