Broadband AlGaN/GaN HEMT MMIC Attenuators with High Dynamic Range

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 (L_g=1μm) with high current gain (ƒT) and maximum power gain (ƒMAX) 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.