How to reduce the digital signal--China PCB Assembly
How to reduce the digital signal and the interference between the simulated signal it? Must be aware of before in the design of electromagnetic compatibility (EMC) of the two basic principles :The first principle is to minimize the current loop area; second principle is that the system using only a reference surface. On the contrary,PCB Assebly if the system there are two reference surface, it is possible to form a dipole antenna (Note: small dipole antenna size and the length of radiation, flow is proportional to the current size and frequency); and if the signals can not be as much as possible small loop back, it may form a large loop antenna (Note ︰ small circular loop antenna the size of the radiation area, the current flowing through the loop is proportional to the size and frequency). PCBA manufacturer In the design as possible to avoid both.
It was suggested that the number of mixed-signal circuit boards to separate land and simulation, this can be achieved between the digital and simulation in isolation. Although this method is feasible, but there are many potential problems in PCBA manufacturer large complex systems problem is particularly prominent. The most critical problems can not be split across the routing space, once divided over the routing space, electromagnetic radiation and crosstalk will increase dramatically. PCB design in the most common problem is the signal or power lines across the division to EMI problems arise.
We use the segmentation method, and the signal line across the gap between the two places, the signal current return path is Shiyao it? Assumed to be split in two connected together somewhere (usually in a position single-point connection),PCB Assembly in this case, the ground current will form a large loop. High-frequency current flowing through the large loop will produce radiation and high ground inductance is too large if the flow is low loop simulation of current, which is vulnerable to external signal interference. The worst is when the split in the power supply when connected together, will form a very large current loop. In addition, simulation and digital ground together through a long wire dipole antenna would constitute.
Understand the current return path to ground and means to optimize the design of mixed-signal circuit board crucial. Many designers only consider flow from where the signal current, while ignoring the current specific path. If the ground plane must be split and must be separated by the gap between the wiring, it can first be divided in to a single point of connection between the form to the connection between the two bridges, and then through the connecting bridge wiring. Thus, in the bottom of each signal line can provide a direct current return path, so that the formation of the loop area is very small.