High-frequency PCB circuit design is a very complicated design process, and its wiring is crucial to the entire design! So, what are the high-frequency PCB circuit wiring methods?
1. Multilayer board wiring
In the PCBLayout stage, reasonably select the size of the printed board with a certain number of layers, make full use of the middle layer to set the shielding, better achieve the nearest grounding, and effectively reduce the parasitic inductance and the transmission length of the sink short signal. Reduce signal cross-interference etc.
2. The less the lead wires between the pins of electronic devices are bent, the better
It is best to use a straight line for the lead wires. If a turning is required, a 45-degree folding line or an arc turning can be used. Meeting this requirement can reduce the external emission and mutual coupling of high-frequency signals.
3. The shorter the leads between the device pins, the more
The radiation intensity of the signal is proportional to the length of the signal line. The longer the high-frequency signal lead, the easier it is to couple to the components close to it.
4. The less the alternation between the lead layers between the device pins, the better
It means that the fewer vias (Via) used in the component connection process, the better. Reducing the number of vias can significantly increase the speed and reduce the possibility of data errors.
5. Pay attention to the "crosstalk" introduced by the close parallel routing of signal lines
Since the high-frequency signal is transmitted along the transmission line in the form of electromagnetic waves, the signal line will act as an antenna, and the energy stars of the electromagnetic field will be
emitted around the transmission line, and the undesired noise generated between the signals due to the mutual coupling of the electromagnetic field The signal is called crosstalk.
6. Add a high-frequency decoupling capacitor to the power pin|pin
A high-frequency decoupling capacitor is added nearby to the power supply pin of each integrated circuit block, which can effectively suppress the interference caused by high-frequency harmonics on the power supply pin.
7. The high-frequency digital signal ground wire and the analo signal ground wire are isolated
Usually, the ground wire of the high-frequency digital signal and the ground wire of the analo signal need to be isolated, and the method of single-point interconnection at a suitable position can be adopted, or the method of interconnection of high-frequency choke magnetic beads can be used.
8. Avoid loops formed by wiring
All kinds of high-frequency signal traces should try not to form a loop. If it cannot be avoided, the loop area should be kept as small as possible.
9. Ensure good signal impedance matching
During the transmission of the signal, when the impedance does not match, the signal will be reflected in the transmission channel, and the reflection will cause the composite signal to form an overshoot, causing the signal to fluctuate near the logic threshold.
10. Maintain the integrity of signal transmission
Maintain the integrity of signal transmission and prevent the "single ground phenomenon" caused by ground wire segmentation.
