RF circuits have become important parts in modern communication. And PCB design skills are the premise for RF circuit design. The RF circuit PCB design skills are as follows:
1. The selection of PCB materials
The selection of PCB materials can directly affect the performance and stability of RF circuits. Common PCB materials include FR4，PTFE and so on. FR4 is mainly composed of glass fibers and phenolic resins, and is less expensive than other materials, but the dielectric constant of FR4 is unstable, which can easily lead to signal attenuation in RF circuits. PTFE is a material with good dielectric properties, and its dielectric constant is more stable than FR4, and the signal in the RF circuit is more intact. Therefore, in the PCB design process of RF circuit, we should give preference to PTFE material.
2. Layout of the ground power plane and the power plane
In PCB layout, the layout of ground power plane and power plane is key, and has a great influence on the performance of RF circuits. In the process of layout, we should try to evenly distribute the ground power plane and the power plane on the entire PCB board to avoid that the ground power plane or the power plane is broken or overlapped. During RF circuit PCB design, we should follow the following layout principles:
3. The wiring in RF circuits
Wiring design is key during RF circuit PCB design. For low frequency circuit, signal transmission distance is relatively short, there are not very high demands for wire width and spacing. For RF circuits, more strict requirements for wiring design are necessary due to the transmission features of high frequency signals. The wiring design principles for RF circuits are as the following:
1) Make sure that the length of the wiring is as short as possible and that the impedance is well matched.
2) The wiring width and spacing are reasonably set to ensure reliable transmission of signal.
3) The wiring layers should be reasonably set to ensure signal transmission security.
4. The method of ensuring signal integrity in RF circuits
In RF circuits, in order to ensure the integrity of the signal, we need to reduce the attenuation and distortion of the signal through some methods. Here are some methods:
1) Ground power plane and the power plane can be laid to decrease interference and attenuation of signals.
2) A reasonable layout of RF circuits should be ensured, and too long and narrow wires and too many corners should be avoided.
3) The signals from different sections should be separated to decrease interference of signals.
4) Attenuators and filters are added to enhance the stability of the signal and to reduce the noise and clutter of the signals.
Summary:
PCB designs in RF circuits are very important, and reasonable PCB designs in RF circuits can improve the performance and security of the RF circuits. The selection of PCB materials, the layout of the ground power plane and the power plane, wiring designs and the method of ensuring signal integrity should be fully considered during PCB designs in RF circuits.
