An Ultra-compact Fully Integrated Circulator in 28 nm CMOS IC Technology

We demonstrated a non-magnetic non-reciprocal circulator in CMOS integrated circuit (IC) technology using a four-path band-pass filter (BPF)-based staggered commutation network, which can break Lorentz reciprocity and replace a ferrite-based circulator used for decades in the history of wireless communication. The circulator IC was implemented in Samsung 28 nm RF CMOS process. The small-signal measurements among three ports showed the minimum insertion loss of 4.5-5.5 dB, and the maximum isolation of 35.7-44.8 dB in the frequency of 2.39-2.4 GHz. The measured maximum IP1dB and minimum noise-figure were 18.5 dBm and 5.8 dB, respectively. The circulator IC consumes 21.6 mW, and the size of the chip without pads is 0.93 mm².