[Keynote lectures]

Summary form only given. Low earth orbit (LEO) satellites play an important role in earth observation and communication fields. Since communication with LEO has time limitation, it is important to have high data rate transmitters in addition to having properties as small volume, lightness and efficiency. In this work, an X-band (8.2 GHz) solid state power amplifier is designed with an output power of 7W, total gain of 18.0dB and bandwidth of 2OOMHz as a part of an onboard transmitter with data rate of 100 Mbps. The power amplifier has two stages designed with FLM7785-4F and FLM7785-12F internally matched transistors from Fujitsu Quantum Devices and the efficiency of the first stage is 22% and the second stage is 35%.