Single Antenna and No Circulator Full-Duplex With 52 dB Wideband Self-Interference Suppression

Full-duplex (FD) enables high spectrum efficiency and dynamic spectrum accessing, although its application is restricted by significant self-interference. In this work, we present an integrated, single antenna, wideband FD self-interference suppression front-end solution, targeting for short-range wireless communication. Based on the characteristic of bi-directional signal transparency of N-phase passive mixer, a mixer-first active electrical balance self-interference suppression architecture is proposed. As no costly and space-consuming out-of-chip circulator is needed, compared with traditional single antenna suppression solutions, it is attractive for cost and area saving. In addition, to alleviate the multi-path effect, a two-tap baseband self-interference suppression is adopted, which also helps broaden the self-interference suppression bandwidth. The fabricated FD front-end chip, employing 180nm CMOS process, has a noise figure (NF) of 8.6dB, and at the maximum TX power, the NF is degrade by 4.9dB. Test results show the achieved self-interference suppression depth is up to 52dB over 30MHz, with a much smaller antenna interface and chip size which is 0.75 mm2, compared with other dual and signal antenna solutions. The wireless communication function of the propose FD front-end has been verified and the operation carrier frequency range is 0.4-1.2GHz.