In PCB design, grounding is an important measure to suppress noise and prevent interference. Depending on the circuit, there are different grounding methods. Only correct grounding can reduce or avoid mutual interference between circuits. So, what are the grounding methods of the PCB circuit?

1. Single point grounding

Single-point grounding is a system where only one physical point is defined as the grounding reference point, and every other point that needs to be grounded is connected to this point.

Single-point grounding is suitable for circuits with lower frequencies (below 1MHZ). If the operating frequency of the system is so high that the operating wavelength is comparable to the length of the system grounding lead, the single-point grounding method is problematic. When the length of the ground wire is close to 1/4 wavelength, it is like a transmission line with a short-circuit terminal. The current and voltage of the ground wire are distributed as standing waves, and the ground wire becomes a radiating antenna instead of playing the role of "ground". .

For the PCBs of digital circuits that are widely used, due to their rich high-order harmonics, it is generally not recommended to use a single-point grounding method.

2. Multi-point grounding

Multi-point grounding means that each grounding point in the device is directly connected to the grounding plane closest to it, so that the length of the grounding lead is the shortest.

The multi-point grounding circuit has a simple structure, and the high-frequency standing wave phenomenon that may appear on the grounding line is significantly reduced, which is suitable for applications with high operating frequencies (>10MHZ). However, multi-point grounding may cause many ground loops to form inside the equipment, thereby reducing the equipment's resistance to external electromagnetic fields. In the case of multi-point grounding, pay attention to the ground loop problem, especially when networking between different modules and devices