Characterization and Modeling of Cryogenic Ultralow-Noise InP HEMTs

Journal article, 2013

Detailed S-parameter and noise characterization and modeling of ultralow-noise InP/InAlAs/InGaAs high-electron mobility transistors (InP HEMTs) optimized for operation at 10 K are presented. At the optimum low-noise bias at 10 K, the InP HEMT exhibited a 60% improvement in cutoff frequency f(T) and a 100% improvement in dc transconductance g(m) compared with 300 K. A small-signal noise model was evaluated at different bias conditions at 10 and 300 K. The bias dependence of the minimum noise temperature at low-noise operation was modeled at 10 K. The temperature dependence of the threshold voltage V-T,V- gm, and gate-source and gate-drain capacitances C-gs and C-gd indicated that the excellent cryogenic noise performance of optimized InP HEMTs is due to a higher degree of confinement in the carrier concentration closest to the gate at 10 K compared with 300 K. As a result, a fast depletion of the HEMT channel with respect to drain current I-d occurs under cryogenic operation.