单点接地和 多点接地详解(Single point grounding and multipoint grounding)

单点接地和多点接地详解（Single point grounding and

multipoint grounding）

Single point earthing multi point earthing

The problem to be solved in a single point is the "public ground impedance coupling" and the "low-frequency loop"",

More often than not, it is aimed at "common mode interference" caused by long running lines

In low frequency circuits, the operating frequency of the signal is less than 1MHz, and its wiring and inductance between the devices are less affected, and the circulation caused by the grounding circuit has a greater impact on interference, so it should adopt one point grounding.

When the signal operating frequency is greater than 10MHz, the ground impedance becomes very large. At this point, the ground impedance should be reduced as far as possible, and the ground multipoint grounding should be adopted.

When the working frequency is between 1 and 10MHz, if one point grounding is adopted, the ground wire length shall not exceed 1/20 of the wavelength, or multipoint grounding method shall be adopted.

Single point earthing between digital and analog ground, multipoint connection within digital ground.

Ground wire interference and ground wire design

Ground design is a problem that people pay attention to in EMC design, but they don't know how to do it. After understanding the mechanism of the interference caused by ground wire, there is a definite idea in the design and implementation of ground wire. This issue begins with the introduction of the principle of interference caused by ground wire, enabling readers to understand the key and principles of designing ground wire. 1 what is the earth wire?

There are two kinds of ground wire: safety and signal. The former is to ensure personal safety and equipment safety and set the ground wire, the latter is to ensure that the circuit works correctly set the ground wire. The main reason for the circuit interference is the signal ground, so the problem of signal ground is only discussed here.

The general definition of the signal field is the potential reference point of the circuit.

More appropriately, this definition is a hypothesis in our design of circuits. From this definition it is impossible to analyze and understand some ground interference problems. From now on, we will use the following definition when we analyze electromagnetic compatibility problems.

The ground line is the ground impedance path of the signal current flowing back to the signal source.

Since the ground wire is a path of the current, then there is a voltage on the ground line according to Ohm's law; since the