A 30 GHz Active Quasi-Circulator With Current-Reuse Technique in $0.18~\mu{\rm m}$ CMOS Technology

An active quasi-circulator at 30 GHz is designed and fabricated in TSMC RF mixed signal CMOS technology. The current-reuse technique is integrated with a common-source stage to form the quasi-circulator core while reducing the power consumption at the same time. The transmitter-to-receiver leakage is alleviated by the out-of-phase cancellation of signals from two paths. The isolation and insertion loss between other pairs of ports are improved with buffer stages. All the measured isolations are higher than 12 dB, all the insertion losses are lower than 7.9 dB, and the total power consumption is 15 mW.