On-chip 100GHz full-duplex circulator/duplexer design based on nonreciprocal transmission line

Abstract

CMOS circulators/duplexers based on nonreciprocal transmission line (TL) are proposed for full-duplex transceiver front ends operating at 100 GHz band. Offering nonreciprocal propagation at millimeter wave regime, the presented nonreciprocal TL is made of two parametric mixing stages modulated by signals at around 1/6 of the RF frequencies. Operating together with integrated hybrid couplers, circulators or duplexers can be implemented for full-duplex communication. Realized in CMOS process, this nonreciprocal TL achieves over 45 dB isolation throughout its isolation bandwidth of 1.5 GHz, a maximum 9.5 dB insertion loss (IL) and an over 10 dB return loss.