User's Guide

MM6108-MF08251 User Guide UG100
IEEE 802.11ah Sub-1G Wi-Fi HaLow Module
Page 10/19
SPI Configuration
3.3. General Layout Guidelines
In order to achieve optimal RF performance, the following steps should be followed:
1. Use a 50Ω impedance controlled trace from the antenna pin (38) and the antenna
connection.
2. Use a solid ground plane under the RF trace and the module.
3. Ensure the ground fill is heavily stitched with vias round the RF traces.
4. Keep all power supply and digital signals away from the RF traces.
5. If an impedance matching circuit is needed, ensure that no RF stubs are created.
6. Keep the RF path short, smooth and near. Use large radius bends, never 90 degree
bends.
7. Choose a pcb stackup so the RF trace width is close to the width of the matching
component pads. This will minimize any impedance mismatch.
8. Do not use thermals on RF traces because of their high loss.