Question

QUESTION

Answer 1

In multilayer boards, vias are significant in facilitating connectivity. We recommend the following to ensure an optimised RF layout:

• Where possible we recommend to place plenty of vias close together between ground fillings at the top layer and the inner ground layer. The spacing between two vias should never be more than one-twentieth of the wavelength of the RF signals.
• Always use separate vias for each pin/pad. Do not share a via with multiple pins/ pads, as this can increase the common-mode noise between different sections of the circuit.
• Try not to use vias to route the RF trace to a different layer.
• In the top layer, use ground vias immediately next to pins or pads. Use more vias whenever possible as having more vias in parallel reduces the parasitic inductance.
• Whenever feasible, use vias to form a ground fencing around the RF section. This would help to isolate it from the rest of the circuit.