Technical info

Grounding (GND) Techniques

PCB Grounding methods

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In the most typical grounding methods, pigtail wires are used to connect to the frame/chassis ground.
Other common methods include metal spacers or folded metal sheets with screws to secure and EMC ground the PCB.

However, there are two problems when working with screws: poor workability and increased number of pieces.
As a solution, we developed our multi-functional FG series that combined mechanical features and EMC grounding elements.

Noise Suppression by Multi-point Ground

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Series ground

 

 In series grounding shown in the right figure, common mode currents I1, I2, and I3 generated in circuits 1, 2, and 3 pass through a common ground and are connected to FG.
In this state, common mode voltage is generated by the current and resistance (common impedance) at each point; and the ground potentials A, B, C, and D of each circuit are unstable and affect each other

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Single-point ground

 

 By using a single-point ground, common impedance is eliminated, and the ground potential of each circuit is determined only by the common mode current and ground impedance of each circuit.

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Multi-point ground

With higher frequencies in circuit designs, wire inductance increases. This leads to higher impedance which is undesirable for noise performance.

Even with a single-point ground, the ground impedance increases at high frequencies and the ground potential becomes high.
In order to reduce the effects of common impedance, it is necessary to have wide and short connections at multiple locations to FGs and other devices to reduce high-frequency impedance.