Reliability improvement technique of GaN SSPA for geo synchronous satellites

This paper presents a novel idea to design highly reliable and simplified line up of high power SSPA to replace the TWTAs for future payloads. Development of Gallium Nitride (GaN) based SSPAs have been reported widely to replace the TWTAs but in absence of sufficient space heritage, failures reported during development and qualification phase of the GaN devices and past experience of GaAs based SSPA failures during 1990's, the authors recommend a new line up using GaAs and GaN devices rather than using all GaN devices in the SSPA. We also propose device level redundancy of GaN along with various techniques such as voltage, current and gain compensation, Automatic level control, dynamic biasing control and different parameter telemetry. The additional techniques will help to understand any unforeseen failures on-board and also to change over to redundant device with necessary corrections thereby providing uninterrupted services. There will not be any impact on the electrical performance of the SSPA while using such hybrid combination of the devices.