PCB Grounding Methods

This Gold Phoenix PCB Knowledge Center article explains PCB grounding methods, including single-point, multi-point, and mixed grounding techniques.

The GND (ground) on a circuit diagram and PCB represents the ground wire or 0 wire, and GND means the common end, which can also be referred to as the ground. PCB grounding refers to connecting all ground wires to the power supply ground wire.

1. Single-Point and Multi-Point Grounding Methods for PCBs

1. Single‑point grounding: The grounding wires of all circuits are connected to the same point on the ground plane, which can be divided into series single‑point grounding and parallel single‑point grounding.

2. Multi‑point grounding: The ground wire of all circuits is grounded nearby, and the ground wire is very short, making it suitable for high‑frequency grounding.

3. Hybrid grounding: A combination of single‑point grounding and multi‑point grounding.

For low-frequency, low-power circuits on the same power layer, single-point grounding is the most suitable and is usually applied in analog circuits. The star-type connection is generally used here to reduce the potential impact of series impedance. High-frequency digital circuits require parallel grounding, which can be handled through grounding holes. Generally, all modules use a combination of the two grounding methods, using a hybrid grounding method to connect the circuit ground wire to the ground plane.

2. PCB Mixed Grounding Method

If the entire plane is not used as a common ground wire, such as when a module itself has two ground wires, the ground plane needs to be segmented, which often interacts with the power plane. The ground-to-ground connection methods are as follows:

1. Common wiring connection between ground circuit boards: This method can ensure reliable low‑impedance conduction between the two ground wires, but is limited to the connection between the grounds of medium‑ and low‑frequency signal circuits.

2. Ground‑to‑ground high‑resistance connection: Once there is a voltage difference between the two ends of the resistance, a weak conduction current will be generated, which releases the charge on the ground wire and ultimately achieves zero voltage difference between the two ends.

3. Ground‑to‑ground capacitance connection: Capacitors provide DC cutoff and AC conduction characteristics and are applied in floating ground systems.

4. Ground‑to‑ground magnetic bead connection: Magnetic beads are equivalent to a resistance that varies with frequency and exhibit resistance characteristics. They are applied between grounds for weak signals with rapid, small current fluctuations.

5. Ground‑to‑ground inductive connection: Inductors have the characteristic of suppressing circuit state changes and can be used for peak shaving and valley filling. They are usually applied between two ground‑to‑ground systems with significant current fluctuations.

6. Ground‑to‑ground small‑resistance connection: The small resistance adds damping that hinders rapid changes in ground‑current overshoot; when the current changes, the rising edge of the impulse current becomes slower.