A double-balanced down converter mixer in GaN-on-Si HEMT technology

A 2–5 GHz MMIC double-balanced Gilbert mixer (DBGM) with a lumped-elements LO balun and IF buffer has been designed, fabricated in GaN-on-Si HEMT MMIC technology and characterized with on-board measurements. This proposed mixer uses on-chip capacitively coupled resonating elements to isolate the dc currents of RF and LO route, which could help to realize low voltage and improve the noise figure (NF). Compared with other conventional baluns, the proposed lumped-element passive LO input balun can reduce chip size. The mixer demonstrates a 3 dB IF bandwidth from DC to 0.5 GHz and the maximum conversion gain (CG) of 9.3 dB at RF input of 3.5 GHz.