I. Introduction
With the success of the global networking of the 3rd generation BeiDou Navigation Satellite System (BDS), the research and design of RF Front Ends in RDSS system has been theoretically and experimentally reported in many literatures and makes tremendous progress in recent years. To ensure the communication quality, the power amplifier needs to feature high output power and high linearity to satisfy the longer communication distance. Furthermore, as a module with large energy consumption, it is necessary to pay more attention to enhance efficiency to prolong the using time of batteries [1]-[2]. Compared with the previous two generations of semiconductor technologies, GaN HEMT is very suitable for high power satellite communications due to its wider band gap and higher breakdown voltage. However, disadvantages such as high difficulty in substrate fabrication and high cost limit its commercial application.