Noise performance of an AlGaN/GaN monolithic microwave integrated circuit (MMIC) low-noise amplifier under laser exposure

The aim of this study is to disclose how the performance of a gallium nitride (GaN)-based X-band low-noise amplifier is modified by applying a blue-ray (404 nm) laser beam. The tested amplifier employs an aluminium gallium nitride/GaN (AlGaN/ GaN) high electron mobility transistor on silicon carbide whose dc and noise behaviour have been first analysed with and without optical illumination. Mild improvement of the gain together with severe degradation of the noise figure has occurred during light exposure with the amplifier operating according to the recommended bias condition. Conversely, pronounced improvement of the performance has taken place when the amplifier has been biased close to the transistor pinch-off point. The results presented in this work follow a previous intense activity carried out on devices and amplifiers based on gallium arsenide technology.