Gan solid-state microwave power amplifiers — State-of-the-art and future trends

The world technical achievements and tendencies in the development of GaN microwave transistors, MMICs and high power amplifiers are considered. The objective of this work is an analysis of state-of-the-art GaN microwave discrete transistors, MMICs and high power (10...100 Watt and more) amplifiers, parameters and basic tendencies in the development of GaN devices. Major properties of wideband gap semiconductors available for microwave transistors are presented in table 1. The highest energy gap, availability of high temperature and high radiation environment, an extremely high density of sheet carrier, higher electric fields and breakdown voltages result in 310 W/mm and more output power density of practical released microwave GaN transistors. Table 2 shows the main parameters of broadband (without internal matching circuits) GaN power transistors. The properties of WCDMA 120 W power transistors (Si LDMOS, GaAs MESFET and GaN HEMT) are compared in table 3. The typical density (for 1 mm gate) of various GaN and GaAs HEMT transistor parameters, including optimal load density, is presented in table 4. Many projects and MMIC topologies, designed for GaAs MMICs might be transferred with minimal corrections into the GaN MMICs based on equal or on (20...50) % wider gate of transistors with x(5-10) corresponding output power (see fig. 1). The main parameters of industrial and laboratorial GaN MMIC technologies are presented in table 5, table 6 shows parameters of commercially available and lab released GaN MMICs. Fig. 2 presents the last five years of an evolution of the pulse output power of X-band GaN MMIC amplifiers for future radar systems with phased array. The parameters of the ultra-wideband GaN high power amplifiers up to 6 GHz are presented in table 7, figure 3 shows the chip sizes of the highest power of X-band GaN and GaAs MMIC amplifiers. In the decade ahead (1...50) GHz frequency range will be a topic of arguing between two power microwave technologies. One of- them is a high performance and a high cost of GaN technology, the second-low cost and widely used in the industry of GaAs technology.