A Dual Interference-Canceling Active Quasi-Circulator Achieving 36-dB Isolation Over 6-GHz Bandwidth

Abstract

Circulator is a key component in full-duplex wireless and radar detection systems. In this letter, a dual interference-canceling active quasi-circulator is proposed to enhance the isolation capability over the range of 1-7 GHz. The circulator is fabricated in the standard 0.18-μm CMOS process occupying 1.03 mm × 0.55 mm including the pads. Measurement results demonstrate more than 36-dB isolation from the Tx to the Rx within 6-GHz bandwidth. The designed circulator is a good candidate for duplexers to allow the integrated transmitter and receiver to share a single antenna in the certain shortrange wideband wireless communication systems, where noise figure (NF) is not strictly demanded but low cost and high integration are urgently required.