An improved empirical large signal model for 0.1 µm AlGaN/GaN high electron mobility transistor (HEMT) process is proposed in this paper. The short channel effect including the drain induced barrier lowering (DIBL) effect and channel length modulation has been considered for the accurate description of DC characteristics. In-house AlGaN/GaN HEMTs with a gate-length of 0.1 μm and different dimensions have been employed to validate the accuracy of the large signal model. Good agreement has been achieved between the simulated and measured S parameters, I-V characteristics and large signal performance at 28 GHz. Furthermore, a monolithic microwave integrated circuit (MMIC) power amplifier from 92 GHz to 96 GHz has been designed for validation of the proposed model. Results show that the improved large signal model can be used up to W band.

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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 R s and R d 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 NF min , R n and opt 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 R s and R d 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 NF min and R n while little effect on opt . © The Author Nowadays, the wide bandgap semiconductor device-AlGaN/GaN high electron mobility transistors (HEMTs) have become popular in radar and wireless communication applications. Their advantages including higher output power, efficiency and operating frequency over other devices and their ability in terms of operating in extreme environment have drawn lots of attentions.1 Besides, they are also excellent candidates for the design of low noise amplifier in the perspective of low noise amplifier-power amplifier (LNA-PA). Recently, low noise amplifier based on AlGaN/GaN HEMTs which can provide 18.22dB gain at 2.6GHz while the noise figure is only 0.34dB has been reported.2 Also, LNA design in millimeter wave frequency band will become a focus issue in the age of 5G communication. 3Normal LNA design is based on massive noise measurement which will induce a lot of cost and longer design period. Under this situation, it's essential to establish noise models to reduce the cost and enhance the efficiency of LNA design. Several work has been done in the past few decades revolving around noise modeling. Besides the conventional noise model such as Pucel's model, 4 Pospieszalski model 5 and Fukui model, 6 many other novel modeling techniques including physical base noise models 7 have sprung up. However, the frequency band of model cannot reach up to millimeter wave in most cases. [8][9][10][11][12] Under this circumstance, many noise characteristics in high frequency band especially in millimeter wave can't be investigated.Apart from the modeling technique itself, several novel characteristics especially the gate leakage current effect and the electro-thermal characteristics in noise performance have drawn lots of attention. The gate leakage current is one of the hot topics as a result of its great effect on output characteristics of transistors. 13 In Ref. ...

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The effect brought by the I–V kink effect on large signal performance of AlGaN/GaN high electron mobility transistors (HEMTs) was investigated in this paper. An improved compact model was proposed to accurately characterize the I–V kink effect. The bias dependence of the I–V kink effect has also been taken into consideration. AlGaN/GaN HEMTs with different gate width were utilized to validate the proposed model. Built on the proposed model, the effect brought by the I–V kink effect on large signal performance has been studied. Results show that the I–V kink effect will lead to the degradation of characteristics, including output power, gain, and power-added efficiency at the saturation region. Furthermore, the influence of the I–V kink effect was found to be related with the input power and the static bias point in this work. The time domain waveform and AC dynamic load line were used for validation of results based on simulation. The consequences of this paper will be useful for the optimization of practical circuit design.