New small-signal modelling method for W-band MHEMT-based amplifier design

An efficient and practical technique for the small-signal modelling of the GaAs-based 0.1-µm metamorphic high electron mobility transistors (MHEMTs) is proposed and applied to realize the W-band (75 ∲ 110 GHz) millimeter-wave monolithic integrated circuit (MMIC) amplifiers. The modelling technique adopts the gradient optimizer with the initial values of parameter set, which are determined from the measurements under the cold FET condition avoiding the forward gate-biasing, to improve the modelling accuracy at W-band frequencies. MMIC amplifiers designed and fabricated based on the proposed small-signal modelling method show the gain of ∲10 dB at 94 GHz, and the measurements show an excellent agreement with simulation data in our design frequency range.