Microwave PCB Design
To ensure these high frequency RF and microwave circuits are successful, suppliers must consider several RF and microwave design techniques for PCBs.
RF and Microwave PCB Basics
The simplest way to describe RF and microwave PCBs is that they contain components that carry RF or microwave signals. These signals vary in frequency, and the differences in frequency define the differences in components between RF and microwave PCBs and other PCB types. However, grasping the basics of RF and microwave frequencies is the first step to understanding RF PCB design and microwave PCB design.
In essence, an electronic signal is a quantity that varies over time and communicates some kind of information. The quantity that varies is usually voltage or current. These signals are passed between devices as a way to send and receive information, like audio, video or encoded data. While these signals are often transmitted through wires, they can also be passed through the air by radio frequency, or RF, waves.
These radio frequency waves vary between 3 kHz and 300 GHz, but they are subdivided into smaller categories for the sake of practicality. These categories include the following:
- Low-Frequency Signals: These are the signals handled by most traditional analog components, and they include signals with frequencies up to 50 MHz.
- RF Signals: While radio frequency, or RF, signals technically cover a wide range of signal frequencies, circuit designers use the term in a narrower scope. Within this field, an RF signal frequency typically ranges from 50 MHz to 1 GHz. These are the same signal frequencies used in AM/FM transmission.
- Microwave Signals: Microwave signals feature frequencies above 1 GHz. The upper limit of these signals is around 30 GHz. These are the same microwaves used to cook our food in microwave ovens. They are also used to communicate very high bandwidth signals.
PCB Design Basics
First of all, RF and microwave PCBs should be designed to minimize any potential for error during the assembly process. Some of the most basic RF layout design guidelines include:
- Keeping Parts Separate: If a board has multiple types of parts, like low-level analog, RF and digital components, they should be kept separate. This is not only easier for the designer to manage, but it minimizes the potential for catastrophic problems during the assembly stage.
- Multilayer PCBs: Ideally, RF and microwave PCBs should include more than one layer. The top layer should include the power stage as well as RF signal lines and components. Be sure that if you have a multilayer PCB, there is a ground layer underneath any layer that includes RF or microwave signal lines.
Sensitivity to Noise: RF and microwave PCB designers must understand how sensitive these high frequency signals are to noise. While most designers are used to working with such sensitivity in high-speed digital signals, they have to be significantly more cautious with RF and microwave signals, since they are even more sensitive. These signals are also susceptible to a wider variety of noise types. This extreme sensitivity means any possibility signal noise, reflection or ringing has to be mitigated.
Please contact with us for more information:
Ms. Sicen Hu