Integrated Self-Interference Suppression for Single Antenna Full-Duplex without Circulator

Full-duplex (FD) enables high spectrum efficiency and dynamic spectrum accessing, although its extensive application is restricted by significant self-interference (SI). In this work, we present a highly integrated, single antenna wideband FD SI suppression 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 FD SI suppression architecture is proposed. As no costly and space-consuming circulator or duplexer is needed compared with traditional single antenna SI suppression solutions, this work is attractive for cost and area saving. In addition, to alleviate the multi-path SI effect, a two-tap baseband SI suppression is adopted, which also helps broaden the SI suppression bandwidth. The fabricated FD SI suppression RF front-end chip shows a satisfactory SI suppression depth up to 52dB over 30MHz, with a 0.4-1.2GHz operation carrier frequency range.