Abstract

GaN-based HEMT Microwave Monolithic Integrated Circuit (MMIC) attenuators were realized for the first time. The MMICs employed AlGaN/GaN HEMTs fabricated by optical contact lithography (Lg=1µm) with high current gain (fT) and maximum power gain (fMAX) cutoff frequencies of 17 and 24GHz, respectively. The MMIC attenuators employing three 100µm-wide AlGaN/GaN HEMTs in π -configuration had minimum insertion of 4dB, high dynamic range (>30dB), and broadband operation (up to 18GHz). On-wafer power characterization at 8GHz confirmed successful operation of the GaN-based attenuator MMICs at power density exceeding 15W/mm.