GaN HEMT Amplifier for C-band Space Applications

1. Introduction With the diversifying functions and increasing traffic of recent satellite communications, the amplifiers installed in satellites must provide higher power and improved efficiency. Commonly-used satellite-mounted amplifiers are, in general, either traveling wave tube amplifiers (TWTAs) or solid state power amplifiers (SSPAs) using gallium arsenide field-effect transistors (GaAs FETs). However, because of this high output power and high efficiency, TWTAs are used more often than SSPAs. Meanwhile, the gallium nitride high electron mobility transistor (GaN HEMT) is expected to improve the output power and efficiency of SSPAs. Owing to its material properties, the GaN HEMT is capable of high voltage operation and produces a high power density, and thus is expected to be a high-frequency device that realizes a high-power and high-efficiency SSPA, and in recent years, high-power GaN HEMT amplifiers are being developed at many research institutions (1)(2)(3)(4). This time, based on Mitsubishi Electric's GaN HEMT device, we have developed a high-power and high-efficiency amplifier transistor, and verified that it provides sufficient reliability for satellite applications.