GaN-HEMT MMIC with Integrated Class-G Switching Stage for Discrete Level Supply Modulation for 20 GHz Space Applications

In this paper a 20 GHz GaN-MMIC PA with integrated switch for discrete level supply modulation (class-G) is presented. It is a single-stage conceptual design developed for the investigation of discrete level supply modulated systems for space applications at 20 GHz and for 5G in the 24 - 28 GHz frequency range. The MMIC is fabricated in the 150 nm FBH GaN-HEMT process. Good consistency with simulations is shown. Small-signal evaluation shows unconditional stability and a 3 dB BW from 19 - 26 GHz at 20 V supply with a maximum 10.4 dB small-signal gain at 25.5 GHz. Static CW power operation at 20 V shows more than 2 W/mm gate width output power density. CW operation indicates a potential maximum efficiency improvement of 28%-points at Pout = 26.6 dBm by reducing the supply voltage from 28 V to 8 V indicting a well optimized design for envelope tracking. Post-processed quasi-static data shows a possible efficiency improvement of 7 - 10%-points depending on signal characteristics and PAPR.