This paper presents a comprehensive classification and comparative overview of CMOS radio-frequency (RF) power amplifiers (PAs) and proposes novel insights into their design and applications. Our research focuses on the significance of RF CMOS power amplifiers in contemporary communication systems, specifically their role in enabling the advancements of emerging technologies such as 5G. We delve into the various RF CMOS power amplifier classes, including linear PA classes (A, AB, B, and C) and switching PAs (Class D, Class E, and Class F). By evaluating essential performance metrics such as output power (P_out), drain efficiency (DE), and power-added efficiency (PAE), we provide a thorough understanding of the operational principles and distinct characteristics of each class. This comparative analysis offers a range of options to meet specific requirements and ensures seamless signal transmission in modern communication systems. With a particular emphasis on the demands of 5G networks for high-speed and high-capacity wireless communication, we emphasize the importance of these power amplifiers in achieving reliable and efficient connectivity. Our research contributes to the advancement of RF CMOS power amplifier design and offers valuable insights for the development of future communication systems.