Design of a GaN-on-Si Single-Balanced Resistive Mixer for Ka-band Satcom

Design and performance of a gallium nitride (GaN)-on-Si mixer for the Ka-band satellite telecom applications are presented in this letter. GaN-on-Si offers the advantage of high-volume production even for millimeter-wave applications. A single-balanced architecture is selected as an optimum tradeoff between circuit complexity and rejection of local oscillator (LO) harmonics. An alternative circuit topology is adopted where the in-phase combiner and hybrid quadrature couplers, used to obtain the desired signal phasing at mixer output, are also employed as circuit elements to inject external bias voltages so to optimize the mixer's conversions loss (CL). The mixer features 11-dB CL, 11- and 22-dBm P1dB and IIP3 respectively, in the 26-31-GHz bandwidth when driven by a 10-dBm LO level. Monolithic microwave integrated circuit area is less than 6 mm(2).