3. Physical Partition in RF Circuit Board Design:
- Component Placement:
- Key to effective RF design.
- Fix components on the RF path, minimizing RF path length.
- Keep RF input away from RF output, high-power circuits, and low-noise circuits.
- Utilize efficient board stacking, placing main ground on the second layer below the surface layer.
- RF Traces and Vias:
- Run RF traces on the surface layer.
- Minimize via size on the RF path to reduce inductance and avoid RF energy leakage.
- Carefully consider linear circuits for RF zone isolation.
- RF and IF Traces Crossing:
- Minimize interference by crossing RF and IF traces with a ground area between them.
- Proper RF routing is crucial for overall PCB performance.
- Component placement, especially in mobile phone PCB design, is time-consuming.
- Special Considerations:
- Use tricks to prevent RF energy passing through vias.
- Place LNA circuit and high-power amplifier on opposite sides, connecting via a duplexer.
4. Metal Shield in RF Circuit Board Design:
- Necessity and Drawbacks:
- Required when maintaining sufficient separation is challenging.
- Drawbacks include high manufacturing and assembly costs, precision challenges, and layout limitations.
- Optimizing Metal Shield:
- Ensure integrity by routing digital signal lines to inner layers.
- Use the next layer as the ground layer.
- RF signal lines can pass through gaps in the shield with a surrounding ground area.
- Drawbacks Mitigation:
- Despite limitations, metal shields remain effective for isolating critical circuits.
