A High-Linearity Broadband GaN-on-SiC Balanced Mixer MMIC

A broadband, high-linearity, and high-isolation balanced mixer MMIC based on the GaN/SiC process platform developed by JFS Laboratory has been successfully designed. The chip leverages the high-power and high-linearity characteristics of GaN devices, combined with a broadband dual-balanced architecture in passive circuits that integrates two broadband on-chip baluns to achieve the desired broadband performance and linearity. The first balun, operating in the frequency range of 2–18 GHz, utilizes an improved Marchand structure, achieving an insertion loss better than 6 dB, return loss better than 10 dB, phase imbalance less than 2 degrees, and amplitude imbalance of less than 1 dB. The second balun achieves a return loss better than 15 dB, insertion loss better than 7 dB, phase imbalance of less than 1.2 degrees, and amplitude imbalance of less than 1.5 dB across its operating frequency range. Based on the excellent performance of the broadband baluns and optimized layout design, the mixer chip demonstrates outstanding overall performance. Across the operating frequency range of 2–10 GHz, the chip exhibits a conversion loss of less than 10 dB, a 1 dB compression point of 25 dBm, an input third-order intercept point (IIP3) of 34 dBm, and isolation better than 50 dB. These performance metrics represent a significant improvement in linearity compared to traditional mixer circuits.