label: pcb board,PCB layout design,Printed circuit boards
A few decades ago, there wasn’t much demand for RF and microwave pcb board circuits. They were difficult to design into the architectures of the time, and so costly that only mil/aero projects could afford them. But today RF circuitry is crammed into a large variety of commercial products. Most of these are handheld wireless devices for medical, industrial, and communications applications, plus applications in a variety of fields are migrating from desktop models to become portable communications units. Not only is RF becoming more ubiquitous, pcb board but microwave circuitry as well, both capturing very high frequencies (VHF) and ultra-high frequencies (UHF).
Printed circuit boards (PCBs) now encompass much more than pure digital or mixed-signal technologies, and the PCB layout designer faces many more challenges when designing sub-assemblies with high frequency RF and microwave. The RF frequency range is typically from 500 MHz to 2 GHz, and designs above 100 MHz are considered RF. The microwave frequency range is anything above 2 GHz. There’s a considerable difference between RF and microwave circuits versus typical digital and analog circuits. In essence, RF signals are very high frequency analog signals. Therefore, unlike digital, at any point in time an RF signal can be at any voltage and current level between minimum and maximum limits. Standard analog signals are assumed to be between DC and a few hundred megahertz. But RF and microwave signals are one frequency or a band of frequencies on a very high frequency carrier. Unlike digital signals associated with one voltage or one current, RF and microwave signals operate on a frequency.
RF and microwave circuits are designed to pass signals within a certain band. They use band pass filters to transmit signals in a so-called band of interest. The signal within a range of frequency passes through this band range pcb board, and the rest of the frequencies of the signal are filtered. A single band can be very narrow or very wide and carried upon a very high frequency carrier wave.
