Precision PCB Fabrication, High-Frequency PCB, High-Speed PCB, Standard PCB, Multilayer PCB and PCB Assembly.
The most reliable PCB & PCBA custom service factory.
In the circuit board industry,high-frequency circuit boards are widely used, and high-frequency signals are the most widely used in the electronic communication industry. I believe everyone has heard of high-frequency circuit board wiring. Today I want to share the six major aspects of high-frequency circuit board wiring. Skills.
1. The shorter the lead between the pins of the high-frequency circuit board device, the better
The radiation intensity of the signal is proportional to the trace length of the signal line. The longer the high-frequency signal lead, the easier it is to couple to the components close to it. Therefore, for signals such as clock, crystal oscillator, DDR data, LVDS lines, USB lines, HDMI lines and other high-frequency signal lines are required to be as short as possible.
2, the less the lead bends between the pins of high-speed electronic devices, the better
The lead wire of the high-frequency circuit board wiring is best to adopt a full straight line, which needs to be turned. It can be turned by a 45-degree broken line or a circular arc. This requirement is only used to improve the fixing strength of the copper foil in the low-frequency circuit, while in the high-frequency circuit board, Satisfying this requirement can reduce the external emission and mutual coupling of high-frequency signals.
3. Isolate the ground wire of the high-frequency digital signal from the ground wire of the analog signal
When the analog ground wire, digital ground wire, etc. are connected to the public ground wire, use high-frequency choke magnetic beads to connect or directly isolate and select a suitable place for single-point interconnection. The ground potential of the ground wire of the high-frequency digital signal is generally inconsistent. There is often a certain voltage difference between the two directly. Moreover, the ground wire of the high-frequency digital signal often contains very rich harmonic components of the high-frequency signal. When the digital signal ground wire and the analog signal ground wire are directly connected, the harmonics of the high-frequency signal will interfere with the analog signal through the ground wire coupling. Therefore, under normal circumstances, the ground wire of the high-frequency digital signal and the ground wire of the analog signal are to be isolated, and a single-point interconnection method can be used at a suitable position, or a method of high-frequency choke magnetic bead interconnection can be used.
4, avoid loops formed by wiring
All kinds of high-frequency signal traces should not form a loop as much as possible. If it is unavoidable, the loop area should be as small as possible.
5, the less the lead layer alternate between the pins of the high-frequency circuit board device, the better
The so-called "the less the inter-layer alternation of the leads, the better" means that the fewer vias (Via) used in the component connection process, the better. A via can bring about 0.5pF distributed capacitance, reducing the number of vias can significantly increase the speed and reduce the possibility of data errors.
6. Add high-frequency decoupling capacitor to the power supply pin of the integrated circuit block
A high-frequency decoupling capacitor is added to the power supply pin of each integrated circuit block nearby. Increasing the high-frequency decoupling capacitor of the power supply pin can effectively suppress the interference caused by the high-frequency harmonics on the power supply pin.
