Flexible High Power GaN Amplifiers

This paper describes a fast envelope-trackin g circuit capable of 10 MHz (up to 17.5 MHz) bandwidth based on RF GaN switching devices and 50 MHz switching frequency. The efficiency of the VHF converter is 84% to 90% which is comparable to a conventional DCIDC converter for spaceborne application. A demonstrator has been built and mated with a RF GaN HEMT output stage. The CII measurement for lO-12W RF output power close to saturation show a linearity improvement by 5-8d8 and an efficiency improvement of up to 8 points when compared to the case of no tracking circuit. Index Terms - SSPA, HPA, envelope-trackin g, HPA, GaN technology, DCIDC converter.