A Highly-integrated Non-magnetic Passive Circulator Based on Rotary Traveling-wave Oscillator and Spatio-temporal Conductivity Modulation in 130 nm CMOS

A fully-integrated non-magnetic passive circulator for full-duplex wireless communication application is presented in this letter. The proposed design is based on spatio-temporal conductivity modulation to achieve non-reciprocity. This circulator also utilizes on-chip quadrature clock signals generated by a rotary traveling-wave oscillator, so it is featured with low-cost and highly integrated. Implemented 130 nm CMOS standard process, the 9 GHz Circulator achieves antenna (ANT) -to-receiver (RX) and transmitter (TX)-to-ANT insertion losses of -3.9 dB and -2.5 dB, respectively, with TX-to-RX isolation of 13.4-18.1 dB. This chip occupies a core area of 1.68 mm ² , while the core power consumption is 38.6 mW with a supply of 1.2 V.