The following guidelines are for the RF interface. Follow guidelines specified in the vendor-specific antenna design guides (including placement of the antenna). Also see CC3135 and CC3235 SimpleLink™ Wi-Fi® and IoT Solution Layout Guidelines for general antenna guidelines.
- Ensure that the antenna is matched for 50-Ω. A π-matching network is recommended. Ensure that the π pad is available for tuning the matching network after PCB manufacture.
- A DC blocking capacitor is required before the antenna. If the antenna matching network contains a series capacitor, this is sufficient to meet the requirement.
- Ensure that the area underneath the BPFs pads have a solid plane on layer 2 and that the minimum filter requirements are met.
- Ensure that the area underneath the RF switch pads have a solid plane on layer 2 and that the minimum switch isolation requirements are met.
- Ensure that the area underneath the diplexer pads have a solid plane on layer 2 and that the minimum diplexer requirements are met.
- Verify that the Wi-Fi RF trace is a 50-Ω, impedance-controlled trace with a reference to solid ground.
- The RF trace bends must be made with gradual curves. Avoid 90-degree bends.
- The RF traces must not have sharp corners.
- There must be no traces or ground under the antenna section.
- The RF traces must have via stitching on the ground plane beside the RF trace on both sides.
- For optimal antenna performance, ensure adequate ground plane around the antenna on all layers.
- Ensure RF connectors for conducted testing are isolated from the top layer ground using vias.
- Maintain a controlled pad to trace shapes using filleted edges if necessary to avoid mismatch.
- Diplexers, switches, BPF, and other elements on the RF route should be isolated from the top layer ground using vias.