Wideband distributed amplifiers in a hybrid microstrip-environment using 0.1 µm (Al,Ga)N/GaN HEMTs grown on Silicon

Two hybrid broadband distributed amplifiers were designed and fabricated in microstrip using deep-submicron AlGaN/GaN HEMTs grown on silicon. One design is optimized for high gain and achieves a measured S21 of 10 dB in the band of 0-17 GHz. The second is optimized for bandwidth and yields a measured S21 of 8 dB in the band of 0-22 GHz. To the best of our knowledge, such performances are unprecedented in GaN hybrid distributed amplifiers implemented in a hybrid microstrip environment. Both amplifiers consist of four transistors with 0.1 mum gate footprints and 1 mum source-drain spacing, and exhibit 1 dB compression output power levels of 20 dBm, third order intercept points >31 dBm and power added efficiencies of ~12 %. The hybrid/microstrip architecture imposes constraints associated with dimensional/impedance control tolerances and parasitic bond wire inductances but careful characterization of bond wires in the design process enable amplifier performances rivaling those of certain MMICs in the same frequency bands.