Fig. 3: RF characteristics of membrane AlGaN/GaN HEMTs and fMIC amplifier design.
From: Heterogeneously integrated flexible microwave amplifiers on a cellulose nanofibril substrate
a–c Cross-sectional schematic views of AlGaN/GaN HEMTs on Si (a), SU8/CNF (b), and PI/SU8/CNF (c) substrates. The magnified views in a–c show schematic views of the HEMTs’ active regions on different substrates. d–f Plots of measured values of current gain (|H21|2), Mason’s unilateral power gain (U), and maximum available gain/maximum stable gain (MAG/MSG) as a function of frequency of HEMTs on Si (d), SU8/CNF (e), and PI/SU8/CNF (f) substrates. g Plots of measured MAG/MSG values of HEMT on PI/SU8/CNF substrate as a function of frequency under flat and two bending radii: 38.5 mm and 28.5 mm). The inset is a detailed view of the MAG/MSG curves from 5 GHz to 6 GHz. h Layout of simulated fMIC amplifier. The amplifier simulations were performed by combining electromagnetic simulations of passive components with measured S-parameters of HEMT on PI/SU8/CNF substrate. i Simulated small-signal gain curve of the amplifier as a function of frequency.
