A 1.5–9.6 GHz Monolithic Active Quasi-Circulator in 0.18 $\mu{\rm m}$ CMOS Technology

An active quasi-circulator MMIC was designed and fabricated in a standard 0.18-mum CMOS technology. The quasi-circulator combines common-source, common-gate, and common-drain configurations to improve the isolation between ports, and has an insertion loss less than 6 dB and an isolation better than 18 dB over 1.5-9.6 GHz.