In recent years, due to the rapid growth of the market for Bluetooth devices, wearable devices, wireless local area network devices and mobile devices, the demand for RF circuits is also increasing. Especially in the coming years, the Internet of Things will be put into use, and the RF circuit market will become more It is a rapid increase. However, the design of RF circuits, like electromagnetic interference, has always been the most difficult problem for engineers. If you want to successfully design a good RF circuit, you must carefully plan each step and detail of the entire design process and strive for stability. The design of the RF circuit and the design of an ordinary pcb are different in theory. First of all, there are uncertainties in RF circuits, but this does not prevent us from designing a good RF circuit. In fact, there are still many rules and techniques that can be used in the design of RF circuits. However, in the actual process, these rules and techniques may not be used due to certain limitations. Therefore, how to deal with this problem has become an important problem in the RF design curriculum. Radio circuit wiring is a key element in the development of wireless products. It may have been perfect in the design of the principle, but in reality there will always be some problems to limit the performance of this circuit. The actual test can not reach the ideal state. Many of these problems are caused by insufficient completion in the wiring process. Here we cut into the issue of wiring, to explain some of the tricks that need attention in the design of RF circuits. PCB structure First of all, before wiring, we must determine the structure of the circuit board. Just like building a house, we must first plan the number of layers of the house. The structure of the battery board is related to the complexity of the circuit design, electromagnetic compatibility and many other factors. In the actual production design, there will be no single-layer board, so we will use the following multilayer board as an example. For example, a four-layer board usually uses the second layer as a complete ground plane during design, and distributes important signals in the top layer. In this way, the impedance can be well controlled. In the design of the six-layer board and more boards, as in the design of the four-layer board, a complete ground plane is required, and then the signal is traced using the top layer. Control impedance In the wiring process, it is necessary to pay attention to the control impedance. For example, the characteristics of the trace should be controlled to be 50Ω as far as possible. The resistance is related to the line width. When performing the principle design and simulation, the formula should be used to calculate the characteristic impedance at 50Ω. Up and down, meet the requirements can be designed as a radio frequency alignment. Component placement In pcb design, we generally follow a rule that the traces are as short as possible, that is, the components are generally close to the power supply, and the corresponding components are closely arranged. This not only ensures that the pcb is beautiful, but also shortens the length of the wiring. In the design of the RF circuit, we should also follow this design rule. RF alignment In addition to the lengths mentioned above, the lengths should be kept as short as possible. One difference from the normal pcb design is that the RF circuit traces should use arcs to implement the corners instead of the usual 45°/135°. corner. Because RF signal lines cannot have any breakpoints. If the RF signal lines inevitably cross in the actual process, then it is necessary to use vias to guide a portion of the signals for transmission. Regardless of which layer is the bottom layer or the middle layer, the video cables are all routed. There must be a reference plane. However, it must be noted that the ground plane must be continuous. Copper Lugs,Copper Cable Lugs,Plating Copper Cable Lugs,Copper Tube Terminal Lugs Taixing Longyi Terminals Co.,Ltd. , https://www.longyicopperlugs.com
