The earlier the signal integrity (SI) problem is solved, the higher the efficiency of the design, which can avoid adding termination devices only after the circuit board design is completed. There are many tools and resources available for SI design planning. This article explores the core issues of signal integrity and several methods to solve SI problems, ignoring the technical details of the design process.

　　With the increase of IC output switching speed, almost all designs have encountered signal integrity issues regardless of the signal cycle. Even if you haven't encountered SI issues in the past, as the working frequency of the circuit increases, you will definitely encounter signal integrity issues in the future.

　　The signal integrity problem mainly refers to the phenomenon of signal overshoot and damping oscillation, which are mainly functions of IC driving amplitude and jump time. That is to say, even if the wiring topology remains unchanged, as long as the chip speed becomes fast enough, the existing design will still be in a critical state or stop working. The circuit board sampling manufacturer uses two examples to illustrate that signal integrity design is inevitable.

　　In the field of communication, cutting-edge telecommunications companies are producing high-speed circuit boards (above 500MHz) for voice and data exchange. At this time, cost is not particularly important, so multi-layer boards can be used as much as possible. The PCB prototype manufacturer tells you that such a circuit board can achieve sufficient grounding and easily form a power circuit. It can also use a large number of discrete termination devices as needed, but the design must be correct and cannot be in a critical state.