Continuously evolving Wi-Fi Technologies, rising customer expectations, and increasing use cases of Wi-Fi from unlicensed radio links to crowded IoT devices, have put extra pressure on the device supporting components. Amongst all, RF is the one that always comes first in the picture. While the CPU acts as the brain of the device, RF functions as the ears, whose performance defines the performance of the device.
We began with 802.11a and have now moved to the 802.11ax standard. This increases the complexity of RF manifolds and demands a high level of engineering expertise to provide an optimized solution. RF design is a step-by-step process that consists of RF circuit design, component selection, Antenna design, and Testing/Validation. Each step is equally important to maximize the performance of the device. While one blog will not be sufficient to explain all the building blocks, we will touch upon the critical factors of RF circuits in this blog.
Signal to Noise Ratio (SNR): One of the most critical factors is the Signal to Noise ratio (SNR) which identifies how much the signal is affected by the noise. The level of noise is inversely proportional to the quality of the signal. At times, noise integrates with the signal so well that even a noisy signal looks fine at an oscilloscope. However, when it is converted to frequency, it clearly shows the signal and the noise level separately. The logarithmic ratio between them is signal to noise ratio and more gaps will lead to better signal.
Noise Factor: Noise figure (NF) and noise factor (F) are measures of degradation of the signal-to-noise ratio (SNR), which are caused by components in a signal chain. The noise factor of a component is the ratio of input SNR to output SNR. However, The complete RF circuit design consists of multiple stages and every further component introduced induces some noise and the next LNA/PA amplifies it, as shown in the figure.