Following these rules will enable one avoid some of the most frequent drawbacks in RF layout. Ideally an engineer project a PCB design should be knowledgeable about the IPC standards as these provide a rich source of information and best practice on the overall fundamentals of PCB design and style.
When planning to layout an RF PCB fabrication , the very first place to start would be to get in touch with your favorite board manufacturer and get some of their tips and manufacturing capabilities. This will include the minimum difference and track widths, drill sizes and other important parameters. The board manufacturer also needs to be able to supply you with their normal layer heap and substance data, this will include the copper weights, dielectric constant, and also the depth of heart and pre-preg layers in multi-layer boards. Unless your circuit is extremely simple I would claim that a 4 layer board is used this ensures that a continuous earth plane. When using a double sided board it is quite tricky to be certain that the bottom plane is un broken. Make use of a micro-strip calculator to determine the required path width to your look impedance and also ensure that it is at the manufactures capabilities, or even you may have to talk about the layer-stack with the manufacturer and select a nonstandard build. Yet another thing to note is that within my own experience wanting to maintain separate ground nets for different signal area’s usually causes issues as opposed to any benefit and is largely a throwback to the days prior to multilayer boards, one low impedance ground plane is the safest path.
It’s very okay to use FR 4 for boards up-to 2.4-ghz unless the highest amount of operation is required. In certain circumstances it is worth specifying the board controlled impedance to present consistent RF performance.
Having ascertained the board and track geometries that the next thing is to cover the component placement. Ensure that the RF components are presented in a way that all the RF monitors can be maintained the top surface with minimum span and changes of management. Focus on very low signal level areas at the antenna or RF input and work backwards towards the baseband or digital area. Keep digital and power supply areas from the analogue RF circuitry and store all of the RF components using a single side of the plank.
Where your RF monitors can not be run at a direct line, use mitered bends in case a CAD system supports them, never use straight angled snaps on RF signal lines.
On RF layouts it’s quite common to supply a floor flood on the top coating and also to”stitch” this into the bottom plane using multiple via’s. If you plan to try it, be sure that the copper is kept a suitable distance from the RF tracks and components otherwise the impedance will be lowered and also cause more damage than good.
Tracks to earth in RF components must be kept as short as possible and use 2 or 3 in parallel via’s to minimize the impedance.