If you find that the design experience accumulated in the previous low-speed era does not seem to work now, the same design, no problem before, but now can not work, then congratulations, you have encountered the core problem in hardware design: signal integrity . It is a good thing for you to meet one day earlier. In the past low-speed era, the signal rise time is longer when the level jumps, usually a few ns. Interconnects between devices do not affect the functionality of the circuit, and there is no need to care about signal integrity issues. But in today's high-speed era, with the increase in IC output switching speed, many are in the picosecond level, and almost all designs have encountered signal integrity problems regardless of the signal period. In addition, the pursuit of low power makes the core voltage lower and lower, 1.2v core voltage is already very common. Therefore, the noise margin that the system can tolerate is getting smaller and smaller, which makes the signal integrity problem more prominent.
Many signal integrity problems are caused by short signal rise time. This article talks about a basic concept: the relationship between signal rise time and signal bandwidth.
Via is one of the important components of a multi-layer PCB. The cost of drilling is usually 30% to 40% of the cost of PCB board. Simply put, each hole in the PCB can be called a via. From the perspective of function, the vias can be divided into two categories:
1. Printed circuit board size and device layout. 2. Decoupling capacitor configuration. 3. The heat dissipation design. 4. Electromagnetic compatibility design. 5. Ground wire design.
The design of the high-frequency circuit PCB is a complicated process, and many factors involved may directly affect the performance of the high-frequency circuit. Therefore, designers need to continuously research and explore in the actual work, accumulate experience, and combine the new EDA (Electronic Design Automation) technology to design high-performance circuit PCB with excellent performance.