Issue link: https://resources.mouser.com/i/1541351
9 | some cases, damage upstream or downstream components. This potential degradation can be especially challenging with nonlinear components such as amplifiers and mixers, as unwanted signal content can be further unintentionally distorted or even mixed into sensitive frequency ranges that conflict with the desired performance of the RF circuit or nearby RF circuits. In communication systems with many closely spaced channels, intermodulation distortion is a common concern. With intermodulation distortion, two or more signals that enter a nonlinear circuit feature could mix, producing the sum and difference frequencies and a series of harmonics (Figure 3). If the signals are of high enough amplitude, the resulting distortions could be enough to desensitize a receiver or even overwhelm a frequency channel and prevent communications. RF Systems There are many different aspects to RF systems; depending on the complexity, an RF system may include electronic power, analog processing circuits, digital control, thermal management, and many other electronic components. Many modern RF systems are now software-defined. This means that the level of digital signal generation, control, and synthesis is significant enough that radio and sensing technologies' transmission and reception functions can be configured using software. Modern smartphone radios and advanced radar function in this way. For many RF systems, the distinct RF parts Figure 3: RF channel measurement showing the frequency spectrum of intermodulation distortion. (Source: RF Intermodulation at 280 MHz, © Nader Moussa, used under Creative Commons Attribution-ShareAlike 3.0 Unported) are contained within the front end, often referred to as the RF front end (RFFE). Of course, digital synthesis and conversion electronics are nominally RF components, but they are traditionally recognized in RF design as distinct and separate domains like baseband signal generation and processing (which was historically analog and now more commonly digital). However, there are many radio, radar, and other sensing technologies for high-performance applications where digital electronics are not yet capable enough to meet high-performance standards. Examples include some test and measurement applications, extreme frequency (i.e., upper microwave and mmWave), high-precision sensing, high power, latency- sensitive applications, and other applications where the flexibility enabled by digital electronics in RF systems does not outweigh the cost and increased complexity. The frequency and power regimes that an RF system operates over largely dictate many aspects of the system. For instance, higher- frequency RF systems are often smaller in critical dimensions than lower-frequency RF systems due to the proportional relationship that transmission lines or waveguides and many RF circuit elements have with the wavelength of the frequency limits. For instance, both waveguides and transmission lines have upper-frequency cutoffs for the dominant or desired transmission or waveguide modes, usually based on the widest bandwidth or lowest loss modes. High-power RF systems are often larger to accommodate higher voltages, which could cause voltage breakdown if conductive
