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This paper presents a technique to make the solid-state power amplifier (SSPA) flexible (adaptive) in terms of frequency for space segment of satellite communication.As compared with the present fixed (static) performance SSPA, the flexible frequency SSPA allows the users to keep themselves updated with the changing scenario of satellite communication. The flexibility can be achieved by using PIN diode for high frequency amplifiers and varactor diode for low frequency amplifiers as switch. The bias voltage of the diode can be changed remotely by means of telecommandable circuit. The gallium nitride-based SSPAs using this concept will be able to compete the travelling wave tube amplifier for onboard applications. It also demonstrates the circuit topology for selecting the required narrow frequency band rather than designing broadband SSPA resulting in improvement of efficiency and device's channel temperature. Improvement of channel temperature in space application improves the reliability of active devices. KEYWORDSgain, power-added efficiency, satellite communication, SSPA | INTRODUCTIONWhen the satellite technology was in its childhood, the space segment was much simplified as compared with ground segment (users' terminal).With advancement in technologies, the users' terminals are made simplified and the complexities are incorporated in the space segment.The business cases for new communication missions are under constant pressure from both competitions within the space segment and from terrestrial solutions. The users continuously demand more and more bandwidth at a lower cost, and the available spectrum is becoming scarcer because of limited orbital slots, frequency allocations, and interference management issues.As compared with terrestrial gateways, the satellite-based solutions are very costly. Moreover, the defined performance of the space segment is unaltered (fixed) for the proposed satellite life of 10 to 15 years, the users' demand for state-of-the art technology cannot be satisfied with existing satellites onboard, or the users have to wait for new satellite to be launched. Therefore, it is necessary to reduce the cost of the satellite-based solution and to provide flexibility in the payload to provide updated services. By increasing the design life, the cost per bit can be reduced but it becomes very difficult for the operator to plan a robust business case over such long period. The concept of flexible payload will be able to keep the satellite users with the changing market trends. [1][2][3] Three axes of flexibility have been presented in previous studies. [1][2][3] In the functional block diagram of the generic flexible payload (GFP) architecture, 1-3 the broadband linearized travelling wave tube amplifiers (TWTAs) are presented, which can be replaced by flexible frequency TWTAs or solid-state power amplifiers (SSPAs). Flexible output power SSPAs and TWTAs have been developed, but flexible frequency SSPAs and TWTAs for space are not known so far to the best of our knowledge. This is the motivati...

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This paper presents a novel adaptive thermal management technique to improve the efficiency of solid-state power amplifier (SSPA) for geo-synchronous satellites. The thermal management for space segment is very important as it determines the reliability of the satellite. The microwave power amplifiers (MPAs), either traveling wave tube amplifiers (TWTAs) or SSPAs, are the maximum power consuming and heat dissipative elements in the satellite and their power efficiency determines weight, volume, cost, and reliability of the satellite. So, it is necessary to improve the efficiency of the SSPA. A novel technique is presented, which improves the efficiency of the SSPA and hence, saving of costly DC power generation on-board and reduction of the heat dissipation.