One-Way Ramp to a Two-Way Highway: Integrated Nonreciprocal Antenna Interfaces for Single- and Multi-Antenna Full-Duplex Wireless
Full-duplex wireless is an exciting emergent wireless paradigm where the transmitter and the receiver operate at the same time and at the same frequency, thus promising to double network capacity at once at the physical layer. An important challenge for full-duplex radios is the antenna interface. Circulators enable a shared antenna between the transmitter and the receiver, but are typically implemented using ferrite materials, which cannot be integrated in a semiconductor chip, and are therefore, bulky and expensive. This talk will cover recent research at Columbia University on CMOS-integrated nonreciprocal circulators based on time-modulation. Over the past three years, this idea has evolved from an intriguing new physical concept to an approach that enables compact, power-efficient CMOS circulators with performance that is relevant for commercial and DoD applications alike.