InAs/AlSb HEMTs for cryogenic LNAs at ultra-low power dissipation

Properties of the InAs/AlSb high electron mobility transistor, essential for the design of a cryogenic low-noise amplifier (LNA) operating at low power dissipation, have been studied. Upon cooling from 300 K to 77 K, the dc transconductance g_m was enhanced by 30% at a drain-source voltage V_DS of 0.1 V. The gate current leakage showed a strong reduction of the Schottky current component at 77 K. Compared to 300 K, the cut-off frequency f_T and maximum oscillation frequency f_max showed a significant improvement at 77 K with a peak f_T (f_max) of 167 (142) GHz at V_DS = 0.2 V. The suitability of the Sb HEMT for a cryogenic LNA design up to 50 GHz, operating at low dc power dissipation, was investigated through the extraction of the NF_tot,min figure of merit. It was found that the best device performance in terms of noise and gain is achieved at a low V_DS of 0.16 V resulting in a minimum NF_tot,min of 0.6 dB for a frequency of 10 GHz when operating at 77 K. A benchmarking between the Sb HEMT and an InP HEMT has been conducted highlighting the device improvement in noise and gain required to reach today’s state-of-the-art cryogenic LNAs.