PCB Technical - RF circuit board routing

How much do you know about the routing of RF circuit boards? Let ipcb take everyone to learn about the RF circuit board routing of Shenzhen circuit board manufacturers today!

In the design of RF circuits, the circuit is usually composed of devices and microstrip lines. The signal trace on the radio frequency circuit board is in the form of a microstrip line, which may have a greater impact on circuit performance than capacitance, inductance, or resistance. Careful handling of wiring is a guarantee for the success of RF circuit design.

For the design of the microstrip line, please refer to the relevant information. In (RF circuit board) PCB circuit board design, 1/4 wavelength is a very important parameter. For RF signals, traces exceeding 1/4 wavelength may change from a short-circuit state to an open-circuit state, or change from zero impedance to infinite impedance. When designing the PCB circuit board, the trace should be kept as short as possible, that is, if the length of the trace is equivalent to or greater than 1/4 wavelength, the trace must be used as a component during circuit simulation. treat.

When designing the RF circuit board, it is required that the traces be as short as possible, as shown in Figure 12-60. The wiring in Figure 12-60(a) is artificially elongated, which is not a good design.

When designing RF circuit boards,ipcb require the corners of the traces to be as smooth as possible. At the corner of the RF PCB,

Especially the sharp turning angle will produce singular points in the electromagnetic field and generate considerable radiation. In the example shown in Figure 12-61, the corner form of Figure (a) is better than Figure (b) and Figure (c) because Figure (a) is smooth and is the shortest connecting line.

When designing the radio frequency circuit board, it is required to draw adjacent traces as perpendicular to each other as much as possible, and avoid parallel traces as much as possible. If two adjacent traces cannot be avoided, the spacing between the two traces must be at least 3 times the width of the trace, so that crosstalk can be reduced to an allowable degree. If the two adjacent traces transmit DC voltage or DC current, this issue may not be considered.

When designing a radio frequency circuit board, not only the corner requirement of the trace is important, but the smooth requirement of the entire trace is also very important. Shenzhen high-frequency board manufacturers have been strictly following their design requirements. As shown in Figure 12-62(a), there is a sudden change in the width of the trace from A to B (point P). The characteristic impedance of the microstrip line mainly depends on its width. The characteristic impedance of point P will jump from Z1 to Z2. Therefore, the trace actually becomes an impedance converter. This additional jump in impedance may have catastrophic consequences for circuit performance: RF power may be reflected back and forth at point P. In addition, at point P, the RF signal will also radiate out, so the trace width is required to gradually change, as shown in Figure 12-62(b), that is, the impedance of the trace is required to change smoothly, so that the trace The additional reflection and radiation on the line are reduced.

How about it? After ipcb takes everyone to study together, do you have a certain understanding of the RF circuit board routing of high-frequency board production?