Temperature-Dependent DC and Small-Signal Analysis of AlGaAs/InGaAs pHEMT for High-Frequency Applications

Temperature-dependent dc and small-signal analysis have been carried out on0.5~μ m \,\, × \,\, 200-μ mAlGaAs/InGaAs pseudomorphic high-electron mobility transistor over the temperature range from −40 °C to 150 °C by on-wafer S-parameter measurements up to 50 GHz. The thermal behavior of dc and equivalent circuit parameters along with their temperature coefficients was analyzed and reported for the first time using the same device. Most of these parameters show a negative trend with temperature, such as drain–source output currentIds, extrinsic transconductancegₘ, effective electron velocityveff, threshold voltageVT, Schottky barrier heightφ b, gate–drain capacitanceCgd, drain–source capacitanceCds, intrinsic transconductancegₘₒ, cutoff frequencyfₜ, and maximum frequencyfₘₐₓ. On the other hand, Two-dimensional electron gas sheet carrier densitynₛ, ON-resistanceRON, series resistanceRₛₑᵣᵢₑₛ, terminal resistances (Rg,Rₛ, andRd), output resistanceRds, input resistanceRᵢ, gate–source capacitanceCgs, and intrinsic delay timeτshow a positive trend with temperature. The results provide some valuable insights for future design optimizations of advanced GaAs-based Monolithic microwave integrated circuits.