What is signal integrity ? Many people may still feel that this term is unfamiliar, especially for engineers who have not been exposed to the so-called high-speed PCB. Dr. Yu will give you an intuitive explanation.
When we measure the signal on the PCB with an oscilloscope, we often find some strange phenomena on the waveform of the signal: for example, a large spike will be generated after the signal jumps, and there may be ups and downs after the spike. Sometimes there is a plateau on the edge of the signal, kind of like a human shoulder. Sometimes you may encounter that the edge of the signal is not rising smoothly, there will be a return groove, and it will suddenly fall down in the middle of the rise and then continue to rise. Think back, have you ever been in a similar situation? These phenomena are typical of signal integrity problems.
The term signal integrity does not have a unique normative definition. It usually refers to a phenomenon in which signals are distorted due to the interaction of signals, interconnect structures, power systems, and other factors in high-speed PCBs. At this time, it can be said that the signal is damaged during transmission and becomes incomplete.
The distortion of the signal waveform may cause the receiving end to fail to receive the signal correctly, thus causing the circuit to fail to work properly. Just imagine, when receiving a signal, there needs to be an edge to sample to judge whether it is 0 or 1, but this is because if the signal is distorted, the originally high-level waveform does drop to the high-level threshold, it may be mistakenly judged as 0, a receive error occurred.
Signal integrity issues must be paid enough attention to by hardware engineers. Sometimes there may be only a few MHz signal rate, and the product will fail frequently due to signal integrity issues. When many people find a problem with the PCB during debugging, they start to debug aimlessly, change this, move that, when it happens that the PCB can barely work, and finally breathe a sigh of relief. Often the people who do it are exhausted and very miserable. In fact, as long as you have a little knowledge of signal integrity, you can completely avoid all the pain and torture when debugging a PCB.
Have you started to pay attention to the signal integrity problem on the PCB? In order to reduce the design and debugging pressure of hardware engineers, Dr. Yu is working hard to popularize the signal integrity design method to help enterprises reduce the number of boards and debugging time.