According to the different manifestations and causes of power supply noise interference analyzed above, the conditions under which it occurs can be targeted, and the interference of power supply noise can be effectively suppressed. The solutions are:
Pay attention to the through holes on the board. The vias require etched openings in the power supply layer to make room for the vias to pass through. If the opening of the power layer is too large, it will inevitably affect the signal loop, the signal will be forced to detour, the loop area will increase, and the noise will increase. At the same time, if some signal lines are concentrated near the opening and share this section of the loop, the common impedance will cause crosstalk.
The connecting wire needs enough ground wires. Each signal needs to have its own dedicated signal loop, and the loop area of the signal and the loop should be as small as possible, that is, the signal and the loop should be parallel.
Place a power supply noise filter. It can effectively suppress the noise inside the power supply and improve the anti-interference and safety of the system. And it is a two-way radio frequency filter, which can not only filter out the noise interference introduced from the power line (to prevent the interference of other devices), but also filter out the noise generated by itself (to avoid interfering with other devices), and interfere with the series mode and common mode. both inhibited.
Power regulator. Regaining a cleaner power supply can greatly reduce the noise level of the power supply.
Wiring. The input and output lines of the power supply should not be placed on the edge of the dielectric board, otherwise radiation will easily occur and interfere with other circuits or devices.
The analog and digital power supplies should be separated. High-frequency devices are generally very sensitive to digital noise, so the two should be separated and connected together at the inlet of the power supply. If the signal is to span the analog and digital parts, a loop can be placed where the signal crosses to reduce the loop area.
Avoid separate power supplies overlapping between different layers. Try to stagger them, otherwise the power supply noise can easily couple through the parasitic capacitance.
Isolate sensitive components. Some components such as phase-locked loops (PLLs) are very sensitive to power supply noise and should be kept as far away from the power supply as possible.
Place the power cord. To reduce signal loops, noise reduction can be achieved by placing power lines next to signal lines.
In order to prevent the interference of power supply noise to the circuit board and the accumulated noise caused by external interference to the power supply, a bypass capacitor can be connected to ground in parallel on the interference path (except radiation), so that the noise can be bypassed to the ground to avoid interfere with other equipment and devices.
In conclusion:
Power supply noise is directly or indirectly generated from the power supply and interferes with the circuit. When suppressing its influence on the circuit, a general principle should be followed, that is: on the one hand, it is necessary to prevent the power supply noise as much as possible. The influence of the circuit, on the other hand, should also minimize the influence of the outside world or the circuit on the power supply, so as not to deteriorate the noise of the power supply.