![]() ![]() High-speed traces that are too close together may inadvertently couple with one signal overpowering the other. Unintentional Electromagnetic Coupling (Crosstalk) If the return path is blocked in any way, the signal will radiate even more noise as it seeks a path back to its source. Another source of EMI is the signal return path, which optimally should be on an adjacent reference plane. Not only can the length and configuration of the traces be a problem, but trace and via stubs can act as an antenna as well. ![]() High-frequency signals can radiate EMI if care isn’t taken with how they are routed on the circuit board. Here are four main areas of poor signal integrity that you should be aware of. Signal integrity fundamentals are critical to the success of circuit boards like thisĪ signal on a circuit board can have its quality degraded due to a number of different effects, and these can be categorized into different groups. The Signal Integrity Fundamentals to Be Aware Of Before we look at how to design for these problems, let's first take a look at some critical signal integrity fundamentals. Additionally, the circuit board must be designed so that it doesn’t create signal integrity problems for its own circuitry or nearby electronics. If the circuit board is not specifically laid out to counter these problems, the signal degradation may continue until it no longer works as designed. These can include signal reflections due to impedance mismatches, ground bounce, and crosstalk. All of these issues can often be traced back to signal integrity problems.Īs signal speeds increase in our electronics, they are more susceptible to a variety of aggressive interferences. However, the majority of problems caused by poor signal integrity are usually more subtle than that-there might be the occasional glitch in performance, data might get dropped, or the device may even fail to operate in extreme cases. Some older computers even radiated so much EMI that they were eventually taken off the market. For years, flight attendants urged us to shut down our cell phones or we were annoyed with radios that produced static instead of clear audio. The effects of interference on the operation of electronic devices can be pretty dramatic. Potential Problems Due to Poor Signal Integrity To successfully design high-speed electronics, it is essential for the designer to understand signal integrity fundamentals. This involves every aspect of PCB design, including the parts used, the fabrication of the raw circuit board, and how the parts are arranged and connected together. To prevent these disruptions and failures, printed circuit boards need to be placed and routed according to specific design criteria to foster the best environment for transmitting high-speed signals. ![]() This can result in all kinds of problems in the electronics we design, from intermittent disruptions to outright failures. However, signals that are degraded, or have poor signal integrity, may not accomplish their intended purpose. ![]() We trust those signals to do the job that they were designed to do. This is why integrity is also used to define the quality of a high-speed electrical signal in modern electronic devices and systems. One of the defining characteristics of integrity is a consistent and uncompromising behavior that can be trusted. Layout tools and features that can help improve signal integrity PCB layout techniques for good signal integrity ![]()
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