A temperature-dependent nonlinear analysis of GaN/AlGaN HEMTs using Volterra series

Gain and intermodulation distortion of an AlGaN/GaN device operating at RF have been analyzed using a general Volterra series representation. The circ uit model to represent the GaN FET is obtained from a physics-based analysi s. Theoretical current-voltage characteristics are in excellent agreement w ith the experimental data. For a 1 mum x 500 mum Al0.15Ga0.85N/GaN FET, the calculated output power, power-added efficiency, and gain are 25 dBm, 13%, and 10.1 dB, respectively, at 15-dBm input power, and are in excellent agr eement with experimental data. The output referred third-order intercept po int (OIP3) is 39.9 dBm at 350 K and 33 dBm at 650 K. These are in agreement with the simulated results from Cadence, which are 39.34 and 35.7 dBm, res pectively. At 3 GHz, third-order intermodulation distortion IM3 for 10-dBm output power is -72 dB at 300 K and -56 dB at 600 K. At 300 K, IM3 is -66 d B at 5 GHz and -57 dB at 10 GHz. For the same frequencies, IM3 increases to -49.3 and -40 dB, respectively, at 600 K.