3 Tips for RF PCB Layout

3 Tips for RF PCB Layout

Because the radio frequency (RF) circuit is a distributed parameter circuit, skin effect and coupling effect are prone to occur in the actual work of the circuit, so in the actual PCB design, it will be found that the interference radiation in the circuit is difficult to control, Such as: mutual interference between digital circuit and analog circuit, noise interference of power supply, interference caused by unreasonable ground wire, etc. Because of this, how to weigh the pros and cons in the PCB design process to find a suitable compromise, to reduce these interferences as much as possible, and even to avoid the interference of some circuits, is the key to the success or failure of the RF PCB design. From the perspective of PCB LAYOUT, this article provides some processing skills, which are of great use to improving the anti-interference ability of radio frequency circuits.To get more news about Cavity PCB, you can visit pcbmake official website.

1.RF layout

What we discussed here is the layout of the components of the multilayer board. The key to the layout of components is to fix the components on the RF path. By adjusting its direction, the length of the RF path is minimized, and the input is far away from the output, and the high-power circuit and the low-power circuit are separated as far as possible. The signal is far away from high-speed digital signals and RF signals.

1.1 One-line layout

The components of the RF main signal are arranged in a straight line as much as possible, as shown in Figure 1. However, due to the limitation of PCB board and cavity space, it cannot be laid out in a straight shape in many cases. At this time, L-shaped layout can be used. It’d be better not to use U-shaped layout (as shown in Figure 2). When it is unavoidable, it’d be better to increase the distance between input and output to at least 1.5cm. In addition, when using an L-shaped or U-shaped layout, the turning point should not turn as soon as it enters the interface, as shown on the left in Figure 3, but after a slight straight line, as shown on the right in Figure The feed inductance of the bias circuit is placed perpendicular to the RF channel, as shown in Figure 6, mainly to avoid mutual inductance between inductive devices. In order to use the space reasonably, the devices can be arranged in a 45-degree direction to make the RF line as short as possible, as shown in Figure 7. 2.RF Routing

The overall requirements for wiring are: RF signal traces are short and straight, reduce line abrupt changes, drill fewer holes, and do not intersect with other signal lines, and add as many ground vias as possible around the RF signal line.