Ka-band High-linearity and Low-noise Gallium Nitride MMIC Amplifiers for Spaceborne Telecommunications

Gallium Nitride is becoming an interesting solution for low-noise applications in the lower part of the millimetre-wave spectrum and is gaining increasing attention in the space community for microwave receiver functionalities. Lately, its maturity level has increased and its performance in terms of noise figure and operating frequency is reaching other advanced III-V technologies such as Gallium Arsenide and Indium Phoshpide. Moreover, Gallium Nitride features higher power handling capability in comparison to the previously mentioned III-V technologies. In this context, we have designed and characterized two demonstrator circuits of critical microwave receiver functionalities: a Low-Noise Amplifier and a Low-Distortion Amplifier operating at Ka-band. It is shown that GaN circuits compare well in terms of noise figure, gain, and operating frequency with respect to other advanced III-V technologies, and most of all exhibit superior linearity in terms of intermodulation distortion. The designed Low-Noise Amplifier exhibits state-of-the-art 1.2 dB Noise Figure in the 27-31 GHz bandwidth thanks to a profitable combination of 60- and 100-nm gate length transistors on the same MMIC. On the other hand, the Low-Distortion Amplifier features state-of-the-art +30 dBm Output Third Order Intercept point in the same operating bandwidth while requiring only 216 mW dc power. The presented electrical performances are validated by comparing these designs to others available in open literature through figures of merit that normalize trade-offs by transistor length (therefore a fair comparison) aiming to highlight the merits of the proposed design methodologies.