# Review of Ka-Band Power Amplifier
###### Abstract  
With the increase in the demand for high-speed transmission communication, satellite communication is developing rapidly. Because of the bandwidth capacity, the K/Ka band is considered the mainstream frequency band of satellite communication. The performance of a power amplifier (PA) directly affects the power of the transmitter, so the application of a power amplifier in Ka-band satellite communication is very important. A review of the state-of-the-art PA in the Ka band is presented in this article. The structure of the PA introduced includes common source, cascode, stacked field-effect transistor (FET), power combining, and Doherty PA, highlighting the advantages and disadvantages. The main solid-state technologies are outlined, including Si, SiGe, GaAs, and GaN, emphasizing Si complementary metal-oxide-semiconductor (CMOS) due to low price and high integration. power amplifier; Ka band; satellite communication 202211942219422194221942219422194221942219422194219422194221942194221942219421942219421942219421942219421942194219421942194219421942194219421942194219421  
manufacturing level, Ka-band microwave circuits have developed rapidly over the past 10 years. In October 2011, the full Ka-band communication satellite ViaSat-1 of VIASAT was successfully launched [5]. The total communication capacity of ViaSat-1 exceeds 140 Gbps, which is more than 70 times that of any Ku-band satellite at that time [6]. In particular, with the launch of the new generation satellite ViaSat-1, the concept of the high price and narrow bandwidth of traditional satellites has been changed. The transmission speed provided by the satellite is higher than that of terrestrial digital subscriber line DSL and wired cable, but the service price of users is almost the same [7]. In 2012, ViaSat-1 was officially put into commercial use, opening a new era of Ka-band satellite communication [8]. In addition to the field of satellite communication, the next generation mobile communication technology 5G is also likely to use the communication technology of the Ka band. Regarding 5G, the Third-Generation Partnership Project (3 GPP) determined the millimeter-wave band 26 GHz/28 GHz/39 GHz as the 5G band to be deployed first in the world [9]. In recent years, many high-tech companies in the United States and South Korea have successively completed the verification test of the 5G communication prototype based on a 28 GHz band [10]. Whether for 5G or broadband communication satellites in the future, Ka-band applications can provide high-speed communication services. With the maturity and promotion of these technologies, there will be a lot of demand for Ka-band communication systems in the future. As an important part of the transmitter in the communication system, the performance of the power amplifier plays a decisive role in the performance of the whole system. Figure 1 is a block diagram of a communication system transmitter. Usually, the power amplifier is located at the end of the transmitter of the whole communication system. After the signal passes through the modulator, mixer, and band-pass filter, it is amplified to a certain power level through the power amplifier and transmitted through the antenna. Among these modules of the communication system, the power amplifier is a core module. Its linearity directly determines the transmission signal quality of the transmitter, its efficiency determines the power consumption of the transceiver, and its output power determines the distance of communication. Therefore, designing a power amplifier with good performance is the key to determine the quality of wireless communication. Therefore, the research of the power amplifier is very important. This article will discuss the mainstream technologies for Ka band PA, focusing on Si complementary metal-oxide-semiconductor (CMOS) because of its low cost and high integration.