In our daily circuit design, it is very important to ensure the integrity of the ground and the connections between various grounds. If the grounding is not handled well, a potential difference will occur, which will generate current and affect the normal operation of the circuit. We have three commonly used grounding methods. kind. Here are three grounding methods explained to you.
- Single point grounding
Single-point grounding means that the ground wires of all circuits are connected to the same point of the common ground wire. This type of grounding can be divided into series single-point grounding and parallel single-point grounding.
Advantages: The advantage of single-point grounding is that it reduces the complexity of the ground loop, making the circuit relatively simple.
Disadvantages: Single-point grounding and too long ground wires may cause the ground wire impedance to increase, affecting the performance of the circuit, especially in some high-frequency circuits.
Application: Single-point grounding is suitable for some low-frequency circuits and is also our commonly used grounding method. It can prevent two-point grounding from causing common-ground impedance circuit coupling. It should be noted that the length of the ground wire cannot exceed 0.05
Series single point grounding
Parallel single point grounding
- Multi-point grounding
Multi-point grounding means that all circuit ground wires in the circuit are grounded nearby to keep the length of the ground wire as short as possible and reduce the inductive reactance generated on the ground wire.
Advantages: The circuit ground wire is shortened, thereby reducing the inductance and high-frequency standing waves.
Disadvantages: When the frequency in the circuit exceeds 10MHz, coupling interference between low-level signals may occur in the circuit.
Application: In high-frequency circuits and digital circuits, we often use multi-point grounding, so that each of our circuits can be connected to the ground plane very close.
Multiple grounding points
- Hybrid grounding
Hybrid grounding uses inductors and capacitors to connect in the ground system, and uses the characteristics of inductors and capacitors to have different impedances at different frequencies, so that the ground system has different ground structures at different frequencies.
Advantages: Hybrid grounding includes the characteristics of both single-point grounding and multi-point grounding.
Disadvantages: More complicated.
Application:low frequency single point-high frequency multi-point hybrid grounding Low frequency: The impedance of the capacitor is large—single point grounding
High frequency: The impedance of the capacitor is small - multiple points of grounding
Low frequency multi-point-high frequency multi-point hybrid grounding
Low frequency: The impedance of the inductor is small - multiple points of grounding
High frequency: The impedance of the inductor is large—single point grounding
hybrid ground
- Summary
To sum up, according to actual applications, single-point grounding is a common practice in some low-frequency circuits (operating frequency below 1MHz) because it can prevent common-ground impedance circuit coupling caused by two-point grounding. However, in high-frequency circuits (operating frequency higher than 30MHz), since the inductive reactance of the grounding lead will be proportional to the frequency and length, multi-point grounding becomes a better choice because it can reduce the generation of common ground impedance and reduce electromagnetic interference. risks of. In addition, for circuits with operating frequencies between 1 and 30MHz, a hybrid grounding method can be used. Depending on the length of the ground wire and the signal wavelength, it is decided whether to use single-point grounding or multi-point grounding. Of course, in some complex circuits , including digital circuits, analog circuits, and some power transmitters, we also need to consider the connection devices between grounds, such as capacitor connections, inductor connections, magnetic bead connections, and other devices.