18.2.2 RF Traces and Components

The following are the recommendations for a better design with respect to RF traces and components in the RF frontend.

• The RF traces routed from RFP and RFN of the ATSAMR30 must be designed for a 100Ω differential impedance. These traces routed to the balun must be kept as short as possible to reduce path loss and avoid opportunity for the trace to pick up noise.

  

• Place guard ground vias along the RF trace. The PCB layer directly below the RF trace must have a ground polygon pour.
• Do not have any signal traces below/adjacent to the RF trace.
• Do not use thermal relief pads for the ground pads of all components in the RF frontend. These pads must be completely flooded with ground copper polygon pour. Place dedicated vias to ground for all these individual components.

  

• Keep any components that may radiate noise or signals within the 850-950 MHz frequency band away from the antenna and the RF traces and, if possible, shield these components. Any noise radiated from the board in this frequency band degrades the RF performance of the module.