Development of high-speed and high-efficiency downlink transmitter with GaN-HEMT amplifier and pre-distortion technique for nano/small satellite

A high-speed downlink telecommunication system is required to meet various applications for small satellites such as earth observation. The purpose of this research is to develop a high-data-rate (typically over 300Mbps) communication system. Generally, the operation at nonlinear region provides high efficiency for a RF power amplifier. However the amplitude-phase modulated signal, which is an efficient scheme in term of frequency band, requires high linearity. In order to amplify amplitude-phase modulated signal for high data rate, a 2W X Band GaN-HEMT power amplifier and digital pre-distortion technique were developed. In this paper measurements and simulations of the system are presented