Modeling of 50-nm Metamorphic HEMTs for Cryogenic Ultra-Low-Power Operation

This paper reports on the small-signal and noise modeling of 50nm metamorphic high-electron-mobility transistors (mHEMTs) for operation with ultra-low dc-power consumption at cryogenic temperatures. The electrical properties of the HEMTs change when the bias current and voltage are reduced for lowest dc-power. A dedicated cryogenic small-signal and noise model for this bias region allows to fine tune low-noise amplifier circuits for low noise in applications that demand for lowest dc-power consumption. A widely scalable cryogenic small-signal and noise model valid at very low drain currents and voltages is proposed. The change of the intrinsic parameters at low power bias is investigated and discussed. A scalable noise model is provided giving insight into the noise properties at cryogenic ultra-low-power operation. The model is valid up to at least 50 GHz. The model is verified both at transistor level and at circuit level using cryogenic S-parameter and noise temperature measurements. To the best of the authors’ knowledge, this is the first cryogenic scalable small-signal and noise model that is valid down to dc-power levels of at least 0.05mW/mm.