Physical Partition in RF Circuit Board Design

• Component Placement:
  • Crucial for effective RF design.
  • Position components along the RF path to minimize length.
  • Separate RF input from RF output, high-power, and low-noise circuits.
  • Implement efficient board stacking with the main ground on the second layer.
• RF Traces and Vias:
  • Run RF traces on the surface layer.
  • Reduce via size on the RF path to lower inductance and prevent RF energy leakage.
  • Use linear circuits for RF zone isolation.
• RF and IF Traces Crossing:
  • Cross RF and IF traces with a ground area in between to minimize interference.
  • Proper RF routing is vital for optimal PCB performance.
  • Component placement, especially in mobile phone PCB design, requires attention to detail.
• Special Considerations:
  • Implement techniques to stop RF energy from passing through vias.
  • Place LNA circuit and high-power amplifier on opposite sides, connected via a duplexer.

Metal Shield in RF Circuit Board Design

• Necessity and Drawbacks:
  • Essential when achieving adequate separation is challenging.
  • Drawbacks include high manufacturing costs, assembly challenges, and layout restrictions.
• Optimizing Metal Shield:
  • Ensure integrity by routing digital signal lines to inner layers.
  • Utilize the next layer as the ground layer.
  • Allow RF signal lines to pass through shield gaps surrounded by a ground area.
• Drawbacks Mitigation:
  • Despite limitations, metal shields effectively isolate critical circuits.