User's Guide
Table Of Contents
- 1. WFM200 Pinout
- 2. Device Configuration
- 3. Features Description
- 4. Power Supplies
- 5. Application Schematic Recommendations
- 6. Typical Application Schematics
- 7. Layout Recommendations
- 7.1 Generic RF Layout Considerations
- 7.2 GND and RF Pads Including the Diversity Port and External Antennas
- 7.3 Module Antenna
- 7.3.1 Small Board Size Recommendations for Good RF Performance
- 7.3.2 Extended X Dimension Recommendation for Good RF Performance
- 7.3.3 Y Dimension (65 to 80 mm) Recommendation for Good RF Performance
- 7.3.4 Y Dimension (80 mm or Larger) Recommendation for Good RF Performance
- 7.3.5 WFM200 Portion One Corner Bias with 3 mm Metal Keep-Outs
- 7.3.6 Recommended Antenna Loop Trace Capacitor Values
- 7.4 WFM200 Reference Evaluation Board
- 8. Recommendations for Certification
- 9. Package Outline
- 10. Integral Antenna Loop and Keep-Out Required Dimensions
- 11. Recommended PCB Land Pattern
7.2 GND and RF Pads Including the Diversity Port and External Antennas
WFM200 ground pads need to be well connected to the PCB ground plane to optimize thermal conductivity and prevent unwanted
emissions that result from ground currents.
The RF pads and RF traces conducting the RF signal should be dimensioned to have a characteristic impedance of 50 Ω. It is vital that
proper RF design principles be used when designing an application using the RF pads.
Antennas external to the module, be they connectorized, off-the-shelf antennas or PCB trace antennas, must be well-matched to 50 Ω.
PCB size and layout recommendations from the antenna manufacturer must be followed. Board size, ground plane size, plastic enclo-
sures, metal shielding, and components in close proximity to the antenna can affect the antenna impedance and radiation pattern.
Therefore, antenna matching should be verified in the final enclosure. See Section 5.2 for antenna specifications.
Ensuring proper antenna impedance matching is also recommended to prevent distortion in the module power amplifier because of the
impedance mismatch. PA distortion can cause significant packet loss and poor overall performance.
UG395: WFM200 Hardware Design User's Guide
Layout Recommendations
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