PCB Blog - What is an RF PCB board?

RF board, is a type of high-frequency alternating current electromagnetic wave. An alternating current that changes less than 1000 times per second is called a low-frequency current, 

while a current that changes more than 1000 times is called a high-frequency current, and radio frequency is this type of high-frequency current.

RF board refers to a circuit that processes the electromagnetic wavelength of a signal in the same order of magnitude as the circuit or device. At this point, due to 

the relationship between device size and wire size, the circuit needs to be processed using distributed parameter theory. This type of circuit can be considered as 

an RF board with no strict frequency requirements. For example, long-distance AC transmission lines (50 or 60Hz) sometimes require RF theory to handle.

Principles of RF Circuit Board Layout

When designing RF PCB layouts, the following general principles should be given priority consideration:

(1) High power RF amplifiers (HPA) and low noise amplifiers (LNA) should be isolated as much as possible. 

In short, high-power RF transmission circuits should be kept away from low-power RF receiving circuits;

(2) The high-power area of the PCB board should have at least one entire area, preferably without via holes. Of course, the larger the area of copper foil, the better.

(3) Decoupling the circuit and power supply is also important;

(4) RF output usually needs to be far away from RF input;

(5) Sensitive analog signals should be kept as far away as possible from high-speed digital signals and RF signals

Application of RF circuit boards

RF circuits are widely used in various fields such as television, broadcasting, mobile phones, radar, and automatic recognition systems. 

The term RFID (Radio Frequency Identification) refers to the application of radio frequency identification signals to identify targets, with the most important 

application area being wireless communication.

In the field of electronic technology, the characteristics of RF circuits are different from ordinary low-frequency circuits. 

The main reason is that the circuit characteristics under high-frequency conditions are different from those under low-frequency conditions, 

so we need to use the theory of RF circuits to understand the working principle of RF circuits.

At high frequencies, stray capacitance and stray inductance have a significant impact on the circuit. Stray inductance exists in the internal self inductance of 

conductor connections and components themselves. There is stray capacitance between the conductors of the circuit and between the components and the ground. 

In low-frequency circuits, these stray parameters have little impact on the performance of the circuit. 

As the frequency increases, the impact of stray parameters becomes increasingly severe. In early VHF band television receivers, 

the impact of stray capacitance was so significant that additional capacitance was no longer needed.

RF PCB board is a printed circuit board specifically designed and manufactured for Radio Frequency circuits. 

RF circuits refer to high-frequency signal circuits used in wireless communication, radar, satellite communication, radio broadcasting, and other fields. 

The characteristics of RF circuits are high operating frequency, fast signal transmission speed, and strict requirements for circuit layout and design.