Effect of material composition on noise performance of sub-micron high electron mobility transistor

Abstract

Noise figure, reflection coefficient and normalized resistance for AlxGa1−xN/GaN based sub-micron high electron mobility transistor is analytically investigated as a function of material composition from small-signal equivalent circuit over the period of C-band to X-band. A few other significant parameters like phase of both reflection coefficient and optimum impedance, average gain are studied; and critical variations are found for optimum impedance phase profile which gives maximum magnitude at a particular frequency for different material systems. Variations of noise figure and other relevance parameters are explored for an assortment of external biasing conditions and threshold parameter, and results suggests very close agreements with experimental data and also with Pospieszalski model. Phase of optimum impedance depicts peak at a particular frequency within the choice of range, and it shifts with change of material composition. Simulated results are significant in designing HEMT based RF oscillator circuits with proper amalgamation of material composition, drain and gate voltages, leakage current and threshold voltage.