In RF circuit design, layout and routing directly determine product performance. A good design not only reduces interference but also improves stability. Today, I'll walk you through the core essentials of RF PCB design, ensuring your product wins from the very beginning!

I. RF Product Layout Techniques

1️⃣ Linear Layout Principle: Within the same shielded cavity, the main RF signal should be arranged in a line, following the direction of signal flow. An L-shape can be used when space is limited, but a U-shape should be avoided to prevent signal self-interference.
2️⃣ When multiple channels are perfectly symmetrical and have multiple receive or transmit channels, the layout and routing of each channel must be identical to ensure phase consistency and balanced performance.
3️⃣ Plan signal routing in advance. Consider the coupling relationship between the main signal path and components during the layout phase to avoid being forced into unreasonable routing later.
4️⃣ Inductor Placement Tip: Inductors should be placed perpendicular to adjacent inductors to reduce mutual inductance interference.
5️⃣ High- and low-power isolation: High-power amplifiers (HPAs) and low-noise amplifiers (LNAs) should be kept as far apart as possible. If space is limited, they can be placed on opposite sides of the PCB or designed to operate alternately.
6️⃣ Cavity isolation: Radio frequency units in different modules should be isolated using cavities, especially between sensitive circuits and strong radiation sources. High-power multi-stage amplifiers should also have each stage isolated.
7️⃣ Shielding cavity design: Design 3mm metalized fixing holes at the corners of the cavity to ensure a secure installation of the shielding shell.
8️⃣ Cavity shape optimization: The shielding cavity should have a large aspect ratio and avoid a square design to reduce resonance effects.

II. RF Signal Routing Key Points
1️⃣ 50Ω Impedance Control: Characteristic impedance is typically designed for 50Ω. Widths are generally greater than 15mil. Use interlayer references to ensure impedance stability. Use rounded corners instead of right angles whenever possible.
2️⃣ Reasonable Spacing and Vias: Maintain a 2Ω spacing (at least 1Ω) between the RF link and the ground copper foil. Shielded via spacing should be less than 1/20 of the signal wavelength. Component pads should be designed for full connectivity.
3️⃣ Partition Design: Separate digital and analog circuits to avoid mutual interference. Power supply routing should also be partitioned; do not simply use a single plane.
4️⃣Grounding in High-Power Areas: A complete ground plane should be maintained in high-power areas, preferably without vias, to ensure heat dissipation and shielding.
5️⃣ Input and Output Isolation: RF outputs should be kept away from RF inputs. Shielding should be added if necessary to prevent signal crosstalk.
6️⃣Protect Sensitive Signals: Analog signals should be kept away from high-speed digital and RF signals to minimize interference.

7️⃣ Copper Foil Processing Tips: The copper foil should be smooth and flat, avoiding sharp corners and thin strips. Add vias along the edges of the copper foil if necessary.
8️⃣ Antenna Area Protection: Place the antenna in a clear area on all layers, at least 5mm away from other circuits.