1) Pay attention to the through holes on the board. The via hole makes it necessary to etch the opening on the power layer in order to leave a space for the via hole to pass through. If the power layer is too large, it will inevitably affect the signal circuit, forcing the signal to bypass, increasing the circuit area and noise. At the same time, if some signal lines are concentrated near the opening and share this section of circuit, the common impedance will lead to crosstalk.
2) Place the power noise filter. It can effectively suppress the noise inside the power supply and improve the anti-interference and safety of the system. In addition, it is a bidirectional RF filter, which can not only filter out the noise interference introduced by the power line (to prevent interference from other devices), but also filter out the noise generated by itself (to avoid interference with other devices) and suppress the common-mode interference in serial mode.
3) Power isolation transformer. Separating the power supply loop or common-mode grounding loop of signal cable can effectively isolate the common-mode loop current generated by high frequency.
4) Power regulator. Getting a cleaner power supply again can greatly reduce power supply noise.
5) wiring. The input and output lines of power supply should not be arranged at the edge of dielectric plate, otherwise it is easy to generate radiation and interfere with other circuits or equipment.
6) Analog power supply and digital power supply should be separated. High-frequency equipment is usually very sensitive to digital noise, so it should be separated and connected together at the power supply entrance. If the signal crosses the analog and digital parts, a loop can be set at the intersection of the signals to reduce the loop area.
7) Avoid overlapping of independent power supplies between different layers. Try to stagger them, otherwise the power supply noise is easily coupled through parasitic capacitance.
8) Isolation of sensitive elements. Some components, such as phase locked loop (PLL), are very sensitive to power supply noise. They should be as far away from the power supply as possible.
9) Connecting wires need enough ground wires. Each signal needs its own dedicated signal loop, and the loop area of the signal and loop should be as small as possible, that is, the signal and loop should be parallel.
10) Place the power cord. In order to reduce the signal loop, noise can be reduced by putting the power line close to the signal line.
11) In order to prevent the power noise interference on the circuit board and the accumulated noise caused by external interference on the power supply, the bypass capacitor can be grounded on the interference path (except radiation) so as to bypass the noise to the ground and avoid interfering with other equipment and devices.
