High Frequency Noise Model of AlGaN/GaN HEMTs

Compared with conventional GaAs HEMTs, the larger gate leakage current and more obviously self-heating effects are two unique macroscopic features in AlGaN/GaN HEMTs. This paper presents the study of the effects brought by temperature-dependent Rs and Rd on noise performance of AlGaN/GaN HEMT. Based on these studies, a noise model up to 35GHz is established. An improved PRC model is proposed and the noise parameters NFmin, Rn and Γopt in the frequency band ranging from 0.1GHz to 35GHz is investigated. The effects brought by gate leakage current have been taken into consideration. Then, noise performance under different ambient temperature has been studied based on the high frequency noise model mentioned above. The parameters in the model except the parasitic inductors and capacitors are all temperature-dependent. With the model, the effects brought by temperature-dependent Rs and Rd have been studied under four different temperatures by comparing the noise performance in two different conditions. Results show that the temperature-dependent characteristics of these two parasitic resistances will have an effect on NFmin and Rn while little effect on Γopt.