Frequency dispersion of transconductance and output conductance in AlInN/GaN high electron mobility transistors is investigated in this paper. Broadband dispersion effects in the microwave frequency range are reported for the first time. A small-signal model is developed. Trapping effects are taken into account with parasitic electrical networks including distributed time constants. The model is compared to experimental data for several bias conditions and different types of dispersion.

The microwave noise parameters measured on AlInN/GaN HEMTs devices with different gate length values are presented in this paper. 0.15-µm HEMTs achieve a maximum current density of 700 mA/mm at V GS = 0 V and a measured extrinsic transconductance of 350 mS/mm. The current gain cutoff frequency and the maximum oscillation frequency are 40 GHz and 70 GHz, respectively. At 10 (20) GHz, the device exhibits a minimum noise figure of 0.8 dB (1.8) dB with an associated power gain of 14 (8.8) dB. Below 8 GHz, the gate leakage current and a generation-recombination noise source with a very short time constant limit the noise performance.

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From the first developments of Nitride technologies using AlGaN/GaN heterostructures for designing high power, high frequency HEMT devices, we now assist to the emergence of new declination with InAlN/GaN heterostructures. Considering the expected better interface quality of this last technology as a consequence of the better lattice match, and better electrical properties, these HEMT devices attract much interest for high frequency applications (transmitter for power, receiver for low noise and robustness versus jamming). Different InAlN/GaN technological developments have been studied considering their frequency and noise parameters for low noise amplifiers in Ka-band. The paper addresses two issues related to noise in InAlN/GaN HEMT devices; one concerns the study of the HF noise performance for different technological processes and for the optimized technology, whereas the second focuses on the gate and drain current LFN spectra of competing technological versions featuring good HF dynamic and noise performance.